LIGHT EARTHQUAKE SHAKES LOS ANGELES, CALIFORNIA

 

EARTHQUAKE SUMMARY FOR OCTOBER 24, 2021

 

A light earthquake of M 3.6 was widely felt in eastern Los Angeles, California today. More than 3000 felt reports were processed by NEIC. These indicated maximum intensity IV in Los Angeles, Huntington Park and Maywood. It may have been felt lightly as far as central California and Las Vegas, Nevada. The only earthquakes in the past year within about 50 km of today's epicenter with M>=3.6 occurred on September 18, 2021 (M 4.3) and on April 5, 2021 with M 4.0. Forecasts 13740 and 138203 had expected this activity within about 25 km  was likely between October 17 and 25 with the current full moon.

 

O: 24OCT2021 14:11:10  34.0N  118.2W Ml=2.0  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 24OCT2021 14:01:01  34.0N  118.1W Mw=3.6  EMSC   GREATER LOS ANGELES AREA, CALI

P: 17OCT2021 137940    34.2N  117.8W 2.5-4.4 CAAAA  So. California             

P: 25OCT2021 138203    33.7N  117.5W 2.5-4.5 AAAAA  So. California              

 

An earthquake of M 2.7 was felt today in eastern Tennessee and North Carolina. This event was reported by NEIC to have been felt with maximum intensity IV in Tallassee, Tennessee and Sugar Grove, North Carolina and II-III in Tennessee at Vonore, Maryville, Tellico Plains, Powell, and in North Carolina at Bryson City,   Three similar earthquakes of M 2.7-2.8 hit within about 100 km of this  epicenter in the past year - on August 30, May 26 and February 12, 2021.  Forecast 138183 had expected today's event within about 50 km of this  epicenter was likely in late October.

 

O: 24OCT2021 17:55:10  35.5N   84.0W mb=2.7  EMSC   EASTERN TENNESSEE            

P: 24OCT2021 138183    35.9N   82.8W 2.0-4.1 AAAAA  Kentucky/Tennessee/NC      

P: 31OCT2021 138183    35.0N   84.0W 2.0-3.9 CAAAA  Kentucky/Tennessee/NC      

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 off the coast of Oregon. NEIC reported it was lightly felt along the coast of Oregon and Washington with I-III in Oregon at Bandon, Port Orford, Junction City, Creswell, Cloverdale, Portland, and in Tacoma and North Bend, Washington. This is the strongest earthquake off the coast of Oregon since two of M 5.9 on June 4, 2021. Forecast 138244 had expected today's event was likely within  about 10 km of this epicenter around October 23. This epicenter is at the seventh node (51 degrees) from the epicenter in Haiti where an M 7.2 did  considerable damage on August 14 and was probably promoted by energy from that source. The eruption of Cumbre Viejo in the Canary Islands is at this same distance from Haiti.

 

O: 24OCT2021 12:11:40  43.2N  126.5W mb=4.5  EMSC   OFF COAST OF OREGON          

O: 24OCT2021 12:11:40  43.2N  126.5W mb=4.7  ANSS   OFF COAST OF OREGON          

P: 23OCT2021 138244    43.1N  126.5W 3.0-4.4 AAAAA  Off Coast of Oregon        

 

A series of light to moderate earthquake hit the region of Mexico from Oaxaca to Guerrero west to Colima and Michoacan States with M 3.8-4.4. These may be a reaction to stresses associated with the imminent landfall of Hurricane Ray as noted in this and previous issues of this summary:

 

A series of moderate earthquake hit the region of Mexico from Oaxaca to Guerrero west to Colima and Michoacan States with M 3.8-4.4. These may be a reaction to stresses associated with the imminent landfall of Hurricane Rick as noted in this and previous issues of this summary:

 

"Hurricane Rick formed south of Guerrero, Mexico today with winds up to 105 kts. It is expected to make landfall in Guerrero near Zihuatanejo and Acapulco, Mexico. Enhanced seismicity is likely in the region of central and western coastal Mexico while this storm is in the area." (October 23-24, 2021)

 

O: 24OCT2021 14:41:01  16.1N   97.9W mb=4.4  EMSC   OAXACA, MEXICO               

P: 22OCT2021 138137    18.0N   97.0W 3.5-5.5 ABAAA  Oaxaca, Mexico             

 

O: 24OCT2021 15:20:34  16.4N  100.2W ML=3.9  EMSC   OFFSHORE GUERRERO, MEXICO    

P: 20OCT2021 137871    16.0N  100.0W 3.5-5.3 BAAAA  Oaxaca, Mexico             

 

O: 24OCT2021 19:13:01  19.1N  103.9W ML=3.8  EMSC   COLIMA, MEXICO               

P: 24OCT2021 138133    18.0N  103.0W 3.5-5.3 AAAAA  Michoacan, Mexico          

 

O: 24OCT2021 16:59:10  19.4N  102.1W ML=3.8  EMSC   MICHOACAN, MEXICO            

P: 24OCT2021 138133    18.0N  103.0W 3.5-5.3 ABAAA  Michoacan, Mexico          

 

The most unusual earthquake of the day was an M 5.0 in Ethiopia. This area has seen several minor earthquakes in the past 10 days with an M 4.5 on October 15 and an M 4.3 on October 17. This follows a long period of quiet in the seismicity of Ethiopia. Only on such event of M>=5 in Ethiopia has occurred in the past 10 years - an M 5.2 on March 24, 2018. The last active period of seismicity occurred in the summer of 2011 and included quakes of 5.7, 5.4 and 5.6 among others. Still today's event is at an unusual epicenter. The only event in the past 30 years within about 200 km of today's epicenter of M>=5 was an M 5.0 on February 26, 2007. Forecast 138126 had expected enhanced seismicity in Ethiopia was likely around October 23.

 

O: 24OCT2021 14:26:20  10.2N   41.3E ML=5.0  EMSC   ETHIOPIA                     

P: 23OCT2021 138126    13.0N   41.0E 3.5-5.3 ACAAA  Ethiopia                   

 

An unusually large M 4.4 shook the region of west-central India in Maharashtra today. The last earthquake within about 200 km of this epicenter with M>=4.7  occurred on April 14, 2012 with M 4.4 but the last of larger magnitude was an M 5.1

 - 12 years ago on December 12, 2009.  Forecast 138147 had expected regional seismic enhancement was likely around October 23. This epicenter is located at 145 degrees from the M 7.0 in Mexico of September 8 and may have been promoted by energy from that source.

 

O: 24OCT2021 11:37:07  17.2N   73.6E ML=4.4  EMSC   MAHARASHTRA, INDIA           

P: 23OCT2021 138147    23.0N   70.0E 3.5-4.9 ACCAA  India                      

 

STRONG EARTHQUAKE SHAKES NORTHERN TAIWAN

 

EARTHQUAKE SUMMARY FOR OCTOBER 23, 2021

 

A strong earthquake of M 6.2-6.5 was widely felt in northern Taiwan today. NEIC reported maximum intensity shaking of VII in Ilan, Taiwan; V in Taipei, Keelung Counties. CWB reported intensity IV in Yilan, Hualien, Taipei, Taoyuan, Taipei, Taichung, Nantou, Hsinchu, Keelung, Miaoli, Changhua, III in Yunlin, Taitung, Chiayi, Kaohsiung, and II in Tainan, Pingtung, Penghu and Lienchiang Counties, Taiwan. There were no immediate reports of damage or injuries associated with this earthquake. An aftershock of M 5.4 was recorded about a minute after the mainshock. A foreshock of M 5.3 hit the region yesterday and was reported in this summary as:

 

 

"A moderate earthquake of M 5.1-5.3 was also widely felt in Taiwan today.  NEIC reported this earthquake of M 5.1 in Taiwan was felt with intensity II-III in the area(s) of Taiwan in Ilan, Taichung, Taipei, Tainan, and IV in Hualien, and Nantou. CWB reported this earthquake was felt with intensity IV in Hualien, III in Yilan, Nantou, Taichung; II in Hsinchu, Yunlin, Chiayi, I in Taoyuan, Taipei, Taitung, Changhua and Tainan Counties, Taiwan. This earthquake, like that in Micronesia was likely triggered by high tidal stresses associated with the full moon. It occurred within about one hour of local solar noon, a time when tidal stresses maximize. Further seismic enhancement is likely in Taiwan in the next several days. Forecast 138157 had expected this event within about 100 km was likely around October 25." (October 22-23, 2021)

 

The mainshock today occurred near local solar noon and was probably promoted by high tidal stresses which maximize near this hour. It also occurred near the longitude of maximum tidal stress with the full moon as noted in previous issues of this summary:

 

"The full moon arrived on October 20 at 14:57 UT. Longitudes which were sub-solar (local solar noon) at this time are near 45 West while those which are anti-solar (local solar mid-night) are near 135 East. In the west these include areas of the northern Mid-Atlantic and the Caribbean while in the east most of the subduction zone from eastern Indonesia north to Japan and the Kuril Islands are included. These are the longitudes where enhanced seismicity with this full moon are most likely. A geomagnetic storm is likely to favor seismicity in the region of Indonesia and at higher latitudes with major events most likely around local solar noon and midnight. The likelihood of a major earthquake in the next week (October 18-24, 2021), as estimated by this summary, is moderate." (October 20-23, 2021)

 

NEIC data suggests this is the strongest earthquake in the region of Taiwan in the past three years - since an M 6.4 on February 6, 2018. The last earthquake listed in NEIC data with M>=6.5 was an M 6.5 on April 26, 2010.  This epicenter is at the third node (120 degrees) from the M 7.1 in Mexico of September 8, 2021 and may have been promoted by energy from that source. Forecasts 138157 and 139158 had expected today's activity within about 100 km was likely around October 24-28.

 

O: 23OCT2021 10:32:38  24.1N  121.7E ML=4.5  EMSC   TAIWAN

O: 24OCT2021 04:38:52  24.1N  121.6E ML=4.5  EMSC   TAIWAN

O: 24OCT2021 05:12:42  24.6N  121.7E ML=5.4  EMSC   TAIWAN

O: 23OCT2021 03:16:03  24.1N  121.8E mb=5.1  EMSC   TAIWAN                       

O: 23OCT2021 03:16:04  24.1N  121.7E ML=5.3  TAI    Hualien, Taiwan              

O: 24OCT2021 05:11:34  24.5N  121.9E Mw=6.2  EMSC   TAIWAN                       

O: 24OCT2021 05:11:34  24.5N  121.7E ML=6.5  TAI    Hualien, Taiwan              

P: 28OCT2021 138158    24.0N  123.0E 4.0-5.5 BAAAA  Taiwan                     

P: 24OCT2021 138158    24.0N  124.0E 4.0-5.4 AABAA  Taiwan                     

P: 25OCT2021 138157    23.0N  122.0E 4.0-5.4 ABAAA  Taiwan                     

 

The strong eruption of Cumbre Viejo, La Palma, Canary Islands continued today. More than  2100 structures have been destroyed in the current eruption which has also displaced nearly 8000 residents. To this point no one has died due to the eruption. This eruption has seen earthquakes of increasing magnitude over the course of the eruption which began in mid-September. An earthquake of M 4.7 in the region today was the largest in the area within about 100 km of La Palma in at least 30 years. More recently an M 4.8 occurred about 250 km to the southwest of this on September 26, 2019 and about 150 km southwest of today's epicenter on December 27, 2013. Forecast 138144 had expected today's activity was likely within about 50 km around October 23.

 

O: 23OCT2021 07:28:25  28.7N   17.8W ML=4.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 23OCT2021 15:34:47  28.6N   17.8W ML=4.7  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 23OCT2021 138144    28.0N   18.0W 3.5-4.9 AAAAA  Canary Islands              

 

UNUSUAL QUAKE IN MICRONESIA LIKELY TIDALLY TRIGGERED

 

EARTHQUAKE SUMMARY FOR OCTOBER 22, 2021

 

 

An unusual earthquake of M 5.4 in Micronesia was the largest earthquake in the world today. NEIC reported light intensity in Micronesia at Polowat and Chuuk.

The last earthquake within about 400 km of this epicenter of M>=5.4 was an M 5.6 on November 11, 2015 but no such earthquakes have hit within about 200 km in at least 30 years. This epicenter is located near the longitude of maximum tidal stress with the recent full moon as noted in previous issues of this summary:

 

"The full moon arrived on October 20 at 14:57 UT. Longitudes which were sub-solar (local solar noon) at this time are near 45 West while those which are anti-solar (local solar mid-night) are near 135 East. In the west these include areas of the northern Mid-Atlantic and the Caribbean while in the east most of the subduction zone from eastern Indonesia north to Japan and the Kuril Islands are included. These are the longitudes where enhanced seismicity with this full moon are most likely. A geomagnetic storm is likely to favor seismicity in the region of Indonesia and at higher latitudes with major events most likely around local solar noon and midnight. The likelihood of a major earthquake in the next week (October 18-24, 2021), as estimated by this summary, is moderate." (October 20-23, 2021)

 

O: 22OCT2021 07:27:53   4.4N  147.2E Mw=5.4  EMSC   FED. STATES OF MICRONESIA REGI

 

A moderate earthquake of M 5.1-5.3 was also widely felt in Taiwan today.

NEIC reported this earthquake of M 5.1 in Taiwan was felt with intensity II-III in the area(s) of Taiwan in Ilan, Taichung, Taipei, Tainan, and IV in Hualien, and Nantou. CWB reported this earthquake was felt with intensity IV in Hualien, III in Yilan, Nantou, Taichung; II in Hsinchu, Yunlin, Chiayi, I in Taoyuan, Taipei, Taitung, Changhua and Tainan Counties, Taiwan. This earthquake, like that in Micronesia was likely triggered by high tidal stresses associated with the full moon. It occurred within about one hour of local solar noon, a time when tidal stresses maximize. Further seismic enhancement is likely in Taiwan in the next several days. Forecast 138157 had expected this event within about 100 km was likely around October 25.

 

O: 23OCT2021 03:16:03  24.1N  121.8E mb=5.1  EMSC   TAIWAN                       

O: 23OCT2021 03:16:04  24.1N  121.7E ML=5.3  TAI    Hualien, Taiwan              

P: 25OCT2021 138157    23.0N  122.0E 4.0-5.4 AAAAA  Taiwan                     

 

The strongest earthquake in the U.S. or Canada today was an M 5.1 in the Rat Islands, Aleutians, Alaska. NEIC reported it was felt with intensity II in Adak, Alaska. The last earthquake in the Rat Islands within about 150 km of this epicenter occurred on July 11, 2021 with M 5.3 and 5.1. The only other such event in the Rat Islands in the past two years occurred on May 17, 2021 with M 5.4. Forecast 138274 had expected today's event with in about 50 km was likely around October 27.

 

O: 23OCT2021 03:10:03  51.6N  178.8E mb=5.1  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 27OCT2021 138274    51.0N  179.0E 4.0-5.6 BAAAA  Rat Islands                

 

The strongest earthquake felt outside Alaska in the U.S. today was an M 3.5-3.7 off the coast of Baja California. NEIC reported this earthquake of M 3.6 off the coast of Baja California  was felt with intensity II-III in the area(s) of California in Imperial Beach, Coronado, San Diego, La Mesa, La Jolla. This is the strongest earthquake within about 100 km of this epicenter since an M 4.2 more than two years ago on June 5, 2019. Forecast 138202 had expected this activity was likely within about 50 km around October 25. 

 

O: 23OCT2021 02:56:32  31.9N  117.9W ML=3.5  EMSC   OFFSHORE BAJA CALIFORNIA, MEXI

O: 23OCT2021 02:56:32  31.9N  117.9W ML=3.7  ANSS   OFFSHORE BAJA CALIFORNIA, MEXI

P: 25OCT2021 138202    32.0N  117.4W 2.5-4.8 AAAAA  So. California             

 

MODERATE QUAKE SHAKES NORTH ISLAND, NEW ZEALAND

 

EARTHQUAKE SUMMARY FOR OCTOBER 21, 2021

 

The strongest earthquake felt in the world today was an M 5.6-5.9 under North Island, New Zealand. NEIC reported it was felt with intensity IV in North Island at Taumaraunui, Manawatu-Wanganui, Taupo, Wakato, Palmerston North, and II-III in Ohura, Te Kuiti, Wanganui, Tokoroa, Hastings, Kapiti, Wellington and Pukekohe. GEONET reported this earthquake was felt with moderate intensity east of Stratford and in southwestern North Island and northern South Island. Light to moderate intensity was reported throughout much of southern North Island and northern South Island. More than 24738 people reported feeling this earthquake with 9670 reporting weak shaking; 11956 light; 2824 moderate and 243 strong intensity; 21 severe and 24 extreme shaking. The last earthquake under North Island with M>=5.9 within about 200 km of today's epicenter occurred on October 30, 2018 with M 6.1 and prior to that on December 7, 2012 with M 6.3. Forecast 138074 had expected today's activity within about 15 km of the epicenter was likely in mid-October.

 

O: 21OCT2021 21:58:19  39.0S  174.9E MS=5.9  GEONET North Island, New Zealand                      

O: 21OCT2021 21:58:18  39.1S  175.0E Mw=5.6  EMSC   NORTH ISLAND OF NEW ZEALAND  

P: 16OCT2021 138074    39.0S  175.0E 3.0-4.4 BAAAA  North Island, N.Z.         

 

A series of moderate earthquakes continued today in the eruption of Cumbre Viejo, La Palma, Canary Islands and in the aftershock zone in Crete, Greece. The activity in the Canary Islands accompanied a major continuing eruption of the volcano with which shut down air traffic today amid continuing ash and lava flows. Forecast 138144 had expected this enhanced activity around October 23.

 

O: 22OCT2021 06:54:49  28.6N   17.8W ML=4.2  EMSC   CANARY ISLANDS, SPAIN REGION 

O: 21OCT2021 22:54:03  28.6N   17.8W ML=4.4  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 23OCT2021 138144    28.0N   18.0W 3.5-4.9 AAAAA  Canary Islands             

 

Earthquakes of M 4.3 and 4.5-4.6 were widely felt in the area of Crete, Greece today. These are the strongest aftershocks to date of the M 6.4 about 100 km to the east of these epicenter of October 12, 2021. Forecasts 137906 and 138160 had expected this activity was likely within about 100 km around October 19-24. The strongest of these, the M 4.5, occurred within minutes of local solar noon, and was probably promoted by high tidal stresses which maximize near this hour. 

 

NEIC reported the earthquake of M 4.5-4.6 in Crete, Greece was felt with intensity II-III in the area(s) of Epano and Nea Alikarnassos and V in Arkalokhorion, Iraklion.

 

O: 21OCT2021 09:38:42  35.1N   25.3E ML=4.5  EMSC   CRETE, GREECE                

O: 21OCT2021 09:38:42  35.1N   25.3E ML=4.6  ANSS   CRETE, GREECE                

P: 19OCT2021 137906    34.0N   24.0E 3.0-4.7 ABAAA  Crete                      

 

O: 21OCT2021 08:12:58  35.2N   25.3E ML=4.3  EMSC   CRETE, GREECE                

P: 24OCT2021 138160    35.0N   25.0E 3.0-4.6 BAAAA  Aegean Sea                 

 

A strong earthquake also occurred as  an M 6.0 in Fiji. It was not reported felt in this remote area. The last earthquake of M>=6 in Fiji within about 150 km of this epicenter occurred on September 16, 2018 with M 6.5 abou 150 km to the southwest and an M 6.1 on June 17, 2017 about 100 km to the north. All the events in this region of magnitudes greater than 6.0 in the past 30 years have occurred at deep focal depths of 450-700 km and are unlikely to trigger tsunamis or local damage. Forecasts 138068 and 138069 had expected today's event was likely to the north around October 19.

 

O: 21OCT2021 08:10:43  25.2S  179.6E mw=6.0  ANSS   Fiji                         

O: 21OCT2021 08:10:44  25.3S  179.7E Mw=6.0  EMSC   SOUTH OF FIJI ISLANDS        

P: 19OCT2021 138068    22.0S  179.0W 4.0-5.6 ACAAA  Tonga Islands              

P: 19OCT2021 138069    23.0S  179.0E 4.0-5.4 ACAAA  Tonga/Fiji                 

 

A moderately strong earthquake also occurred as an M 5.5 in the Izu Islands, Japan. NEIC reported this earthquake was felt with maximum intensity IV in Japan in Kanagawa and II-III in Shizuoka, Tokyo, and Saitama. A moderate geomagnetic disturbance with maximum Kp 4 coincident with this and the earthquake in Tonga and may have helped trigger them. This earthquake follows the eruption of the volcano Mount Aso in southwestern Japan. This eruption blew ash up to 3500 meters and a lava flow accompanied the eruption, the first since October 2016. It also  occurred near local solar noon and was probably promoted by high tidal stresses associated with the full moon today as it was located at 138 East longitude near the longitude of maximum tidal stress with this alignment (at 135 E). This summary had noted this possibility in previous issues as:

 

"The full moon arrives on October 20 at 14:57 UT. Longitudes which are sub-solar (local solar noon) at this time are near 45 West while those which are anti-solar (local solar mid-night) are near 135 East. In the west these include areas of the northern Mid-Atlantic and the Caribbean while in the east most of the subduction zone from eastern Indonesia north to Japan and the Kuril Islands are included. These are the longitudes where enhanced seismicity with this full moon are most likely. A geomagnetic storm is likely to favor seismicity in the region of Indonesia and at higher latitudes with major events most likely around local solar noon and midnight. The likelihood of a major earthquake in the next week (October 18-24, 2021), as estimated by this summary, is moderate." (October 18-20, 2021)

 

This is the strongest earthquake within about 200 km of today's epicenter since an M 5.6 on July 6, 2020. The last of significantly larger magnitude was an M 6.3 on July 27, 2019. All of these events occurred between 325 and 500 km depth and caused little damage on the surface. Forecasts 137925 and 137904 had expected today's activity in mid-October around October 17-18. This earthquake is located at 105 degrees from the M 7.2 Guerrero Mexico quake of September 8 and may have been promoted by energy from this source.

 

O: 21OCT2021 08:36:47  32.1N  138.2E Mw=5.5  EMSC   IZU ISLANDS, JAPAN REGION    

P: 17OCT2021 137904    30.0N  139.0E 3.5-5.1 BCAAA  Central/So. Honshu Japan   

P: 18OCT2021 137925    31.0N  141.0E 4.0-5.5 BBBAA  Off East Coast Honshu      

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 South of Alaska. The last earthquake of M>=4.7 in the area south of Alaska within about 150 km of this epicenter occurred with the mainshock in the Alaska Peninsula of

M 8.2 on July 30, 2021. A strong M 6.9 aftershock about 200 km to the northwest of today's event in the Alaska Peninsula was felt in the area on October 11, 2021.  Forecast 138011 had expected today's event in this area in mid-October.

 

O: 21OCT2021 08:24:40  55.5N  154.8W mb=4.7  EMSC   SOUTH OF ALASKA              

P: 15OCT2021 138011    54.7N  155.9W 3.5-4.9 CAAAA  Alaska Peninsula           

 

MODERATE EARTHQUAKE SHAKES SOUTHEASTERN HONSHU, JAPAN

 

EARTHQUAKE SUMMARY FOR OCTOBER 20, 2021

 

The strongest earthquake in the world today was an M 6.0 in Fiji. It was not reported felt in this remote area. The last earthquake of M>=6 in Fiji within about 150 km of this epicenter occurred on September 16, 2018 with M 6.5 abou 150 km to the southwest and an M 6.1 on June 17, 2017 about 100 km to the north. All the events in this region of magnitudes greater than 6.0 in the past 30 years have occurred at deep focal depths of 450-700 km and are unlikely to trigger tsunamis or local damage. Forecasts 138068 and 138069 had expected today's event was likely to the north around October 19.

 

O: 21OCT2021 08:10:43  25.2S  179.6E mw=6.0  ANSS   Fiji                          

O: 21OCT2021 08:10:44  25.3S  179.7E Mw=6.0  EMSC   SOUTH OF FIJI ISLANDS        

P: 19OCT2021 138068    22.0S  179.0W 4.0-5.6 ACAAA  Tonga Islands              

P: 19OCT2021 138069    23.0S  179.0E 4.0-5.4 ACAAA  Tonga/Fiji                 

 

A moderately strong earthquake also occurred as an M 5.5 in the Izu Islands, Japan. NEIC reported this earthquake was felt with maximum intensity IV in Japan in Kanagawa and II-III in Shizuoka, Tokyo, and Saitama. A moderate geomagnetic disturbance with maximum Kp 4 coincident with this and the earthquake in Tonga and may have helped trigger them. This earthquake follows the eruption of the volcano Mount Aso in southwestern Japan. This eruption blew ash up to 3500 meters and  a lava flow accompanied the eruption, the first since October 2016. It also  occurred near local solar noon and was probably promoted by high tidal stresses associated with the full moon today as it was located at 138 East longitude  near the longitude of maximum tidal stress with this alignment (at 135 E). This summary had noted this possibility in previous issues as:

 

"The full moon arrives on October 20 at 14:57 UT. Longitudes which are sub-solar (local solar noon) at this time are near 45 West while those which are anti-solar (local solar mid-night) are near 135 East. In the west these include areas of the northern Mid-Atlantic and the Caribbean while in the east most of the subduction zone from eastern Indonesia north to Japan and the Kuril Islands are included. These are the longitudes where enhanced seismicity with this full moon are most likely. A geomagnetic storm is likely to favor seismicity in the region of Indonesia and at higher latitudes with major events most likely around local solar noon and midnight. The likelihood of a major earthquake in the next week (October 18-24, 2021), as estimated by this summary, is moderate." (October 18-20, 2021)

 

This is the strongest earthquake within about 200 km of today's epicenter since an M 5.6 on July 6, 2020. The last of significantly larger magnitude was an M 6.3 on July 27, 2019. All of these events occurred between 325 and 500 km depth and caused little damage on the surface. Forecasts 137925 and 137904 had expected today's activity in mid-October around October 17-18. This earthquake is located at 105 degrees from the M 7.2 Guerrero Mexico quake of September 8 and may have been promoted by energy from this source.

 

O: 21OCT2021 08:36:47  32.1N  138.2E Mw=5.5  EMSC   IZU ISLANDS, JAPAN REGION    

P: 17OCT2021 137904    30.0N  139.0E 3.5-5.1 BCAAA  Central/So. Honshu Japan   

P: 18OCT2021 137925    31.0N  141.0E 4.0-5.5 BBBAA  Off East Coast Honshu      

 

A light earthquake of M 3.7 was widely felt in central California today and was followed by several lightly felt aftershocks and a foreshock. NEIC reported the mainshock was felt with intensity II-III in Central California at Gonzales, Hollister, Salinas, San Juan Bautista, Soledad, Paicines and Castroville among others. NEIC reported the aftershock of M 2.6 in Central California was felt with intensity II-III in the area(s) of Central California at Salinas, Paicines, Marina, Los Banos and Seaside. While a similar M 3.7 hit the area on October 4 with the new moon, the last earthquake of larger magnitude in the area was an M 4.1 on August 31, 2021. Today's M 3.7 occurred within minutes of local solar midnight and was probably promoted by high tidal stresses associated with today's full moon, as was the event on October 4. Forecast 137898 had expected today's event in the region was likely around October 19.

 

O: 20OCT2021 08:52:50  36.7N  121.3W ML=2.4  EMSC   CENTRAL CALIFORNIA           

O: 20OCT2021 08:57:14  36.7N  121.4W ML=3.6  EMSC   CENTRAL CALIFORNIA

O: 20OCT2021 14:07:02  36.7N  121.3W Md=2.6  EMSC   CENTRAL CALIFORNIA

P: 19OCT2021 137898    36.2N  120.8W 2.5-4.8 AAAAA  Central California         

 

An earthquake of M 4.1-4.2 in Alberta, Canada was the largest in the U.S. or Canada today. It may have been lightly felt in this remote area of the Rocky Mountains. Five earthquakes of M>=4.1 have hit within about 150 km of this epicenter in the past 30 years - all of which were M 4.1-4.4. The last of these was an M 4.4 about 150 km southwest of today's epicenter on February 14, 2021. An M 4.3 hit nearer today's epicenter on March 10, 2019. Forecast 138012 had expected today's event this area was likely around October 18.

 

O: 21OCT2021 03:23:20  52.7N  114.5W MB=4.2  ECAN OF ROCKY MOUNTAIN HOUSE, AB 

O: 21OCT2021 03:23:24  52.7N  115.0W ML=4.1  EMSC   ALBERTA, CANADA               

P: 18OCT2021 138012    52.0N  115.0W 2.0-4.2 BAAAA  Alberta                    

 

An earthquake of M 3.4 was also felt in southeastern Idaho today.  NEIC reported this earthquake of M 3.4 in Southeastern Idaho was felt with intensity II-III in the area(s) of Southeastern Idaho in Pocatello and Hayden with IV in Montpelier and in Wyoming with III in Afton, Auburn and Freedom. The last earthquake of greater or equal magnitude within about 100 km of this epicenter was an M 4.2 on January 3, 2021. Forecast 138009 had expected enhanced seismicity in this area was likely in mid-October.

 

O: 21OCT2021 02:38:50  42.5N  111.2W ML=3.4  EMSC   SOUTHERN IDAHO

O: 21OCT2021 02:25:59  42.5N  111.2W ML=2.9  EMSC   SOUTHERN IDAHO               

P: 14OCT2021 138009    43.0N  111.5W 2.0-3.9 CAAAA  Yellowstone/Wyoming        

 

A similar M 3.4 was felt in the area of south-central Idaho in the aftershock area of the M 6.1 of March 31, 2020. This is not an unusual aftershock in this long term aftershock sequence but is the largest since an M 4.0 on October 2, 2021. Forecast 137982 had expected this event was likely around October 17.  NEIC reported this earthquake of M 3.1-3.4 in Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho at Stanley and Meridian.

 

O: 20OCT2021 07:25:52  44.1N  115.1W Ml=3.4  EMSC   SOUTHERN IDAHO               

O: 20OCT2021 15:03:06  44.3N  115.2W Ml=2.0  EMSC   SOUTHERN IDAHO

P: 17OCT2021 137982    44.4N  115.1W 2.0-4.0 BAAAA  Montana/Idaho              

 

SOUTHWEST PACIFIC ACTIVE

 

EARTHQUAKE SUMMARY FOR OCTOBER 19, 2021

 

The strongest earthquake in the world today was an M 5.6 in Tonga. NEIC reported it was felt with maximum intensity V in Tonga at Haveloloto; IV in Nuku'alofa and III in Tofoa-Koloua, Tonagtapu. The last earthquake within about 200 km of this epicenter with M>=5.6 occurred as an M 5.9 on September 5, 2021 about 100 km southeast of today's epicenter. Forecast 138067 had expected this earthquake was likely around October 18. This event occurred within about an hour of local solar midnight and was probably promoted by high tidal stresses which maximize near this hour.

 

O: 19OCT2021 10:28:45  21.3S  175.8W mb=5.0  EMSC   TONGA                        

O: 19OCT2021 10:28:45  21.3S  175.8W mb=5.6  ANSS   TONGA                        

P: 18OCT2021 138067    20.0S  174.0W 4.0-5.8 ABBAA  Tonga Islands              

 

An earthquake of M 5.1 also occurred today in the Santa Cruz Islands north of

Vanuatu. It was not reported felt in this remote area. An M 5.4 hit about 100 km north of this on September 12, 2021.  NEIC reported this earthquake of M 5.1 in the Santa Cruz Islands was felt with intensity II-III in the area(s) of the Solomon Islands at Kirakira Makira and Ulawa.  Forecasts 138059 and 138052 had expected enhanced seismicity in this region was likely in mid-October.

 

O: 20OCT2021 06:38:28  11.8S  166.8E mb=5.1  EMSC   SANTA CRUZ ISLANDS           

P: 15OCT2021 138059    11.0S  165.0E 4.0-5.4 BABAA  Vanuatu Islands            

P: 19OCT2021 138052    11.0S  162.0E 4.0-5.5 AACAA  Vanuatu Islands            

 

A moderate earthquake of M 4.7-5.3 also occurred south of New Zealand in the Snares Island area today. GEONET reported this earthquake was felt by five persons, four with weak intensity and 1 with moderate shaking. The last earthquake in the Snare's Island area of New Zealand with M>=5.3 occurred on November 24, 2018 with M 5.8. A strong quake of M 6.6 occurred on July 11, 2017. Forecast 138081 had expected today's activity was likely around October 17.

 

O: 19OCT2021 21:11:17  47.1S  165.7E mb=4.7  EMSC   OFF W. COAST OF S. ISLAND, N.Z

O: 19OCT2021 21:11:22  46.8S  165.8E ML=5.3  GEONET Felt by five persons,

P: 17OCT2021 138081    45.0S  168.0E 3.0-5.1 ACBAA  So. Island, N.Z.           

 

The strongest earthquake in the U.S. or Canada today was an M 4.9 in the Rat Islands, Aleutians, Alaska. It was not reported felt in this remote area. The last earthquake within about 200 km of this epicenter in the Rat Islands with M>=4.9 occurred on July 11, 2021 with M 5.4 and 5.1. Today's earthquake occurred within about 30 minutes of local solar noon and may have been promoted by high tidal stresses which maximize near this hour. Forecast  138024 had expected today in this region was likely around October 17. 

 

O: 19OCT2021 23:30:05  50.3N  178.7E mb=4.9  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 17OCT2021 138024    52.0N  177.0E 4.0-5.8 ABAAA  Rat Islands                

 

STRONG QUAKE IN EASTERN MEDITERRANEAN

 

EARTHQUAKE SUMMARY FOR OCTOBER 18, 2021

 

The strongest earthquake in the world today was an M 5.9-6.1 in the eastern Mediterranean south of Greece. NEIC reported it was felt with maximum intensity VI in the Dodecanese Islands at Karpathos and V in Falirakion and II-III in Afantou, Koskinou, Lilisos, Kremasti, Rodoa, and in Turkey at Fethiye and Marmara. This may be a regional aftershock of an earthquake of M 6.4 which hit Crete a week ago on October 12, 2012 but is about 200 km to the southeast of that epicenter. The last earthquake of larger size in this region was an M 6.4 on July 15, 2008, the only such event in this area of larger or equal size in the past 30 years. Forecast 137906 had expected today's event was likely in this region around October 13. This epicenter is at 147 degrees from the M 7.2  in Vanuatu of October 2 and may have been promoted by energy from that source.

 

O: 19OCT2021 05:32:32  34.6N   28.3E Mw=6.0  EMSC   EASTERN MEDITERRANEAN SEA    

P: 13OCT2021 137906    34.0N   27.0E 3.0-5.6 CAAAA  Crete                      

 

The eruption of Cumbre Viejo continued today with strong lava fountains from the cone in the Canary Islands. The largest earthquake in the area today was an M 4.2. Larger earthquakes are possible with this eruption as the lava flows continue through new vents. Forecast 137880 had expected enhanced seismicity in the area in mid-October.

 

O: 19OCT2021 01:29:35  28.6N   17.9W ML=3.8  EMSC   CANARY ISLANDS, SPAIN REGION 

O: 18OCT2021 11:33:54  28.6N   17.8W ML=4.2  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 14OCT2021 137880    28.0N   18.0W 4.0-5.5 AAAAA  Canary Islands             

 

A strong earthquake of M 6.1 also occurred today in northern Vanuatu. NEIC reported it was felt with maximum intensity V in Sola Torba, Vanuatu with IV in Port Olry, Sanma and III in Luganville. This is the strongest earthquake within about 100 km of this epicenter since an M 6.1 on March 18, 2020 but the last of stronger magnitude in the region was an M 6.6 on January 15, 2019. Forecast 138059 had expected this activity in this region was likely around October 14.

 

O: 18OCT2021 07:26:52  13.7S  167.0E Mw=6.1  EMSC   VANUATU                      

P: 14OCT2021 138059    15.0S  167.0E 4.0-5.4 BBAAA  Vanuatu Islands            

 

An unusual earthquake in the Yukon Territory of Canada also occurred today with M 4.4-4.8. This is the strongest earthquake within about 200 km of this epicenter in the Northern Yukon since an M 6.0 about 100 km to the west occurred on December 22, 2017. Forecast 138044 had expected this event was likely within in this area around October 15. This epicenter is at 144 degrees from the M 8.1 in the South Sandwich Islands of August 12, 2021 and was likely promoted by energy from  that source.

 

 

O: 18OCT2021 07:35:38  65.3N  133.4W ML=4.8  EMSC   NORTHERN YUKON TERRITORY, CANADA

O: 18OCT2021 15:17:49  65.3N  133.4W ML=3.9  EMSC   NORTHERN YUKON TERRITORY, CANADA

O: 18OCT2021 15:17:49  65.2N  133.3W MB=3.9  ECAN Keno, YT    

O: 18OCT2021 07:35:38  65.3N  132.9W MB=4.4  ECAN OF ELSA, YT   

O: 18OCT2021 07:35:38  65.3N  133.4W MB=4.8  ECAN Keno, YT    

O: 18OCT2021 09:10:05  65.2N  133.6W MB=3.5  ECAN Keno, YT    

O: 18OCT2021 09:10:05  65.2N  133.6W ML=3.5  EMSC   NORTHERN YUKON TERRITORY, CANA

P: 17OCT2021 138041    66.9N  135.8W 3.0-4.6 ABAAA  Northern Alaska            

 

An M 3.4 was widely felt in central California today near Coalinga. NEIC reported intensity II-III with this quake was felt in Coalinga, Huron, Lemoore, Visalia, Clovis, Los Banos, San Juan Bautista. This area has seen four earthquakes of M>=3.4 in the past year - the largest of which was an M 3.8 on September 14, 2021. Forecast 137898 had expected today's event was likely within about 25 km of this epicenter around October 17.

 

O: 19OCT2021 06:49:25  36.0N  119.8W Md=2.3  EMSC   CENTRAL CALIFORNIA           

O: 18OCT2021 09:42:15  36.2N  120.2W ML=2.6  EMSC   CENTRAL CALIFORNIA

O: 18OCT2021 09:45:06  36.2N  120.2W ML=3.4  EMSC   CENTRAL CALIFORNIA           

P: 17OCT2021 137898    36.1N  120.1W 2.5-4.8 AAAAA  Central California         

 

 

STRONG QUAKE SHAKES VANUATU

 

EARTHQUAKE SUMMARY FOR OCTOBER 17, 2021

 

The strongest earthquake in the world today was an M 6.1 in northern Vanuatu. NEIC reported it was felt with maximum intensity V in Sola Torba, Vanuatu with IV in Port Olry, Sanma and III in Luganville. This is the strongest earthquake within about 100 km of this epicenter since an M 6.1 on March 18, 2020 but the last of stronger magnitude in the region was an M 6.6 on January 15, 2019. Forecast 138059 had expected this activity in this region was likely around October 14.

 

O: 18OCT2021 07:26:52  13.7S  167.0E Mw=6.1  EMSC   VANUATU                      

P: 14OCT2021 138059    15.0S  167.0E 4.0-5.4 BBAAA  Vanuatu Islands            

 

An M 4.4 earthquake in northern Albania today was widely felt. NEIC reported maximum shaking with intensity V in Albania at Lezhe, IV in Shkoder, and II-III in Shengjn, Ulcinj, Tirana. It was also felt lightly in Serbia and Montenegro, Croatia and Macedonia. The last earthquake of M>=4.4 within about 150 km of this epicenter in Albania was an M 4.5 on January 26, 2021 and an M 4.6 on March 22, 2021. Forecast 137998 had expected today's event was likely within about 100 km  of this epicenter around October 15.

 

O: 17OCT2021 20:13:30  41.8N   19.8E mb=4.4  EMSC   ALBANIA                      

P: 15OCT2021 137998    41.0N   20.0E 3.0-5.1 AAAAA  Romania/NW Turkey          

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 aftershock  in the Alaska Peninsula. It may have been felt lightly in the epicentral area. An M 6.9 hit the Alaska Peninsula on October 11 and was followed by an M 4.9 later in the day but this is the largest event in the Alaska Peninsula since those events. Today's M 4.7 is located about 200 km southwest of the M 6.9 on October 11 but is probably a regional aftershock. Forecast 138011 had expected this event was likely within about 50 km around October 18.

 

O: 17OCT2021 19:32:22  55.1N  157.6W ML=3.2  EMSC   ALASKA PENINSULA

O: 17OCT2021 19:27:07  55.1N  157.7W mb=4.7  EMSC   ALASKA PENINSULA             

O: 18OCT2021 01:34:47  56.3N  156.6W ml=3.0  EMSC   ALASKA PENINSULA             

P: 18OCT2021 138011    55.7N  157.9W 3.5-4.9 AAAAA  Alaska Peninsula           

 

An unusual earthquake in the Yukon Territory of Canada also occurred today with M 4.4. This is the strongest earthquake within about 200 km of this epicenter in the Northern Yukon since an M 6.0 about 100 km to the west occurred on December 22, 2017. Forecast 138044 had expected this event was likely within in this area around October 15.

 

O: 18OCT2021 07:35:38  65.3N  132.9W MB=4.4  ECAN  ELSA, YT   

O: 18OCT2021 07:35:38  65.3N  132.9W ML=4.4  EMSC   NORTHERN YUKON TERRITORY, CANA

P: 15OCT2021 138044    66.0N  130.0W 2.5-4.1 BAAAA  Yukon Territory, Canada    

 

The strongest earthquake in the U.S. or Canada outside Alaska today was an M 4.0 in the Olancha area of Central California. NEIC reported it was felt with maximum intensity IV in Lone Pine and II-III in Ridgecrest,  Independence, Lake Isabella, Exeter, Bakersfield, Dinuba, Clovis, Los Angeles and Los Banos, California. This is the strongest earthquake in this aftershock area of Ridgecrest, California since an M 4.0 on February 12 and January 17, 2021 but the last event of significantly larger magnitude in this area was an M 5.8  - the mainshock and an M 4.6 aftershock on June 24, 2020. Forecast 137894 had expected today's event within about 25 km was likely around October 15.

 

O: 17OCT2021 13:18:59  36.2N  117.9W Mw=4.0  EMSC   CENTRAL CALIFORNIA           

P: 15OCT2021 137894    36.1N  118.1W 2.5-4.7 AAAAA  California/Nevada area     

 

An earthquake of M 3.8-4.0 in Hawaii also was widely felt today. It was reported with intensity VI in Pahala and II-III in Naalehu, Hawaii National Park, Captain Cook, Volcano, Holualoa, Hilo, Mountain View, Pahoa and Kealakekua. This is the strongest earthquake in the region of the Kilauea eruption since an M 4.6 on October 6, 2021. An event of M 6.2 south of Hawaii was followed by an M 4.3 aftershock on October 10, 2021. Forecast 137858 had expected today's event was likely within about 25 km around October 12.

 

O: 17OCT2021 15:52:11  19.2N  155.5W ML=4.0  EMSC   ISLAND OF HAWAII, HAWAII

P: 12OCT2021 137858    18.9N  155.4W 3.0-4.6 BAAAA  Hawaii                     

 

A second moderate earthquake occurred with M 4.2 in eastern Poland today. This was reported felt with intensity IV in Poland at Glogow and II in Wroclaw and possibly in Belarus.  A similar earthquake, both of which may be related regional mining, occurred on October 16, 2021 and was reported in this summary as:

 

 

"An unusually large M 4.3 occurred in Poland today.  NEIC reported this earthquake of M 4.3 in Lubin, Poland was felt with intensity V in the area(s) of Lubin, Poland. The last earthquake in Poland within about 200 km of this epicenter with M>=4.3 was recorded by NEIC as occurring a year ago near today's epicenter on November 19, 2020; the last of larger magnitude was an M 4.9 on July 8, 2020. Forecast 137738 had expected today's event in early October." (October 16, 2021)

 

Forecast 138021 had expected the area of northern Germany and western Poland could see enhanced seismicity around October 16.

 

O: 17OCT2021 12:20:54  51.6N   16.2E mb=4.2  EMSC   POLAND                       

P: 16OCT2021 138021    50.0N   12.0E 3.0-4.4 ABCAA  No. Germany                

 

MODERATE QUAKE SHAKES CAYMAN ISLANDS AND CUBA

 

EARTHQUAKE SUMMARY FOR OCTOBER 16, 2021

 

A series of moderate earthquakes struck the area near the Caribbean today. These events occurred as an M 5.3 in the Cayman Islands; an M 5.1 in the North Atlantic and an M 4.9 in the Trinidad and Tobago area.

 

The earthquake of M 5.3 was felt with intensity II-III in the area of the Cayman Islands south of Cuba at George Town, Bodden Town, and West Bay and possibly in southern Cuba. This was the strongest earthquake in the world today following a similar quiet global lull in seismicity yesterday. This appears to be the strongest aftershock of the M 7.7 and 6.1 in the Cayman Islands of January 28, 2020 and the M 7.6 to the southwest of this on January 10, 2018. Forecast 137586 had expected today's event within about 50 km was likely around October 8. This epicenter is near 105 degrees from the M 7.2 in Vanuatu of October 2, 2021 and may have been promoted by energy from that source.

 

O: 16OCT2021 18:27:29  18.7N   81.7W Mw=5.3  EMSC   CAYMAN ISLANDS REGION        

P:  8OCT2021 137586    19.0N   81.0W 3.5-5.4 CAAAA  Caribbean Sea              

 

An earthquake of M 5.1 also hit east of the event in the Cayman Islands in the North Atlantic Ocean today. It was not reported felt in this remote area. The lsat earthquake within about 200 km of this epicenter with M>=4.9 as an M 6.3 on November 11, 2018 followed by aftershocks of M 5.5-5.6 on November 17 and 27, 2018. An event of M 5.5 occurred about 250 km southeast of today's epicenter on May 17, 2021. Forecast 137865 had expected today's event in the Mid-Atlantic around October 16.

 

O: 16OCT2021 22:56:15  15.5N   50.0W mb=5.1  EMSC   NORTH ATLANTIC OCEAN         

P: 16OCT2021 137865    17.0N   47.0W 4.0-5.5 ABCAA  Mid-Atlantic Ridge         

 

An M 4.9 also hit the southern Caribbean in the Tobago region of Trinidad and Tobago. NEIC reported an earthquake of M 4.9 in Trinidad and Tobago was felt with intensity II-III in the area(s) of Trinidad and Tobago at Scarborough.  This is the strongest event within about 250 km of this epicenter since a similar M 4.9 on May 4, 2020, an aftershocks of an M 5.2 on April 7, 2020. Forecast 137877 had expected today's event in this region was likely around October 20.

 

O: 16OCT2021 07:07:45  11.6N   60.1W mb=4.9  EMSC   TOBAGO REGION, TRINIDAD-TOBAGO

P: 20OCT2021 137877    11.0N   63.0W 3.4-5.3 BACAA  Windward Islands           

 

The strongest earthquake in the U.S. or Canada today was an M 4.6-4.9 in Southern Alaska. NEIC reported it was felt with intensity IV in Alaska at Ninilchik and III in Clam Gulch, Kasilof, Anchor Point, Soldotna, Sterling, Home, Kenai, Cooper Landing and the West Kenai Peninsula. The last earthquakes within about 150 km of this epicenter in the Kenai Peninsula of Alaska with M>=4.9 occurred on November 5, 2017 with M 5.0 and M 5.1. Forecasts 138031 and 130833 had expected today's event within about 25 km  in mid-October.

 

O: 16OCT2021 17:47:22  60.1N  151.5W mb=4.9  EMSC   KENAI PENINSULA, ALASKA      

P: 13OCT2021 138033    60.2N  151.7W 3.2-5.2 BAAAA  Central Alaska             

P: 15OCT2021 138031    60.0N  153.5W 3.2-5.4 AAAAA  Central Alaska             

 

An earthquake of M 4.9 occurred in the south Atlantic-Indian Ridge southwest of Africa today. It was not reported felt in this remote area. A similar M 5.3 hit the area on August 29, 2021 within tens of km of today's epicenter. A series of events of M 4.9-5.2 hit about 200 km east of this in May, 2021. Forecast 137811 had expected today's activity in early to mid-October.  This epicenter is near 103 degrees from the M 7.2 in Haiti of August 14, 2021 and the M 7.2 in Vanuatu of October 2, 2021 and may have been promoted by energy from that source.

 

O: 16OCT2021 17:33:17  52.4S   13.5E mb=4.9  EMSC   SOUTHWEST OF AFRICA          

P:  6OCT2021 137811    53.0S   19.0E 4.0-5.4 CACAA  Atlantic-Indian Ridge      

 

QUIET CONDITIONS RETURN TO GLOBAL SEISMICITY

 

EARTHQUAKE SUMMARY FOR OCTOBER 15, 2021

 

It was a very quiet day in global seismicity. There were no event of M>=5.2 located in the world in the past day and no significant regional events were identified. Ongoing eruptions in the Canary Islands at Cumbre Viejo, La Palma and in Kiluaea, Hawaii, however continued with considerable energy. The strongest earthquake associated with the La Palma eruption was an M 4.5, the largest to date in this eruption which began in mid-September. This was noted in the previous issue of this summary as:

 

 

"The eruption at Cumbre Viejo in La Palma, Canary Islands, Spain continued today at elevated levels. An M 4.4 in the region today was the strongest earthquake in the current eruption and before since an M 5.4 on December 27, 2013. Lava overflowed the cone of Cumbre Viejo today for the first time indicating a further strong eruption is likely.  Forecast 137880 had expected today's activity in the Canary Islands within  about 50 km around October 14." (October 13-14, 2021)

 

Forecast 137880 had expected continuing activity in the Canary Islands was likely around October 14.

 

O: 15OCT2021 17:47:42  28.6N   17.8W ML=4.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 15OCT2021 10:48:30  28.7N   17.8W ML=4.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 16OCT2021 04:41:52  28.7N   17.7W ML=4.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 15OCT2021 07:02:17  28.6N   17.8W ML=4.5  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 14OCT2021 137880    28.0N   18.0W 4.0-5.5 AAAAA  Canary Islands             

 

The strongest earthquake in the U.S. or Canada today was an M 3.6-3.9 in Hawaii. NEIC reported this earthquake of M 3.6-3.9 in Hawaii was felt with intensity II-III in the area(s) of Hawaii at Naalehu, Volcano, Captain Cook, Mountain View, Hilo, Holualoa, Kealakekua, Papaikou, Kailua Kona and Kamuela. This continues active conditions in this area which began with the eruption of Kilauea last month and included a large M 6.2 on October 10. Today's event occurred within minutes of local solar midnight and may have been promoted by high tidal stresses which maximize near this hour. Forecast 137858 had expected today's event within about 25 km around October 17.

 

O: 15OCT2021 10:03:12  19.2N  155.4W ML=3.9  EMSC   ISLAND OF HAWAII, HAWAII     

P: 17OCT2021 137858    19.4N  155.1W 3.0-4.6 AAAAA  Hawaii                     

 

 

The strongest earthquake in the world today was an M 5.1 in the Kuril Islands. It was not reported felt in this remote area. The only event within about 150 km of this epicenter in the past year was an M 5.3 on August 2, 2021 and an aftershock of M 5.1 on August 10, 2021. The last event with significantly larger magnitude in this area was an M 7.0 on February 13, 2020. Forecast 137975 had expected today's activity in this region around October 16.

 

O: 16OCT2021 02:02:12  45.8N  149.3E mb=5.1  EMSC   KURIL ISLANDS                

P: 16OCT2021 137975    44.0N  148.0E 3.5-5.8 ABAAA  Hokkaido, Japan            

 

The strongest earthquake in the U.S. or Canada outside Hawaii today was an M 3.4 in Central Alaska. The last earthquake within about 100 km of this epicenter with M>=3.4 was an M 3.4 on August 13 and another on August 3, 2021. An M 4.4 hit this area on July 19, 2021 and these may be regional aftershocks of that event. Forecast 138037 had expected this event within about 50 km was likely around October 16.

 

O: 15OCT2021 18:46:38  63.3N  150.7W ML=3.4  EMSC   CENTRAL ALASKA               

P: 16OCT2021 138037    62.9N  150.2W 3.2-5.4 AAAAA  Central Alaska             

 

An unusually large M 4.3 occurred in Poland today.  NEIC reported this earthquake of M 4.3 in Lubin, Poland was felt with intensity V in the area(s) of Lubin, Poland. The last earthquake in Poland within about 200 km of this epicenter with M>=4.3 was recorded by NEIC as occurring a year ago near today's epicenter on November 19, 2020; the last of larger magnitude was an M 4.9 on July 8, 2020. Forecast 137738 had expected today's event in early October.

 

O: 16OCT2021 04:01:44  51.6N   16.2E mb=4.3  EMSC   POLAND                       

P:  6OCT2021 137738    51.0N   16.0E 3.0-4.7 CAAAA  Poland                     

P: 16OCT2021 138021    50.0N   12.0E 3.0-4.4 ABCAA  No. Germany                

STRONG QUAKE IN SOLOMON ISLANDS ON GEOMAGNETIC EQUATOR

 

EARTHQUAKE SUMMARY FOR OCTOBER 14, 2021

 

Strong seismicity continued today near the geomagnetic equator. This activity  included an M 6.4 in the central Solomon Islands and an M 5.5 in the Molucca Sea of Indonesia. This activity follows the strong geomagnetic storm which has now concluded. This summary noted this possibility in previous summaries as:

 

"The strongest geomagnetic storm in more than three years occurred today. Bright, mostly green aurora were seen throughout most of North America and Asia with this storm. The height of the storm occurred between 09:00 and 10:00 UT. At the same time an M 6.5 occurred in the sub-solar region of Crete, Greece and the Dodecanese Islands. This summary had noted this geomagnetic storm as:

 

"The geomagnetic field saw major storm  conditions today. The AP level was 45.  High latitude geomagnetic field  saw stormy conditions with AP 60. This is the strongest geomagnetic storm since AP reached 45 on September 1, 2019. The last of greater disturbance occurred on August 26, 2018 when AP reached 76 and high latitude AP reached 90. Enhanced seismicity is likely at higher latitudes and near the geomagnetic equator with this storm in the next several days." (October 12, 2021)

 

The strongest earthquake in the world today was an M 6.4 in the Central Solomon Islands. NEIC reported it was felt with maximum intensity VII in Honiara, Guadalcanal; VI in Buala Isabel; V in Tulagi; IV in Kirakira and Ulawa, Arawa, and Kokopo, New Britain and in Pranguna, Northern Solomon Islands. This event is directly on the local geomagnetic equator. This is the strongest earthquake within about 200 km of this epicenter since an M 7.0 on November 18, 2015, a regional aftershock of four earthquakes in the area in July and August, 2015. Forecast 137843 had expected today's event within about 50 km was likely around October 16. This event is at 103 degrees from the M 7.2 in Guerrero, Mexico of September 8 and was probably promoted by strong energy from  that source.

 

O: 15OCT2021 02:44:58   8.9S  158.5E Mw=6.4  EMSC   SOLOMON ISLANDS              

P: 16OCT2021 137843     9.0S  158.0E 4.0-5.4 AAAAA  Solomon Islands            

 

A moderately strong earthquake of M 5.5 also occurred in Indonesia in the Molucca Sea where it was felt with intensity II in Bitung, Sulawesi and Ternate Maluku. BMG reported this earthquake with M 5.8 was felt with intensity III in Manado, Bitung, Bolaang Mongondow Timur, Bolaang Mongondow Selatan and II-III in Minahasa, Minahasa Utara, Ternate and Tidore. The M 5.6 occurred within minutes of local solar midnight, a time when tidal and geomagnetic effects maximize and was probably promoted by those stresses. This is probably an aftershock of an M 5.7 on October 11, 2021 and an M 6.1 on June 3, 2021. Forecast 137824 expected today's activity to the north around October 18. This epicenter is at the seventh node (52 degrees) from the M 7.2 in the Vanuatu region of October 2 and was probably promoted by energy from that source.

 

O: 14OCT2021 15:32:07   1.2N  126.3E mb=4.4  EMSC   MOLUCCA SEA

O: 14OCT2021 15:16:29   1.2N  126.2E Mw=5.6  EMSC   MOLUCCA SEA                  

P: 18OCT2021 137824     3.0N  126.0E 4.0-5.4 BBAAA  Mindanao, Philippines      

 

The strongest seismicity in the U.S. or Canada today were events of M 4.3 in the Alaska Peninsula following an M 6.9 in that area three days ago and an M 4.1 in the Rat Islands. Neither of these were reported felt and are not unusual earthquakes at this time. They had been expected in forecasts 138011 and 138024 within about 50 km in mid-October.

 

O: 14OCT2021 14:09:58  56.3N  156.4W ML=3.0  EMSC   ALASKA PENINSULA

O: 14OCT2021 23:50:09  56.3N  156.5W ML=3.4  EMSC   ALASKA PENINSULA

O: 15OCT2021 02:45:40  56.3N  156.4W ML=3.1  EMSC   ALASKA PENINSULA

O: 15OCT2021 02:50:29  55.2N  157.4W Mw=4.3  EMSC   ALASKA PENINSULA             

P: 18OCT2021 138011    55.7N  157.9W 3.5-4.9 BAAAA  Alaska Peninsula           

 

O: 14OCT2021 21:30:53  51.8N  176.8E mb=4.1  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 17OCT2021 138024    52.0N  177.0E 4.0-5.8 BAAAA  Rat Islands                

 

The eruption of Cumbre Viejo in the Canary Islands continued today. This continues the intensification of this eruption which was noted in the previous issue of this summary as:

 

 

"The eruption at Cumbre Viejo in La Palma, Canary Islands, Spain continued today at elevated levels. An M 4.4 in the region today was the strongest earthquake in the current eruption and before since an M 5.4 on December 27, 2013. Lava overflowed the cone of Cumbre Viejo today for the first time indicating a further strong eruption is likely.  Forecast 137880 had expected today's activity in the Canary Islands within  about 50 km around October 14." (October 13-14, 2021)

 

Note that the M 4.5 today - larger than yesterday's M 4.4 – is now the strongest recent earthquake in the Canary Islands.

 

O: 14OCT2021 12:38:57  28.7N   17.8W ML=3.7  EMSC   CANARY ISLANDS, SPAIN REGION

O: 15OCT2021 07:02:17  28.6N   17.8W ML=4.5  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 14OCT2021 137880    28.0N   18.0W 4.0-5.5 AAAAA  Canary Islands             

 

GEOMAGNETIC STORM ACTIVATES GEOMAGNETIC EQUATOR AND HIGH LATITUDES

 

EARTHQUAKE SUMMARY FOR OCTOBER 13, 2021

 

The strongest geomagnetic storm in nearly three years was described in the previous issue of this summary was followed today by moderate and unusual earthquakes near the geomagnetic equator in Vanuatu (M 5.6), the Banda Sea, Indonesia (M 5.0) and in  Southern Argentina (M 5.4). The note on this storm in the previous issue of this summary was:

 

 

"The strongest geomagnetic storm in more than three years occurred today. Bright, mostly green aurora were seen throughout most of North America and Asia with this storm. The height of the storm occurred between 09:00 and 10:00 UT. At the same time an M 6.5 occurred in the sub-solar region of Crete, Greece and the Dodecanese Islands. This summary had noted this geomagnetic storm as:

 

"The geomagnetic field saw major storm  conditions today. The AP level was 45.  High latitude geomagnetic field  saw stormy conditions with AP 60. This is the strongest geomagnetic storm since AP reached 45 on September 1, 2019. The last of greater disturbance occurred on August 26, 2018 when AP reached 76 and high latitude AP reached 90. Enhanced seismicity is likely at higher latitudes and near the geomagnetic equator with this storm in the next several days." (October 12, 2021)

 

The strongest earthquake in the world today was an M 5.6 in central Vanuatu. NEIC reported this earthquake of M 5.6 in Central Vanuatu was felt with intensity II-III in the area(s) of Central Vanuatu a Norsup, Malampa. Vila Shefa; IV in Sola Torba, Luganville and V in Port Olry and Longama Paname.  This is probably an aftershock of an M 6.9 north of this on August 18, 2021 Forecast 138059 had expected today's activity was likely within about 50 km of this epicenter around October 14.

 

O: 14OCT2021 05:51:56  15.0S  167.5E Mw=5.6  EMSC   VANUATU

O: 13OCT2021 22:05:03  15.8S  167.9E mb=4.4  EMSC   VANUATU

O: 13OCT2021 22:25:57  14.2S  167.4E mb=4.5  EMSC   VANUATU                      

P: 14OCT2021 138059    15.0S  167.0E 4.0-5.4 AAAAA  Vanuatu Islands            

 

The most unusual earthquake of the day was an M 5.4 in southern Argentina and Chile in Santa Cruz, Argentina.  GUC reported this earthquake was felt with intensity IV in  Magallanes and Antartica, Chilena at Torres del Paine and III in Natales, Chile. NEIC reported this earthquake of M 5.4 in the southern Argentina-Chile border was felt with intensity II-III in the area(s) of the southern Argentina-Chile border at Rio Gallegos, Santa Cruz, Argentina.  This is the largest earthquake within about 300 km of this epicenter since an M 5.4-5.5 on July 30, 1992 near this same epicenter. That was the only earthquake of M>=5.4 in this area located in the past 30 years. This earthquake is located at the fifth node (72 degrees) from the M 7.2 in Guerrero, Mexico of September 8, 2021 and was probably promoted by energy from that source.

 

O: 13OCT2021 07:55:30  50.3S   72.1W Mw=5.4  EMSC   SANTA CRUZ, ARGENTINA        

O: 13OCT2021 07:55     50.3S   72.3W mb=5.4  GUC    Magallanes and Antartica, Chil

 

The strongest earthquake in the U.S. or Canada today was an M 4.2 south of Alaska near the Alaska Peninsula. An M 6.9 hit north of this epicenter two days ago on October 11, 2021 and today's event is probably a regional aftershock of that event. There have been two earthquakes of equal or greater magnitude within about 100 km of today's epicenter in the past year - an M 5.0 a month ago on September 16, 2021 and an M 5.5 on July 29, 2021 with the M 8.2 Alaska Peninsula quake of the same day. Forecast 138011 had expected this activity was likely within about 50 km around October 12.

 

O: 13OCT2021 11:34:18  55.1N  156.4W mb=4.2  EMSC   SOUTH OF ALASKA              

P: 12OCT2021 138011    54.7N  156.9W 3.5-5.9 AAAAA  Alaska Peninsula           

 

An unusual earthquake of M 5.3 hit the southwest Indian Ridge today. It was not reported felt in this remote area. The last earthquake within about 250 km of today's epicenter of M>=5.3 was an M 5.8 more than a year ago on August 18, 2020 and an M 5.4 on November 7, 2019. This epicenter is located near the antipode of Central California and some seismic enhancement is likely in that area\ in mid-October. This is normal with the most seismic periods in  Central California around April 15 and six months later near October 15. Forecast 138075 had expected today's earthquake in this area around October 15. This epicenter is at 101 degrees from the M 7.2 in Vanuatu of October 2, 2021 and was probably promoted by energy from that source. Similar events  near 103 degrees from the Vanuatu epicenter occurred today in Peru, Chile, Ecuador. 

 

O: 14OCT2021 03:47:04  36.3S   52.4E mb=5.3  EMSC   SOUTHWEST INDIAN RIDGE       

P: 15OCT2021 138075    34.0S   55.0E 4.0-5.8 ACBAA  So. Indian Ocean            

 

The eruption at Cumbre Viejo in La Palma, Canary Islands, Spain continued today at elevated levels. An M 4.4 in the region today was the strongest earthquake in the current eruption and before since an M 5.4 on December 27, 2013. Lava overflowed the cone of Cumbre Viejo today for the first time indicating a further strong eruption is likely.  Forecast 137880 had expected today's activity in the Canary Islands within  about 50 km around October 14.

 

O: 14OCT2021 01:27:58  28.6N   17.8W ML=4.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13OCT2021 14:33:48  28.6N   17.8W ML=4.4  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 14OCT2021 137880    28.0N   18.0W 4.0-5.5 AAAAA  Canary Islands             

 

STRONGEST GEOMAGNETIC STORM IN TWO YEARS BRINGS STRONG QUAKE IN CRETE

 

EARTHQUAKE SUMMARY FOR OCTOBER 12, 2021

 

The strongest geomagnetic storm in more than three years occurred today. Bright, mostly green aurora were seen throughout most of North America and Asia with this storm. The height of the storm occurred between 09:00 and 10:00 UT. At the same time an M 6.5 occurred in the sub-solar region of Crete, Greece and the Dodecanese Islands. This summary had noted this geomagnetic storm as:

 

"The geomagnetic field saw major storm  conditions today. The AP level was 45.  High latitude geomagnetic field  saw stormy conditions with AP 60. This is the strongest geomagnetic storm since AP reached 45 on September 1, 2019. The last of greater disturbance occurred  on August 26, 2018 when AP reached 76 and high latitude AP reached 90. Enhanced seismicity is likely at higher latitudes and near the geomagnetic equator with this storm in the next several days." (October 12, 2021)

 

A strong aftershock of M 6.4 also hit eastern Crete, Greece today. This event was reported with maximum intensity VII in Crete at Sitia; IV in Ierapetra, Iraklion, and II-III in Nea Alikarnassos and Khanion, Greece. Many buildings were damaged including a chapel which collapsed. People fled from their homes during the quake but there were no immediate reports of casualties. After a lull in the geomagnetic storm, it resumed about 07:00 UT on October 12, 2021 with high latitude AP 7 at about 09:00. It is likely that this helped promote the earthquake in Crete at this same time. A strong M 6.0 hit Crete about 200 km west of today's epicenter occurred on September 27, 2021, an earthquake which killed one and did considerable damage, and this may be a regional aftershock of that event. The last earthquake of larger magnitude in Crete occurred on May 2, 2020 with M 6.6, the strongest in the region in the past 30 years. A similar M 6.6 about 200 km northeast of this occurred on July 20, 2017. The only event of M>=6.4 within about 100 km of today's event in the past 30 years was an M 6.4 on July 1, 2009. Today's earthquake in Crete occurred within about an hour of local solar noon and was probably promoted by high tidal stresses which maximize near this hour. Forecasts 137629,m 137893 and 137906 had expected today's event in the region of Crete was likely around October 9-13. This epicenter is at 148 degrees from the M 7.2 in Vanuatu of October 2, 2021 and at 103 degrees from the M 8.1 of August 12. 2021 in the South Sandwich Islands and may have been promoted by energy from those sources.

 

 

O: 12OCT2021 09:24:04  35.0N   26.3E Mw=6.4  EMSC   CRETE, GREECE                

O: 12OCT2021 09:36:28  35.1N   26.3E ML=4.1  EMSC   CRETE, GREECE

O: 12OCT2021 09:32:42  35.6N   27.2E ML=4.5  EMSC   DODECANESE ISLANDS, GREECE

P:  6OCT2021 137646    35.0N   26.0E 3.0-4.8 CAAAA  Crete                      

P: 12OCT2021 137893    35.0N   25.0E 3.0-4.6 AAAAA  Aegean Sea                 

P:  9OCT2021 137629    37.0N   27.0E 3.0-4.8 BBAAA  Aegean Sea                 

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 off the west coast of Vancouver, British Columbia, Canada. NEIC reported this earthquake of M 4.1 off western Vancouver, Canada  was felt with intensity II-III in the area(s) of British Columbia in Port Alberni and VI in Courtenay. An M 4.3 about 50 km southwest of this occurred on September 21, 2021. These may be aftershocks of an event of M 5.4 on July 22, 2020. Forecast 138005 had expected today's event in the area was likely around October 13.

 

O: 12OCT2021 14:56:19  49.2N  128.1W mb=4.1  EMSC   VANCOUVER ISLAND, CANADA REGIO

P: 13OCT2021 138005    48.7N  129.0W 2.8-5.1 AAAAA  Vancouver Island area      

 

MAJOR AFTERSHOCK SHAKES ALASKA PENINSULA

 

EARTHQUAKE SUMMARY FOR OCTOBER 11, 2021

 

A major aftershock of M 6.9 shook the Alaska Peninsula today. NEIC reported maximum intensity VI in Chignik Lagoon, Alaska and V in Chignik with IV in Port Heiden, South Naknek, King Salmon, Sand Point, Manokotak, and II-III in Kodia, Naknek, and King Cove. This event occurred at the height of the current geomagnetic storm near local solar midnight and was probably promoted by geomagnetic effects from this storm as noted in this and previous issues of this summary:

 

"The geomagnetic field saw quiet  conditions today. The AP level was 13.  High latitude geomagnetic field  saw stormy conditions with AP 23. Enhanced seismicity is likely at higher latitudes and near the geomagnetic equator with this disturbance in the next several days." (October 10-11, 2021)

 

Today's earthquake occurred at 156 West longitude. This is the same longitude as the M 6.2 earthquake yesterday in Hawaii. The note in the previous issue of this summary expected this event could follow at this time as:

 

 

"While the Alaska Peninsula remained quiet today with only an M 3.2 reported in the area, the area is at the same longitude (156 West) as Hawaii and as noted above in the tidal forecast could see enhanced seismicity and the possibility of a strong earthquake in the next several days. A strong geomagnetic storm at high latitudes would reinforce this possibility." (October 10-11, 2021)

 

The forecast for this new moon as reported in  previous issues of this summary had read:

 

"The New moon arrived at 11:05 UT on October 6. Longitudes which were at local solar noon at this time are near 15 East while those at local solar midnight are near 165 West longitude. In the west these include most areas of Europe and Africa and in the east the central Aleutians and the Alaska Peninsula, Hawaii and the Tonga-Fiji-Kermadec arc. These area are the most likely to see a strong tidally triggered earthquake in the next week. Other areas may also see tidal triggering. These are most likely to occur near local solar midnight and local solar noon. The possibility of a strong to major earthquake is considered moderate to strong before October 10." (October 4-10, 2021)

 

As discussed in the previous issue the quake in Alaska was probably  promoted by tidal stresses. Not only did it occur near local solar midnight but also at the longitude of maximum tidal stress with that event. The previous issue noted this in regard to Hawaii as:

 

"Readers should note that Hawaii is located near the longitude of maximum tidal stress with this new moon. The mainshock also occurred as a strong geomagnetic storm was reaching maximum intensity" (October 10-11, 2021)

 

While today's event is about 150 km northeast of the M 8.2 of July 29 and the M 7.0 of August 14, 2021 it is likely a regional aftershock caused by stress redistribution in the area. Forecast 138011 had expected today's activity about 150 km south of this around October 12. This epicenter is at the fifth node from Haiti where an M 7.2 occurred on August 14, 2021 and was probably promoted by strong energy from that source.

 

O: 11OCT2021 13:59:30  56.3N  156.6W mb=4.4  EMSC   ALASKA PENINSULA

O: 11OCT2021 17:56:23  56.3N  156.5W mb=4.3  EMSC   ALASKA PENINSULA

O: 11OCT2021 19:35:56  56.3N  156.5W ML=3.3  EMSC   ALASKA PENINSULA

O: 11OCT2021 19:40:24  56.3N  156.6W mb=4.9  EMSC   ALASKA PENINSULA

O: 12OCT2021 00:54:11  56.3N  156.6W ML=3.4  EMSC   ALASKA PENINSULA

O: 12OCT2021 04:41:22  56.3N  156.7W ml=3.5  EMSC   ALASKA PENINSULA

O: 11OCT2021 09:10:24  56.4N  156.7W Mw=6.9  EMSC   ALASKA PENINSULA

O: 11OCT2021 09:30:52  56.4N  156.5W ml=3.2  EMSC   ALASKA PENINSULA

O: 11OCT2021 09:26:20  56.3N  156.6W ML=3.9  EMSC   ALASKA PENINSULA             

P: 12OCT2021 138011    54.7N  156.9W 3.5-5.9 ABAAA  Alaska Peninsula           

 

A strong aftershock of M 6.4 also hit eastern Crete, Greece today. This event was reported with maximum intensity VII in Crete at Sitia; IV in Ierapetra, Iraklion, and II-III in Nea Alikarnassos and Khanion, Greece. Many buildings were damaged including a chapel which collapsed. People fled from their homes during the quake but there were no immediate reports of casualties. After a lull in the geomagnetic storm, it resumed about 08:00 UT on October 12, 2021 with high latitude AP 6 at about 08:00. It is likely that this helped promote the earthquake in Crete at this same time. A strong M 6.0 hit Crete about 200 km west of today's epicenter on September 27, 2021, an earthquake which killed one and did considerable damage, and this may be a regional aftershock of that event. The last earthquake of larger magnitude in Crete occurred on May 2, 2020 with M 6.6, the strongest in the region  in the past 30 years. A similar M 6.6 about 200 km northeast of this occurred on July 20, 2017. The only event of M>=6.4 within about 100 km of today's event in the past 30 years was an M 6.4 on July 1, 2009. Today's earthquake in Crete occurred within about an hour of local solar noon and was probably promoted by high tidal stresses which maximize near this hour. Forecasts 137629,m 137893 and 137906 had expected today’s event in the region of Crete was likely around October 9-13.

 

O: 12OCT2021 09:24:03  35.2N   26.3E mw=6.4  ANSS   SSE of Palekastro Greece     

P:  9OCT2021 137629    37.0N   27.0E 3.0-4.8 BBAAA  Aegean Sea                 

P: 12OCT2021 137893    35.0N   25.0E 3.0-4.6 AAAAA  Aegean Sea                 

P: 13OCT2021 137906    34.0N   27.0E 3.0-5.6 ABAAA  Crete                      

 

A moderately strong M 5.6-5.7 quake shook regions of the Molucca Sea today. NEIC reported it was felt with intensity II-III in Indonesia at Ternate, Bitung, Manado, Ambon, Palu, Sulawesi and Polewali Sulawesi. Forecast 137824 had expected today's seismic enhancement in this area was likely in mid-October. NEIC reported an aftershock of M 5.1 in Molucca, Indonesia was felt with intensity II-III in the area(s) of Molucca, Indonesia at Manado, Sulawesi.

 

O: 11OCT2021 17:30:31   0.8N  126.1E mb=5.0  EMSC   MOLUCCA SEA

O: 11OCT2021 15:27:52   0.9N  126.1E mb=5.1  EMSC   MOLUCCA SEA

O: 11OCT2021 12:34:36   0.8N  126.2E Mw=5.6  EMSC   MOLUCCA SEA                  

P: 18OCT2021 137824     3.0N  126.0E 4.0-5.4 CCAAA  Mindanao, Philippines      

 

 

The antipode of Sumatra, where a large earthquake occurred yesterday, was active today. An M 5.0 was widely felt in Colombia at Floridablanca, Bucaramanga, San Gil, Santander, Paip;a, Guatape, Bogota, Ejido, Retiro, Itagui, Antioquia and Cartagena. Forecast 137820 had expected this earthquake in mid-OCtober within about 25 km.

 

O: 12OCT2021 04:51:46   6.8N   73.0W mb=5.0  EMSC   NORTHERN COLOMBIA            

P: 18OCT2021 137820     7.0N   73.0W 4.0-5.5 CAAAA  Colombia                   

 

STRONG EARTHQUAKE SHAKES HAWAII

 

EARTHQUAKE SUMMARY FOR OCTOBER 10, 2021

 

A strong earthquake of M 6.2 shook most of the state of Hawaii, U.S. today. It was reported with maximum intensity VI in Naalehu; V in Hawaii National Park, Captain Cook, Honaunau, Volcano, Mountain View, IV in Pahala, Holualoa, Pahoa, Kealakekua with lesser shaking as far to the west as Waimea. There have been only two earthquakes in Hawaii with M>=6.2 in the past 30 years – both north of today's epicenter in central and northern Hawaii Island - on May 4, 2018 with M 6.9 and as an M 6.7 on October 15, 2006. Today's earthquake occurred near the Loi'hi Seamount south of Hawaii and is not directly associated with the current major eruption of Kilauea volcano to the north. The shaking caused some doors to open and some items to be thrown from shelves in businesses. No major damage or casualties were reported and a tsunami does not appear to have been generated with this earthquake. The earthquake occurred within minutes of the maximum of a geomagnetic storm at local solar noon and was probably promoted by high tidal stresses associated with the new moon and the geomagnetic storm, which stresses maximize near this hour,  as noted in this and previous issues of this summary as:

 

 

"The New moon arrived at 11:05 UT on October 6. Longitudes which were at local solar noon at this time are near 15 East while those at local solar midnight are near 165 West longitude. In the west these include most areas of Europe and Africa and in the east the central Aleutians and the Alaska Peninsula, Hawaii and the Tonga-Fiji-Kermadec arc. These areas are the most likely to see a strong tidally triggered earthquake in the next week. Other areas may also see tidal triggering. These are most likely to occur near local solar midnight and local solar noon. The possibility of a strong to major earthquake is considered moderate to strong before October 10." (October 4-10, 2021)

 

Readers should note that Hawaii is located near the longitude of maximum tidal stress with this new moon. The mainshock also occurred as a strong geomagnetic storm was reaching maximum intensity as noted in this summary:

 

"The geomagnetic field saw quiet  conditions today. The AP level was 9.  High latitude geomagnetic field  saw active conditions with AP 15. Enhanced seismicity is likely at higher latitudes and near the geomagnetic equator with this disturbance in the next several days." (October 9-10, 2021)

 

Forecast 137594 had expected enhanced seismicity in Hawaii was likely with the new moon on October 6 within about 50 km of today's epicenter. Today's event was located at the seventh note (52 degrees) from an M 7.0 in Guerrero, Mexico of September 8 and the strong seismicity of March 4 and following in the Kermadec Islands as well as near this distance from the M 7.2 and 6.9 in Vanuatu of early October, 2021.

 

O: 10OCT2021 21:48:36  18.8N  155.5W ml=6.2  ANSS   SSE of Naalehu Hawaii

O: 10OCT2021 21:48:36  19.0N  155.6W Mw=5.7  EMSC   HAWAII REGION, HAWAII

O: 10OCT2021 22:45:47  19.0N  155.6W ML=3.3  EMSC   ISLAND OF HAWAII, HAWAII

O: 10OCT2021 09:31:49  19.2N  155.5W ML=3.0  EMSC   ISLAND OF HAWAII, HAWAII

O: 11OCT2021 01:29:14  19.2N  155.5W ML=3.1  EMSC   ISLAND OF HAWAII, HAWAII

O: 10OCT2021 21:53:07  18.9N  155.6W ML=4.3  EMSC   HAWAII REGION, HAWAII        

P:  6OCT2021 137594    19.4N  155.4W 3.0-4.8 BAAAA  Hawaii                     

 

The strong eruption of Cumbre Vieja Volcano in La Palma, Canary Islands, Spain continued at a higher intensity today. This included a partial collapse of the cone causing huge chunks of lava, some the size of three-story building to roll down the slope. The lava reached an industrial complex and destroyed more buildings. So far 1186 buildings have been destroyed in the eruption including nearly all structures in the village of Todoque. The eruption has also covered about 1200 acres of land and caused about 6000 of the islands 80,000 residents to be evacuated according to accounts in Reuters. The strongest earthquake of the day was an M 4.3, matching the strongest event recorded in the current eruption as noted in a previous issue of this summary:

 

 

" The strongest earthquake in the current eruption occurred today with M 4.3, also the strongest in the Canary Islands since an M 5.4 on December 27, 2013 following a similar eruptive phase.

 

The M 4.3 occurred within about an hour of local solar noon and may have been promoted by high tidal stresses with the new moon which maximize near this hour." (October 8, 2021)

 

Today's activity is located at the seventh node (51-52 degrees) from the M 7.2 in Haiti of August 14, 2021 and was probably promoted by energy from that source.

 

O: 10OCT2021 09:26:27  28.6N   17.8W ML=3.7  EMSC   CANARY ISLANDS, SPAIN REGION

O: 10OCT2021 21:46:27  28.6N   17.8W ML=4.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 10OCT2021 13:05:38  28.7N   17.8W ML=3.9  EMSC   CANARY ISLANDS, SPAIN REGION

O: 10OCT2021 07:04:52  28.6N   17.8W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION 

 

While the Alaska Peninsula remained quiet today with only an M 3.2 reported in the area, the area is at the same longitude (156 West) as Hawaii and as noted above in the tidal forecast could see enhanced seismicity and the possibility of a strong earthquake in the next several days. A strong geomagnetic storm at high latitudes would reinforce this possibility.

 

O: 11OCT2021 00:16:09  58.1N  154.4W ML=3.2  EMSC   ALASKA PENINSULA             

P:  9OCT2021 137748    60.1N  153.4W 3.2-5.4 ABAAA  Central Alaska             

 

An M 4.8 occurred today in the Reykjanes Ridge south of Iceland. It was not reported felt in this remote area. This epicenter is within about 100 km of the exact antipode of an M 6.1 which hit the Macquarie Island area on October 7. This summary suggested this possibility at the time as:

 

"The antipode of this epicenter in the Macquarie Island area is in the Reykjanes Ridge, north Atlantic south of Iceland. This area often sees enhanced seismicity following strong earthquakes in Macquarie Island." (October 7-8, 2021)

 

Forecast 137737 had expected today's event within about 100 km of this epicenter was likely around October 10.

 

O: 10OCT2021 16:09:34  57.9N   32.7W mb=4.8  EMSC   REYKJANES RIDGE              

P: 10OCT2021 137737    59.0N   31.0W 4.0-5.8 ABAAA  North Mid-Atlantic Ridge   

 

STRONG VANUATU QUAKE FOLLOWED BY QUAKE IN CENTRAL PERU

 

EARTHQUAKE SUMMARY FOR OCTOBER  9, 2021

 

The strongest earthquake in the world today was an M 6.8 in the region southeast of the Vanuatu Islands. It appears to be an aftershock of the M 7.2 that hit this region on October 2, 2021. Today's event ws felt lightly with intensity II-III in Fiji at Sigatoka, Nadi, Lautoka, Ba, Suba, Isangel, Labasa, Vila, Vanuatu, Yale, and Mont-Dore, New Caledonia. The mainshock had been noted in this summary on October 2 as:

 

"Today's event of M 7.3 is the strongest recorded within about 200 km of this epicenter in the past 30 years. An M 7.2 hit the area on August 12, 2016 and a larger event of M 7.6 occurred in the area on March 3, 1990 with M 7.6. A major earthquake of M 7.7 and large aftershocks hit the area of the Loyalty Islands on February 10, 2021 about 400 km to the southwest of today's epicenter." (October 2, 2021)

 

Forecasts 137786 and 137793 had expected today's activity was likely within about 150 km was likely around October 5-7.

 

O:  9OCT2021 10:58:30  21.2S  174.5E Mw=6.8  EMSC   VANUATU REGION               

P:  5OCT2021 137793    21.0S  176.0E 4.0-5.8 BAAAA  Tonga/Fiji                 

P:  7OCT2021 137786    22.0S  172.0E 4.0-5.4 AABAA  Loyalty Islands             

 

The M 6.8 in the southern Vanuatu region was followed later in the day by an M 5.7 in Central Peru. This event was felt with intensity IV in Cusco Peru a Santa Ana and II-III in Cusco, Ayacucho, Rio Branco, Acre, Brazil and in La Paz, Bolivia. A similar earthquake of M 5.6 occurred in Southern Peru yesterday as noted in the previous issue of this summary:

 

"An earthquake of M 5.5-5.6 in Southern Peru today was felt with moderate intensity VII in Arequipa, Peru. This was the strongest earthquake in the world today. It occurred on the geomagnetic equator and may have been promoted by the geomagnetic disturbance two days ago. The last earthquake of greater magnitude within about 150 km of this epicenter occurred as an M 6.0 on May 31, 2020. This followed a major quake about 200 km to the northeast of this on March 1, 2019. Forecast 137766 had expected today's event within about 50 km of this epicenter was likely around October 9. This epicenter is at 103-104 degrees from the M 8.1 in the Alaska Peninsula and at M 7.2 in Vanuatu of October 2, 2021 and was probably promoted by energy from those sources. Further aftershocks in the Vanuatu region are expected as the seismic ping-pong effect from Peru is likely." (October 8-9, 2021)

 

Today's epicenter is also at 105 degrees from the mainshock and aftershock today in the area east of southern Vanuatu and was probably promoted by energy from that source. Further reverberation between the two areas is still possible. Other earthquakes today near 103 degrees from the Vanuatu epicenter occurred in the South Sandwich Islands (M 4.9); Costa Rica (M 4.3), central Peru (M 4.3); Atacama, Chile (M 4.0); Antofagasta Chile (M 4.8). The last earthquake of larger magnitude within about 150 km of today's epicenter was an M 7.1 at a deep focus on August 24, 2018. The last of larger magnitude of shallow focus was an M 6.4 on January 10, 1998. Forecast 137766 had expected enhanced seismicity in Central Chile around October 9.

 

O: 10OCT2021 00:20:40  11.7S   71.6W Mw=5.7  EMSC   CENTRAL PERU                 

P:  9OCT2021 137766    15.0S   71.0W 4.0-5.4 ACAAA  Central Peru               

 

An earthquake of M 5.6 also occurred in the Sea of Okhotsk, Russia west of the

Kuril Islands today. It was not reported felt in this remote area. This may be an aftershock of an M 5.8 in the Sea of Okhotsk on September 3, 2021. Forecast 137721 had expected regional seismic enhancement in early October.

 

O:  9OCT2021 07:19:26  50.0N  149.9E Mw=5.6  EMSC   SEA OF OKHOTSK               

P:  3OCT2021 137721    49.0N  153.0E 3.5-5.6 CACAA  So. Kurils                 

 

A further earthquake of M 3.6-3.9 occurred today in the current eruption of Kilauea Volcano, Hawaii. NEIC reported today's earthquake was felt with intensity IV in Naalehu and II-III in Volcano, Hilo, Kurtistown and Papaikou, Hawaii. A similar event hit the region yesterday and was reported in this summary as:

 

"An M 3.7 earthquake in Hawaii continued the eruption of Kilauea today. NEIC reported it was felt with intensity II-III in Hawaii at Pahala, Naalehu, Captain Cook, Holualoa and Kailua Kona. Forecast 137594 expected today's event within the eruptive area was likely around October 6, 2021. This is the strongest earthquake in the U.S. or Canada today. An M 4.5-4.6 hit this area two days ago on October 6 but this is one of the strongest earthquakes to date associated with the current Kilauea eruption." (October 7-8, 2021)

 

Forecast 137594 had expected today's event within about 25 km of this epicenter was likely around October 6.

 

O:  9OCT2021 23:08:42  19.2N  155.4W ML=3.9  EMSC   ISLAND OF HAWAII, HAWAII     

P:  6OCT2021 137594    19.4N  155.4W 3.0-4.8 BAAAA  Hawaii                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.0 in the Rat Islands, Aleutians. The last earthquake in the Rat Islands of M>=4 was an M 4.3 on September 20, 2021 but the last within about 140 km of today's epicenter was an M 4.6 on August 24, 2021. Forecast 137740 had expected today's event within about 50 km was likely around October 7.

 

O:  9OCT2021 15:46:49  51.7N  178.4E mb=4.0  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P:  7OCT2021 137740    52.0N  178.0E 4.0-5.8 AAAAA  Rat Islands                

 

 

MODERATE QUAKE SHAKES SOUTHERN PERU

 

EARTHQUAKE SUMMARY FOR OCTOBER  8, 2021

 

An earthquake of M 5.5-5.6 in Southern Peru today was felt with moderate intensity VII in Arequipa, Peru. This was the strongest earthquake in the world today. It occurred on the geomagnetic equator and may have been promoted by the geomagnetic disturbance two days ago. The last earthquake of greater magnitude within about 150 km of this epicenter occurred as an M 6.0 on May 31, 2020. This followed a major quake about 200 km to the northeast of this on March 1, 2019. Forecast 137766 had expected today's event within about 50 km of this epicenter was likely around October 9. This epicenter is at 103-104 degrees from the M 8.1 in the Alaska Peninsula and at M 7.2 in Vanuatu of October 2, 2021 and was probably promoted by energy from those sources. Further aftershocks in the Vanuatu region are expected as the seismic ping-pong effect from Peru is likely.

 

O: 09OCT2021 05:21:07  16.0S   72.0W mb=4.3  EMSC   SOUTHERN PERU

O: 09OCT2021 04:47:52  15.6S   71.8W Mw=5.5  EMSC   SOUTHERN PERU

O: 09OCT2021 04:47:52  15.6S   71.9W Mw=5.6  ANSS   SOUTHERN PERU

O: 09OCT2021 05:50:11  15.6S   71.7W mb=4.7  EMSC   SOUTHERN PERU

O: 09OCT2021 06:12:50  15.7S   72.0W ML=4.0  EMSC   SOUTHERN PERU

O:  8OCT2021 09:28:00  15.5S   71.9W mb=4.2  EMSC   SOUTHERN PERU                

P:  9OCT2021 137766    15.0S   71.0W 4.0-5.4 AAAAA  Central Peru               

 

An earthquake of M 4.8 was widely felt in southeastern Puerto Rico today. NEIC reported intensity IV in Puerto Rico at Vieques, Mumacao, Luquillo, and II-III in Yabucca, Culebra, Ceiba, Punta Santiago, Puerto Real, Fajardo, and Naguabo. This is not an aftershock of the long-standing aftershock zone in southwestern Puerto Rico.  This is the strongest earthquake in southeastern Puerto Rico in the past year. An M 5.3 occurred a year ago on October 7, 2020 and an M 5.0 occurred a year before that on October 6, 2019. These seasonal earthquakes appear to be related to regional weather patterns. Forecast 137596 had expected today's event with in about 50 km was likely around October 8.

 

O: 08OCT2021 20:22:30  18.0N   65.4W ML=3.1  EMSC   PUERTO RICO REGION

O:  8OCT2021 18:28:23  18.0N   65.4W mb=4.6  EMSC   PUERTO RICO REGION           

P:  8OCT2021 137596    18.0N   65.0W 3.0-5.3 AAAAA  Leeward Islands            

 

An unusual earthquake of M 4.9 occurred in Victoria, Australia today. NEIC reported it was felt with intensity II-III in Victoria and South Australia at Murray Bridge, Horsham, Midua, Mount Barker, Victor Harbor, Adelaide, Mount Gambler, Swan Hill, Hamilton and Maryborough. This is the strongest earthquake within about 300 km of this epicenter in at least 30 years. An M 4.8 hit the area on October 27, 2001 and about 400 km northwest of this on May 3, 1997, the only similar quakes in Victoria since 1990. This follows an M 5.9 about 450 km southeast of this epicenter on September 21 in Victoria, Australia and may represent regional stress migration following that earthquake.

 

Forecast 137331 had expected today's event in late September or early October about 150 km south of today's epicenter. This epicenter is at 144-145 degrees from the M 7.2 in Haiti of August 14 and was probably promoted by energy  from that source.

 

O: 08OCT2021 17:02:25  35.4S  141.1E ML=3.0  EMSC   VICTORIA, AUSTRALIA

O: 08OCT2021 18:12:08  35.4S  141.1E ML=2.6  EMSC   VICTORIA, AUSTRALIA

O: 08OCT2021 17:20:40  35.5S  141.0E ML=2.8  EMSC   VICTORIA, AUSTRALIA

O: 08OCT2021 18:01:49  35.5S  141.1E ML=2.8  EMSC   VICTORIA, AUSTRALIA

O: 08OCT2021 23:44:33  35.5S  141.1E ML=2.6  EMSC   VICTORIA, AUSTRALIA

O:  8OCT2021 16:47:27  35.4S  141.0E mb=4.9  EMSC   VICTORIA, AUSTRALIA          

P: 28SEP2021 137331    37.0S  142.0E 4.0-5.0 CBAAA  Australia                  

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Fox Islands, Aleutians, Alaska. This is the strongest earthquake in the eastern Fox Islands since an M 4.5 on August 17, 2021. The last of significantly larger magnitude was an M 4.7 on July 3, 2021. Today's event was not reported felt in this remote area. Forecast 137733 had expected this activity in the eastern Fox Islands was likely about 100 km to the east around October 7.

 

O:  9OCT2021 05:59:49  53.2N  166.8W mb=4.4  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P:  7OCT2021 137733    53.7N  165.3W 3.5-4.9 AAAAA  Fox Islands, Aleutians     

 

The volcanic eruption at La Palma, Canary Islands, Spain intensified and spewed lava with rivers of lava emptying into the sea and causing further destruction of property today. The strongest earthquake in the current eruption occurred today with M 4.0, also the second strongest in the Canary Islands since an M 5.4 on December 27, 2013 following a similar eruptive phase. Hundreds have been evacuated and more than 800 buildings have been destroyed in the eruption, but no deaths have been attributed to the eruption to date. The M 4.0 occurred within about an hour of local solar noon while an M 3.9  occurred within minutes of local solar noon and may have been promoted by high tidal stresses with the new moon which maximize near these hour. Forecast 137308 had expected continuing eruptive earthquakes in the Canary Island at the end of September and early October.

 

O: 08OCT2021 23:55:05  28.6N   17.8W ML=4.0  EMSC   CANARY ISLANDS, SPAIN REGION

O:  8OCT2021 12:46:00  28.6N   17.9W ML=3.9  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 DAAAA  Canary Islands             

 

STRONG QUAKE JOLTS TOKYO, JAPAN

 

EARTHQUAKE SUMMARY FOR OCTOBER  7, 2021

 

A series of moderately strong to strong earthquakes occurred at high latitudes today. These included an M 6.1 in the Macquarie Island region south of New Zealand, an M 5.9 near Tokyo, Japan and an M 5.5 in the northern South Sandwich Islands. These may have been promoted by a strong disturbance in the high latitude geomagnetic field yesterday as reported in this summary:

 

"The geomagnetic field saw quiet  conditions today. The AP level was 8.  High latitude geomagnetic field  saw minor storm conditions with AP 23. Enhanced seismicity is likely at higher latitudes with this disturbance in the next several days." (October 6-7, 2021)

 

The strongest earthquake felt in the world today was an M 5.9 in the region of southeastern Honshu, Japan near Tokyo. NEIC reported it was felt with maximum intensity V in Chiba and Tokyo, Japan at Chiba, Ichihara, Funabashi, Narashino, Yotsukaido, Urayasu, Yachiyo, Ichikawa, Kamagaya, Sakura among others. As noted, when an M 5.6 hit north of this in northern Honshu Japan, in the previous issue of this summary, this earthquake was probably promoted by the passage of Typhoon Mindulle east of this several days ago as:

 

"Super Typhoon Mindulle (TS 20W) continued in the area east of Honshu, Japan today with winds up to 70 kts. This system is moving to the northeast and is currently south of eastern Honshu, Japan. It is  expected to track  north reaching areas south of  Honshu, Japan this week. Major seismic enhancement is possible in the area of Central and eastern Honshu in the next several days as this storm passes to the east." (October 2-3, 2021)

 

Today's event is the first within about 150 km of Tokyo, Japan with M>=5.9 in more than an year - since an M 5.9 on June 24, 2020. The last event of larger magnitude in this area was an M 6.2 five years ago on September 23, 2106. Forecast 137661 had expected today's event within this area was likely in early October. This epicenter is located at 103 degrees from the M 7.2 in Guerrero, Mexico of September 8 and, as previous noted in this summary was expected as a result of strong seismic energy concentrated at this distance from that event.

 

O:  7OCT2021 13:41:24  35.5N  140.1E Mw=5.9  EMSC   NEAR EAST COAST OF HONSHU, JAP

P:  2OCT2021 137661    35.0N  141.0E 4.0-5.6 BAAAA  Off East Coast Honshu      

 

The strongest earthquake in the world today was an M 6.1 south of New Zealand in

the region of Macquarie Island. This is a remote, but seismically active area and this event was not reported felt. The last earthquake in the Macquarie Island area of M>=6.1 was an M 6.1 about 500 km west of today's epicenter on March 20, 2021. The last earthquake within about 300 km of today's epicenter with M>=6.1 was an M 6.1 on October 13, 1995. The antipode of this epicenter in the Macquarie Island area is in the Reykjanes Ridge, in the north Atlantic south of Iceland. This area often sees enhanced seismicity following strong earthquakes in Macquarie Island.

 

O:  7OCT2021 20:13:01  58.9S  158.4E Mw=6.1  EMSC   MACQUARIE ISLAND REGION      

 

Also at high latitudes, an M 5.5 occurred in the South Sandwich Islands at the opposite longitude to the event in the Macquarie Island region. This continues regional aftershock activity in the South Sandwich Islands following the M 8,1 there on August 12, but is far to the north of most of the aftershocks of that event. Aftershocks of M 5.5-5.7 have hit within about 200 km of today's epicenter in the aftershock sequence on September 5, August 14 and 16, 2021.  A moderate foreshock of M 5.7 to the M 8.1 of August 12 occurred on July 17, 2021, the first such event in the region since 2019. Forecast 137813 had expected today's event was likely within about 50 km around October 2. This epicenter is located at 101 degrees from the M 7.2 in Vanuatu of October 2 and was probably promoted by energy from that source.

 

O:  7OCT2021 17:56:14  55.8S   26.5W mb=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  2OCT2021 137813    56.0S   27.0W 4.0-5.7 BAAAA  So. Sandwich Islands       

 

An earthquake of M 5.5 shook regions of Myanmar today. NEIC reported maximum intensity V in Myanmar at Monywa Sagang and Alzawi Mizoram, India with lesser shaking of II-III in Pakokku, Myanmar; and in Bangladesh at Dhemsa, Fatekharkui Koka, Chattagam, Coxs Bazar, Dacca and in India at Sichar, Assam and Shillong, Meghalaya. This earthquake occurred within about 30 minutes of local solar midnight and may have been promoted by high tidal stresses which maximize near this hour. This is the strongest earthquake in Myanmar within about 200 km of this epicenter since an M 5.6 on June 21, 2020. That event appears to have been triggered by the total solar eclipse which was visible a day earlier in Myanmar. Stresses associated with the new moon appear to help enhance regional seismicity in this area. At the time of the June, 2020 eclipse, this summary noted:

 

"A moderately strong earthquake also occurred with M 5.7-5.8 today in the region of Mizoram, India near Bangladesh and Myanmar. ... The area had just experienced an annular solar eclipse several hours earlier and an M 5.1 foreshock with that eclipse.

 

The earthquake in India/Myanmar today occurred near the sub-solar point at the time of the total eclipse." (June 21-22, 2020)

 

Forecast 137619 had expected today's event was likely within about 100 km around October 5.

 

O:  7OCT2021 18:28:04  22.3N   94.8E Mw=5.5  EMSC   MYANMAR                      

P:  5OCT2021 137619    23.0N   95.0E 4.0-5.6 AAAAA  Myanmar                    

 

An M 3.7 earthquake in Hawaii continued the eruption of Kilauea today. NEIC reported it was felt with intensity II-III in Hawaii at Pahala, Naalehu, Captain Cook, Holualoa and Kailua Kona. Forecast 137594 expected today's event within the eruptive area was likely around October 6, 2021. This is the strongest earthquake in the U.S. or Canada today. An M 4.5-4.6 hit this area two days ago on October 6 but this is one of the strongest earthquakes to date associated with the current Kilauea eruption.

 

O:  8OCT2021 06:25:04  19.2N  155.5W ML=3.7  EMSC   ISLAND OF HAWAII, HAWAII     

P:  6OCT2021 137594    19.4N  155.4W 3.0-4.8 AAAAA  Hawaii                     

 

The volcanic eruption at La Palma, Canary Islands, Spain continued to spew lava with rivers of lava emptying into the sea today. The strongest earthquake in the current eruption occurred today with M 4.3, also the strongest in the  Canary Islands since an M 5.4 on December 27, 2013 following a similar eruptive phase.

Hundreds have been evacuated and hundreds of buildings destroyed in the eruption, but no deaths have been attributed to the eruption to date. The M 4.3 occurred within about an hour of local solar noon and may have been promoted by high tidal stresses with the new moon which maximize near this hour. Forecast 137308 had expected continuing eruptive earthquakes in the Canary Island at the end of September and early October.

 

O: 07OCT2021 07:18:45  28.6N   17.8W ML=3.5  EMSC   CANARY ISLANDS, SPAIN REGION

O: 07OCT2021 14:26:04  28.6N   17.8W ML=3.8  EMSC   CANARY ISLANDS, SPAIN REGION

O: 07OCT2021 15:49:15  28.6N   17.8W ML=3.6  EMSC   CANARY ISLANDS, SPAIN REGION

O: 08OCT2021 06:49:01  28.6N   17.8W ML=3.8  EMSC   CANARY ISLANDS, SPAIN REGION

O:  7OCT2021 11:17:08  28.7N   17.8W ML=4.3  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 DAAAA  Canary Islands             

 

 

STRONG EARTHQUAKE SHAKES SOUTHERN PAKISTAN WITH NEW MOON

 

EARTHQUAKE SUMMARY FOR OCTOBER  6, 2021

 

The strongest earthquake in the world today occurred as an M 5.9 in Pakistan. NEIC reported slight damage and intensity VIII in Baluchistan, Pakistan at Sibi; VII in Harnai; V in Kot Abdul, Charman; IV in Quetta and Bhag and II-III in Loralai, Multan, Punjab and in Kandahar, Afghanistan. An aftershock of M 4.6 was reported with intensity V in Harnai, and IV in Quetta, Baluchistan, Pakistan. This event was probably promoted by a Tropical Cyclone, the strongest in the area in years, that passed over this epicenter several days ago as noted in previous issues of this summary:

 

"Tropical Cyclone Shaheen-Gulab (03B) continued today south of eastern Iran with winds up to 85 kts. It is expected to track to the west areas south of Iran in the next several days. Some enhanced seismicity may occur in southern Iran as this storm is in the area." (October 1-3, 2021)

 

and

 

"Tropical Cyclone Gulab (03B) resumed today south of Pakistan with winds up to 65 kts. It is expected to track to the west areas south of Iran in the next several days. Some enhanced seismicity may occur in southern Iran as this storm is in the area." (October 1-2, 2021)

 

Today's M 5.9 is the strongest earthquake in Pakistan within about 250 km of this epicenter since an M 6.4 on October 28 and again on October 29, 2008.  Forecast 137647 had expected regionally enhanced seismicity in Pakistan was likely around October 6.

 

O: 07OCT2021 00:00:56  30.2N   68.0E mb=4.6  EMSC   PAKISTAN

O:  6OCT2021 22:01:08  30.2N   68.1E Mw=5.9  EMSC   PAKISTAN                     

P:  6OCT2021 137647    36.0N   69.0E 3.8-5.4 ACAAA  Hindu Kush/Pakistan        

 

A series of earthquakes occurred today in connection with the new moon which arrived this morning of October 6 as noted in this and previous issues of this summary as:

 

"The New moon arrived at 11:05 UT on October 6. Longitudes which were at local solar noon at this time are near 15 East while those at local solar midnight are near 165 West longitude. In the west these include most areas of Europe and Africa and in the east the central Aleutians and the Alaska Peninsula, Hawaii and the Tonga-Fiji-Kermadec arc. These area are the most likely to see a strong tidally triggered earthquake in the next week. Other areas may also see tidal triggering. These are most likely to occur near local solar midnight and local solar noon. The possibility of a strong to major earthquake is considered moderate to strong before October 10." (October 3-6, 2021)

 

An earthquake of M 4.9 in Bosnia and Herzegovina was widely felt today. NEIC reported it was felt with maximum intensity V in Makarska Split, Dalmacia, Croatis and IV in Supetar, Split, Jesenice, Mravince, Vranjic, and in Tomisiavgrad, Bosnia and Herzegovina with lesser shaking at Katuni, Breia, and Tucepi, Croatia. This epicenter is at the longitude of maximum tidal stress with this new moon and was probably promoted by high tidal stresses. This is the strongest earthquake within about 200 km of this epicenter since an M 5.4 on November 26, 2019 and prior to that an M 4.9 on November 18, 2013. A series of events about 200 km north of this on March 22, 2020 and December 28-29, 2020 included an M 6.4 which was damaging in the area. Forecast 137695 had expected today's event within about 100 km was likely around October 3. This event is at 102-103 degrees from the M 8.1 in the South Sandwich Islands of August 12 and from the M 7.2 in Haiti of August 14 and was probably promoted by energy from those sources.

 

O:  6OCT2021 19:57:34  43.6N   16.8E mb=4.8  EMSC   CROATIA                      

P:  3OCT2021 137695    43.0N   16.0E 3.0-5.3 BAAAA  Italy                      

 

An M 4.6 was widely felt in North Island, New Zealand today. NEIC reported intensity IV in Taumarunui Manawatu-Wanganui and II-III in Palmerston North, Levin, Kapiti, Upper Hutt and Lower Hutt, North Island, New Zealand.

GEONET reported this earthquake was felt with moderate intensity east of Stratford and in southwestern North Island and northern South Island. Light to moderate intensity was reported throughout much of southern North Island and northern South Island. More than 684 people reported feeling this earthquake with 538 reporting weak shaking; 132 light; 13 moderate and 1 strong intensity. This earthquake occurred within about an hour of local solar noon in an area of the highest tidal stresses with today's new moon and was probably tidally promoted. A similar M 4.6 occurred in this area on November 29, 2020 following an M 4.8 on November 20, 2020, the only such events within about 100 km  of this epicenter of M>=4.6 in the past year. Forecast 137805 had expected today's event in this area was likely around October 5.

 

O:  7OCT2021 00:09:21  39.2S  174.8E mb=4.6  EMSC   NORTH ISLAND OF NEW ZEALAND  

O: 07OCT2021 00:09:22  39.2S  174.8E MS=4.7  GEONET Felt with moderate intensity

P:  5OCT2021 137805    40.0S  174.0E 3.0-4.5 AAAAA  North Island, N.Z.         

 

An earthquake of M 5.4 was also felt in Tonga today. This event was reported by NEIC with intensity IV in Apia, Samoa and in American Samoa with intensity III. Like events in New Zealand and the Unimak Islands, Alaska, this is located near the longitude of maximum tidal stress with the current new moon and was probably promoted by tidal stresses. It is likely an aftershock of an  M 5.7 about 50 km north of this that occurred on October 2, 2021. The only other events in the area of larger magnitude in the past year occurred as an M 6.2 on November 7 and an M 5.9 on October 25, 2020.  Forecast 137779 had expected today's event was likely within about 100 km around October 5.

 

O:  6OCT2021 15:54:20  15.4S  173.3W mb=5.4  ANSS   NE of Hihifo Tonga           

P:  5OCT2021 137779    16.0S  174.0W 4.0-5.6 AAAAA  Tonga Islands              

 

An earthquake of M 5.4 was also felt in the region of Kyushu, Japan today. NEIC reported this was felt with maximum intensity VI in Miyazaki; V in Kagoshima, Japan. This is the strongest earthquake in Kyushu, Japan within about 200 km of this epicenter since an M 6.1 on May 9, 2019 more than two years ago.  Forecast 137650 had expected today's event within about 100 km was likely around October 8.

 

O:  6OCT2021 08:12:55  31.3N  131.3E Mw=5.5  EMSC   KYUSHU, JAPAN                

P:  8OCT2021 137650    31.0N  130.0E 3.5-4.9 AAAAA  Kyushu, Japan area         

 

An unusual earthquake of M 4.2 occurred in eastern Argentina near Formosa today. This event occurred at the maximum of a strong C4.0+ class solar flare and was probably promoted by effects from this flare (SFE) as it occurred near local solar midnight, a prime time for SFE. This is the first earthquake of M>=4.2 within about 300 km of this epicenter in at least 30 years. A deep focus event hit about 300 km west of this with M 5.6 on January 17, 2015, the only such regional event since at least 1990.

 

O:  7OCT2021 02:43:54  25.1S   60.8W ML=4.2  EMSC   FORMOSA, ARGENTINA           

 

The strongest earthquake in the U.S. or Canada today was an M 3.5 south of Mammoth Lakes, California. NEIC reported this earthquake of M 3.5 in Big Pine, California was felt with intensity II-III in the area(s) of Big Pine, California and Merced. The only event within about 50 km of this epicenter in the past year was an M 3.7 on February 14, 2021. An M 3.5 also hit the area a year ago on October 5, 2020. Forecast 137632 had expected today's event in this area was likely around October 7.

 

O:  6OCT2021 14:25:27  37.0N  118.3W Mw=3.5  EMSC   CENTRAL CALIFORNIA           

O: 06OCT2021 15:45:27  37.0N  118.3W Md=2.1  EMSC   CENTRAL CALIFORNIA

P:  7OCT2021 137632    37.4N  118.6W 2.5-4.8 AAAAA  California/Nevada area     

 

MODERATE QUAKE SHAKES NORTHERN HONSHU, JAPAN WITH TYPHOON MINDULLE

 

EARTHQUAKE SUMMARY FOR OCTOBER  5, 2021

 

The strongest earthquake in the world today was an M 5.6 off the east coast of northern Honshu, Japan. NEIC reported it was felt with maximun intensity VII in Miyako, Iwate and VI in Iwate and Tono with V in Nachinohe, Aomori; IV in Misawa, Morioka, Kesennuma, and III in Aomori, Sendai and Namie, Fukushima. This earthquake may have been promoted by stresses from Typhoon Mindulle which passed over this epicenter two days ago as reported in previous issues of this summary:

 

"Super Typhoon Mindulle (TS 20W) continued in the area east of Honshu, Japan today with winds up to 70 kts. This system is moving to the northeast and is currently south of eastern Honshu, Japan. It is  expected to track  north reaching areas south of  Honshu, Japan this week. Major seismic enhancement is possible in the area of Central and eastern Honshu in the next several days as this storm passes to the east." (October 2-3, 2021)

 

Today's event is the strongest within about 200 km of this epicenter in the current year. An M 6.3 hit the are about 100 km to the north on December 20, 2020, the last such event in the region. Forecast 137408 had expected today's activity within about 25 km at the end of September or in early October.

 

O: 05OCT2021 22:33:30  40.0N  142.2E ML=4.0  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 05OCT2021 14:22:02  40.4N  143.9E mb=4.5  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O:  5OCT2021 17:46:02  40.0N  142.2E Mw=5.6  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 28SEP2021 137408    40.0N  142.0E 3.5-5.5 CAAAA  Hokkaido, Japan            

 

An earthquake of M 5.4 also occurred in the Ryukyu Islands of Japan today.

NEIC reported these earthquakes of M 5.4 and an aftershock of 5.2 in the Ryukyu Islands, Japan were felt with intensity II-III in the area(s) of the Ryukyu Islands, Japan at Okinawa. This is the strongest earthquake in the Ryukyu Islands in more than a year. This shallow focus earthquake is the strongest in the Ryukyu Islands within about 150 km of this epicenter since an M 5.4 on August 8, 2012. Forecast 137622 had expected this activity around October 3.

This activity is at 142 degrees from the M 8.1 in the South Sandwich Islands of August 12 and may have been promoted by energy from that source.

 

O: 05OCT2021 17:30:28  25.8N  125.1E Mw=5.4  EMSC   SOUTHWESTERN RYUKYU ISL., JAPAN

O:  5OCT2021 18:03:43  25.6N  125.1E Mw=5.2  EMSC   SOUTHWESTERN RYUKYU ISL., JAPA

P:  3OCT2021 137622    25.0N  123.0E 4.0-5.6 AABAA  Ryukyu Islands             

 

The strongest earthquake in the U.S. or Canada today was an M 4.5-4.6 in the current eruption at Kilauea, Hawaii. NEIC reported this event was felt with intensity IV in Hawaii at Hawaii National Park, Pahala, Volcano, with III in Naalehu, Captain Cook, Pahoa, Mountain View, Hilo, Kurtistown and Holualoa.

This activity was apparently triggered by the new moon. It occurred near the maximum stress associated with the current new moon as described in previous issues of this summary as:

 

"The New moon will arrive at 11:05 UT on October 6. Longitudes which are at local solar noon at this time are near 15 East while those at local solar midnight are near 165 West longitude. In the west these include most areas of Europe and Africa and in the east the central Aleutians and the Alaska Peninsula, Hawaii and the Tonga-Fiji-Kermadec arc. These area are the most likely to see a strong tidally triggered earthquake in the next week. Other areas may also see tidal triggering. These are most likely to occur near local solar midnight and local solar noon. The possibility of a strong to major earthquake is considered moderate to strong before October 10." (October 3-5, 2021)

 

The last earthquake in the area of Kilauea, Hawaii with greater magnitude than M 4.6 was an M 5.5 on March 13, 2019. An M 4.5 also occurred at exactly the same depth (32.7 km) as today's event on June 18, 2021. Forecast 137594 had expected today's event, part of the current eruption of Kilauea, around October 6.

 

O: 06OCT2021 06:39:23  19.2N  155.5W ML=3.4  EMSC   ISLAND OF HAWAII, HAWAII

O:  6OCT2021 06:36:55  19.3N  155.5W ML=4.5  EMSC   ISLAND OF HAWAII, HAWAII     

O:  6OCT2021 06:36:55  19.3N  155.5W ML=4.6  ANSS   ISLAND OF HAWAII, HAWAII     

P:  6OCT2021 137594    19.4N  155.4W 3.0-4.8 AAAAA  Hawaii                     

 

Elsewhere in the U.S. and Canada a series of moderate earthquakes occurred in the Unimak Island region of Alaska today with M 3.7, 4.4 and 4.5. These may be aftershocks of an M 5.1 event on September 9, 2021 with the last new moon.    Forecast 137743 had expected today's events within about 100 km of these epicenters in the Unimak Island area was likely around October 7.

 

O: 06OCT2021 03:42:21  53.5N  163.4W mb=4.5  EMSC   UNIMAK ISLAND REGION, ALASKA

O: 06OCT2021 05:21:53  53.7N  163.6W ml=3.7  EMSC   UNIMAK ISLAND REGION, ALASKA

O:  6OCT2021 06:42:48  53.4N  163.5W mb=4.4  EMSC   UNIMAK ISLAND REGION, ALASKA 

P:  7OCT2021 137743    54.0N  164.9W 3.5-4.9 AAAAA  Unimak Islands, Aleutians   

 

A set of unusual earthquakes in northwestern Canada also occurred today. These included an M 3.9 near Grande Prairie, Alberta; an M 3.3 in the Northern Yukon Territory, Canada and an M 3.7-4.0 near Beaver Creek, Yukon Territory about 500 km to the southwest of this event. Forecasts 137445, 137756 and 137470 had expected this activity in late September or early October. None of these events were reported felt.

 

O:  5OCT2021 19:16:13  54.5N  118.5W ML=3.9  EMSC   ALBERTA, CANADA              

O: 05OCT2021 19:16:13  54.5N  118.5W MB=3.9  ECAN Grande Prairie, AB   

P: 30SEP2021 137445    56.0N  120.0W 2.0-4.0 BBAAA  Alberta                    

 

O: 05OCT2021 07:28:47  66.0N  135.1W MB=3.3  ECAN Fort McPherson, NT   

O:  5OCT2021 07:28:47  66.0N  135.1W ML=3.3  EMSC   NORTHERN YUKON TERRITORY, CANA

P:  9OCT2021 137756    66.9N  135.8W 3.0-4.8 BAAAA  Northern Alaska            

 

NEIC reported the earthquake of M 3.9-4.0 in East-central Alaska was felt with intensity II-III in the area(s) of East-central Alaska at Palmer.

 

O: 05OCT2021 18:24:30  62.2N  141.6W MB=4.0  ECAN Beaver Creek, YT   

O:  5OCT2021 18:24:29  62.2N  141.6W ML=3.7  EMSC   CENTRAL ALASKA               

P: 28SEP2021 137470    61.0N  140.0W 3.2-4.9 CBAAA  Central Alaska             

 

EUROPE ACTIVE NEAR NEW MOON

 

EARTHQUAKE SUMMARY FOR OCTOBER  4, 2021

 

A series of unusual to moderate earthquakes occurred in Europe today with the

coming New Moon. The largest of these was an M 4.3 near the Swiss-French-Italian

border, but other unusual events occurred in Turkey and the Dodecanese Islands, Greece and the eruption of the volcanic eruption in La Palma, Canary Islands intensified.

 

An unusually large M 4.3 earthquake shook the region of Switzerland and Italy today. NEIC reported maximum intensity shaking in Switzerland at Sion Wallis; III in Italy at Aosta Valle d Aosta, Issogne, in France at Bassens Rhone-Alpes and in Karisfeld, Bayern Germany. This event may have been promoted by high tidal stresses associated with tomorrow's new moon as previously noted in this summary:

 

"The New moon will arrive at 11:05 UT on October 6. Longitudes which are at local solar noon at this time are near 15 East while those at local solar midnight are near 165 West longitude. In the west these include most areas of Europe and Africa and in the east the central Aleutians and the Alaska Peninsula and the Tonga-Fiji-Kermadec arc. These area are the most likely to see a strong tidally triggered earthquake in the next week. Other areas may also see tidal triggering. These are most likely to occur near local solar midnight and local solar noon. The possibility of a strong to major earthquake is considered moderate to strong before October 10." (October 4-5, 2021)

 

The last earthquake of M>=4.3 within about 150 km of this epicenter in northern Italy was an M 4.4 on October 24, 2016. Forecast 137690 had expected today's  event was likely in this area around October 6. This earthquake is located at 103-104  degrees from the M 7.1 in Mindanao, Philippines of August 11, 2021 and may have been promoted by energy from that source. Other earthquakes at this distance from Mindanao today occurred as an M 3.8 in Central California, in  Southern Idaho with M 2.9, and in northern California and Nevada.

 

O:  5OCT2021 05:39:25  46.0N    7.5E ML=4.3  ANSS   SWITZERLAND                  

O:  5OCT2021 05:39:25  46.0N    7.5E ML=4.1  EMSC   NORTHERN ITALY               

P:  6OCT2021 137690    45.0N    8.0E 3.0-5.3 AAAAA  Austria                    

 

NEIC reported the earthquake of M 4.4 in Dodecanese Islands, Greece was felt with intensity II-III in the area(s) of  Greece at Kos.

 

O:  4OCT2021 14:03:23  36.5N   27.2E mb=4.4  EMSC   DODECANESE IS.-TURKEY BORDER R

P:  6OCT2021 137629    36.0N   27.0E 3.0-5.1 AAAAA  Aegean Sea                  

 

The eruption at La Palma, Canary Islands, Spain also intensified today becoming explosive with falling pyroclasts and bombs. This eruptio hs forced the evacuation of more than 6000 residents and destroyed at least 946 houses since it began on September 19. The largest earthquake yet in the current eruption occurred today with M 3.9-4.0 and was included among a series of other earthquakes of similar size, unlike previous eruptive phases where the strongest associated earthquakes were in the M 3-3.5 range. An M 3.8-3.9 also occurred in the Canary Islands just prior to the eruption in mid-September on September 14.

Forecast 137308 had expected today's activity in late September or early October.

 

O: 04OCT2021 18:58:51  28.6N   17.8W ML=3.7  EMSC   CANARY ISLANDS, SPAIN REGION

O: 05OCT2021 03:36:38  28.6N   17.8W ML=3.9  EMSC   CANARY ISLANDS, SPAIN REGION

O:  4OCT2021 14:30:59  28.6N   17.8W ML=3.7  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 AAAAA  Canary Islands             

 

An earthquake of M 3.8 rocked Central California today. NEIC reported intensity IV in California at Soledad, and II-III in Gonzales, Salinas, Hollister, Paicines, Carmel Valley among others. NEIC reported an aftershock of M 2.7 in Northern California was felt with intensity II-III in the area(s) of Northern California at Discovery Bay, Byron, Brentwood, Antioch, Tracy, San Ramon, Stanford, Felton, Santa Cruz and Los Banos. NEIC reported other aftershocks of M 2.8 and 2.8 in Central California was felt with intensity II-III in the area(s) of Central California at Greenfield, Los Banos, Salinas and Dos Palos.

The last earthquake of M>=3.8 in this region of California was an M 4.1 on August 31, 2021. Other events in the area in the past year included an M 5.2 on January 17, 2021. Forecast 137649 had expected today's seismic enhancement in this area was likely around October 3.

 

O: 04OCT2021 23:07:48  36.6N  121.3W ML=3.3  EMSC   CENTRAL CALIFORNIA

O: 04OCT2021 23:07:48  36.6N  121.3W ML=3.8  ANSS   CENTRAL CALIFORNIA

O: 05OCT2021 05:03:36  36.6N  121.3W Md=2.0  EMSC   CENTRAL CALIFORNIA

O:  4OCT2021 16:36:50  37.9N  121.6W ML=2.5  EMSC   NORTHERN CALIFORNIA          

P:  3OCT2021 137640    37.9N  122.0W 2.5-4.7 AAAAA  Central California          

 

A series of minor earthquake hit the Yellowstone National Park, Wyoming today. The last similar swarm in Yellowstone occurred on September 8, 2021 with the last new moon. Today's activity was also probably promoted by the new moon of September 6. At that time this summary noted in this regard:

 

 

"Seismicity in the Yellowstone National Park area of Wyoming was enhanced today. A pair of earthquakes of M 3.0 each was recorded. This is the strongest activity in Yellowstone since an M 3.6 on July 17, 2021. It occurred near local solar  noon and may have been promoted by energy from the M 7.0 in Mexico or geomagnetic or tidal stresses." (September 8, 2021)

 

Forecast 137726 had expected today's activity in Yellowstone was likely around

October 4.

 

O: 04OCT2021 22:39:56  44.8N  110.6W Ml=2.4  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 04OCT2021 23:38:47  44.8N  110.6W Ml=2.1  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 05OCT2021 00:30:08  44.8N  110.6W ML=2.5  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O:  4OCT2021 22:37:02  44.8N  110.6W Ml=2.5  EMSC   YELLOWSTONE NAT. PARK, WYOMING

P:  4OCT2021 137726    44.2N  110.3W 2.0-4.1 AAAAA  Yellowstone/Wyoming        

 

An M 4.6 in the region of Negros, Philippines was widely felt today.

 

"A tropical cyclone may be forming over Negros, Philippines. This storm is currently located at 10N 122W and moving to the west with winds up to 22 kts. Seismic enhancement in the central Philippines may occur as this storm moves through the area." (October 4, 2021)

 

Today's event occurred as this storm passed over the epicenter. Two earthquakes of equal or greater magnitude have occurred in Negros, Philippines in the past year - an M 4.8 on September 5 and an M 4.6 on June 29, 2021.

Forecast 137552 had expected activity in this area in early October.

 

NEIC reported this earthquake of M 4.6 in Negros, Philippines was felt with intensity II-III in the area(s) of Negros, Philippines at Sipalay, Western Visayas.

 

O:  4OCT2021 20:12:05   9.9N  122.1E mb=4.6  EMSC   NEGROS, PHILIPPINES          

P:  6OCT2021 137552     8.0N  125.0E 4.0-5.4 AABAA  Central Philippines        

 

MODERATE QUAKE IN IRAN PROMOTED BY TC SHAHEEN-GULAB

 

EARTHQUAKE SUMMARY FOR OCTOBER  3, 2021

 

An M 5.6 earthquake was widely felt in western Iran today with some damage reported. NEIC reported it was felt with intensity VII in Khuzestan, Iran at Masjed Soleyman and Izeh; IV in Arac and al-Baarah and II-III in Ahwaz, Borujen, Mcbaakeh, Aspanada, and Salmya, Kuwait. This epicenter may have been promoted by stresses associated with Tropical Cyclone Shaheen-Gulab which is passing to the south of this epicenter at this time and was expected in previous issues of this summary as:

 

"Tropical Cyclone Shaheen-Gulab (03B) continued today south of eastern Iran with winds up to 85 kts. It is expected to track to the west areas south of Iran in the next several days. Some enhanced seismicity may occur in southern Iran as this storm is in the area." (October 1-3, 2021)

 

Today's event in Iran is the strongest within about 200 km of this epicenter since an M 5.7 more than two years ago on July 8, 2019. An M 5.6 also shook the area on September 25, 2002 but since then most activity of larger magnitude in the area has occurred about 200 km to the west of today's epicenter. Forecast 137677 and 137387 had expected today's activity within this are was likely at the end of September or in early October. This epicenter is at 105 degrees from the M 7.2 in Haiti of August 14, 2021 and may have been promoted by energy from that source.

 

O:  4OCT2021 02:39:27  32.3N   49.8E Mw=5.6  EMSC   WESTERN IRAN                 

P:  4OCT2021 137677    31.0N   50.0E 3.8-5.3 ABAAA  So. Iran                   

P: 25SEP2021 137387    32.0N   49.0E 3.8-5.3 CAAAA  So. Iran                   

 

The strongest earthquake in the world today was an M 6.2 in the South Sandwich Islands. This is the strongest earthquake in the South Sandwich Islands since an M 7.1 on  August 22. These are aftershocks of an M 8.1 in the area on August 12. This epicenter, like those yesterday in Brazil and the South Indian Ocean is located near 103 degrees from the M 7.2 in Vanuatu of October 2 and was probably promoted by energy from that source. An earthquake of M 5.2 in the Prince Edward Islands today was also at 103 degrees from the Vanuatu epicenter. The last earthquake within about 200 km of this epicenter with M>=5.2 was an M 6.2 on November 17, 2014. An earthquake about 200 km from this epicenter also occurred with M 5.2-5.3 on August 7, 2021. Forecast 137811 had expected the event in the Prince Edward Islands was likely around October 6 wile forecast 137813 had expected the event in the South Sandwich Islands was likely around October 6. Other activity today near 103 degrees from Vanuatu occurred as an M 4.9 in Nicaragua an M 4.6 in northern Chile, light quakes in Peninsular India and an M 3.8 in northern Kansas.

 

O:  4OCT2021 04:12:41  47.0S   33.7E mb=5.2  EMSC   PRINCE EDWARD ISLANDS REGION 

P:  6OCT2021 137811    51.0S   29.0E 4.0-5.4 ACCAA  Atlantic-Indian Ridge      

 

O:  4OCT2021 03:54:07  60.4S   27.7W Mw=6.2  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  6OCT2021 137813    60.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 in the Fox Islands, Aleutians, Alaska. This appears to be an aftershock of the M 5.1 which shook the area on October 1, 2021. Forecast 137729 had expected today's activity was likely within about 15 km of this epicenter around October 6.

 

O:  3OCT2021 15:53:37  52.2N  171.2W mb=4.6  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P:  6OCT2021 137729    52.1N  171.3W 3.5-5.3 AAAAA  Andreanoff Isls, Aleutians 

 

A light to moderate earthquake of M 3.8 was felt in north-central Kansas today. NEIC reported this earthquake of M 3.8 in Kansas was felt with intensity II-III in the area(s) of Kansas at Lindsborg, Salina, Solomon, Galva, Abilene, Marquette, McPherson and Hutchinson and IV in Gypsum and Assaria.  This is the strongest earthquake in Kansas since an M 3.9 on March 14, 2021. A similar M 3.8 hit about 100 km north of today's epicenter on May 6, 2001. The only other event in Kansas in the past year of M>=3.5 was an M 3.8 on December 30, 2020. Forecast 137681 had expected today's activity within about 100 km was likely in Kansas around October 3.

 

O:  4OCT2021 02:58:14  38.7N   97.5W mb=3.8  EMSC   KANSAS                       

P:  3OCT2021 137681    39.0N   99.0W 2.0-4.1 AAAAA  Southern Plains            

 

STRONG QUAKES SHAKE LATITUDES NEAR GEOMAGNETIC EQUATOR

 

EARTHQUAKE SUMMARY FOR OCTOBER  2, 2021

 

Two earthquakes - of M 5.9 on the Peru-Brazil border and M 6.1 in the South Indian Ocean - today occurred near the geomagnetic equator. These were probably promoted by stresses associated with the geomagnetic storm still in progress at this time. Both were near 103 degrees from the M 7.2 in the Vanuatu Islands which occurred yesterday – October 2. Other events at this distance from Vanuatu today occurred in Chile, Costa Rica and Tennessee among others. In the previous issue of this summary it had been noted as:

 

"The geomagnetic field saw disturbed  conditions today. The AP level was 15.  High latitude geomagnetic field  saw minor storm conditions with AP 6. The coming geomagnetic storm is likely to enhance seismicity at high latitudes and near the geomagnetic equator. The only similar storm in the past month occurred with  AP 24 on September 17 and with AP 14 on September 8. The geomagnetic storm of September 8 accompanied the M 7.1 in Guerrero, Mexico. Today's storm is likely to trigger a strong earthquake near the geomagnetic equator." (October 1-2, 2021)

 

A strong deep focus earthquake occurred with M 5.9 today under the Peru-Brazil border. NEIC reported it was lightly felt in Acre, Brazil at Tarauaca and Porto Walter. This epicenter is on the geomagnetic equator and was likely enhanced by stresses associated with today's geomagnetic storm. This is the strongest earthquake within about 250 km of this epicenter since an M 6.8 about 200 km northwest of this on January 5, 2019 and an M 7.1 to the south on August 24, 2018. Forecast 137488 had expected a moderate quake in this region of Brazil was likely in late September or early October. This epicenter is at 108 degrees from the M 7.2 in Vanuatu which occurred yesterday - October 2 - and was probably promoted by energy from that source.

 

O:  2OCT2021 12:52:35   9.6S   71.3W Mw=5.9  EMSC   PERU-BRAZIL BORDER REGION    

P: 29SEP2021 137488    10.0S   75.0W 3.5-5.2 BACAA  Brazil                     

 

The strongest earthquake in the world today was an M 6.0 in the Mid-Indian Ridge. This is an unusual epicenter well to the north of the normal seismicity in the region. The only earthquake within about 300 km of this epicenter in the past 30 years of M>=6 was an M 6.1 on March 22, 1998. Forecast 137774 expected regional activity south of this in the Southern Indian Ocean was likely around October 5.  This epicenter is at 103 degrees from the M 7.2 in Vanuatu which occurred yesterday - October 2 - and was probably promoted by energy from that source.

 

O:  2OCT2021 20:43:41   9.2S   67.1E Mw=6.0  EMSC   MID-INDIAN RIDGE             

P:  5OCT2021 137774    15.0S   67.0E 4.0-5.6 BCAAA  So. Indian Ocean           

 

A moderate earthquake of M 5.4 was felt in Mindoro, Philippines today. NEIC reported maximum intensity VIII with slight damage in Soujthern Tagalog at Tuban; VI at Sablayan, V at Mamburao, IV in Bacoor and III in San Vicente, Philippines. Like the events in Brazil and the South Indian Ocean today, this epicenter is also on the geomagnetic equator and was probably promoted by stresses associated with the current geomagnetic storm. This is an aftershock of an M 6.7 in Mindoro, Philippines on July 23, 2021. Moderately strong aftershocks in this region have also occurred on August 13 (M 5.8) and September 26 (M 5.7). Forecast 137598 had expected today's activity was likely around October 5.

 

O: 02OCT2021 23:33:33  12.9N  121.0E mb=4.7  EMSC   MINDORO, PHILIPPINES

O:  2OCT2021 21:59:27  12.9N  120.9E mb=5.2  EMSC   MINDORO, PHILIPPINES         

O:  2OCT2021 21:59:27  12.9N  120.9E mb=5.4  ANSS   MINDORO, PHILIPPINES         

O:  3OCT2021 00:45:42  13.9N  120.7E mb=4.4  EMSC   MINDORO, PHILIPPINES         

P:  5OCT2021 137598    13.0N  121.0E 3.5-5.2 AAAAA  Luzon, Philippines         

 

The eruption of Kilauea on Hawaii continued today uninterrupted. The strongest earthquake in Hawaii today was an M 3.4 which NEIC reported was felt with intensity II in Hilo and Holualoa, Hawaii. Forecast 137594 had expected this activity was likely in early October.

 

O: 02OCT2021 19:59:22  19.3N  155.4W ML=3.6  EMSC   ISLAND OF HAWAII, HAWAII

O:  2OCT2021 13:47:40  19.2N  155.5W ML=3.0  EMSC   ISLAND OF HAWAII, HAWAII     

P:  3OCT2021 137594    19.9N  156.1W 3.0-4.8 AAAAA  Hawaii                     

 

An M 3.4 was also widely felt in the San Francisco Bay, California area today. NEIC reported maximum intensity IV in Oakland and San Leandro, California and III in Castro, Alameda among others. This is the strongest earthquake in the San Francisco Bay area since an M 3.9 near this epicenter occurred on June 29, 2021. Three events of M 3.6 hit the region in the first half of 2021. Forecast 137640 had expected today's earthquake was likely within about 15 km of this epicenter around October 3. Today's event occurred within about half an hour of local solar noon and may have been promoted by high tidal stresses which maximize near this hour.

 

O:  2OCT2021 19:22:26  37.8N  122.1W ML=3.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O:  2OCT2021 19:22:26  37.8N  122.1W ML=3.4  ANSS   SAN FRANCISCO BAY AREA, CALIF.

P:  3OCT2021 137640    37.9N  122.0W 2.5-4.7 AAAAA  Central California         

 

The strongest activity in the U.S. or Canada today were events of M 4.1 in Western Texas and an M 4.0 in Southern Idaho. These are part of long-term series in these areas and do not represent unusual changes in seismicity in these area. The event in western Texas had been expected to occur around October 4 in forecast 137664,

 

NEIC reported this earthquake of M 4.1 in Western Texas was felt with intensity II-III in the area(s) of Western Texas at Pecos. Smaller earthquakes of M 3.6 and M 3.4 were registered with similar intensities earlier in the day near Mentone, Texas.

 

O: 02OCT2021 18:55:43  31.7N  104.0W ML=3.6  EMSC   WESTERN TEXAS

O: 02OCT2021 18:57:45  31.7N  104.0W ML=2.8  EMSC   WESTERN TEXAS

O: 03OCT2021 01:39:18  31.7N  104.0W ML=4.1  EMSC   WESTERN TEXAS

O: 03OCT2021 01:48:10  31.7N  104.0W ML=3.4  EMSC   WESTERN TEXAS

O: 03OCT2021 01:58:09  31.7N  104.0W ML=3.0  EMSC   WESTERN TEXAS

O:  2OCT2021 13:46:37  31.6N  104.1W ML=2.6  EMSC   WESTERN TEXAS                

P:  4OCT2021 137664    31.2N  104.1W 2.0-4.0 AAAAA  SW U.S.A                   

 

The M 4.0 in Southern Idaho is another in a strong aftershock sequence which began with an M 6.5 on March 31, 2020. The last event of M>=4 in this area was an M 4.0 on September 19, 2021. Forecast 137700 had expected today's event was likely around October 4.

 

NEIC reported this earthquake of M 4.0 in Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho at Lowman, Boise, Meridian, Leadore, Jerome, and IV in Stanley.

 

O: 02OCT2021 23:47:42  44.3N  115.0W Mw=4.0  EMSC   SOUTHERN IDAHO

O: 03OCT2021 01:34:37  44.3N  115.0W ML=2.8  EMSC   SOUTHERN IDAHO

O:  2OCT2021 07:50:57  44.3N  115.0W Ml=2.0  EMSC   SOUTHERN IDAHO               

P:  4OCT2021 137700    44.4N  115.1W 2.0-4.1 AAAAA  Montana/Idaho              

 

Seismicity in Iran continued at an elevated level today as Tropical Cyclone Shaheen-Gulab passed to the south. This storm has killed at least 3 people as it hit the area of Oman today. An unusual M 3.6 in northeastern Iran today may have been promoted by stresses associated with this storm which was noted in the previous summary as:

 

"Tropical Cyclone Shaheen-Gulab (03B) continued today south of eastern Iran with winds up to 85 kts. It is expected to track to the west areas south of Iran in the next several days. Some enhanced seismicity may occur in southern Iran as this storm is in the area." (October 1-2, 2021)

 

O:  3OCT2021 05:21:13  34.2N   57.2E ML=3.6  EMSC   NORTHEASTERN IRAN            

P: 30SEP2021 137330    33.0N   60.0E 3.8-5.2 BBCAA  Afghanistan                

 

An earthquake of M 4.6 also occurred today in the region of the northern mid-Atlantic Ridge. This occurred as Tropical Storm Victor passed over the area and probably was promoted by stresses associated with this storm as noted previously  in this summary:

 

"TS Victor continued today over the mid-Atlantic Ridge with winds up to 35 kts. It is expected to track to the northwest as a Tropical Depression as it passes over the northern mid-Atlantic ridge. Some enhanced seismicity in this region is likely while this storm is in the area." (October 1-2, 2021)

 

Forecast 137618 had expected this earthquake was likely in early October within about 50 km of this epicenter. This epicenter is at 143 degrees from the M 7.2 in Vanuatu of October 2 and was probably promoted by energy from that source.

 

O:  2OCT2021 15:57:41  22.6N   45.2W mb=4.6  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P:  3OCT2021 137618    21.0N   46.0W 4.0-5.8 ABAAA  Mid-Atlantic Ridge         

P:  5OCT2021 137618    23.0N   45.0W 4.0-5.8 BAAAA  Mid-Atlantic Ridge          

 

Today's event was not reported felt in this remote area.

 

MAJOR DEEP FOCUS QUAKE IN VANUATU SHAKES FIJI

 

EARTHQUAKE SUMMARY FOR OCTOBER  1, 2021

 

A major earthquake of M 7.2-7.3 occurred today in the area east of the Loyalty Islands at deep focal  depth. NEIC reported it was felt within about 1000 km of the epicenter with intensity III in Tonga at Ohonua Eua, and in Fiji at Deuba, Nadi, Suva and in Nuku'alofa Tongatapu, Tonga. There were no deaths, damage or casualties reported with this event. This earthquake followed the second strongest geomagnetic storm in the past month. This was emphasized in this and previous issues of this summary as:

 

"The geomagnetic field saw disturbed  conditions today. The AP level was 15.  High latitude geomagnetic field  saw minor storm conditions with AP 6. The coming geomagnetic storm is likely to enhance seismicity at high latitudes and near the geomagnetic equator. The only similar storm in the past month occurred with  AP 24 on September 17 and with AP 14 on September 8. The geomagnetic storm of September 8 accompanied the M 7.1 in Guerrero, Mexico. Today's storm is likely to trigger a strong earthquake near the geomagnetic equator." (October 1-2, 2021)

 

Because of the depth of this event (535 km) no tsunami was expected nor observed.

 

Today's event of M 7.3 is the strongest recorded within about 200 km of this epicenter in the past 30 years. An M 7.2 hit the area on August 12, 2016 and a larger event of M 7.6 occurred in the area on March 3, 1990 with M 7.6. A major earthquake of M 7.7 and large aftershocks hit the area of the Loyalty Islands on February 10, 2021 about 400 km to the southwest of today's epicenter. Forecasts 137793 and 137521 had expected today's earthquake within  about 100 km was likely between September 30 and October 5.

 

O: 02OCT2021 06:45:24  21.5S  174.7E mb=4.7  EMSC   VANUATU REGION

O:  2OCT2021 06:29:18  21.1S  174.9E Mw=7.2  EMSC   VANUATU REGION               

O:  2OCT2021 06:29:18  21.1S  174.9E Mw=7.3  ANSS   VANUATU REGION               

P:  5OCT2021 137793    21.0S  176.0E 4.0-5.8 BAAAA  Tonga/Fiji                 

P: 30SEP2021 137521    21.0S  176.0E 4.0-5.8 AAAAA  Tonga/Fiji                 

 

The earthquake in Vanuatu followed about an hour after an M 5.7 event to the northeast in the region of Samoa. This event was reported by NEIC to have been felt with maximum intensity IV in Samoa at Saanapu Uta and at Sll Savall. The last event of larger magnitude within about 200 km of today's epicenter in Samoa occurred on November 7, 2020 and prior to that as an M 5.9 on October 24, 2020. Forecast 137495 and 137772 had expected today's activity was likely in late September or early October.

 

O:  2OCT2021 04:24:40  14.9S  173.7W Mw=5.7  EMSC   SAMOA ISLANDS REGION         

P:  5OCT2021 137772    15.0S  174.0W 4.0-5.4 BAAAA  Samoa Islands              

P: 27SEP2021 137495    15.0S  174.0W 4.0-5.5 BAAAA  Samoa Islands              

 

A report in "Nature" today details the seismicity accompanying the eruption of an underwater volcano near Mayotte, which began with a series of earthquakes on May 10, 2018. This is the largest active submarine eruption ever documented according to the authors and now runs 31 miles between East Africa and Madagascar. The eruption has created a new underwater volcano up to 1000 feet tall and is the strongest in the area in at least 4,000 years.

 

Meanwhile the new eruptions of Kilauea, Hawaii and Cumbre Viejo, Canary Islands volcanoes continued unabated. The La Palma eruption of Cumbre Viejo took on new life as lava erupted from two new vents and exploded into the sky with ash and gas sent up to 20,000 feet into the air. More than 1000 buildings have been destroyed in this eruption which began two weeks ago while up to 6000 have been evacuated. Worsening air quality has forced the Spanish government to issue a stay-at-home order to residents advising them to  keep windows and doors closed to prevent outside air from entering homes and shops. Forecast 137308 had expected this activity was likely in late September.

 

O: 01OCT2021 16:53:29  28.6N   17.8W ML=3.4  EMSC   CANARY ISLANDS, SPAIN REGION

O: 01OCT2021 18:45:12  28.6N   17.8W ML=3.4  EMSC   CANARY ISLANDS, SPAIN REGION

O:  1OCT2021 14:13:01  28.6N   17.9W ML=3.6  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 CAAAA  Canary Islands             

 

 

The eruption in Hawaii which began September 29 also continued with lava flows and ejections from fissures in the Halemaumau crater. Volcanic glass from this eruption has been detected high in the atmosphere above Kilauea Volcano. Volcanic glass in the area is commonly referred to as "Pele's Hair". An unusual M 3.0 earthquake also occurred west of Hawaii today. Forecast 137594 had expected this event about 25 km to the north was likely around October 3.

 

O:  2OCT2021 06:09:06  19.6N  156.1W ML=3.0  EMSC   HAWAII REGION, HAWAII        

P:  3OCT2021 137594    19.9N  156.1W 3.0-4.8 AAAAA  Hawaii                     

 

The strongest earthquakes in the U.S. or Canada today occurred in Alaska with an M 5.0 aftershock in the Alaska Peninsula and an M 4.7 in the central Andreanof Islands. The event in the Andreanof Islands is the strongest in that region since an M 4.9 on July 11, 2021. The last event in the regionof M>=5 was and M 5.3 exactly one year ago on October 1, 2020. Forecast 137447 had expected today's event was likely within about 25 km around September 29.

 

O:  1OCT2021 21:21:41  52.2N  176.2W mb=4.7  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 29SEP2021 137447    51.9N  176.0W 3.5-5.1 AAAAA  Andreanoff Isls, Aleutians 

 

The earthquake of M 5.0 in the Alaska Peninsula is an aftershock of the M 8.2 there on July 29, 2021. The only aftershocks since late July in the area within about 100 km of the mainshock were an M 5.6 on September 16, 2021 and an M 6.9 on August 14, 2021. Forecast 137444 had expected a moderate aftershock in the Alaska Peninsula around September 29.

 

O:  1OCT2021 14:12:52  56.0N  156.5W Mw=5.0  EMSC   ALASKA PENINSULA             

P: 29SEP2021 137444    54.8N  158.7W 3.5-5.0 ABBAA  Alaska Peninsula           

 

QUAKE SHAKES FOX ISLANDS, ALASKA; VOLCANIC ERUPTION AT KILAUEA, HAWAII

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 30, 2021

 

The strongest earthquake in the U.S. or Canada today was an M 5.1 in the Fox Islands, Aleutians, Alaska. NEIC reported it was felt with intensity II in Nikolski, Atka and Adak, Alaska. This event is near the antipode of an M 5.8 in the region south of Africa  on September 25 and was possibly affected by antipodal focusing of energy from that event. The last earthquake with M>=5.1 within about 200 km of this epicenter occurred a year ago on September 27, 2020 and September 28 with M 5.2 and 5.5 respectively. Today's event had been expected within about 50 km around September 29.

 

O: 01OCT2021 00:10:53  52.1N  171.2W Mw=5.1  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O:  1OCT2021 00:24:41  52.0N  171.2W mb=4.8  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 29SEP2021 137448    52.4N  170.7W 3.5-4.9 AAAAA  Andreanoff Isls, Aleutians 

 

Kilauea Volcano in Hawaii resumed a major eruption today after three years of  quieter volcanism since the eruption of the summer of 2018. This follows several moderate earthquakes in the area in the past several days as noted in this summary in previous issues as:

 

 

"The strongest earthquake in the U.S. or Canada today was an M 3.8 in Hawaii. NEIC reported it was felt with maximum intensity in Mountain View and II-III in Naalehu, Captain Cook, Volcano, Holualoa, Hilo, Panoa, Paauilo, Kailua Kona, Hakalau.

 

The epicenter of this earthquake is near Mauna Loa, unusual for the current seismicity of Hawaii. An M 3.9 hit northwest of Hawaii on September 25, also an unusual epicenter as noted in this summary at the time:

 

 

"An earthquake of M 3.9 also occurred in northwestern Hawaii near Oahu today. It was not reported felt in this remote area. Two other earthquakes of M>=3.9 have occurred within about 150 km of this epicenter in the Oahu area of Hawaii have been recorded in the past 30 years - an M 4.1 on May 20, 2005 and an M 3.9 (September 25, 2021)

 

 

NEIC reported an earthquake of M 3.1 in Hawaii was felt with intensity II-III in the area(s) of Hawaii in Hilo.  Forecast 137284 had expected enhanced seismicity in Hawaii at the end of September.

 

O: 30SEP2021 20:31:15  19.3N  155.3W Ml=3.1  EMSC   ISLAND OF HAWAII, HAWAII     

P: 27SEP2021 137284    19.4N  155.1W 3.0-4.6 BAAAA  Hawaii                     

 

Major volcanic eruptions also continued in the Canary Islands, Spain and in Iceland today. Lava from the eruption at La Palma, Canary Islands reached the sea and exploded with great clouds of sulfuric acid. Forecast 137308 had expected this eruption in late September.

 

O: 30SEP2021 18:50:29  28.6N   17.8W ML=3.4  EMSC   CANARY ISLANDS, SPAIN REGION 

O: 30SEP2021 20:30:12  28.6N   17.9W ML=3.5  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 CAAAA  Canary Islands             

 

O: 30SEP2021 22:10:25  63.9N   22.2W ML=3.2  EMSC   ICELAND REGION

O:  1OCT2021 02:06:49  63.9N   22.2W ML=3.4  EMSC   ICELAND REGION               

P:  2OCT2021 137754    64.0N   25.0W 3.0-4.6 AABAA  Iceland area               

 

A moderate earthquake of M 5.2 also shook southern Iran today. NEIC reported this earthquake of M 5.2 in Iran was felt with intensity II-III in the area(s) of Iran with VI in Dogonbadan; V in Bandar-e Genaveh; IV in Omidieh and II in Bandar-e Mah Shahr, Khuzestan. This event may have been  promoted by stresses associated with Tropical Cyclone Gulab which made landfall to the east of this today. This summary had noted this possibility as:

 

"Tropical Cyclone Gulab (03B) resumed today south of Pakistan with winds up to 65 kts. It is expected to track to the west areas south of Iran in the next several days. Some enhanced seismicity may occur in southern Iran as this storm is in the area. " (September 30, 2012)

 

The last earthquake in Iran of M>=5.2 within about 250 km of this epicenter was an M 5.8 within about 25 km of this epicenter on April 18, 2021. Today's event may be an aftershock of that mainshock. Forecast 137387 had expected today's quake within about 100 km was likely in late September. This epicenter is at the third node (120 degrees) from the M 6.9 in Vanuatu of August 18, 2021 and may have been promoted by energy from that source.

 

O: 01OCT2021 02:33:21  29.8N   50.5E mb=4.6  EMSC   SOUTHERN IRAN

O:  1OCT2021 01:15:21  29.8N   50.5E mb=5.2  EMSC   SOUTHERN IRAN                

P: 25SEP2021 137387    30.0N   52.0E 3.8-5.3 CABAA  So. Iran                   

 

STRONG QUAKE SHAKES HONSHU, JAPAN

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 29, 2021

 

The strongest earthquake in the world today was an M 6.1 in the Sea of Japan. This deep focus earthquake was felt widely in Japan with maximum intensity VI in Ishikawa; V in Fukushima and II-III in Miyagi Saitama, Tokyo and Kanagawa.

This epicenter is at 103 degrees from the M 7.1 in Guerrero, Mexico of September 8, 2021 the last major earthquake in the world and was probably promoted by energy from that source. It occurred as Typhoon Mindulle was making landfall on the continental slope south of Honshu, Japan and was also probably triggered by strong stresses associated with that storm as noted in the previous issue of this summary:

 

"Super Typhoon Mindulle (TS 20W) continued in the area south of Japan today with winds up to 140 kts. This system is moving to the northwest and is currently south of central Honshu, Japan. It is  expected to track  north reaching areas south of  Honshu, Japan this week. Major seismic enhancement is possible in the area of Central and eastern Honshu in the next several days as this storm approaches." (September 28-29, 2021)

 

The M 6.1 in the Sea of Japan today is the strongest earthquake in that area within about 200 km since an M 6.2 on March 31, 1995. The only other such event in the area in the past 30 years was an M 6.6 on January 19, 1993. Forecast 137433 had expected a strong earthquake in this region was possible around September 29.

 

O: 29SEP2021 08:37:05  38.9N  135.4E Mw=6.1  EMSC   SEA OF JAPAN                 

P: 29SEP2021 137433    41.0N  136.0E 3.5-5.6 ABAAA  Sea of Japan               

 

An earthquake of M 5.3 near the antipode of the Sea of Japan occurred several hour before that event in the area of Mendoza, Argentina. NEIC reported this  earthquake was felt with maximum intensity V in Argentina at San Martin, Mendoza; IV in Mendoza at Mendoza and San Rafael, II-III in Puente Alto, Chile and in Corrientes, Argentina. This is the strongest earthquake in Mendoza, Argentina since an M 6.4 about 150 km to the north on January 19, 2021 and before that an M 5.5 on June 20, 2019. Forecast 137524 had expected activity in this area was likely around September 28. Like the current volcanic eruption in La Palma, Canary Islands, Spain, this epicenter is at the seventh node (51.5 degrees) from the M 7.2 in Haiti of August 14 and was probably promoted by energy from that source.

 

O: 29SEP2021 07:53:57  33.1S   68.1W mb=5.3  EMSC   MENDOZA, ARGENTINA           

P: 28SEP2021 137524    35.0S   70.0W 4.0-5.5 ABBAA  Central Chile              

 

The strongest earthquake in the U.S. or Canada today was an M 4.5 in the Near Islands, Aleutians, Alaska. It was not reported felt in this remote area. The last earthquake of M>=4.5 in the Near Islands was an M 5.2 on August 9 and this appears to be an aftershock of that event. Forecast 139453 had expected today's epicenter would be active within about 50 km around September 28.

 

O: 29SEP2021 23:29:18  53.3N  170.9E mb=4.5  EMSC   NEAR ISLANDS, ALEUTIAN ISLANDS

P: 28SEP2021 137453    53.0N  170.0E 4.0-5.6 AAAAA  Near Islands               

 

The swarm of earthquakes in western Texas continued today. NEIC reported this earthquake of M 4.2 in  Western Texas was felt with intensity II-III in the area(s) of Western Texas  at Pecos and in New Mexico at Roswell and Carlsbad.

The largest of these was the M 4.2 within about half an hour of local solar midnight and was probably promoted by high tidal stresses which maximize near this hour. This follows an M 4.3 on September 23, 2021, an event associated with the full moon and which also occurred shortly after 07:30 UT (local solar midnight). Forecast 137371 had expected today's activity was likely at the end of September.

 

O: 29SEP2021 11:11:25  31.6N  104.4W ML=2.0  EMSC   WESTERN TEXAS

O: 30SEP2021 04:19:43  31.6N  104.3W ML=2.8  EMSC   WESTERN TEXAS

O: 29SEP2021 07:22:08  31.7N  104.4W mb=4.1  EMSC   WESTERN TEXAS

O: 29SEP2021 07:30:51  31.7N  104.4W ML=2.2  EMSC   WESTERN TEXAS

O: 29SEP2021 07:34:39  31.7N  104.4W ML=2.4  EMSC   WESTERN TEXAS

O: 29SEP2021 08:18:20  31.7N  104.4W ML=2.5  EMSC   WESTERN TEXAS

O: 29SEP2021 20:02:51  31.7N  104.2W ML=3.1  EMSC   WESTERN TEXAS

O: 29SEP2021 07:54:55  31.5N  104.4W ML=2.4  EMSC   WESTERN TEXAS                

P: 25SEP2021 137371    32.5N  104.6W 2.0-3.9 BAAAA  SW U.S.A                   

 

AFTERSHOCKS CONTINUE IN CRETE; CENTRAL CALIFORNIA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 28, 2021

 

Aftershocks continued today in Crete, Greece. The largest of these were felt with maximum intensity IV in Iraklion, Greece at Ano Korakiana with lesser shaking at Gournai and Koutouloufarion. Forecast 137327 had expected this activity within about 100 km was likely in Crete around September 30.  This epicenter is at 103 degrees from the M 8.1 in the South Sandwich Islands of August 12, and may have been promoted by energy from that source.

 

 

O: 28SEP2021 15:13:16  35.1N   25.2E mb=4.3  EMSC   CRETE, GREECE                

P: 30SEP2021 137327    35.0N   24.0E 3.0-4.6 AAAAA  Aegean Sea                 

 

Two earthquakes of M 3.8 hit the area of the Nevada-California border today near Markleeville. NEIC reported this activity was felt with intensity IV in Coleville, California and II-III shaking in California at Topaz, Markleeville, South Lake Tahoe, Arnold, and in Nevada at Glenbrook, Minden, Gardnerville, and Wellington. These are aftershocks of the M 6.0 in the area that occurred on July 8, 2021. The only events in the past two months in the area with M>=3.8 occurred September 18 (M 4.0 and August 27 (M 4.4). Forecast 137336 had expected today's activity was likely around September 27. This activity is at 103 degrees from the  M 7.1 in Mindanao of August 11 and may have been promoted by energy from that source.

 

O: 28SEP2021 14:10:17  38.5N  119.5W ml=2.0  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 15:12:38  38.5N  119.5W ML=3.4  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 15:12:38  38.5N  119.5W ML=3.8  ANSS   CENTRAL CALIFORNIA

O: 28SEP2021 17:30:27  38.5N  119.5W Md=2.1  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 19:08:19  38.5N  119.5W Md=2.2  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 13:55:23  38.6N  119.6W ML=2.5  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 15:12:12  38.6N  119.5W Mw=3.8  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 15:14:22  38.6N  119.5W MD=2.4  EMSC   CENTRAL CALIFORNIA

O: 28SEP2021 13:58:36  38.5N  119.5W ml=2.2  EMSC   CENTRAL CALIFORNIA           

P: 27SEP2021 137336    38.8N  119.6W 2.5-4.6 AAAAA  California/Nevada area     

 

The strong sequence reported in the northern Gulf of California in the previous issue of this summary continued unabated today. The largest earthquakes in the area today were M 3.8 and 3.9. Forecast 137370 had expected this activity was likely around September 25 within about 50 km.

 

O: 28SEP2021 09:56:41  30.8N  114.4W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 09:56:41  30.8N  114.4W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 17:41:46  30.8N  114.3W ML=3.8  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 18:23:39  30.8N  114.3W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 18:55:58  30.8N  114.2W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 18:59:19  30.8N  114.2W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 17:21:16  30.9N  114.3W ML=3.5  EMSC   GULF OF CALIFORNIA

O: 28SEP2021 09:18:13  30.8N  114.4W ML=3.9  EMSC   GULF OF CALIFORNIA           

P: 25SEP2021 137370    30.2N  114.1W 2.0-3.9 BAAAA  SW U.S.A                   

 

 

The strongest earthquake felt in the world today was an M 5.2 in the state of Yap, Micronesia. NEIC reported this earthquake of M 5.2 in Yap, Micronesia was felt with intensity II-III in the area(s) of Yap, Micronesia. Two earthquakes occurred with M 5.2 on February 26 in Micronesia about 200 km south of today's event. A foreshock of M 4.7 occurred  at today's epicenter with M 4.7 on September 26. Today's activity occurred  shortly after Typhoon Mindulle passed over this epicenter and Guam as noted in previous issues of this summary:

 

"Tropical Storm 20W (Mindulle) formed in the area of Guam today with winds up to 45 kts. This system is moving to the northwest and is currently over the island of Guam. Guam often shows seismic enhancement with tropical systems passing through and may with the current storm." (September 23-27, 2021)

 

Forecast 137277 had expected today's event within about 100 km was likely around

September 30.

 

O: 28SEP2021 16:26:54  10.5N  139.1E mb=5.2  EMSC   STATE OF YAP, MICRONESIA     

P: 30SEP2021 137277    10.0N  138.0E 3.5-4.9 AAAAA  Caroline Islands           

 

Typhoon Mindulle continued today south of central Honshu, Japan. This summary had expected this storm could reach Honshu in the next several days and could influence seismicity in the area as reported in previous issues as:

 

“Super Typhoon Mindulle (TS 20W) continued in the area south of Japan today with winds up to 140 kts. This system is moving to the northwest and is currently south of central Honshu, Japan. It is  expected to track  north reaching areas south of  Honshu, Japan this week. Major seismic enhancement is possible in the area of Central and eastern Honshu in the next several days as this storm approaches.” (September 26-28, 2021)

 

An M 4.2 near the east coast of Honshu was lightly felt in eastern Honshu. Forecast 137367 had expected this activity within about 100 km was likely around September 26. Further enhanced seismicity in Honshu is likely in the next several days as Typhoon Mindulle passes by the area. This epicenter is at 103 degrees from the M 7.1 in Mexico of September 8,  and may have been promoted by energy from that source.

 

O: 29SEP2021 03:26:30  36.4N  140.7E ML=4.2  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 26SEP2021 137367    36.0N  140.0E 4.0-5.5 BAAAA  Off East Coast Honshu      

 

Seismicity was also up in the Canary Islands where a volcanic eruption has been occurring in La Palma, Spain for several weeks. Earthquakes M 3.4 and three of M 3.3 today were the strongest since an M 3.9 the day before the eruption on September 14 and an M 3.6 on September 19. This coincides with  the continuing eruption of lava in the area reached the sea today producing plumes of sulfuric acid. Forecast 137308 had expected this activity in late September.

 

O: 28SEP2021 15:51:48  28.6N   17.8W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 28SEP2021 16:23:28  28.6N   17.8W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 28SEP2021 17:15:46  28.6N   17.9W ML=3.4  EMSC   CANARY ISLANDS, SPAIN REGION

O: 28SEP2021 22:19:00  28.6N   17.8W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 29SEP2021 02:53:40  28.5N   17.8W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 BAAAA  Canary Islands              

 

VOLCANIC ERUPTION IN CANARY ISLANDS RESUMES; DANGEROUS AFTERSHOCKS IN CRETE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 27, 2021

 

A strong aftershock sequence followed the M 6.0 in Crete, Greece today. The largest of these were in the mid-5's magnitudes and were reported by NEIC to have been felt with maximum intensity V in Iraklion, Greece at Anissaras, IV in Skalanion, Dafries, Iraklion, Ayia Eirini, Kato Gouvai, Ayios Dimitrios, Greece among others. Slight damage continued following the strongest aftershocks. The number of injured people is now listed at more than 20. Forecasts 137348 and 137327 had expected today's activity in Crete at the end of September.

 

O: 27SEP2021 08:21:58  35.1N   25.3E ML=4.5  EMSC   CRETE, GREECE

O: 27SEP2021 10:23:12  35.1N   25.3E ML=4.0  EMSC   CRETE, GREECE

O: 27SEP2021 11:02:25  35.1N   25.2E ML=4.8  EMSC   CRETE, GREECE

O: 27SEP2021 21:37:10  35.1N   25.3E mb=4.7  EMSC   CRETE, GREECE

O: 28SEP2021 04:48:09  35.1N   25.1E Mw=5.3  EMSC   CRETE, GREECE

O: 27SEP2021 07:46:30  35.2N   25.2E ML=4.1  EMSC   CRETE, GREECE

O: 27SEP2021 20:10:01  35.2N   25.2E ML=4.4  EMSC   CRETE, GREECE

O: 27SEP2021 07:30:49  35.1N   25.3E mb=4.6  EMSC   CRETE, GREECE                

P: 27SEP2021 137348    34.0N   24.0E 3.0-4.6 ABAAA  Crete                       

P: 30SEP2021 137327    35.0N   24.0E 3.0-4.6 BAAAA  Aegean Sea                 

 

The volcanic eruption in the Canary Islands resumed today following a calm period over the past two days. Lava flows from the Cumbre Vieja volcano in La Palma, Spain destroyed many buildings and proceeded towards the shoreline. Thousands have been evacuated from this eruption. Air flights were also disrupted. This activity had been expected in late September in forecast 137308.

 

O: 28SEP2021 05:37:38  28.6N   17.9W ML=2.6  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 BAAAA  Canary Islands             

 

A light earthquake of M 3.3 was widely felt in South Carolina today. NEIC reported maximum intensity VI in South Carolina at Summerville, Lasson and North Charleston with II-III shaking in Charleston, Goose Creek, Johns Island, Saint George, Walterboro, Sumter, Tybee. It was also reported lightly felt in Georgia, North Carolina, Virginia and Florida among others. A foreshock of M 2.8 was felt with intensity II-III in South Carolina at Summerville, Ladson, North Charleston, Ridgeville, Charleston, Goose Creek, Moncks Corner. This activity may be related to Hurricane Teresa which has been lingering off the east coast of the Carolinas for the past several days as noted in previous issues of this summary:

 

"TS Teresa formed today in the area east of North Carolina with winds up to 40 kts. It is expected to track to the north over the next day and stay in the central Atlantic." (September 24-26, 2021)

 

This system is currently off the coast of South and North Carolina at 35N 60W.

 

The M 7.7 in Charleston, South Carolina of August 31, 1886 followed a great

earthquake in southern Greece several days earlier and has been suggested on several occasions in this and other reports (even at the time of that quake) to have been a far-field aftershock of the M 8.4 in Greece as noted in the history section of this summary:

 

"The Charleston, South Carolina earthquake. This earthquake was preceded by four days of small foreshocks which began immediately after an M 8.4 in central Greece. That earthquake may have disturbed the groundwater sufficiently to lubricate the fault responsible for the for the Charleston quakes ultimately triggering the strong event." (August 31, 2021)

 

Today's activity may also have been related to the M 6.0 in Crete several hours earlier.

 

The M 3.3 today is the strongest earthquake within about 150 km of this epicenter since an M 3.6 on December 16, 2008. Forecast 137351 had expected today's activity to the north was possibly in late September.

 

O: 27SEP2021 16:57:19  33.0N   80.2W Md=2.0  EMSC   SOUTH CAROLINA

O: 27SEP2021 16:49:14  33.1N   80.2W mb=3.1  EMSC   SOUTH CAROLINA

O: 27SEP2021 22:21:57  32.9N   80.2W Md=3.3  EMSC   SOUTH CAROLINA               

P: 23SEP2021 137351    35.0N   83.0W 2.0-4.1 BCBAA  Kentucky/Tennessee/NC      

 

Some of the felt reports from Virginia may have been related to an M 2.6 in northern Virginia earlier in the day directly north of the South Carolina epicenters. NEIC reported this event was felt with maximum intensity IV in Virginia at Roanoke and II-III in Elliston, Salem. Catawba, Blacksburg, Christiansburg, Cooper Hill, Bedford, Alta Vista and Lynchburg. Forecast 137351 had expected this activity was likely in late September.

 

O: 27SEP2021 13:37:24  37.3N   80.2W mb=2.1  EMSC   VIRGINIA                     

O: 27SEP2021 13:37:24  37.3N   80.2W mb=2.6  ANSS   VIRGINIA                     

P: 27SEP2021 137351    37.0N   77.0W 2.0-4.4 AABAA  Kentucky/Tennessee/NC      

P: 28SEP2021 137351    37.0N   83.0W 2.0-3.9 AABAA  Kentucky/Tennessee/NC      

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in Hawaii. NEIC reported it was felt with maximum intensity in Mountain View and II-III in Naalehu, Captain Cook, Volcano, Holualoa, Hilo, Panoa, Paauilo, Kailua Kona, Hakalau. The epicenter of this earthquake is near Mauna Loa, unusual for the current seismicity of Hawaii. An M 3.9 hit northwest of Hawaii on September 25, also an unusual epicenter as noted in this summary at the time:

 

 

"An earthquake of M 3.9 also occurred in northwestern Hawaii near Oahu today. It was not reported felt in this remote area. Two other earthquakes of M>=3.9 have occurred within about 150 km of this epicenter in the Oahu area of Hawaii have been recorded in the past 30 years - an M 4.1 on May 20, 2005 and an M 3.9 on August 5, 2002." (September 25-26, 2021)

 

The last earthquake in the active zone of Hawaii of M>=3.9 was an M 4.1 on

August 18, 2021 and an M 3.9 on August 14, 2021. Forecast 137284 had expected today's activity was likely around September 27.

 

O: 27SEP2021 13:42:35  19.2N  155.5W ML=3.9  EMSC   ISLAND OF HAWAII, HAWAII     

P: 27SEP2021 137284    19.4N  155.1W 3.0-4.6 AAAAA  Hawaii                      

 

A strong series of earthquakes including an M 4.4 and 4.0 also hit in the northern Gulf of California today. This region has been active in recent weeks, but this is the strongest activity at this epicenter since an 4.4 on December 12, 2019 and June 13, 2019. The last event of larger magnitude in the region was an M 5.2 on April 6, 2019. Forecast 137370 had expected today's activity within about 50 km was likely around September 25.

 

O: 27SEP2021 20:03:30  30.8N  114.2W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 20:10:04  30.8N  114.3W ML=3.5  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 20:53:19  30.8N  114.3W ML=3.5  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 21:23:42  30.8N  114.3W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 21:49:56  30.8N  114.3W ML=4.0  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 21:57:05  30.8N  114.3W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 21:57:05  30.8N  114.3W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 17:20:41  30.9N  114.1W mb=4.4  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 19:36:46  30.9N  114.4W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 20:08:57  30.9N  114.3W ML=3.3  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 19:48:35  31.0N  114.4W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 20:11:07  31.0N  114.3W ML=3.2  EMSC   GULF OF CALIFORNIA

O: 27SEP2021 19:51:18  30.8N  114.4W ML=3.8  EMSC   GULF OF CALIFORNIA           

P: 25SEP2021 137370    30.2N  114.1W 2.0-3.9 AAAAA  SW U.S.A                   

 

STRONG EARTHQUAKE STRIKES CRETE, GREECE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 26, 2021

 

The strongest earthquake in the world today was an M 6.0 in Crete, Greece. NEIC reported it was felt with minor damage in Iraklion, Greece with VIII in Episkopi, Khanion tou Kokkini, Arkalokhorion, VI in Gournai, Skalanion, Kato Gouval, V in Thrapsonon, IV in Epano Arkhanai and Nea Alkarnassoa and II in Anissaras. Reuters reported today's event killed at least one person when the dome of a church at Arkalochori collapsed and damaged many buildings near the epicenter. In addition several people were injured and some were trapped in debris from damaged buildings. Evacuations took place through much of the island. Aftershocks could damage older buildings further. The last earthquake in Crete with M>=6 was an M 6.6 about 150 km southeast of today's epicenter on May 2, 2020. At the time of this event this summary noted:

 

"Today's earthquake in Crete is the strongest within about 200 km of that epicenter in at least 30 years. The area has been active in recent months with an M 5.8 to the east on January 30, 2020 and an M 6.0 on November 27, 2019. These events were more than 200 km from today's epicenter." (May 3, 2020)

 

Forecasts 137328 and 137348 had expected today's activity in Crete was likely around September 27. This epicenter is at 141 degrees from the M 6.9 in Vanuatu of August 18 and at 103 degrees from the M 8.1 in the South Sandwich Islands of

August 12 and may have been promoted by energy from those sources.

 

O: 27SEP2021 06:37:43  35.1N   25.3E mb=4.6  EMSC   CRETE, GREECE

O: 27SEP2021 06:22:13  35.2N   25.3E ML=4.0  EMSC   CRETE, GREECE

O: 27SEP2021 06:17:22  35.1N   25.2E Mw=6.0  EMSC   CRETE, GREECE                

P: 27SEP2021 137328    35.0N   27.0E 3.0-5.0 AABAA  Aegean Sea                 

P: 27SEP2021 137348    34.0N   24.0E 3.0-4.6 ABAAA  Crete                      

 

A moderately strong M 5.7 shook regions of Mindoro, Philippines today. NEIC reported intensity VI in Southern Tagalog, Philippines at Calatagan and Tuy; V in Lubang, Terenate, Alas-asin, Central Luzon; IV in Matabungkay, Balayan, Calantas, Kaytitinga, and Anuling. Minor damage was reported. An aftershock of M 4.5 was felt in Mindoro at Balite, Malanday, IV in Dasmarinas, Cainta, and light shaking in San Pedro, Mariveles, Manila, Niogan, Guiguinto. This appears to be an aftershock of an M 6.7 within about 25 km of this epicenter which occurred July 23. An M 5.8 aftershock also shook the region on August 13, 2021. At the time of the mainshock in July this summary had noted in this regard:

 

"Today's event is the strongest event within about 250 km of today's epicenter

in more than 20 years - since an M 7.3 about 250 km to the northwest on December 11, 1999. The strongest earthquake in the area in the past 31 years was an M 7.7 on July 16, 1990. July 16, 1990 about 250 km northeast of today's epicenter. This event in 1990, like today's, occurred at the sub-solar latitude." (July 24, 2021)

 

Forecast 137288 had expected seismic enhancement in this region of Mindoro, Philippines was likely within about 100 km of this epicenter around September 25. This epicenter is at 144 degrees from the M 7.2 in Haiti of August 14 and at the fifth node (72 degrees) from the M 8.1 in the Alaska Peninsula of July 29 and was probably promoted by energy from those sources.

 

O: 26SEP2021 17:12:05  13.9N  120.6E Mw=5.7  EMSC   MINDORO, PHILIPPINES

O: 26SEP2021 17:40:51  13.9N  120.8E mb=4.5  EMSC   MINDORO, PHILIPPINES         

P: 25SEP2021 137288    13.0N  121.0E 3.5-5.4 AAAAA  Luzon, Philippines         

 

Earthquakes of M 4.5 and 4.4 hit the region of northern Canada in the Baffin Bay area and near the north coast of Greenland today. The earthquake in Greenland was not reported felt, but the event in Baffin Bay may have been felt lightly. In the previous issue this summary noted in regard to the Baffin Bay event:

 

"The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Baffin Bay area of Nunavut, Canada. ECAN reported it was lightly felt in the area. This is the strongest earthquake within about 200 km of this epicenter since an M 4.6 on October 22, 2109 and an M 4.6 on May 22, 2017.  Forecast 137482 had expected today's event within about 50 km was likely around September 23." (September 25-26, 2021)

 

O: 26SEP2021 08:55:26  74.0N   73.4W mb=4.3  EMSC   BAFFIN BAY                   

O: 26SEP2021 08:55:26  74.0N   73.4W mb=4.5  ECAN   BAFFIN BAY                   

P: 23SEP2021 137482    73.3N   73.5W 2.5-4.1 BAAAA  Baffin/Davis Strait Canada 

 

The only earthquake of M>=4.4 within about 400 km the event in northern Greenland in the past 10 years was an M 4.6 on March 30, 2020. A  similar M 4.6 hit about 400 km southeast of today's epicenter on December 27, 2014.

 

O: 26SEP2021 16:06:15  82.9N   25.6W mb=4.4  EMSC   NEAR NORTH COAST OF GREENLAND

 

HIGH LATITUDES ACTIVE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 25, 2021

 

The strongest seismicity in the world today occurred at high latitudes - in northern Canada (M 4.4), the Reykjanes Ridge in the North Atlantic (M 4.6); at the antipode of the M 8.1 in the  Alaska Peninsula in the area south of Africa (M 4.7) and in the South Sandwich Islands. The largest of these was an M 5.4 in the South Sandwich Islands, an area where a long-standing aftershock sequence continues. These follow an M 8.1 on August 12, 2021 in the South Sandwich Islands. Forecast 137545 had expected this activity was likely around September 28.

 

O: 26SEP2021 04:23:09  58.8S   25.7W Mw=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 28SEP2021 137545    58.0S   26.0W 4.0-5.8 AAAAA  So. Sandwich Islands       

 

The M 4.7 in the area south of Africa is an aftershock of an M 5.8 in the area two days ago. This summary noted that event in the previous issue as:

 

 

"A moderately strong earthquake of M 5.8 also occurred near the antipode of the Andreanof Islands today in the region south of Africa. It was not reported felt in this remote area. The only events in the past 30 years within about 300 km  of this epicenter with M>=5.8 was an M 5.9 on February 18, 2009 and an M 5.8 on August 2, 1998. The true antipode of today's epicenter south of Africa is near the epicenter of the M 8.1 in the Alaska Peninsula of July 27, 2021. Antipodal concentration of energy from that event probably helped promote today's event in the area south of Africa. Forecast 137543 had expected today's event within about 200 km was likely around September 23. This epicenter is at 103 degrees from the M 7.1 in Mindanao, Philippines of August 11 and was probably promoted by energy from that source." (September 24-25, 2021)

 

O: 26SEP2021 01:40:32  53.5S   23.8E mb=4.7  EMSC   SOUTH OF AFRICA              

P: 23SEP2021 137543    53.0S   19.0E 4.0-5.5 BACAA  Atlantic-Indian Ridge      

 

The M 4.6 in the Reykjanes Ridge of the northern Mid-Atlantic Ridge follows similar events in the area on September 15 of M 4.6. These are apparently aftershocks of an M 5.4 on June 5. Today's event occurred near local solar midnight and may have been promoted by high tidal stresses.  Forecast 137455 had expected today's event within about 50 km around September 24.

 

O: 26SEP2021 03:07:34  58.2N   32.5W mb=4.6  EMSC   REYKJANES RIDGE              

P: 24SEP2021 137455    58.0N   32.0W 4.0-5.6 AAAAA  North Mid-Atlantic Ridge   

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Baffin Bay area of Nunavut, Canada. ECAN reported it was lightly felt in the area. This is the strongest earthquake within about 200 km of this epicenter since an M 4.6 on October 22, 2109 and an M 4.6 on May 22, 2017.  Forecast 137482 had expected today's event within about 50 km was likely around September 23.

 

O: 26SEP2021 08:55:27  73.8N   74.1W MB=4.4  ECAN OF POND INLET, NU              

P: 23SEP2021 137482    73.3N   73.5W 2.5-4.1 BAAAA  Baffin/Davis Strait Canada 

 

An earthquake of M 3.9 also occurred in northwestern Hawaii near Oahu today. It was not reported felt in this remote area. Two other earthquakes of M>=3.9 have occurred within about 150 km of this epicenter in the Oahu area of Hawaii have been recorded in the past 30 years - an M 4.1 on May 20, 2005 and an M 3.9 on August 5, 2002. Forecasts 137039 and 137311 had expected today's event in this region was likely in mid-September.

 

O: 25SEP2021 21:18:10  20.7N  158.6W ML=3.9  EMSC   OAHU REGION, HAWAII          

P: 18SEP2021 137039    20.1N  156.1W 4.0-5.6 CABAA  Hawaii area                

P: 27SEP2021 137311    20.3N  155.1W 4.0-5.6 AACAA  Hawaii area                

 

An earthquake of M 5.0-5.7 was reported felt in Taiwan today.  NEIC reported this earthquake of M 5.0 in Taiwan was felt with intensity II-III in the area(s) of Taiwan in Hsinchu, Taipei, Maoli, Taoyuan, an Taitung. CWB reported this earthquake was felt with intensity IV in Hualien, Yilan, Hsinchu, Taichung,  III in Nantou, Taoyuan, Taipei, Chiayi, Yunlin II in Chiayi, Tainan, Kaohsiung and I in Penghu and Pingtung Counties, Taiwan. This event was probably an aftershock of the M 5.2 in the area which occurred September 6. The last earthquake in Taiwan reported with M>=5.7 by EMSC was an M 5.8 on August 4, 2021. Forecast 137322 had expected today's activity was likely at the end of September within about 100 km of today's epicenter.

 

 

O: 25SEP2021 22:21:19  24.3N  121.8E Mw=5.0  EMSC   TAIWAN                       

O: 25SEP2021 22:21:19  24.3N  121.7E ML=5.7  TAI    Hualien, Taiwan              

P: 29SEP2021 137322    25.0N  123.0E 4.0-5.6 BAAAA  Ryukyu Islands             

 

STRONG TIDALLY TRIGGERED EARTHQUAKE IN ANDREANOF ISLANDS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 24, 2021

 

The strongest earthquake in the world today was an M 6.1 in the Andreanof Islands, Aleutians, Alaska. NEIC reported it was felt with maximum intensity IV in Atka and III in Unalaska, Alaska. The M 6.1 was preceded by an M 5.5 earlier in the day. The previous issue of this summary had noted this event as:

 

 

"The strongest earthquake in the U.S. or Canada today was an M 5.5 in the western Andreanof Islands of the Alaska Aleutian Islands. It was not reported felt in this remote area. It appears to have been triggered by a strong C-class solar flare (SWPC #6540) which reached maximum output X-ray flux within about a minute of the occurrence of this earthquake in the Andreanof Islands as detailed in this summary and by SWPC.

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

 

6740       0656   0701      0705   C2.9      (September 24, 2021)   8.8E-04  

 

The earthquake in the Andreanof Islands was also promoted by high tidal stresses associated with full moon of September 20 as expected in this and previous issues of this summary:

 

"The full moon  arrived at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 18-23, 2021)

 

Note that this epicenter is at the exact longitude where tidal stresses were expected to maximize with this full moon. The Andreanof Islands earthquake today is the strongest in that region since an M 5.6 on February 19, 2021 and an M 6.1 on January 3, 2021 - the only such activity in the past year.  Past history suggests this may be the first of several moderately large to large events in the western Aleutians in the next several days. Forecast 137446 had expected this earthquake within about 50 km was likely around September 25. This epicenter is near the fifth node (72 degrees) from the M 7.2 in Mexico of September 8 and may have been promoted by energy from that source." (September 23-24, 2021)

 

Today's M 6.1 occurred within a couple of minutes of local solar midnight and was probably enhanced by tidal stresses with the full moon which maximized at this hour on the earth as noted in the tidal forecast (see above).

 

The last earthquake in the Andreanof Islands with M>=6.1 was an M 6.1 on January 3, 2021 while the last of significantly larger size was an M 6.5 on August 15, 2018. The last of M>6.5 was an M 6.6 on May 2, 2008. Forecast 137446 had expected today's event within about 50 km was likely around September 25.  This epicenter is near the fifth node (72 degrees) from the M 7.2 in Mexico of September 8 and may have been promoted by energy from that source.

 

O: 24SEP2021 07:02:31  51.2N  179.1W Mw=5.5  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS.

O: 24SEP2021 11:52:29  51.3N  179.1W Mw=6.1  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 25SEP2021 137446    51.0N  179.9W 3.5-5.3 AAAAA  Andreanoff Isls, Aleutians 

 

A moderately strong earthquake of M 5.8 also occurred near the antipode of the Andreanof Islands today in the region south of Africa. It was not reported felt in this remote area. The only events in the past 30 years within about 300 km  of this epicenter with M>=5.8 was an M 5.9 on February 18, 2009 and an M 5.8 on August 2, 1998. The true antipode of today's epicenter south of Africa is near the epicenter of the M 8.1 in the Alaska Peninsula of July 27, 2021. Antipodal concentration of energy from that event probably helped promote today's event in the area south of Africa. Forecast 137543 had expected today's event within about 200 km was likely around September 23. This epicenter is at 103 degrees from the M 7.1 in Mindanao, Philippines of August 11 and was probably promoted by energy from that source.

 

O: 25SEP2021 05:21:35  53.4S   23.6E Mw=5.8  EMSC   SOUTH OF AFRICA              

P: 23SEP2021 137543    53.0S   19.0E 4.0-5.5 AACAA  Atlantic-Indian Ridge      

 

An earthquake of M 5.1 occurred today in the region of Guadeloupe, Leeward Islands. NEIC reported it was felt with maximum intensity VI in Anse-Bertrand and La Desirade, Guadeloupe and V in Potters Village, Antigua and Barbuda with intensity II-III in Guadeloupe at La Moule, Ooint-a-Pitre, Lamentink, and in Antigua and Barbuda at All Saints, Cedar Grove, Saint-John and Balands.  While this event is west of the M 5.8 in Guadeloupe of March 26, 2021, it is likely a regional aftershock of the earthquake. Forecast 137285 had expected today's event within about 25 km was likely around September 25.

 

O: 25SEP2021 03:12:15  16.8N   61.2W mb=5.1  EMSC   GUADELOUPE REGION, LEEWARD ISL

P: 25SEP2021 137285    17.0N   61.0W 3.0-4.9 AAAAA  Leeward Islands            

 

An unusually large earthquake of M 5.4 occurred in the Nicobar Islands of India today. NEIC reported this earthquake of M 5.4 in the Nicobar Islands, India was felt with intensity II-III in the area(s) of the Nicobar Islands, India at Port Blair. This follows a series of recent earthquakes in the area which suggest active seismicity is returning following the M>9 event of December 26, 2004 south of this. It is apparently the strongest aftershock to date of the M 6.1 which hit the area on August 3, 2021. At the time this summary noted in this regard:

 

 

"The strongest earthquake in the world today was an M 6.1 in the Nicobar Islands, India. NEIC reported it was felt with intensity II in Port Blair, Andaman and Nicobar Islands and possibly in Sumatra, Indonesia at Sabang Aceh and Banda Aceh. It followed a strong foreshock sequence felt in the same area. 

This event of M 6.1 is the strongest in the Nicobar Islands within about 200 km  of this epicenter since an M 6.4 about 200 km to the south on November 8, 2015." (August 3, 2021)

 

Forecast 137246 had expected today's earthquake was likely within about 100 km of this epicenter around September 26.

 

O: 24SEP2021 15:04:14   8.6N   93.9E Mw=5.4  EMSC   NICOBAR ISLANDS, INDIA REGION

P: 26SEP2021 137246     8.0N   93.0E 4.0-5.4 AAAAA  Nicobar Islands            

 

A minor earthquake of M 2.1 hit southeastern Maine today. It was not reported felt in this area near Portland. The only earthquake reported by NEIC in the area in the past year of M>=2.1 was an M 2.4 n March 19, 2021. Forecast 137420 had expected seismic enhancement in this area was likely around September 22.

 

O: 25SEP2021 04:23:43  43.6N   70.2W ML=2.1  EMSC   MAINE                        

P: 22SEP2021 137420    42.0N   71.0W 2.0-4.3 BBAAA  New England                

 

QUAKES IN GULF OF CALIFORNIA AND ALASKA OCCUR WITH STRONG SOLAR FLARES

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 23, 2021

 

Moderately strong earthquakes occurred on the western rim of the North American Tectonic Plate today simultaneously with two moderately large solar flares.

These events were an M 5.6 in the Gulf of California and an M 5.5 in the Andreanof Islands, Aleutians, Alaska. The strongest  earthquake in the world today was an M 5.6 in the Gulf of California. NEIC reported it was felt with maximum intensity V in La Palma, Sinaloa and IV in Escuinapa and II-III in Mazatlan, Costa Rica Culiacan, Los Mochis, and Puerto Vallarta, Jalisco. The mainshock was preceded about a minute earlier by a foreshock of M 5.2. The earthquake in the Gulf of California occurred during the occurrence of a strong solar flare as detailed in this summary below. This is the strongest earthquake within about 200 km of this epicenter in the Gulf of California since an M 6.1 about 100 km southwest of this on May 22, 2020 and an M 6.2 on October 8, 2014. Strong earthquakes in this region have occasionally preceded enhanced activity to the north in Southern California as stress migrates from the Gulf of California northwards. Forecast 137309 had expected today's activity within about 150 km of this epicenter was likely at the end of September. This epicenter is at 105 degrees from the M 8.1 in the South Sandwich Islands of August 12 and at the third node (120 degrees) from the M 7.1 in Mindanao of August 11 and may have been promoted by energy from those sources.

 

O: 23SEP2021 16:47:50  22.9N  108.0W mb=5.6  EMSC   OFF COAST OF BAJA CALIFORNIA SUR

O: 23SEP2021 16:47:07  23.1N  108.1W mb=5.2  EMSC   GULF OF CALIFORNIA           

P: 29SEP2021 137309    24.0N  109.0W 3.5-4.9 CAAAA  Gulf of California         

 

The strongest earthquake in the U.S. or Canada today was an M 5.5 in the western Andreanof Islands of the Alaska Aleutian Islands. It was not reported felt in this remote area. It appears to have been triggered by a strong C-class solar flare (SWPC #6540) which reached maximum output X-ray flux within about a minute of the occurrence of this earthquake in the Andreanof Islands as detailed in this summary and by SWPC.

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

 

6540       1503   1530      1650   C9.0      (September 23, 2021)   4.5E-03  

XXXX       0630   0702      0710   C4.0      (September 24, 2021)   3.6E-03  

 

The earthquake in the Andreanof Islands was also promoted by high tidal stresses associated with full moon of September 20 as expected in this and previous issues of this summary:

 

"The full moon  arrived at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 18-23, 2021)

 

Note that this epicenter is at the exact longitude where tidal stresses were expected to maximize with this full moon. The Andreanof Islands earthquake today is the strongest in that region since an M 5.6 on February 19, 2021 and an M 6.1 on January 3, 2021 - the only such activity in the past year.  Past history suggests this may be the first of several moderately large to large events in the western Aleutians in the next several days. Forecast 137446 had expected this earthquake within about 50 km was likely around September 25. This epicenter is near the fifth node (72 degrees) from the M 7.2 in Mexico of September 8 and may have been promoted by energy from that source.

 

O: 24SEP2021 07:02:30  51.2N  179.1W Mw=5.5  ANSS   WSW of Adak Alaska

O: 24SEP2021 07:02:31  51.2N  179.1W Mw=5.5  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 25SEP2021 137446    51.0N  179.9W 3.5-5.3 AAAAA  Andreanoff Isls, Aleutians 

 

The strongest earthquake felt in the U.S. or Canada today was an M 4.3 in western Texas. NEIC reported the earthquake of M 4.3 in Western Texas was felt with intensity II-III in the area(s) of Western Texas at Pecos and Mentone.

NEIC reported the aftershock of M 3.2 in Western Texas was felt with intensity II-III in the area(s) of New Mexico at Carlsbad. Only two earthquakes in the region of western Texas have equaled or exceeded this magnitude in the past year - an M 4.5 on March 17 and an M 4.3 on July 28, 2021. This sequence has been continuing for several years. Forecast 137371 had expected today's activity was likely around September 25 within about 100 km of this epicenter. It may have been promoted by high tidal stresses as the mainshock occurred within about an hour of local solar midnight, a time when tidal stresses maximize.

 

O: 23SEP2021 08:19:31  31.6N  104.0W ML=2.3  EMSC   WESTERN TEXAS

O: 23SEP2021 16:08:34  31.6N  104.5W ML=2.2  EMSC   WESTERN TEXAS

O: 23SEP2021 14:27:38  31.7N  104.4W ML=2.1  EMSC   WESTERN TEXAS

O: 23SEP2021 20:45:25  31.7N  104.2W ML=2.8  EMSC   WESTERN TEXAS

O: 23SEP2021 23:20:26  31.7N  104.4W ML=3.1  EMSC   WESTERN TEXAS

O: 23SEP2021 07:52:06  31.6N  104.0W ML=4.3  EMSC   WESTERN TEXAS                

P: 25SEP2021 137371    32.5N  104.6W 2.0-3.9 AAAAA  SW U.S.A                   

 

STRONG EARTHQUAKE HITS NICARAGUA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 22, 2021

 

The strongest earthquake in the world today was an M 6.6 in Nicaragua. NEIC reported this earthquake was felt with maximum intensity VI in Nicaragua and El Realejo, VII in San Francisco Chinandega; V in Chichigalpa, Leon, IV in Chinandega, Choluleca, Usulutan and II-III in Ciudad Sandino, Managua and Ticuantepe. The largest aftershock in Nicaragua was an M 5.6. NEIC reported this was felt with maximum intensity IV in Esteli and II-III in Ciudad Sandino, Managua, Nicaragua. This activity is located at 144 degrees from the M 7.1 in Mindanao, Philippines, similar to recent major earthquakes in Central Chile and Haiti (M 7.2). Activity was expected in this area as noted in the previous issue of this summary:

 

 

"The earthquake in Central Chile is at 144 degrees from the M 7.1 of August 11 in Mindanao, Philippines. This is the distance at which seismic energy is reflected to the surface after reflections and refractions off earth core boundaries. Strong seismic enhancement is commonly seen at this distance following strong earthquakes. Areas which have seen strong seismic enhance from Mindanao in the past month include Haiti (M 7.2); northern Mid-Atlantic (swarm including M 5.0 on August 31); the Central Mid-Atlantic (M 5.7); Dominican Republic. Some areas which have not yet seen strong seismicity at this distance from Mindanao in the past month include Costa Rica and Nicaragua. These area are due for an earthquake of M>=6." (September 21-22. 2021)

 

Nicaragua is no stranger to large earthquakes, but the last event of equal or larger magnitude than today's M 6.5 in Nicaragua was an M 7.0 on November 24, 2016 and an M 7.3 on October 14, 2014. The strongest earthquake near today's epicenter in the past 30 years was an M 7.7 on September, 1992 - an event which triggered a deadly tsunami. Forecasts 137021 and 137292 had expected enhanced seismicity in this area of Nicaragua within about 50 km of today's mainshock beginning in mid-September and lasting through September 24.

 

Today's activity in Nicaragua is located at 141 degrees from the M 7.1 in Mindanao, Philippines of August 11 and was likely promoted by energy from that source.

 

O: 22SEP2021 11:04:16  12.0N   87.9W ML=4.1  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 12:39:53  12.0N   87.9W ML=4.1  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 13:01:48  12.0N   87.7W ML=4.3  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 16:20:47  12.0N   87.8W mb=4.4  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 10:42:33  12.1N   87.8W mb=4.2  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 12:56:59  12.1N   87.7W Mw=5.6  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 13:29:45  12.1N   87.8W ML=4.0  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 09:57:08  12.2N   87.8W Mw=6.5  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 10:20:13  12.2N   87.7W mb=4.5  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 12:27:12  12.2N   87.6W mb=5.1  EMSC   NEAR COAST OF NICARAGUA

O: 23SEP2021 00:39:25  12.2N   87.8W mb=4.5  EMSC   NEAR COAST OF NICARAGUA

O: 22SEP2021 12:37:45  12.3N   87.8W mb=4.4  EMSC   NEAR COAST OF NICARAGUA

O: 23SEP2021 04:45:37  12.6N   88.3W ML=4.0  EMSC   OFFSHORE EL SALVADOR

O: 22SEP2021 11:15:51  11.7N   87.8W mb=4.1  EMSC   NEAR COAST OF NICARAGUA      

P: 14SEP2021 137021    13.0N   88.0W 3.5-5.5 AAAAA  Nicaragua                  

P: 23SEP2021 137292    12.0N   87.0W 3.5-5.8 AAAAA  Nicaragua                  

P: 24SEP2021 137292    13.0N   87.0W 3.5-6.3 AAAAA  Nicaragua                  

 

 

A series of light earthquakes also occurred today in the Virgin Islands. This included four events of M>=3.5 and one of M 4.0. This activity was probably promoted by the passage of Tropical Storm Peter and had been expected at this time in previous issues of the summary as:

 

"Tropical Storm Peter continued east of the Virgin Islands with winds up to 50 kts. It is expected to track to the west and north over the next week and not to make landfall. Some enhanced seismicity in the Virgin  Islands and northern Caribbean may occur in the next several days as this storm passes to the east." (September 20-22, 2021)

 

Forecast 137305 had expected today's enhanced seismicity was likely around September 24.

 

O: 23SEP2021 03:01:13  19.1N   65.2W Md=3.7  EMSC   VIRGIN ISLANDS REGION

O: 22SEP2021 22:36:09  19.2N   65.0W Md=3.5  EMSC   VIRGIN ISLANDS REGION

O: 23SEP2021 00:29:48  19.2N   65.2W ML=3.6  EMSC   PUERTO RICO REGION

O: 23SEP2021 01:08:10  19.2N   65.1W Md=3.3  EMSC   VIRGIN ISLANDS REGION

O: 22SEP2021 18:50:14  19.6N   64.4W ML=3.2  EMSC   VIRGIN ISLANDS REGION

O: 23SEP2021 02:55:05  19.0N   65.3W Md=3.5  EMSC   PUERTO RICO REGION           

P: 24SEP2021 137305    20.0N   66.0W 3.0-4.8 AAAAA  Bahamas/No. Caribbean      

 

An M 3.4 shook the area of Monterey Bay, California today. NEIC reported it was felt with intensity II-III in Moss Landing, Castroville, Marina, Pacific Grove, Seaside, Capitola, Santa Cruz, Salinas, Pebble Beach and Watsonville among others.   This is a somewhat unusual epicenter south of San Francisco. Such events in this region of Central California may indicate regional stress and a larger earthquake may shortly occur to the north of this epicenter. This is the farthest west of any event in the region off the coast of Central California of M>=3.4 since an M 3.4 on February 25, 2011, more than 10 years ago. Forecast 137340 had expected today's activity between September 22 and 26.

 

Today's activity in Central California is located at 103 degrees from the M 7.1 in Mindanao, Philippines of August 11.

 

O: 22SEP2021 09:57:44  36.8N  122.0W ML=2.8  EMSC   OFFSHORE CENTRAL CALIFORNIA  

O: 22SEP2021 09:57:44  36.8N  122.0W ML=3.4  ANSS   OFFSHORE CENTRAL CALIFORNIA  

P: 22SEP2021 137340    36.8N  121.3W 2.5-4.6 AAAAA  Central California         

P: 26SEP2021 137340    36.9N  121.7W 2.5-4.7 BAAAA  Central California         

 

A moderately strong M 5.5 also hit in southern Siberia today in the Chitinskaya Oblast' area. It was not reported felt in this region. This is the strongest earthquake within about 250 km of this epicenter since an M 5.6 on May 23, 2014. The strongest event in the area in the past 30 years was an M 5.9-6.0 on August 21, 1994. Forecast 137460 had expected today's event in this area was likely around September 24. This epicenter is at 103 degrees from the M 7.1 in Mexico of September 8 and was probably promoted by energy from that source.

 

O: 22SEP2021 17:01:27  56.4N  117.7E mb=5.5  EMSC   CHITINSKAYA OBLAST', RUSSIA  

P: 24SEP2021 137460    57.0N  121.0E 3.0-4.6 AABAA  So. Siberia                

 

STRONG EARTHQUAKE SHAKES VICTORIA, AUSTRALIA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 21, 2021

 

A strong earthquake of M 5.9 occurred today in Victoria, Southeastern Australia. It was reported by NEIC to have been felt with intensity V in Victoria at Healesville, Moe-Yallourn Taralgon, Morwell, Warragui, Sale, Pakenham, Benalia, Bairnsdale and IV in Cranbourne. It was also felt with light to moderate intensity in South Australia, Wales, New South Wales, Tasmania. Several moderate aftershocks were also felt in the area. Reuters reported this earthquake caused damage to many buildings and pictures on the web showed littered debris and bricks on streets. Melbourne was especially hard hit and saw a number of power outages. The epicenter was near Mansfield where some damage occurred. No deaths or major injuries were reported but minor injuries occurred with falling debris. Local geoscientists noted this may be the strongest earthquake in Victoria  since European settlement in the area. This epicenter is near the antipode of the volcanic eruption in the Canary Islands and Tropical Storm Rose in the North Atlantic. It may have been promoted by energy from those sources as suggested in previous issues of this summary:

 

 

"TS Rose continued today in the area of Central eastern Atlantic with winds up to 35 kts west of the Canary Islands. It is expected to track to the northwest over the next week and staying in the central Atlantic. Some enhanced seismicity in the Central Mid-Atlantic ridge may occur later in the week. The antipode of this storm is off the coast of eastern Australia and, along with the eruption of the Canary Islands this storm may enhance seismicity in that region." (September 19-21, 2021)

 

and

 

"The antipode of the Canary Islands is east of southern Australia. This area may see enhanced seismicity at this time due to antipodal effects associated with the volcanic eruption in the Canary Islands." (September 20-21, 2021)

 

and

 

"A tropical cyclone is forming in the North Atlantic. This system is currently located at 38N 40W. This is at the antipode of the strong earthquake in southern Australia today and that event may be related to antipodal energy from this source in the North Atlantic." (September 21, 2021)

 

 

An M 6.0 was recorded about 100 km south of this epicenter on June 20, 1969. The only other earthquake in recorded history of M>=5.9 in eastern Australia was an M 6.5 on May 10, 1897. Forecast 137331 expects enhanced seismicity  in this region of Australia at the end of September. This epicenter is located at 104 degrees from the M 8.1 in the Alaska Peninsula of July 29, 2021; at 142 degrees from the M 7.2 in Haiti of August 14 and at the third node (120 degrees) from the M 7.1 in Guerrero, Mexico of September 8 and may have been promoted by energy from those sources.

 

O: 22SEP2021 00:15:08  37.4S  146.3E ML=2.4  EMSC   NEAR S.E. COAST OF AUSTRALIA

O: 21SEP2021 23:15:53  37.5S  146.3E Mw=5.9  EMSC   NEAR S.E. COAST OF AUSTRALIA

O: 21SEP2021 23:33:39  37.5S  146.3E mb=4.1  EMSC   NEAR S.E. COAST OF AUSTRALIA

O: 21SEP2021 23:24:42  37.4S  146.4E ML=3.5  EMSC   NEAR S.E. COAST OF AUSTRALIA 

O: 21SEP2021 23:33:38  37.4S  146.3E mb=4.1  ANSS   Mount Buller Australia       

O: 21SEP2021 23:15:53  37.5S  146.4E mw=5.9  ANSS   Mount Buller Australia       

P: 28SEP2021 137331    37.0S  142.0E 4.0-5.0 CACAA  Australia                  

 

The strongest earthquake in the world today was an M 6.4-6.6 in Central Chile in the region of Bio-Bio. NEIC reported this event was felt with maximum intensity VII in Bio-Bio at Arauco; IV in Lebu, and II-III in Talcahuano, Coronel, Concepcion, Chiguayante, Tome, Laja, Nacimento and in Angol. Araucania. GUC reported this earthquake was felt with intensity  V in  Bio-Bio at Chiguayante, Coronel, Florida, Hualpen, Lota, Santa Juana, Talcahuano, Tome; IV in Concepcion and III in Cabrero, Yumbel, Lebu, and in Nuble with V in Portezuelo and Trehuaco; IV in Yungay, Coelemu and III inChillan and Quillon, Chile. This is the culminating earthquake of a series which began at this epicenter two days ago. This summary noted this series in the previous issue as:

 

 

"An earthquake in Central Chile of M 5.1 in the Bio-Bio area was felt today. NEIC reported intensity IV in Bio Bio at Coronel, and II-III in Talcahuano, Angol, Araucania and Valdivia, Los Lagos, Chile. A smaller event hit the same region yesterday. This is an area which has often seen seismicity associated with the new or full moon tides. A larger earthquake is possible following this activity with the full moon in the next several days. The last earthquake within about 150 km of this epicenter with M>=5.1 occurred more than a year ago on March 25, 2020, an aftershock of an M 5.6 on March 17, 2020. Forecast 137220 had expected today's activity within about 100 km was likely around September 17. This activity is at 103 degrees from the M 7.1 in Vanuatu of August 18 and 144 degrees from the M 7.1 in Mindanao, Philippines of August 11 and may have been promoted by energy from those sources." (September 20-21, 2021)

 

Today's event occurred within a day of the full moon and was probably promoted by tidal stresses associated with that event as noted in this and previous issues of this summary:

 

 

"The full moon  arrived at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 17-20, 2021)

 

The largest aftershocks of M 4.3 and 4.6 occurred near local solar noon and were probably promoted by high tidal stresses with the full moon. This is the strongest earthquake within about 150 km of this epicenter since an M 6.4 on June 20, 2015 and an M 6.8 on February 11, 2011. A stronger event of M 6.8 hit about 200 km northeast of today's epicenter on  September 29, 2019. These may be aftershocks of the great earthquake of M 8.8 which hit about 100 km northeast of today's epicenter on February 27, 2010. Forecasts 137220 and 137526 had expected today's activity between September 17 and 22. Like earthquakes in Haiti before it, this event is at 144 degrees from the epicenter of the M 7.1 in Mindanao, Philippines of August 11 and at 103 degrees from the M 7.1 in Vanuatu of August 18 and at the sixth node (60 degrees) from the M 7.2 in Guerrero, Mexico of September 8 and may have been promoted by energy from that source.

 

O: 21SEP2021 14:29:00  36.8S   74.3W mb=4.2  EMSC   OFFSHORE BIO-BIO, CHILE

O: 21SEP2021 15:27:23  36.8S   74.0W Mw=4.6  EMSC   OFFSHORE BIO-BIO, CHILE

O: 21SEP2021 13:20:29  36.9S   73.9W ML=4.0  EMSC   OFFSHORE BIO-BIO, CHILE

O: 21SEP2021 15:26:19  36.9S   74.1W mb=4.3  EMSC   OFFSHORE BIO-BIO, CHILE

O: 21SEP2021 13:14:32  36.8S   74.0W Mw=6.4  EMSC   OFFSHORE BIO-BIO, CHILE      

O: 21SEP2021 13:14     36.7S   74.9W mb=6.6  GUC    Bio-Bio at Chiguayante, Corone

P: 16SEP2021 137220    38.0S   74.0W 4.0-5.6 BAAAA  Central Chile               

P: 17SEP2021 137220    36.0S   73.0W 4.0-5.6 BAAAA  Central Chile              

P: 17SEP2021 137220    36.0S   73.0W 4.0-5.6 BAAAA  Central Chile              

P: 22SEP2021 137526    37.0S   73.0W 4.0-6.4 AAAAA  Central Chile              

 

The earthquake in Central Chile is at 144 degrees from the M 7.1 of August 11 in

Mindanao, Philippines. This is the distance at which seismic energy is reflected to the surface after reflections and refractions off earth core boundaries. Strong seismic enhancement is commonly seen at this distance following strong earthquakes. Areas which have seen strong seismic enhance from Mindanao in the past month include Haiti (M 7.2); northern Mid-Atlantic (swarm including M 5.0 on August 31); the Central Mid-Atlantic (M 5.7); Dominican Republic. Some areas which have not yet seen strong seismicity at this distance from Mindanao in the past month include Costa Rica and Nicaragua. These area are due for an earthquake of M>=6.

 

Eruptions in the Canary Islands today continued unabated. Thousands have been evacuated from the eruption area and at least 100 homes have been destroyed in this  eruption. This intensification of the eruption of Cumbre Vieja volcano is probably related to the effects of the tidal stresses accomopanying the current full moon. Towers of magma were reported by Reuters to be heading to the sea. The lava has mostly covered towns of El Paso and Los Llanos de Aridane. About 80,000 people live on the island and about 10% have been evacuated. While no fatalities or injuries have been reported with this eruption, two rivers of lava are headed towards the sea and the coast has been evacuated. When the lava reaches the ocean explosions and toxic gasses are expected in that area.  Forecast 137308 had expected today's activity in the Canary Islands around September 24.

 

O: 21SEP2021 08:08:49  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 24SEP2021 137308    28.0N   18.0W 3.0-4.5 BAAAA  Canary Islands             

 

STRONG QUAKE IN KURIL ISLANDS

 

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 20, 2021

 

The strongest earthquake in the world today was an M 6.0 in the Kuril Islands. It was reported felt with intensity III in Kurilsk, Russia. The only event in the past year in the Kuril Islands with M>=6 was an M 6.0 on August 24, 2021, but the last of larger magnitude was an M 7.0 on February 13, 2020. This event occurred within several hour of the full moon in a region near the IDL and was probably promoted by high tidal stresses associated with that tidal alignment. Forecast 137147 had expected today's event within about 100 km was likely  around September 19.  This epicenter is at 103 degrees from the M 7.1 in Vanuatu of August 18 and may have been promoted by energy from that source.

 

O: 20SEP2021 20:25:23  46.4N  152.4E Mw=6.0  EMSC   KURIL ISLANDS                

P: 19SEP2021 137147    47.0N  151.0E 3.5-5.6 AAAAA  So. Kurils                 

 

Seismicity with the full moon today had been expected to be enhanced near 180 West longitude (IDL) The second largest event of the day was an M 5.8 in the Tonga Islands where it was lightly felt. Forecast 137200 had expected this area would see enhanced seismicity in mid-September.

 

O: 20SEP2021 18:34:50  21.1S  173.8W Mw=5.8  EMSC   TONGA                         

P: 15SEP2021 137200    19.0S  173.0W 4.0-5.8 BCAAA  Tonga Islands              

 

O: 20SEP2021 08:35:54  20.9S  178.2W mb=4.4  EMSC   FIJI REGION                  

P: 18SEP2021 137215    21.0S  178.0W 4.0-5.5 AAAAA  Tonga Islands               

 

An M 5.4 in the South Sandwich Islands today occurred near the antipode of the M 6.0 in the Kuril Islands. It was note reported felt. This event occurred south of the recent activity in the South Sandwich Islands and was preceded by an M 4.7 foreshock about 12 hours earlier in the day. While moderate seismicity in  this area has been a daily occurrence since the M 8.1 there on August 12, 2021 the last event of M>=5.4 in the area was an M 5.5 more than a week ago on  September 11, 2021. Forecast 137234 had expected this activity was likely in mid-September. This activity is near the GMT and may have been promoted by high tidal stresses with the full moon today.

 

O: 20SEP2021 07:47:17  59.6S   25.8W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20SEP2021 19:07:44  59.8S   26.6W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16SEP2021 137234    58.0S   26.0W 4.0-5.8 BBAAA  So. Sandwich Islands       

 

An earthquake in Central Chile of M 5.1 in the Bio-Bio area was felt today. NEIC reported intensity IV in Bio Bio at Coronel, and II-III in Talcahuano, Angol, Araucania and Valdivia, Los Lagos, Chile. A smaller event hit the same region yesterday. This is an area which has often seen seismicity associated with the new or full moon tides. A larger earthquake is possible following this activity with the full moon in the next several days.  The last earthquake within about 150 km of this epicenter with M>=5.1 occurred more than a year ago on March 25, 2020, an aftershock of an M 5.6 on March 17, 2020. Forecast 137220 had expected today's activity within about 100 km was likely around September 17. This activity is at 103 degrees from the M 7.1 in Vanuatu of August 18 and 144 degrees from the M 7.1 in Mindanao, Philippines of August 11 and may have been promoted by energy from those sources.

 

O: 20SEP2021 13:58:30  36.8S   74.1W mb=4.4  EMSC   OFFSHORE BIO-BIO, CHILE

O: 20SEP2021 13:48:34  36.9S   74.0W ML=3.5  EMSC   OFFSHORE BIO-BIO, CHILE

O: 20SEP2021 13:12:04  36.8S   73.9W Mw=5.1  EMSC   OFFSHORE BIO-BIO, CHILE      

P: 17SEP2021 137220    36.0S   73.0W 4.0-5.6 BAAAA  Central Chile              

 

The eruption in the Canary Islands continued today at high intensity with  lava flows and seismicity. A similar eruption may be beginning in the area of Mt. Etna, Italy where an ash and smoke eruption occurred today as well as continuing in Popocatepetl Volcano north of Mexico City. Tidal stresses associated with the full moon can help enhance global volcanism, but changes associated with the geomagnetic storm of a day ago can also contribute to this change. This summary had expected increased seismicity and volcanism near the Greenwich Meridian and the International Date line at this time as:

 

"The full moon  arrived at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 17-20, 2021)

 

Some concern has been raised that the eruption in the Canary Islands may trigger a landslide and subsequent significant tsunami in the Atlantic Ocean. At the moment this possibility is not considered high by this summary. The antipode of the Canary Islands is east of southern Australia. This area may see enhanced seismicity at this time due to antipodal effects associated with the volcanic eruption in the Canary Islands. Forecast 137036 had expected continuing seismicity in the Canary Islands at this time. This activity may have been promoted by strong tidal stresses and by effects from the nearby Tropical Storm Rose as previously described in this summary:

 

"TS Rose continued today in the area of Central eastern Atlantic with winds up to 35 kts west of the Canary Islands. It is expected to track to the northwest over the next week and staying in the central Atlantic. Some enhanced seismicity in the Central Mid-Atlantic ridge may occur later in the week. The antipode of this storm is off the coast of eastern Australia and, along with the eruption of the Canary Islands this storm may enhance seismicity in that region." (September 20, 2021)

 

O: 20SEP2021 22:53:30  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 21SEP2021 05:06:50  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 20SEP2021 20:32:46  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 15SEP2021 137036    28.0N   17.0W 3.0-4.5 BAAAA  Canary Islands             

 

Other earthquakes which were probably promoted by strong Tropical Storms today were events in the Virgin Islands (M 3.9) and Puerto Rico (M 3.9).  Forecast 137012 had expected this activity was likely in the Virgin Islands around September 20. Tropical Storm Peter passed near this epicenter as this earthquake occurred and probably helped promote it as noted in previous issues of this summary:

 

"Tropical Storm Peter continued east of the Virgin Islands with winds up to 35 kts. It is expected to track to the west and north over the next week and not to make landfall. Some enhanced seismicity in the Virgin  Islands and northern Caribbean may occur in the next several days as this storm passes to the east." (September 19-20, 2021)

 

O: 20SEP2021 23:44:59  19.4N   63.9W Md=3.9  EMSC   VIRGIN ISLANDS REGION        

P: 20SEP2021 137012    18.0N   64.0W 3.0-5.2 ABAAA  Leeward Islands            

 

NEIC reported the earthquake of M 3.8-3.9 in Puerto Rico was felt with intensity II-IV in the area(s) of Puerto Rico at Guayanilla, Ensenada, Yauco, Ponce, San German, Cabo Rojo.

 

O: 20SEP2021 21:58:24  18.0N   66.8W ML=3.9  EMSC   PUERTO RICO REGION

O: 21SEP2021 05:47:31  18.0N   66.8W Md=3.2  EMSC   PUERTO RICO                   

P: 20SEP2021 137027    18.0N   67.0W 3.4-5.3 AAAAA  Puerto Rico                

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 in the Southern Yukon Territory near Norman Wells, NT, Canada. It was reported lightly felt in this remote area. The last earthquake of equal or larger magnitude within about 200 km of this epicenter was an M 4.7 on March 2, 2012. Forecast 137186 had expected today's event within about 50 km was likely in mid-September. This activity is at the seventh node (51.4 degrees) from Guerrero Mexico's M 7.1 of September 8 and at 144 degrees from the M 8.1 in the South Sandwich Islands of August 12 and may have been promoted by energy from those sources.

 

O: 21SEP2021 00:44:24  63.9N  130.1W MB=4.6  ECAN Norman Wells, NT   

O: 21SEP2021 00:44:24  63.9N  130.1W ML=4.6  EMSC   SOUTHERN YUKON TERRITORY, CANA

P: 13SEP2021 137186    64.0N  131.0W 2.5-4.3 CAAAA  Yukon Territory, Canada    

 

 

 

 

 

 

 

MODERATE QUAKES WITH FULL MOON

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 19, 2021

 

A series of light earthquakes including an M 3.8 and 3.6 occurred today in northwestern Oklahoma. NEIC reported maximum intensity VI in Oklahoma at Jet, and II-III in Pond Creek, Carrier, Cherokee, Helena, Medford, Enid, Deer Creek and in Sharon, Kansas.  The only earthquakes of larger magnitude within about 100 km of today's activity in the past year occurred as events of M 4.2 on February 5 and February 19, 2021. Earthquakes in Oklahoma often are enhanced at times of new and full moon alignment and are probably promoted by tidal stresses. Forecast 137106 had expected today's activity was likely within about 25 km around September 17.

 

This activity is at 101 degrees from the M 7.1 in Vanuatu of August 18 and was

probably promoted by energy from that source.

 

O: 19SEP2021 22:24:34  36.8N   98.1W mb=3.6  EMSC   OKLAHOMA

O: 19SEP2021 22:28:19  36.8N   98.1W ML=3.2  EMSC   OKLAHOMA

O: 19SEP2021 22:38:54  36.8N   98.1W ML=2.5  EMSC   OKLAHOMA

O: 19SEP2021 22:21:38  36.8N   98.1W Mw=3.8  EMSC   OKLAHOMA                     

P: 17SEP2021 137106    37.0N   98.0W 2.0-4.1 AAAAA  Southern Plains            

 

An earthquake of M 4.5 was felt with moderate intensity in northwestern South Island, New Zealand today. NEIC reported intensity IV in Karamea and Westport.

GEONET reported it was felt with light intensity in the area southeast of Wellington, New Zealand and in southern North Island and northern South Island. 16 reports of light and 20 of weak intensity with two reports of moderate shaking came from the area. This is the strongest earthquake in northwestern South Island in more than a year - since an M 4.7 on September 3, 2020. An M 6.1 hit the area on April 24, 2015 but earthquakes similar to today's last occurred on March 15, 2020, August 11, 2019 and February 11, 2017. Forecast 137230 had expected activity within about 100 km of this event was likely around September 19. This activity occurred near local solar midnight and may have been promoted by high tidal stresses with the current full moon. This summary had forecast tidally associated seismicity with this full moon as:

 

"The full moon will arrive at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 18-20, 2021)

 

This activity is at 103 degrees from the M 8.1 in Alaska of July 29 and was probably promoted by energy from that source.

 

O: 19SEP2021 11:22:20  42.4S  173.3E ML=3.4  EMSC   SOUTH ISLAND OF NEW ZEALAND

O: 19SEP2021 14:10:34  41.4S  172.0E mb=4.5  EMSC   SOUTH ISLAND OF NEW ZEALAND  

O: 19SEP2021 14:10:34  41.4S  171.9E MS=3.8  GEONET Felt with light intensity

P: 19SEP2021 137230    42.0S  173.0E 3.0-4.9 AAAAA  So. Island, N.Z.           

 

An unusual earthquake of M 2.6 occurred in the region of Rhode Island, U.S. today. NEIC reported it was felt with intensity II-III in Rhode Island at Warwick, West Greenwich, North Kingstown, Cardina, Westerly, Wakefield, Narragansett and Block Island, and in New London, Connecticut and Fishers Island, New York. Three earthquakes of M>=2.6 have occurred in the past 30 years within about 100 km of today's event. These included an M 3.0 on April 9, 2019; an M 2.7 on August 14, 2014 and an M 2.8 on March 10, 1992. Forecast 137130 had expected activity in this area would be enhanced in mid-September.

 

O: 19SEP2021 07:21:20  40.8N   71.3W ML=2.6  EMSC   OFF EAST COAST OF UNITED STATE

P: 11SEP2021 137130    43.0N   71.0W 2.0-4.1 CCAAA  New England                

 

A series of moderate earthquakes beginning with an M 5.2 hit eastern Honshu, Japan today. NEIC reported this earthquake of M 5.2 in Central Honshu, Japan was felt with intensity II-III in the area(s) of Central Honshu, Japan with V in Gifu, IV in Nagano and Ishikawa, and II-III in Nagano, Kanagawa and Niigata.  The M 5.2 is the strongest within about 100 km of this epicenter since an M 5.1 more than a year ago on May 29, 2020. This activity follows a similar event of M 5.4 three days ago about 150 km northwest of today's epicenter. This was discussed in this summary at the time as:

 

 

"A moderate earthquake of M 5.4 in central Honshu, Japan was widely felt today. NEIC reported maximum intensity VI in Honshu at Ishikawa, Toyama, Nagano; V in Niigata. This event occurred as Typhoon Chanthu was passing near this epicenter and was probably promoted by stresses associated with this strong storm as noted in previous issues of this summary:

 

"Typhoon Chanthu (TD 19W) continued today west of Honshu, Japan with winds up to 65 kts. It is expected to track to the east and north over the next week and possibly to impact regional seismicity in Honshu, Japan around September 15-18. A moderate to large earthquake near Honshu is possible in the next several days with this storm." (September 14-16, 2021)

 

Today's event of M 5.4 is the strongest within about 200 km of this epicenter since an M 6.2 on November 22, 2014 nearly seven years ago. An M 6.3 also occurred in the area March 11, 2011. Forecast 137083 had expected enhanced seismicity in this area was likely around September 15. This epicenter is at 103 degrees from the M 7.1 in Guerrero, Mexico of September 8, 2021 and was probably promoted by energy from that source. An M 5.0 in the Solomon Islands also occurred today at this distance from Guerrero." (September 16, 2021)

 

Today's event occurred as Typhoon Chanthu's eye was passing over this epicenter and was probably triggered by atmospheric loading effects. Forecast 137083 had expected this event was likely within about 100 km around September 19.  This epicenter is at 103 degrees from the M 7.1 in Guerrero, Mexico of September 8, 2021 and was probably promoted by energy from that source.

 

O: 19SEP2021 09:59:30  36.3N  137.6E ML=4.4  EMSC   EASTERN HONSHU, JAPAN

O: 19SEP2021 10:04:30  36.3N  137.6E ML=4.6  EMSC   EASTERN HONSHU, JAPAN

O: 19SEP2021 08:18:31  36.3N  137.7E mb=5.0  EMSC   EASTERN HONSHU, JAPAN        

O: 19SEP2021 08:18:32  36.3N  137.7E mb=5.2  ANSS   EASTERN HONSHU, JAPAN        

P: 19SEP2021 137083    37.0N  139.0E 3.5-5.1 AAAAA  No. Honshu, Japan          

 

The strongest earthquake in the U.S. or Canada today was an M 4.3 in the aftershock zone of the M 8.1 of July 29, 2021 in the Alaska Peninsula. Aftershocks at this magnitude level have been common since the mainshock with four in the past month. The last was an M 5.0 on September 16, 2021. Forecast 137153 had expected enhanced seismicity within about 100 km of this epicenter was likely around September 19.

 

O: 19SEP2021 13:17:45  54.8N  158.6W mb=4.3  EMSC   SOUTH OF ALASKA              

P: 19SEP2021 137153    54.7N  156.9W 3.5-5.2 AAAAA  Alaska Peninsula           

 

The volcanic eruption in the Canary Islands of Spain continued at a high level today with extensive lava flows. The earthquake activity, as is normal, reduced with the eruption. The strongest earthquake today was an M 3.6. This activity was strongest near local noon and may have been promoted by tidal stresses with the full moon. Forecast 137036 had expected today's activity in mid-September.

 

O: 19SEP2021 09:52:03  28.6N   17.9W ML=3.2  EMSC   CANARY ISLANDS, SPAIN REGION

O: 19SEP2021 10:16:45  28.6N   17.9W ML=3.6  EMSC   CANARY ISLANDS, SPAIN REGION

O: 19SEP2021 11:09:17  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 20SEP2021 06:34:43  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 19SEP2021 07:12:27  28.6N   17.9W ML=3.2  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 15SEP2021 137036    28.0N   17.0W 3.0-4.5 BAAAA  Canary Islands             

 

CANARY ISLANDS VOLCANO CUMBRE VIEJA ERUPTS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 18, 2021

 

The anticipated eruption in the Canary Islands occurred today after a week of light earthquakes in the area. Today's eruption occurred at five vents with lava flow from several. Spanish officials on the La Palma Island where the eruption of Cumbre Vieja is now occurring reported no injuries or deaths from the eruption to this point, but evacuated at least 1000 people who were in immediate danger. The lava flow also threatened some homes and buildings. The last eruption of this volcano occurred in 1971, fifty years ago. The eruption occurred within a day of the full moon. Strong tidal forces associated with this alignment likely triggered this eruption at this time.

 

This had been discussed in the previous issue of this summary as:

 

"The series of light earthquakes in the Canary Islands re-energized today in what appears to be precursory activity to the eruption of a volcano in that area. This may be triggered in the next several days by today's geomagnetic storm and by the full moon of September 20 which will have maximum tidal stresses in the eastern Atlantic near the Canary Islands. These can heat the magma and the mobility of the lava making an eruption likely at this time. The seismic forecast associated with this full moon in this summary is:

 

 

"The full moon will arrive at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 18, 2021)

 

Forecast 137036 had expected enhanced seismicity in the Canary Islands was likely in mid-September. This summary has been following this series of event for several days as for example:

 

 

"A series of minor earthquakes has been occurring the the Canary Islands of Spain over the past week. This may be exacerbated by a tropical weather system which is currently located north of the Canary Islands and which may become a tropical depression. Low atmospheric pressures from tropical depressions can help unload volcanic areas such as this leading to volcanism." (September 11-12, 2021)

 

and on September 15:

 

 

"The swarm of earthquakes in the Canary Islands of Spain continued today. Only four events of M>=2.9 occurred in the area today but lesser events were common as well. This appears to be a significant decline in regional activity following the M 3.9 yesterday. This could be precursory to a change - to quiet or to active - conditions in the next several days. Forecast 137036 had expected this event was likely around September 15. This activity is at the fourth node (90 degrees) from the M 8.1 in the Alaska Peninsula of March, 2021 and the seventh node (51.4 degrees) from the M 7.2 in Haiti of August 14, 2021 and may have been promoted by energy from those sources."  (September 15, 18, 2021)

 

Forecast 137036 had expected today's activity in the Canary Islands was likely within about 100 km in mid-September.

 

O: 19SEP2021 06:28:35  28.6N   17.9W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 15SEP2021 137036    28.0N   17.0W 3.0-4.5 BAAAA  Canary Islands             

 

An eruption of Popocatepetl Volcano north of Mexico City today also spewed ash and lava. This may have been related to the current geomagnetic storm and the strong M 7.1 earthquake to the south in Guerrero Mexico of September 8, 2021. No damage nor injuries have been reported with this eruption. It is located at the seventh node (51 degrees) from the Canary Islands and may have been promoted by energy from that source.

 

The strongest earthquake in the U.S. or Canada today was an M 4.0 in the aftershock zone of the M 6.5 of March 31, 2020 in Southern Idaho. Aftershocks in this area are often enhanced by tidal stresses associated with the full or new moons. Today's event of M 4.0 was followed several felt aftershocks. The mainshock was felt with maximum intensity IV in Challis, Idaho and II-III in Stanley, Lowman, Garden Valley, Idaho City, Sweet, Halley, Boise, Idaho. Today's M 4.0 is the strongest earthquake in this aftershock zone since an M 4.1 on

November 15, 2020. Forecast 137126 had expected today's enhanced aftershocks were likely around September 18. This activity is at 104 degrees from the Mindanao, Philippines quake of M 7.1 of August 11, 2021 and may have been affected by energy from that source.

 

O: 19SEP2021 04:38:00  44.3N  115.2W ML=2.6  EMSC   SOUTHERN IDAHO

O: 19SEP2021 05:06:58  44.3N  115.2W ML=3.5  EMSC   SOUTHERN IDAHO

O: 19SEP2021 05:18:59  44.3N  115.2W ML=3.4  EMSC   SOUTHERN IDAHO

O: 19SEP2021 05:39:57  44.3N  115.2W ML=3.0  EMSC   SOUTHERN IDAHO

O: 19SEP2021 05:43:49  44.3N  115.2W ML=3.4  EMSC   SOUTHERN IDAHO

O: 18SEP2021 17:36:06  44.4N  114.9W Ml=2.4  EMSC   SOUTHERN IDAHO

O: 19SEP2021 04:18:15  44.3N  115.1W Mw=4.0  EMSC   SOUTHERN IDAHO               

P: 18SEP2021 137126    44.4N  115.1W 2.0-4.0 AAAAA  Montana/Idaho              

 

Other earthquakes in the Western U.S. of M 4.0 also occurred today in the area of western Texas in northern Baja California and in the aftershock zone near the California-Nevada border. This event was reported by NEIC to have been felt with maximum intensity V in Topaz, California; IV in Coleville, California and II-III in South Lake Tahoe, Long Barn, Pinecrest, Markleeville, and in Nevada at Wellington, Smith, Gardnerville, and Minden. Forecast 137062 had expected the event on the California-Nevada border was likely within about 30 km around September 17. It occurred within minutes of local solar noon and was probably promoted by high tidal stresses which maximize near this hour. This activity is at 103 degrees from the Mindanao, Philippines quake of M 7.1 of August 11, 2021 and may have been affected by energy from that source.

 

O: 18SEP2021 13:46:21  38.5N  119.5W Md=2.2  EMSC   CENTRAL CALIFORNIA

O: 18SEP2021 19:20:30  38.6N  119.5W Mw=3.9  EMSC   CENTRAL CALIFORNIA

O: 18SEP2021 19:20:30  38.6N  119.5W Mw=4.0  ANSS   CENTRAL CALIFORNIA

O: 18SEP2021 19:34:10  38.1N  119.0W ml=2.4  EMSC   CENTRAL CALIFORNIA           

P: 17SEP2021 137062    38.3N  119.3W 2.5-4.6 AAAAA  California/Nevada area     

 

NEIC reported the earthquake of M 4.0 in Western Texas was felt with intensity II-III in the area(s) of Western Texas at Pecos (IV) and Mentone. An M 4.2 hit the area on September 8, 2021. Forecast 137091 had expected today's event was likely around September 18.

 

O: 18SEP2021 08:41:50  31.7N  104.4W ML=2.6  EMSC   WESTERN TEXAS

O: 18SEP2021 22:27:01  31.6N  104.0W ML=4.0  EMSC   WESTERN TEXAS                

P: 18SEP2021 137091    32.5N  104.6W 2.0-4.0 AAAAA  SW U.S.A                   

 

The two earthquakes in the Gulf of California of M 4.0 also began within minutes of local solar noon and were probably promoted by high tidal stresses associated with the full moon. The only earthquakes in this region within about 100 km of today's epicenter of M>=4 in the past year was an M 4.4 on December 28, 2020. These continue smaller events in the area which has seen a series of events of M 3.0-3.9 beginning around September 13. Forecast 137038 expected today's activity was likely within about 25 km around September 14.

 

O: 18SEP2021 21:59:48  30.8N  114.1W ML=3.3  EMSC   GULF OF CALIFORNIA

O: 18SEP2021 18:15:29  30.9N  114.2W ML=4.0  EMSC   GULF OF CALIFORNIA

O: 18SEP2021 07:54:05  31.0N  114.6W ML=3.4  EMSC   GULF OF CALIFORNIA

O: 18SEP2021 19:52:15  31.1N  114.6W ML=3.3  EMSC   GULF OF CALIFORNIA

O: 18SEP2021 21:04:47  31.1N  115.0W ML=3.5  EMSC   BAJA CALIFORNIA, MEXICO

O: 18SEP2021 21:46:14  31.2N  114.9W ML=3.3  EMSC   BAJA CALIFORNIA, MEXICO

O: 18SEP2021 19:57:19  31.3N  114.6W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 18SEP2021 20:09:27  30.3N  114.0W ML=4.0  EMSC   GULF OF CALIFORNIA           

P: 14SEP2021 137038    30.0N  114.0W 3.5-4.9 BAAAA  Gulf of California         

 

A pair of moderate earthquakes were felt in New Zealand today - an M 4.8-5.4 off northern North Island and an M 4.6-4.8 in the Te Anau area of South Island.

Both occurred near local solar noon and may have been promoted by high tidal stresses. GEONET reported the earthquake of M 4.8-5.4 was felt with moderate intensity in Northeast North Island, New Zealand. It was reported felt by 59 with weak intensity by 41, light 15, moderate 2 and extreme 1.  Forecast 137222 had expected this earthquake was likely within about 100 km in mid-September.

 

O: 19SEP2021 01:42:00  37.5S  179.3E mb=4.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z

O: 19SEP2021 01:42:09  37.5S  178.3E ML=5.4  GEONET Felt with moderate intensity

P: 15SEP2021 137222    38.0S  177.0E 3.0-4.5 BABAA  North Island, N.Z.         

 

 

 

NEIC reported the earthquake of M 4.4 in South Island, New Zealand was felt with intensity II-III in the area(s) of South Island, New Zealand at Te Anau, Queenstown, Otago. GEONET reported the earthquake of M 4.6-4.8 was felt with weak intensity in the area southwest of Te Anau, South Island. 170 reports of felt intensity came from the area east and north of the epicenter. More than 170 people reported feeling this earthquake with 97 reporting weak shaking and 68 light intensity; 5 with moderate intensity and none with strong, 0 with  severe and 0 with extreme shaking. This event occurred within minutes of local solar midnight and was probably triggered by high tidal stresses. Forecast 137231 had expected this event within about 25 km of the epicenter around September 17. This activity is located at 103 degrees from the M 7.1 in Guerrero, Mexico and 104 degrees from the M 8.1 of July 29, 2021 in Alaska Peninsula and was probably promoted by energy from those sources.

 

O: 18SEP2021 12:56:23  45.1S  167.3E ML=4.6  EMSC   SOUTH ISLAND OF NEW ZEALAND

O: 18JUL2021 12:56:23  45.1S  167.3E MS=4.8  GEONET Felt with weak intensity

O: 18SEP2021 17:14:59  45.0S  167.9E ML=3.2  EMSC   SOUTH ISLAND OF NEW ZEALAND  

P: 17SEP2021 137231    45.0S  167.0E 3.0-5.0 AAAAA  So. Island, N.Z.           

 

GEOMAGNETIC STORM TRIGGERS M 4.2 IN LOS ANGELES, CALIFORNIA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 17, 2021

 

A moderate earthquake of M 4.2-4.3 was widely felt in the central Los Angeles, California area today. This event was felt with intensity V in Carson, Torrance, Harbor City, Long Beach, Gardena and Compton as well as in much of the Los Angeles, California area. More than 10,000 people reported to the USGS that they felt this quake with light shaking as far as Central California. An aftershock of M 3.0 was also widely felt with intensity II-III in Torrance, Carson, Gardena, Harbor City, Lomita, Wilmington, Long Beach and Compton. Today's activity coincided with the strongest geomagnetic storm in the past four months and was probably triggered by that storm. It has been relatively common in recent years for moderate quakes in Los Angeles to coincide with the beginning of strong geomagnetic storms.  For example:

 

"A moderate earthquake of M 3.9 was felt throughout the region of greater Los Angeles, California today. While it was widely felt with maximum intensity V no damage or casualties were reported with this event. The earthquake occurred simultaneously with the beginning of the strongest geomagnetic storm in  more than a month - since mid-March, 2012." (April 23, 2012)

 

Hair-triggering of this type suggest a high level of regional stress which could induce a stronger event with a stronger triggering stress. This geomagnetic storm was described in this summary as:

 

"The geomagnetic field saw stormy  conditions today. The AP level was 24.  High latitude geomagnetic field also saw minor storm conditions with AP 32. The last time global AP reached a higher disturbance than AP 24 was on May 20, 2021 and prior to that on May 12, 2012 when it was AP 41. This storm is likely to increase global seismicity in the next several days, especially at high latitudes and near the geomagnetic equator." (September 18, 2021)

 

The last earthquake of equal or larger magnitude within central Los Angeles area was an M 4.5 one year ago on September 19, 2020 in connection with the new moon.  At the time this summary noted:

 

"The M 4.5 is the strongest earthquake in Los Angeles within about 50 km of this epicenter since an M 5.1 on March 29, 2014 and prior tot that an M 4.5 on August 8, 2012. The only other such event in the area in the past 12 years was and M 4.7 on May 18, 2009." (September 19, 2020)

 

An earthquake of M 3.6 preceded today's event in western Los Angeles on September 13, 2021. Likewise, a possible foreshock of M 3.0 hit the San Fernando Valley on September 15. This summary had noted at the time:

 

"An M 3.6 was widely felt in western Los Angeles, California today. NEIC reported it was felt with intensity IV in Moorpark and III in Thousand Oaks, Westlake Village, Camarillo, Newbury Park, Oak Park, Sun Valley, Agoura Hills and many other communities in southern California. An M 4.0 last hit in western Los Angeles on April 5, 2021 and a year ago as an M 4.5 in central Los Angeles on September 19, 2020 - a year ago." (September 14, 2021)

 

This activity is at the third node (120 degrees) from the strong quakes in the South Sandwich Islands of the past month and may have promoted from energy associated with that source.

 

O: 18SEP2021 06:06:09  33.8N  118.3W ML=2.7  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 18SEP2021 02:58:33  33.9N  118.1W Mw=4.2  EMSC   GREATER LOS ANGELES AREA, CALI

O: 18SEP2021 02:58:34  33.9N  118.1W Mw=4.3  ANSS   GREATER LOS ANGELES AREA, CALI

P: 17SEP2021 137095    34.0N  118.7W 2.5-4.6 AAAAA  So. California             

 

The strongest earthquake in the world today was an M 5.8 in Vanuatu. NEIC reported it was felt with intensity VI in Sola Torba and V in Port Orly and Vila Shefa, Vanuatu. The northern Vanuatu Islands have been active in the past month since M 6.9 south of today's epicenter on August 18 was followed by events of M 5.2-5.4 on September 10, September 4 and August 31. Forecast 137202 had expected today's epicenter would see enhanced seismicity within about 50 km around September 14. This activity is near 103 degrees from the M 7.1 in Mexico of September 8 and may have been promoted by energy from that source.

 

 

O: 17SEP2021 10:48:09  13.4S  167.3E Mw=4.8  EMSC   VANUATU

O: 17SEP2021 10:28:40  13.4S  167.4E Mw=5.8  EMSC   VANUATU                       

P: 14SEP2021 137202    14.0S  167.0E 4.0-5.4 BAAAA  Vanuatu Islands            

 

The series of light earthquakes in the Canary Islands re-energized today in what appears to be precursory activity to the eruption of a volcano in that area. This may be triggered in the next several days by today's geomagnetic storm and by the full moon of September 20 which will have maximum tidal stresses in the eastern Atlantic near the Canary Islands. These can heat the magma and the mobility of the lava making an eruption likely at this time. The seismic forecast associated with this full moon in this summary is:

 

 

"The full moon will arrive at 23:55 UT on September 20, 2021. As with several new and full moons in the past several months, the longitudes at local solar midnight lie near the Greenwich Meridian (GM) at 0 West longitude and those at solar noon lie near the International Date Line (IDL) and include the central Atlantic and western Europe -  including the Canary Islands where a volcanic eruption appears imminent - in the west and the Tonga/New Zealand arc and the Aleutians in the east. These are the most likely areas to see enhanced seismicity with this full moon. A strong earthquake at this time has a moderate probability of occurring." (September 18, 2021)

 

Forecast 137036 had expected enhanced seismicity in the Canary Islands was likely in mid-September. This summary has been following this series of event for several days as for example:

 

 

"A series of minor earthquakes has been occurring in the Canary Islands of Spain over the past week. This may be exacerbated by a tropical weather system which is currently located north of the Canary Islands and which may become a tropical depression. Low atmospheric pressures from tropical depressions can help unload volcanic areas such as this leading to volcanism." (September 11-12, 2021)

 

and on September 15:

 

"The swarm of earthquakes in the Canary Islands of Spain continued today. Only four events of M>=2.9 occurred in the area today but lesser events were common as well. This appears to be a significant decline in regional activity following

the M 3.9 yesterday. This could be precursory to a change - to quiet or to active - conditions in the next several days. Forecast 137036 had expected this event was likely around September 15. This activity is at the fourth node (90 degrees) from the M 8.1 in the Alaska Peninsula of March, 2021 and the seventh node (51.4 degrees) from the M 7.2 in Haiti of August 14, 2021 and may have been promoted by energy from those sources."  (September 15, 2021)

 

 

 

O: 18SEP2021 03:26:10  28.6N   17.9W ML=3.2  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 15SEP2021 137036    28.0N   17.0W 3.0-4.5 BAAAA  Canary Islands             

 

Another area in the Atlantic where strong seismicity and volcanism is occurring in Iceland. The current eruption  of Mount Fagradalsfjall near Reykjavik began exactly six months ago and is the longest eruption in Iceland in more than 50 years. The eruption of Holuhraun in 2014 and 2015 was slightly shorter lived. Also in the Atlantic, the strong aftershocks sequence in the South Sandwich Islands is continuing and may see enhanced seismicity at this time. Several tropical storms are also active in the north Atlantic including TD 17 which will stall over the northern Mid-Atlantic Ridge in the next several days and may help promote seismicity in that region. This storm is currently west of the Canary Islands as noted in this summary:

 

 

"TD 17 formed today in the area of Central eastern Atlantic with winds up to 35 kts. It is expected to track to the northwest over the next week and staying in the central Atlantic. Some enhanced seismicity in the Central Mid-Atlantic ridge may occur later in the week." (September 18, 2021)

 

MODERATELY STRONG ALASKA PENINSULA AFTERSHOCK

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 16, 2021

 

The strongest earthquake in the world today was an M 5.6 south of Alaska. It may have been felt lightly in Chignik, Anchorage and/or Fairbanks, Alaska. An aftershock of M 5.1 followed near local solar noon and may have been promoted by strong tidal stresses which maximize near this hour. This is an aftershock of the M 8.2 which hit about 100 km to the west of this on July 29, 2021. Since the event on July 29, only one aftershock of larger magnitude has been recorded within about 200 km of the mainshock - an M 6.9 on August 14, 2021. Forecast 137153 had expected today's event was likely within about 50 km around September 19. This activity is at the fifth node (72 degrees) from the M 7.2 in Haiti of August 14 and may have been promoted by energy from that source.

 

O: 16SEP2021 18:35:01  55.0N  156.5W ml=3.4  EMSC   SOUTH OF ALASKA

O: 16SEP2021 17:51:56  55.2N  156.6W Mw=5.6  EMSC   SOUTH OF ALASKA

O: 16SEP2021 23:05:07  55.2N  156.5W Mw=5.1  EMSC   SOUTH OF ALASKA              

P: 19SEP2021 137153    54.7N  156.9W 3.5-5.2 BAAAA  Alaska Peninsula           

 

A moderate earthquake of M 5.4 in central Honshu, Japan was widely felt today. NEIC reported maximum intensity VI in Honshu at Ishikawa, Toyama, Nagano; V in Niigata. This event occurred as Typhoon Chanthu was passing near this epicenter and was probably promoted by stresses associated with this strong storm as noted in previous issues of this summary:

 

"Typhoon Chanthu (TD 19W) continued today west of Honshu, Japan with winds up to 65 kts. It is expected to track to the east and north over the next week and possibly to impact regional seismicity in Honshu, Japan around September 15-18. A moderate to large earthquake near Honshu is possible in the next several days with this storm." (September 14-16, 2021)

 

Today's event of M 5.4 is the strongest within about 200 km of this epicenter since an M 6.2 on November 22, 2014 nearly seven years ago. An M 6.3 also occurred in the area March 11, 2011. Forecast 137083 had expected enhanced seismicity in this area was likely around September 15. This epicenter is at 103 degrees from the M 7.1 in Guerrero, Mexico of September 8, 2021 and was probably promoted by energy from that source. An M 5.0 in the Solomon Islands also occurred today at this distance from Guerrero.

 

O: 16SEP2021 10:01:30  37.5N  137.3E ML=3.6  EMSC   NEAR WEST COAST OF HONSHU, JAPAN

O: 16SEP2021 09:42:29  37.5N  137.3E mb=5.4  EMSC   NEAR WEST COAST OF HONSHU, JAP

P: 15SEP2021 137083    37.0N  135.0E 3.5-5.1 AABAA  No. Honshu, Japan          

P: 19SEP2021 137083    37.0N  139.0E 3.5-5.1 BABAA  No. Honshu, Japan          

 

MODERATE EARTHQUAKE SHAKES SICHUAN, CHINA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 15, 2021

 

The strongest earthquake felt in the world today was an M 5.4 in Sichuan, China. NEIC reported maximum intensity VII in Yngchang, Chongqing, China and VI in Zigogn, Sichuan. Intensity V was felt in Chongqing at Chongqing and Beibei and IV in Sichuan at Luzhou, Yilbin, Jiancheng, Chengdu, Dawan. An earthquake of M 5.8 occurred within about 100 km of this epicenter on June 17, 2019 following an M 6.6 on April 20, 2013 and an M 5.8 on May 13, 2008, the only events of larger magnitude within about 250 km of today's epicenter in at least 30 years. Forecast 137044 had expected today's event to the southwest of this epicenter was likely around September 15. Forecast 135608 had expected enhanced activity in this region within about 200 km of this epicenter was likely in late August or early September

 

O: 15SEP2021 20:33:32  29.2N  105.4E Mw=5.4  EMSC   SICHUAN-CHONGQING BDR REG, CHI

P: 25AUG2021 136508    27.0N   97.0E 4.0-5.6 ACCAA  Myanmar                    

P: 15SEP2021 137044    28.0N  104.0E 4.0-5.4 DBAAA  Myanmar                    

 

An M 5.4 also occurred today in the South Georgia Island area west of the  South  Sandwich Islands where events of M 5.0 and 5.2 continued the month-long aftershocks sequence following the M 8.1 in that region on August 12, 2021. None of this activity was reported felt in these remote areas. The M 5.4 in the South Georgia Island area within about 300 km of today's epicenter was the strongest in that area since an M 5.6 on November 15, 2002. Larger earthquakes about 500 km southeast of this epicenter occurred in May, 2017 and in September, 2003 and in July through September, 2006. An M 5.0 occurred in this area about 400 km northeast of today's event  on May 15, 2021 and an M 4.9 occurred about 150 km northeast of this on August 12, 2021. Forecast 137235 had expected enhanced seismicity south of this was likely around September 16.

 

O: 16SEP2021 01:20:39  56.4S   36.2W mb=5.4  EMSC   SOUTH GEORGIA ISLAND REGION  

P: 16SEP2021 137235    61.0S   34.0W 4.0-5.6 ACAAA  Southern  Ocean            

 

O: 16SEP2021 04:58:37  59.6S   26.0W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15SEP2021 10:22:57  58.0S   23.4W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 12SEP2021 137234    58.0S   25.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

P: 14SEP2021 137235    61.0S   22.0W 4.0-5.6 ACAAA  Southern  Ocean            

 

The strongest earthquake in the U.S. or Canada today was an M 5.0 in the central Andreanof Islands. This epicenter saw the last such event of M>=5 within about 150 km on September 9, 2017 when an M 5.4 occurred about 75 km west of today's epicenter. Most moderate earthquakes in the area occur at least 100 km north of today's epicenter. Forecast 137156 had expected today's event was likely in this area around September 15.

 

O: 15SEP2021 13:27:53  50.4N  176.3W mb=5.0  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 15SEP2021 137156    51.3N  176.8W 3.5-5.1 AAAAA  Andreanoff Isls, Aleutians 

 

MODERATE SYMMETRIC QUAKES IN ATLANTIC

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 14, 2021

 

The largest earthquakes in the world today were an M 5.3 and 5.2 in the South Sandwich Islands, continuing the month-long aftershock sequence in that region. These events at 59 South latitude were joined today by an M 4.6 at 59 North Latitude in the Reykjanes Ridge directly to the north of the South Sandwich Islands. These events occurred near local solar midnight and may have been promoted by high tidal stresses which maximize near this hour. The event  in the Reykjanes Ridge had been expected within about 100 km to occur in mid-September in forecasts 136901 and 137165. The activity in the South Sandwich Islands had been forecast in # 137234 and 137235 within about 50 km of these events.

 

O: 15SEP2021 03:31:35  58.4S   25.6W Mw=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 12SEP2021 137234    58.0S   25.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

 

O: 15SEP2021 04:43:04  58.9S   23.8W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 12SEP2021 137234    58.0S   25.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

P: 14SEP2021 137235    61.0S   22.0W 4.0-5.6 ABAAA  Southern  Ocean            

 

O: 15SEP2021 03:47:05  58.7N   31.9W mb=4.6  EMSC   REYKJANES RIDGE              

P:  7SEP2021 136901    58.0N   32.0W 4.0-5.8 CAAAA  North Mid-Atlantic Ridge   

P: 13SEP2021 137165    59.0N   30.0W 4.0-5.4 AAAAA  North Mid-Atlantic Ridge   

 

Moderate earthquakes of M 5.2 and 5.3 also occurred today in Indonesia in Minahasa, Sulawesi and in northern Sumatra and in Tonga. These are not unusual events and had been expected within about 100 km in forecasts 136975, 136976 and 137194.

 

O: 15SEP2021 00:49:49   1.2N  122.2E Mw=5.2  EMSC   MINAHASA, SULAWESI, INDONESIA

P: 14SEP2021 136975     1.0N  123.0E 4.0-5.4 AAAAA  Mindanao, Philippines      

 

O: 14SEP2021 20:13:54   3.0N   95.4E Mw=5.3  EMSC   OFF W COAST OF NORTHERN SUMATR

P: 15SEP2021 136976     2.0N   95.0E 4.0-5.4 AAAAA  Nicobar Islands            

 

NEIC reported the earthquake of M 5.2 in Tonga was felt with intensity II-III in the area(s) of Tonga at Pangai Ha'apai. Forecast 137194 had expected this event within about 100 km of this epicenter was likely around September 18.

 

O: 14SEP2021 10:28:18  15.1S  174.0W Mw=5.2  EMSC   TONGA                         

P: 18SEP2021 137194    15.0S  173.0W 4.0-5.6 BAAAA  Samoa Islands              

 

A series of light earthquakes including events of M 3.4 and 3.4 occurred  in Baja California, Mexico today. These occurred near local solar midnight and local solar noon and may have been promoted by high tidal stresses which maximize near these hours. Forecast 137092 had expected this activity was likely around September 12 to the northwest of these epicenters.

 

O: 14SEP2021 18:53:31  31.4N  115.5W ML=3.4  EMSC   BAJA CALIFORNIA, MEXICO

O: 14SEP2021 18:58:58  31.4N  115.4W ML=3.1  EMSC   BAJA CALIFORNIA, MEXICO

O: 14SEP2021 19:01:19  31.4N  115.5W ML=3.2  EMSC   BAJA CALIFORNIA, MEXICO

O: 14SEP2021 17:46:23  31.5N  115.6W Ml=2.6  EMSC   BAJA CALIFORNIA, MEXICO

O: 15SEP2021 06:57:03  31.3N  115.4W ML=3.4  EMSC   BAJA CALIFORNIA, MEXICO      

P: 12SEP2021 137092    31.9N  116.3W 2.5-4.8 BAAAA  So. California             

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in the Parkfield, California area. NEIC reported this earthquake of M 3.8 in Central California was felt with intensity II-III in the area(s) of Central California at Coalinga, King City, Bradley, Paso Robles, Los Banos, Fresno, Salinas and San Juan Bautista.  This is the strongest earthquake within about 50 km of this epicenter since an M 3.9 more than a year ago on July 30, 2020. The only other event in the past six years in the area was an M 4.0 on March 3, 2020. Forecasts 137064 and 137065 had today's event within this area around September 14. This epicenter is at 103 degrees from the M 7.1 in Mindanao, Philippines of August 11 and may have been promoted by energy from that source.

 

O: 14SEP2021 07:38:50  36.4N  120.5W ML=3.8  EMSC   CENTRAL CALIFORNIA           

P: 14SEP2021 137064    36.1N  120.1W 2.5-4.8 AAAAA  Central California         

P: 14SEP2021 137065    36.4N  121.0W 2.5-4.6 AAAAA  Central California         

 

The swarm of earthquakes in the Canary Islands of Spain continued today. Only four events of M>=2.9 occurred in the area today but lesser events were common as well. This appears to be a significant decline in regional activity following the M 3.9 yesterday. This could be precursory to a change - to quiet or to active - conditions in the next several days. Forecast 137036 had expected this event was likely around September 15. This activity is at the fourth node (90 degrees) from the M 8.1 in the Alaska Peninsula of March, 2021 and the seventh node (51.4 degrees) from the M 7.2 in Haiti of August 14, 2021 and may have been promoted by energy from those sources.

 

O: 14SEP2021 22:00:56  28.6N   17.9W ML=2.9  EMSC   CANARY ISLANDS, SPAIN REGION

O: 15SEP2021 05:15:23  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 15SEP2021 06:07:41  28.6N   17.9W ML=2.9  EMSC   CANARY ISLANDS, SPAIN REGION

O: 14SEP2021 21:11:08  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 15SEP2021 137036    28.0N   17.0W 3.0-4.5 AAAAA  Canary Islands             

 

 

SUPER TYPHOON CHANTHU PROMOTES SEISMICITY IN TAIWAN AND JAPAN

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 13, 2021

 

The strongest earthquake in the world today was an M 5.8 in the Izu Islands, Japan. NEIC reported it was felt with intensity II-III in Japan in Shizuoka, Kanagawa, Tokyo, Saitama, Ibaraki and Fukushima. Super-Typhoon Chanthu was near this epicenter when this earthquake occurred and probably helped trigger this event as it made landfall in southern Japan as noted in this summary:

 

"Typhoon Chanthu (TD 19W) continued today north of Taiwan with winds up to 40 kts. It is expected to track to the west and north over the next week and possibly to impact regional seismicity in Central and northern Philippines and southern Japan around September 13-16." (September 13-14, 2021)

 

Today's event is the strongest within about 250 km of this epicenter since an M 6.3 on July 27, 2019 and prior to that an M 6.0 on April 1, 2016. These may be aftershocks of earthquakes of M 7.2 and 7.4 on September 5, 2004 to the west of today's epicenter.  Forecast 137070 had expected enhanced seismicity within about 100 km of today's event around September 13.

 

The activity in Japan on September 5, 2004 was also associated with a strong typhoon as noted at the time in this summary:

 

"The earthquakes occurred at the same time as a strong typhoon which has caused considerable flooding and landslides in the area and a strong eruption of

Mount Asama, the major volcano in Japan." (September 5, 2004)

 

This epicenter in the Izu Islands, Japan is near 103 degrees from the event in Guerrero, Mexico of M 7.1 and was probably promoted by energy from that source.

 

O: 13SEP2021 22:46:06  32.5N  137.8E Mw=5.8  EMSC   IZU ISLANDS, JAPAN REGION    

P: 13SEP2021 137070    33.0N  137.0E 3.5-4.9 AAAAA  Central/So. Honshu Japan   

 

An earthquake of M 4.9-5.6 also occurred in Taiwan today. NEIC reported this event was felt with intensity IV in Taiwan in Taichung, and Taipei. CWB reported this earthquake was felt with intensity IV in Nantou, Taichung, Changhua, Hualien, Yilan; III in Miaoli, Yunlin, Hsinchu, Taitung; II in Taoyuan, Hsinchu, Taipei, Chiayi, Kaohsiung, Tainan and I in Penghu and Pingtung Counties, Taiwan.

The last event in Taiwan of M>=5.6 was an M 5.8 on August 4, 2021. Similar events  also occurred on April 18 and March 25, 2021. The strongest event in Taiwan in the past year was an M 6.2 on December 10, 2020. Today's event followed the passage of Super-Typhoon Chanthu over this epicenter two days ago as noted in the summary at the time:

 

"Typhoon Chanthu (TD 19W) continued today over the Taiwan with winds up to 135 kts. It is expected to track to the west and north over the next week and possibly to impact regional seismicity in Central and northern Philippines and Taiwan around September 9-12." (September 11-12, 2021)

 

Forecast 137047 had expected today's event in Taiwan was likely within about  100 km of this epicenter around September 15.

 

 

O: 13SEP2021 10:41:28  24.1N  121.0E mb=4.9  EMSC   TAIWAN                       

O: 13SEP2021 10:41:27  24.1N  121.0E ML=5.6  TAI    Hualien, Taiwan              

P: 15SEP2021 137047    25.0N  122.0E 4.0-5.8 AAAAA  Ryukyu Islands             

 

The strongest earthquake in the U.S. or Canada today occurred as an M 4.7-4.9 in Central Alaska. NEIC reported it was felt with intensity V in Salcha with IV in Eielson AFB, Alaska. Also felt with intensity III in Fairbanks, North Pole, Fort Wainwright, Delta Junction, Healy and Nenana. At M 4.9 this event is the strongest within about 100 km of this epicenter since an M 5.5 on January 7, 1990. A foreshock of M 4.7 hit the area on July 23, 2021. Forecasts 137180 and 137181 had expected enhanced activity in this area was likely in mid-September.

 

O: 14SEP2021 05:56:37  64.4N  146.8W Mw=4.7  EMSC   CENTRAL ALASKA                

O: 14SEP2021 05:56:37  64.4N  146.8W Mw=4.9  ANSS   CENTRAL ALASKA               

P: 11SEP2021 137180    62.7N  149.3W 3.2-5.3 BBBAA  Central Alaska             

P: 19SEP2021 137181    63.0N  148.6W 3.2-5.3 BBAAA  Central Alaska              

 

An M 3.6 was widely felt in western Los Angeles, California today. NEIC reported it was felt with intensity IV in Moorpark and III in Thousand Oaks, Westlake Village, Camarillo, Newbury Park, Oak Park, Sun Valley, Agoura Hills and many other communities in southern California. An M 4.0 last hit in western Los Angeles on April 5, 2021 and a year ago as an M 4.5 in central Los Angeles on September 19, 2020 - a year ago. Forecasts 136834 and 137095 had expected today's activity was likely within about 25 km between September 10 and 17.

 

O: 13SEP2021 14:59:33  34.2N  119.0W Mw=3.6  EMSC   GREATER LOS ANGELES AREA, CALI

P: 10SEP2021 136834    34.0N  118.7W 2.5-4.6 BAAAA  So. California             

P: 17SEP2021 137095    34.0N  118.7W 2.5-4.6 BAAAA  So. California             

 

A series of light earthquakes also continued in the northern Baja California region today. This is an active region following geomagnetic storms. Today's activity included at least six events of M>=3. This activity was centered near local solar noon and local solar midnight with one of the strongest events occurring as an M 3.7 at 19:52 UT, within minutes of local solar noon, and may have been promoted by strong tidal stresses which maximize near these hours. Forecast 137038 had expected this activity around September 14.

 

O: 13SEP2021 09:51:06  30.9N  114.2W ML=3.8  EMSC   GULF OF CALIFORNIA

O: 13SEP2021 09:53:10  30.9N  114.2W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 13SEP2021 19:52:11  30.9N  114.2W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 13SEP2021 20:35:09  30.9N  114.2W ML=3.6  EMSC   GULF OF CALIFORNIA

O: 14SEP2021 05:40:53  31.0N  113.8W ML=3.7  EMSC   GULF OF CALIFORNIA

O: 13SEP2021 20:14:51  30.8N  114.2W ML=3.6  EMSC   GULF OF CALIFORNIA           

P: 14SEP2021 137038    30.0N  114.0W 3.5-4.9 AAAAA  Gulf of California         

 

An event of M 3.8 also shook southeastern Colorado today. NEIC reported maximum intensity was felt with V at Pritchett with light shaking of II-III in Colorado at Springfield, Kim, Campo, Walsh, Lamar, La Junta, Rocky Ford and in Kenton, Oklahoma and Elkhart, Kansas. This is the strongest earthquake in Southeastern Colorado within about 100 km of this epicenter in the past 30 years. Forecast 137071 had expected today's activity to the west was likely around September 14.

 

O: 13SEP2021 09:27:14  37.4N  102.9W mb=3.8  EMSC   COLORADO                     

P: 14SEP2021 137071    36.9N  105.1W 2.0-3.9 AABAA  Colorado area              

 

The strong series of light earthquakes in the Canary Islands, Spain continued today. The strongest of today's events was an M 3.9, getting into the range

where moderate quakes could be important in triggering a volcanic eruption or landslide-triggering tsunami. The M 3.9 is the strongest event in the Canary Islands in the past year. While an M 4.8 hit west of the Canary Islands on September 26, 2019, the last in the Canary Islands of M>=3.9 was an M 5.4 on December 27, 2013.  At the time of the activity in December, 2013, this summary noted:

 

"A series of light earthquake began hitting the Canary Islands today. This appears to be a reinvigoration of the eruptive status of El Hierro Volcano and bears watching. This appears to have begun about the time of the full moon and tidal effects may have been an initiating effect. It is also likely that these earthquake were prompted by the renewed solar flare activity which began at the same time these small events began in the Canary Islands." (December 23, 2013)

 

"The swarm under El Hierro volcano in the Canary Islands continued at a reduced rate today. A volcanic eruption does not seem imminent in this region but a strong storm, solar flare or geomagnetic storm combined with strong astronomical tides could intensify this pre-eruption sequence." (December 25, 2013)

 

This earthquake is the strongest since volcanic activity began in 2011. It caused damage to buildings and rock slides but no injuries. Two roads were closed due to rock falls blocking them. A sudden elevation and the previous earthquakes caused local scientists to issue a warning raising the volcano alert level to yellow hours before this earthquake. Strong earthquakes such as this  can lead to subsequent eruptions as they move materials around often opening vents for magma to reach the surface. Residents reported strong shaking and the quake was felt throughout the Canary Islands.

 

This is the strongest earthquake recorded in the past 25 years in the Canary Islands. The largest (and only ) previous earthquake recorded within 250 km of this  epicenter of M>=5.4 occurred on May 22, 1964 with M 5.5. There has been some concern that sliding blocks, perhaps triggered by an earthquake of this size or larger, could slide from the volcanic slopes into the sea generating an Atlantic-wide tsunami." (December 27, 2013)

 

Forecast 137036 had expected today's activity in the Canary Islands between September 12 and 15.

 

O: 13SEP2021 23:14:25  28.6N   17.9W ML=3.2  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 23:30:36  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 23:32:17  28.6N   17.9W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 14SEP2021 00:19:48  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 14SEP2021 03:25:59  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 14SEP2021 04:52:13  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 14SEP2021 06:00:00  28.6N   17.9W ML=3.9  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 23:10:17  28.6N   17.9W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 12SEP2021 137036    28.0N   16.0W 3.0-4.5 AABAA  Canary Islands             

P: 15SEP2021 137036    28.0N   17.0W 3.0-4.5 AAAAA  Canary Islands             

 

 

STRONG M 6.2 SHAKES JUJUY, ARGENTINA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 12, 2021

 

A strong earthquake of M 6.2 shook the area on the northern Argentina-Chile border in the Jujuy, Argentina area. NEIC reported maximum shaking of VII in Jujuy and VI in Salta, Argentina. Inensity V was reported from Tucumen, Argentina and IV in Bolivia at Tarija, Potosi and Villazon, Bolivia and in Antofagasta, Chile with intensity III. GUC reported this earthquake was felt with intensity  IV in  Atacama at Caldera, Chanaral, Copiapo, Diego de Almagro, Tierra Amarilla; Antofagasta with IV in Antofagasta, Baquedano, Maria Elena, Mejillone, Sierra Gorda, Taltal, Tocopill III in Calama and II in Sierra Gorda, Chile. A similar earthquake of M 6.3 hit south of this on November 30, 2020 and prior to that an M 6.3 on April 15, 2017. Today's mainshock occurred near local solar midnight and was probably promoted by tidal stresses which maximize near this hour. Forecast 137204 had expected today's activity was likely within about 150 km around September 14. This epicenter, like the M 4.2 in Hawaii today is located at the seventh node (52 degrees) from the M 7.1 in Mexico of September 8, 2021 and was probably promoted by energy from that source.

 

O: 12SEP2021 11:45:59  24.1S   66.8W ML=3.6  EMSC   JUJUY, ARGENTINA

O: 12SEP2021 13:54:08  24.1S   67.5W mb=4.2  EMSC   SALTA, ARGENTINA

O: 13SEP2021 05:18:11  23.9S   67.0W Mw=6.2  EMSC   JUJUY, ARGENTINA             

O: 13SEP2021 05:18     23.8S   67.5W mb=6.1  GUC    Atacama at Caldera, Chanaral,

P: 14SEP2021 137204    23.0S   66.0W 4.0-5.5 AAAAA  Argentina                  

 

An M 3.8-4.2 was widely felt in Hawaii today. NEIC reported intensity II-III in Hawaii at Hawaii National Park, Naalehu, Volcano, Captain Cook, Mountain View, Hilo, Kailua Kona, Kamuela, Kapauu. The area has been seeing increased and enhanced seismicity for several weeks. But the last earthquake in Hawaii of M>=4.2 occurred on August 18 (M 4.4) and June 3 (M 4.5). Forecast 137010 had expected today's activity in Hawaii was likely around September 14.

 

O: 12SEP2021 11:45:04  19.2N  155.4W ML=4.2  EMSC   ISLAND OF HAWAII, HAWAII

O: 12SEP2021 14:31:45  19.2N  155.5W ML=3.2  EMSC   ISLAND OF HAWAII, HAWAII     

P: 14SEP2021 137010    18.8N  155.2W 3.0-4.4 AAAAA  Hawaii                      

 

The series of light earthquakes continued today in western Texas with the largest of the day an M 3.8. NEIC reported this earthquake of M 2.6 in Western Texas was felt with intensity II-III in the area(s) of Western Texas at Rotan.

This is an aftershock of an M 3.6 in western Texas which was reported by NEIC to have been felt with intensity IV in Rotan, Snyder and II-III in Roby, Hamlin, Jayton, Hughes Springs and in Elmore City, Oklahoma. This area increased its activity on September 8, 2021 following an M 4.0-4.2 at that time and was noted in this summary as:

 

"A series of earthquakes north of Mexico in Western Texas was also energized today. The strongest of these was an M 4.2 but the swarm began near local solar  midnight about 6 hours after the M 7.0 in Mexico and may have been promoted from Mexico or by tidal and geomagnetic stresses. An M 4.2 last occurred in this area on September 3 and is among the four largest such events in the region in the past year. Many of these have occurred at full or new moons and appear tidally related." (September 9, 2021)

 

Forecast 137091 had expected enhanced seismicity in this area was likely around

September 14.

 

O: 12SEP2021 15:37:16  31.6N  104.2W ML=2.8  EMSC   WESTERN TEXAS

O: 12SEP2021 21:04:15  31.6N  104.2W ML=2.5  EMSC   WESTERN TEXAS

O: 12SEP2021 21:15:42  31.6N  104.2W ML=2.5  EMSC   WESTERN TEXAS

O: 12SEP2021 10:21:52  31.8N  103.8W ML=2.6  EMSC   WESTERN TEXAS

O: 12SEP2021 23:20:21  31.8N  103.8W ML=3.2  EMSC   WESTERN TEXAS

O: 12SEP2021 13:30:08  31.6N  104.2W ML=3.8  EMSC   WESTERN TEXAS                

P: 14SEP2021 137091    31.6N  103.6W 2.0-4.0 AAAAA  SW U.S.A                   

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 in the Unimak Island region of Alaska. This appears to be an aftershock of the M 5.1 on September 9, 2021. At the time this summary noted in this regard:

 

"The strongest earthquake in the U.S. or Canada today was an M 5.1 in the Unimak Island Region, Aleutians, Alaska. It was not reported felt in this remote area. The only earthquakes of M>=5 in the Unimak Islands in the past year were an M 5.1 on January 11, 2021 and an M 5.0 on November 4, 2020. Both occurred about 100 km west of today's epicenter. Forecast 136908 had expected today's activity was likely in early September within about 100 km of today's epicenters." (September 9, 2021)

 

Forecast 137171 had expected today's event within about 100 km was likely around

September 11.

 

O: 12SEP2021 17:03:09  53.4N  163.5W mb=4.7  EMSC   UNIMAK ISLAND REGION, ALASKA 

P: 11SEP2021 137171    54.1N  162.8W 3.5-5.1 AAAAA  Unimak Islands, Aleutians  

 

A strong series of earthquakes occurred in the Canary Islands today. More than 150 events were initially recorded. These may be foreshocks to a larger event or to a volcanic eruption perhaps at Teneriffe. This series began shortly after a Gamma Ray Burst (GMB) with maximum events around local solar midnight and may have been triggered by effects from these events. In the previous summary this summary had noted this as:

 

"A series of minor earthquakes has been occurring the Canary Islands of Spain over the past week. This may be exacerbated by a tropical weather system which

 is currently located north of the Canary Islands and which may become a tropical depression. Low atmospheric pressures from tropical depressions can help unload volcanic areas such as this leading to volcanism." (September 12, 2021)

 

Forecasts 136777 and 137036 had expected this activity was likely around September 10-12. This area is at the 7th node (51.4 degrees) from the M 7.2 of August 14, 2021 and may have been promoted by energy from that source.

 

O: 12SEP2021 23:56:08  28.6N   17.9W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 00:05:33  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 00:15:10  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 00:21:06  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 02:56:11  28.6N   17.9W ML=3.2  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 03:02:56  28.6N   17.9W ML=3.1  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 03:08:00  28.6N   17.9W ML=3.2  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 03:13:31  28.6N   17.9W ML=3.3  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 03:23:31  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 13SEP2021 03:36:47  28.6N   17.9W ML=3.0  EMSC   CANARY ISLANDS, SPAIN REGION

O: 12SEP2021 23:46:55  28.6N   17.9W ML=3.4  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 10SEP2021 136777    28.0N   16.0W 3.0-4.6 AABAA  Canary Islands             

P: 12SEP2021 137036    28.0N   16.0W 3.0-4.5 AABAA  Canary Islands             

 

 

MODERATE ACTIVITY IN KURIL; SOUTH SANDWICH ISLANDS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 11, 2021

 

The strongest earthquakes in the world today were an M 5.3 in the Kuril Islands and an M 5.5 in the South Sandwich Islands. The event in the Kuril Islands is the strongest earthquake in this region northwest of the Kuril Islands since an M 5.5 on July 9, 2019 and prior to that an M 6.0 on November 2, 2018. Forecastg 137156 had expected today's activity within about 50 km was likely around September 11. This event occurred within minutes of local solar midnight and may have been promoted by strong tidal stresses which maximize near this hour.

 

O: 12SEP2021 02:32:25  47.2N  146.8E Mw=5.3  EMSC   NORTHWEST OF KURIL ISLANDS   

P: 11SEP2021 137146    47.0N  146.0E 3.5-5.4 AAAAA  So. Kurils                 

 

The M 5.5 in the South Sandwich Islands was not far from the antipode of the Kuril Islands event of M 5.3. This is part of the aftershock sequence following the M 8.1 in the South Sandwich Islands of August 12, 2021. Forecast 136964 had expected today's activity around September 9. This activity was near local solar noon and may have been promoted by high tidal stresses.

 

O: 11SEP2021 12:43:53  57.4S   26.1W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 11SEP2021 09:23:03  59.6S   26.4W Mw=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 11SEP2021 09:10:47  56.1S   27.9W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  9SEP2021 136964    57.0S   25.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

The activity in the South Shetland Islands west of the South Sandwich Islands re-energized today with an M 4.8. This continues activity in this area which concentrated in April 1021. The only earthquake of M>=4.8 in the region in the past three month was an M 4.9 on August 28, 2021. Forecast 137235 had expected today's activity was likely in the South Shetland Islands in mid-September.

 

O: 12SEP2021 03:58:21  62.3S   57.9W mb=4.8  EMSC   SOUTH SHETLAND ISLANDS       

P: 15SEP2021 137235    61.0S   58.0W 4.0-5.6 BBAAA  Southern  Ocean            

 

The strongest earthquake in the U.S. or Canada today was an M 3.6 in Southern Alaska. NEIC reported this earthquake of M 3.4 in Southern Alaska was felt with intensity II-III in the area(s) of Southern Alaska at Wasilla, Willow, Anchorage, Chugiak. This is not an uncommon earthquake for southern Alaska and is probably an aftershock of the M 7.0 in the Anchorage, Alaska area of November 30, 2018. The last such aftershock of M>=3.6 hit the area as an M 4.3 on August 12, 2021 with the M 8.1 in the South Sandwich Islands. Forecast 137176 had expected today's activity around September 14.

 

O: 11SEP2021 16:20:54  61.5N  149.9W ML=3.6  EMSC   SOUTHERN ALASKA              

P: 14SEP2021 137176    60.1N  150.6W 3.2-5.3 BAAAA  Central Alaska              

 

A series of minor earthquakes has been occurring the the Canary Islands of Spain over the past week. This may be exacerbated by a tropical weather system which

is currently located north of the Canary Islands and which may become a tropical depression. Low atmospheric pressures from tropical depressions can help unload volcanic areas such as this leading to volcanism.

 

O: 12SEP2021 00:16:12  28.5N   17.8W ML=1.5  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 10SEP2021 136777    28.0N   16.0W 3.0-4.6 AAAAA  Canary Islands             

P: 12SEP2021 137036    28.0N   16.0W 3.0-4.5 AAAAA  Canary Islands             

 

MODERATE QUAKES IN INDIA, VANUATU AND ANDAMAN ISLANDS MARK QUIET DAY

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 10, 2021

 

It was a relatively quiet day in global seismicity. Earthquakes of M 5.2 occurred in the Andaman Islands of India and in Vanuatu. But neither of these were reported felt. The earthquake in Vanuatu is an aftershock of the M 7.1 ther of August 18, The M 5.2 in the Andaman Islands is the strongest in that region this year. The last earthquake in the Andaman Islands within about 250 km of today's epicenter with M>=5.2 occurred as an M 5.6 on May 22, 2019. The area can see great earthquakes so a resurgence in regional seismicity may be important to note. Forecast 136743 had expected today's activity in the Andaman Islands in early September. This epicenter is located at 144-146 degrees from both events

of M 7.1-7.2 in Mexico  of September 8 and in Haiti of August 14, 2021 and was probably promoted by energy from those sources.

 

O: 11SEP2021 03:20:20  14.0N   93.0E mb=5.2  EMSC   ANDAMAN ISLANDS, INDIA REGION

P:  5SEP2021 136743    13.0N   96.0E 4.0-5.8 CACAA  Andaman Islands            

 

O: 10SEP2021 17:45:21  14.6S  168.0E Mw=5.2  EMSC   VANUATU                      

P: 10SEP2021 136933    14.0S  167.0E 4.0-5.5 AAAAA  Vanuatu Islands            

 

The largest event felt in the world today was an M 4.7 in Uttaranchal,  India.

NEIC reported this earthquake of M 4.7 in Uttaranchal, India was felt with intensity IV-V in the area(s) of Uttaranchal, India in  Chamoli and Gopeshwan, Karnaprayang, Rudraprayag, Srinagar, Dev Prayag, Dwarahat, Ranikhet, Vithara, Dehra Dun and Naintal. The last earthquake of equal or larger magnitude in the Uttaranchal region of India within about 200 km occurred on December 1, 2016 with  5.2. A strong earthquake M 6.6 occurred in the area on March 28, 1999 and also with M 6.8 on October 19, 1991.  Forecast 136850 had expected today's activity to the east in early September.

 

O: 11SEP2021 00:28:32  30.5N   79.2E mb=4.7  EMSC   UTTARANCHAL, INDIA           

P:  4SEP2021 136850    30.0N   82.0E 3.8-5.2 CABAA  Xizang                     

 

The largest earthquake in the world today was an M 5.6 in the South Sandwich Islands – another in the series of moderately strong daily earthquakes in this aftershock sequence which follows the M 8.1 of August 12. Today's event, like others in the area was not reported felt in this remote region. Forecast 136964 had expected today's activity was likely within about 150 km around September 7-9.

 

O: 10SEP2021 17:07:17  60.4S   26.4W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 BBAAA  So. Sandwich Islands       

P:  9SEP2021 136964    57.0S   25.0W 4.0-5.6 ACAAA  So. Sandwich Islands       

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 in the Kenai Peninsula, Alaska. NEIC reported this earthquake of M 3.9 in the Kenai Peninsula, Alaska was felt with intensity II-III in the area(s) of the Kenai Peninsula, Alaska at Kasilof, Soldotna, Ninilchik, Sterling, Anchor Point, Kenai, Cooper Landng, Homer, Moose Pass, Anchorage. Three earthquakes of M>4.1 have occurred in the Kenai Peninsula area of Alaska in the past year - an M 4.7 on July 1, 2021; an M 4.4 on January 26, 2021 and an M 4.3 on July 19, 2021. Forecast 136912 had expected today's event within about 100 km was likely around September 8.

 

O: 11SEP2021 05:58:43  60.3N  151.3W Mw=4.1  EMSC   KENAI PENINSULA, ALASKA      

O: 11SEP2021 05:58:43  60.3N  151.3W Mw=4.9  ANSS   KENAI PENINSULA, ALASKA      

P:  8SEP2021 136912    61.3N  150.9W 3.2-5.3 BAAAA  Central Alaska             

 

MODERATE EARTHQUAKE ROCKS GUADELOUPE, LEEWARD ISLANDS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 9, 2021

 

An M 5.0 was felt widely in the Guadeloupe area of the Leeward Islands today. NEIC reported it was felt with maximum intensity IV in Guadeloupe at Anse-Bertrand Grande-Terre and Les Abymes with intensity II-III in Guatdeloup at Le Moule, Sante-Anne, Le Gosier, Point-a-Pitre, Baie-Mahault and Lamentin Basse-Terre and in Antigua and Barbuda at English Harbour Saint Paul and All Saints Saint John. The only earthquake of larger magnitude in Guadeloupe in the past year was an M 5.8 on March 26, 2021 and today's event may be an aftershock of that. Forecast 136753 had expected today's activity was likely within about  100 km of the epicenter in early September.

 

O: 10SEP2021 00:43:19  16.8N   61.2W mb=5.0  EMSC   GUADELOUPE REGION, LEEWARD ISL

P:  4SEP2021 136753    17.0N   60.0W 3.0-5.0 CAAAA  Leeward Islands            

 

An M 4.3 off the coast of Northern California today was widely felt in Northern California with intensity II-III in Petrolia, Ferndale, Fortuna, Whitethorn, Loleta,m Eureka, Aracata, Petaluma and Earlmart. This is the strongest earthquake off the coast of northern California within about 150 km of this epicenter since an M 5.1 on July 18 and an M 4.4 aftershock on July 21, 2021.  Forecast 136873 had expected today's event within about 50 km of this epicenter was likely around September 8. The mainshock occurred within about an hour of local solar noon and may have been promoted by strong tidal stresses which maximize near this hour with this new moon as noted in this and previous issues of this summary:

 

"The new moon arrived at 00:52 UT on September 7, 2021. Longitudes which were near local solar midnight at this time are in the Atlantic Ocean and western Europe near 15 West and include areas of the Central Mid-Atlantic and the South Sandwich Islands while those at local solar noon are near 165 East and include areas of the northern Kurils and the Sea of Okhotsk, Near Islands and western Aleutians as well as the Vanuatu/Loyalty Islands, Kermadec-Tonga-Fiji-New Zealand arc. These areas will see maximum tidal stresses with this new moon and are most likely to see enhanced seismicity in the next week." (September 6-9, 2021)

 

O:  9SEP2021 21:57:52  40.3N  124.7W Mw=4.3  EMSC   OFFSHORE NORTHERN CALIFORNIA 

O: 10SEP2021 00:03:53  40.3N  124.4W Md=2.2  EMSC   OFFSHORE NORTHERN CALIFORNIA

P:  8SEP2021 136873    40.7N  124.6W 2.5-4.4 AAAAA  Off Coast of No. Calif     

 

 

The strongest earthquake in the U.S. or Canada today was an M 5.1 in the Unimak Island Region, Aleutians, Alaska. It was not reported felt in this remote area. The only earthquakes of M>=5 in the Unimak Islands in the past year were an M 5.1 on January 11, 2021 and an M 5.0 on November 4, 2020. Both occurred about 100 km west of today's epicenter. Forecast 136908 had expected today's activity was likely in early September within about 100 km of today's epicenters. Like the M 5.1 in the West Chile Rise today this epicenter is located at the sixth node (60 degrees) from the epicenter of the M 7.1 in Mexico two days ago and may have been promoted by energy from that source.

 

O:  9SEP2021 19:23:26  53.6N  163.6W mb=5.1  EMSC   UNIMAK ISLAND REGION, ALASKA 

O: 10SEP2021 05:57:54  53.2N  163.4W mb=4.0  EMSC   UNIMAK ISLAND REGION, ALASKA

P:  2SEP2021 136908    54.6N  163.6W 3.5-5.0 CAAAA  Unimak Islands, Aleutians  

P:  6SEP2021 136908    54.0N  164.9W 3.5-5.1 BAAAA  Unimak Islands, Aleutians  

 

A light earthquake of M 2.4-2.8 occurred today in the St. Lawrence Valley area of Quebec, Canada. ECAN reported it was lightly felt in the Lake Pocatiere region. The only event in this region in the past year within about 200 km of this epicenter with greater magnitude was an M 3.4 on December 28, 2020. Forecast 136860 had expected today's event within about 50 km was likely around September 9.

 

O: 09SEP2021 13:37:56  47.4N   70.2W MB=2.8  ECAN La Pocatiere, QC. Felt  

O: 08SEP2021 12:05:42  47.4N   70.4W MB=0.9  ECAN Charlevoix Seismic Zone     

O:  9SEP2021 13:37:55  47.4N   70.2W ML=2.4  EMSC   ST. LAWRENCE VALLEY REG., CANA

P:  9SEP2021 136860    47.0N   70.0W 2.0-4.1 AAAAA  Maine                      

 

Moderate earthquakes also continued in the series in the West Chile Rise which began shortly after the M 7.1 in Mexico of September 8. The largest of these today was also the largest event in the world on this day - an M 5.1 south of the previous swarm. It was not reported felt in this remote area. Like the M 5.0 in the Unimak Islands area of Alaska today located at 60 degrees (node 6) from the Mexico event and was probably promoted by energy from that source. Forecast 136956 had expected this event was likely within about 50 km of this epicenter around September 9. This event occurred within about an hour of local solar midnight and may have been  promoted by high earth tides which maximize near this hour.

 

O: 10SEP2021 04:21:29  42.8S   83.7W mb=5.1  EMSC   WEST CHILE RISE              

P:  9SEP2021 136956    43.0S   83.0W 4.0-5.5 AAAAA  Chile Rise                  

 

Earthquakes also continued to the north of this near the previous swarm.

When this swarm began two days ago, this summary noted in this regard:

 

"A strong series of events also hit the West Chile Rise in the Pacific Ocean today and included events of M 5.6, 5.4, 5.3 and 5.2. The largest of these occurred near local solar noon and may have been promoted by tidal effects with the new moon, but energy from the M 7.0 in Mexico may also have enhanced this activity. This is the strongest activity within about 200 km on the West Chile Rise in more than 10 years - following an M 5.9 about 200 km southeast of this on  May 20, 2010 and an M 6.0 to the east on June 5, 2008. Forecast 136956 had expected today's activity was likely to the southeast in the Chile Rise around September 7. This activity is at the sixth node from the M 7.2 in Haiti of August 14 and may have been promoted by energy from that source." (September 8-9, 2021)

 

 

O: 09SEP2021 16:27:22  38.0S   94.0W mb=4.6  EMSC   WEST CHILE RISE

O:  9SEP2021 11:52:31  38.0S   94.1W mb=4.5  EMSC   WEST CHILE RISE              

P:  7SEP2021 136956    41.0S   91.0W 4.0-5.6 ACBAA  Chile Rise                 

 

 

STRONG EARTHQUAKE IN MEXICO OCCURS ON 4TH ANNIVERSARY OF MEXICO M 8.1 SEPT 8, 2017

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 8, 2021

 

Aftershocks of the M 7.0-7.1 earthquake in the Guerrero area of Mexico of September 8, 2021 continued today. An interesting phenomenon was observed with the mainshock. Strong earthquake lights accompanied the event and were recorded as far as Mexico City. Some of these recordings can be viewed on the web. The cause of earthquake lights is not known but many hypotheses have been proposed but the relation with strong geomagnetic storms and accompanying aurora is especially in the current situation as such a storm within an hour or two of the time of the M 7.0 in Mexico today. Videos of the lights appeared similar to aurora and to heat lightning. The blue lights followed the earthquake and were viewed with alarm by local citizens. Such lights often accompany major earthquakes in subduction zones such as in Japan and Mexico and often coincide with strong geomagnetic storms. Power outages occurred in Acapulco and Mexico City allowing better viewing of the earthquake lights. The strongest aftershock today was an M 4.6. It was reported felt with intensity II in Tlalnepantla, Mexico.

 

The second strongest geomagnetic storm in the past four months hit mid-latitudes at the end of September 7 and early September 8. This reached maximum strength near 01:00 UT (SWPC data) and reached high latitude AP of 6 in mid-day starting around 02:00 UT. This storm may have triggered the M 7.0 mainshock about 02:00 UT in Guerrero, Mexico. It may also have helped trigger the earthquake lights at the same time. This geomagnetic storm is described in this summary as:

 

"The geomagnetic field saw disturbed  conditions today. The AP level was 14.  High latitude geomagnetic field also saw minor storm conditions with AP 33. The last geomagnetic storm of larger intensity occurred on August 28, 2021 and the second strongest at mid and high latitudes since late May, 2021. Seismicity  at low latitudes, near the geomagnetic equator and at high latitudes is likely to be enhanced in the next several days due to this storm." (September 8, 2021)

 

The relation between the new moon and strong geomagnetic storms in the region of Mexico had been discussed in previous issues of this summary as for example with an M 7.4 in Oaxaca on June 23, 2020:

 

"The new moon arrived June 21 (2020) at 06:41 UT. ...  Longitudes which are sub-solar at this time are near 77 East and 103 West. These include areas of central Asia including Hindu Kush, India and Tajikistan in the east and the central and western U.S. and western Mexico in the west. These will experience the maximum tidal stresses and are most likely to see tidally triggered seismicity at this time. Many area, especially those where fluids are important modulators of seismicity, can experience tidal enhancement of seismicity, and several large earthquakes are likely in the next eight days. Tidal triggering often occurs near local solar midnight and noon when alignment is most linear." (June 18-22, 2020)

 

The last major event in eastern or central Mexico of M>=7.4 on September 8, 2017, while primarily triggered by a strong geomagnetic excursion, occurred two days after the full moon, much as occurred in the current situation. Previous major quakes in the area have also coincided with full and new moons suggesting strong tidal triggering in the region as detailed below:

 

"The full moon will arrive on September 6 (2017) at 07:03 UT. Longitudes which are antisolar at this time (local solar midnight) are near 110 West while those which are subsolar (local solar noon) are near 70 East longitude. These include areas of the Rocky Mountains and western Mexico in the west and central Asia in the east. It is in these regions where the highest probability of tidal triggering exists for the next week." (September 8, 2017)

 

Likewise the event of March 30, 2012 of M 7.4 to the west of today's epicenter was also associated with the new moon. At the time this summary noted this as:

 

"This could have been finalized by the tidal effects of the new moon alignment which is complete tomorrow.  Activity near Tokyo, Japan is at exactly 103 degrees from the Oaxaca epicenter. This area may see enhanced seismicity in the coming days due to this relation. The Oaxaca event is also at 103-104 degrees from an M 5.6 in South Island, New Zealand which occurred several hours earlier and at 104 degrees from Crete" (March 20, 2012)

 

Likewise an M 7.2 on February 16, 2018, the last such quake in central Mexico of M>=7 occurred, the new moon was complete the day before as noted in this summary at the time:

 

"The new moon arrived on February 15 (2018) at 21:05 UT." (February  16-17. 2018)

 

It is not coincidental that the last great earthquake in Mexico occurred exactly four  years ago on September 8, 2017. Similar weather and geomagnetic conditions at the time of that M 8.1 in eastern Mexico to those current in the region had been discussed at the time i this summary in part as:

 

"several factors including the X9.3 solar flare yesterday, tidal stresses and the severe geomagnetic storms. It occurred within about an hour of local solar midnight, a time when these effects maximize. It is also directly west of  Hurricane Irma. Stresses on land associated with Irma probably were the major promotional effect triggering this earthquake" (September 8, 2017)

 

Forecasts 136767 had expected today's activity within about 25 km was likely around  September 4-7.

 

O: 08SEP2021 09:26:48  16.7N   99.7W ML=4.2  EMSC   GUERRERO, MEXICO

O: 08SEP2021 11:11:54  16.7N   99.8W ML=4.0  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 20:01:19  16.7N   99.7W ML=4.0  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 12:20:07  16.8N   99.8W ML=4.5  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 13:18:44  16.8N  100.0W ML=4.1  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 13:28:09  16.8N   99.8W ML=4.1  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 23:08:49  16.8N   99.8W ML=4.0  EMSC   GUERRERO, MEXICO

O: 08SEP2021 09:50:20  16.9N   99.8W mb=4.6  EMSC   GUERRERO, MEXICO

O:  8SEP2021 09:34:11  16.6N   99.6W ML=4.3  EMSC   OFFSHORE GUERRERO, MEXICO    

P:  4SEP2021 136767    17.0N  100.0W 3.5-5.5 BAAAA  Oaxaca, Mexico             

P:  7SEP2021 136767    18.0N  100.0W 3.5-5.5 ABAAA  Oaxaca, Mexico             

 

Moderate earthquakes in the South Sandwich Islands aftershock sequence also continued today. The strongest of these was an M 5.6 and none were reported felt. This is normal seismicity in this active aftershock area at this time. The M 5.6 occurred near local solar midnight and may have been promoted by strong tidal stresses associated with yesterday's new moon as noted in this and previous issues of this summary:

 

"The new moon arrived at 00:52 UT on September 7, 2021. Longitudes which were near local solar midnight at this time are in the Atlantic Ocean and western Europe near 15 West and include areas of the Central Mid-Atlantic and the South Sandwich Islands while those at local solar noon are near 165 East and include areas of the northern Kurils and the Sea of Okhotsk, Near Islands and western Aleutians as well as the Vanuatu/Loyalty Islands, Kermadec-Tonga-Fiji-New Zealand arc. These areas will see maximum tidal stresses with this new moon and are most likely to see enhanced seismicity in the next week." (September 6-9, 2021)

 

Forecast 136964 had expected today's activity within about 50 km was likely around September 7.

 

O: 09SEP2021 03:47:10  58.7S   25.2W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 09SEP2021 04:37:00  58.7S   25.0W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 09SEP2021 03:54:18  58.8S   25.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  8SEP2021 21:42:18  58.4S   25.5W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands        

 

A strong series of events also hit the West Chile Rise in the Pacific Ocean today and included events of M 5.6, 5.4, 5.3 and 5.2. The largest of these occurred near local solar noon and may have been promoted by tidal effects with the new moon, but energy from the M 7.0 in Mexico may also have enhanced this activity. This is the strongest activity within about 200 km on the West Chile Rise in more than 10 years - following an M 5.9 about 200 km southeast of this on  May 20, 2010 and an M 6.0 to the east on June 5, 2008. Forecast 136956 had expected today's activity was likely to the southeast in the Chile Rise around September 7. This activity is at the sixth node from the M 7.2 in Haiti of August 14 and may have been promoted by energy from that source.

 

O: 09SEP2021 03:08:20  38.1S   94.0W mb=4.6  EMSC   WEST CHILE RISE

O: 08SEP2021 15:33:58  38.2S   93.9W mb=4.9  EMSC   WEST CHILE RISE

O: 08SEP2021 15:37:17  38.2S   93.9W mb=4.6  EMSC   WEST CHILE RISE

O: 08SEP2021 16:37:27  38.2S   93.9W Mw=5.6  EMSC   WEST CHILE RISE

O: 08SEP2021 23:13:47  38.2S   94.0W Mw=5.3  EMSC   WEST CHILE RISE

O: 08SEP2021 23:48:44  38.2S   93.9W Mw=5.4  EMSC   WEST CHILE RISE

O: 08SEP2021 21:17:33  38.3S   93.7W mb=4.9  EMSC   WEST CHILE RISE

O: 09SEP2021 01:12:10  38.3S   93.9W mb=4.8  EMSC   WEST CHILE RISE

O: 09SEP2021 01:43:33  38.3S   93.9W mb=4.6  EMSC   WEST CHILE RISE

O: 09SEP2021 06:42:48  38.3S   93.7W mb=5.2  EMSC   WEST CHILE RISE

O:  8SEP2021 10:33:14  36.3S   98.1W mb=4.6  EMSC   SOUTHEAST OF EASTER ISLAND    

O:  8SEP2021 21:56:48  38.1S   93.9W mb=4.7  EMSC   WEST CHILE RISE              

P:  7SEP2021 136956    41.0S   91.0W 4.0-5.6 ACBAA  Chile Rise                 

 

 

Seismicity in the Yellowstone National Park area of Wyoming was enhanced today. A pair of earthquakes of M 3.0 each was recorded. This is the strongest activity in Yellowstone since an M 3.6 on July 17, 2021. It occurred near local solar  noon and may have been promoted by energy from the M 7.0 in Mexico or geomagnetic or tidal stresses. Forecast 136889 had expected today's activity in Yellowstone was likely around September 10.

 

O: 08SEP2021 17:18:06  44.2N  110.8W Md=2.3  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 08SEP2021 18:00:12  44.2N  110.8W ML=3.0  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O:  8SEP2021 17:01:33  44.2N  110.8W ML=3.0  EMSC   YELLOWSTONE NAT. PARK, WYOMING

P: 10SEP2021 136889    44.6N  110.8W 2.0-4.2 AAAAA  Yellowstone/Wyoming        

 

A series of earthquakes north of Mexico in Western Texas was also energized today. The strongest of these was an M 4.2 but the swarm began near local solar  midnight about 6 hours after the M 7.0 in Mexico and may have been promoted from Mexico or by tidal and geomagnetic stresses. An M 4.2 last occurred in this area on September 3 and is among the four largest such events in the region in the past year. Many of these have occurred at full or new moons and appear tidally related. Forecast 136829 had expected today's activity was likely around September 6.

 

NEIC reported this earthquake of M 4.2 in Western Texas was felt with intensity II-III in the area(s) of  Carlsbad, New Mexico.  An earlier event of M 2.6 was felt in western Texas with intensity II.

 

O: 08SEP2021 07:28:24  31.7N  104.4W ML=2.8  EMSC   WESTERN TEXAS

O: 08SEP2021 08:50:22  31.7N  104.4W ML=2.0  EMSC   WESTERN TEXAS

O: 08SEP2021 11:22:16  31.7N  104.4W ML=2.5  EMSC   WESTERN TEXAS

O: 08SEP2021 12:05:56  31.7N  104.4W ML=2.2  EMSC   WESTERN TEXAS

O: 08SEP2021 22:02:05  31.7N  104.4W Mw=4.0  EMSC   WESTERN TEXAS

O: 08SEP2021 22:02:05  31.7N  104.4W Mw=4.2  ANSS   WESTERN TEXAS

O:  8SEP2021 13:44:41  31.6N  104.2W ML=2.4  EMSC   WESTERN TEXAS                

O:  8SEP2021 13:44:41  31.6N  104.2W ML=2.4  EMSC   WESTERN TEXAS                

P:  6SEP2021 136827    31.6N  103.6W 2.0-3.9 AAAAA  SW U.S.A                   

 

Another moderately strong event of M 5.8 also occurred in the Tonga/Fiji area today - the third such event in the area in the past three days. Forecast 136944 had expected this event within about 150 km was likely around September 8. It occurred near the geomagnetic equator and may have been promoted by the strong geomagnetic storm today.

 

O:  9SEP2021 04:59:43  19.2S  176.5W Mw=5.8  EMSC   FIJI REGION                  

P:  8SEP2021 136944    20.0S  175.0W 4.0-5.7 AABAA  Tonga Islands              

 

MAJOR EARTHQUAKE DAMAGING, DEADLY IN GUERRERO, MEXICO

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 7, 2021

 

A major earthquake of M 7.0 shook the region of Guerrero, Mexico south of Mexico City today. A foreshock of M 4.2 occurred several hours before the mainshock and was felt in Guerrero with IV at Acatlan, Zihuatanejo, Coatepec,Mexico City and II-III in Tlapa, Santos Reys, Oaxaca, Vista Hermosa, Naucalpan, Chautla, Puebla and in Cuernavaca, Morelos, Mexico. NEIC reported the mainshock was felt with maximum intensity VII with slight damage in Guerrero, Mexico at Acapulco, Chipancingo, and VI in El Ocotilo, Tepecoacuillc, Tizapotla and Taxco with IV in Tlapa and Huamuxtitlan and II-III in Xaltianguis and Petatlan and in Mexico City. A number of aftershocks were lightly felt in the Mexico City and Tlalnepantla, Mexico area. Reuters reported at least one person died in the quake when a pole fell on him. The earthquake was centered near Acapulco, Mexico and caused damage as far north as Mexico City with landslides. Tall buildings swayed and cars were crushed by falling debris. A tsunami alert was not issued but minor sea level fluctuations may have occurred. No earthquakes of M>=7 have occurred within about 100 km of today's epicenter in the past 30 ye3ars. Earthquakes within about 250 km of this occurred about 250 km northeast on September 19, 2017 and to the northwest on April 18, 2014. Similar events hit to the east of this on March 20, 2012 (M 7.4); February 25, 1996 (M 7.1) and September 14, 1995 (M 7.4). This earthquake occurred with the new moon and was probably promoted by strong tidal stresses associated with that alignment. This report had expected enhanced seismicity with this new moon in previous issues as:

 

 

"The new moon will arrive at 00:52 UT on September 7, 2021. Longitudes which are near local solar midnight at this time are in the Atlantic Ocean and western Europe near 15 West and include areas of the Central Mid-Atlantic and the South Sandwich Islands while those at local solar noon are near 165 East and include areas of the northern Kurils and the Sea of Okhotsk, Near Islands and western Aleutians as well as the Vanuatu/Loyalty Islands, Kermadec-Tonga-Fiji-New Zealand arc. These areas will see maximum tidal stresses with this new moon and are most likely to see enhanced seismicity in the next week." (September 5-6, 2021)

 

The last major earthquake of M>=7 in the world was an M 7.0 on August 18, 2021 in the Vanuatu Islands. It is located near 100 degrees from both the South Sandwich Islands quake of M 8.1 of August 12 and the Vanuatu earthquake and was probably promoted by energy from those sources.

 

A Tropical Depression made landfall off the coast of Guerrero, Mexico about the time of the M 7.0. Stresses associated with this storm probably also  helped promote seismicity in this region of Mexico at this time as reported in this summary as:

 

"Tropical Depression 15E formed  south of western Mexico today with winds up to 40 kts. This system is expected to track to the north and west and may enhance seismicity in western and central Mexico. The M 7.0 in Guerrero, Mexico today may have been promoted by stresses associated with this storm." (September 6-7, 2021)

 

A series of moderate earthquakes north of this epicenter has been occurring over the past two days. It is likely that this was precursory to today's event in Guerrero, Mexico. This summary had noted this activity in previous issues as:

 

 

"Moderate earthquakes of M 4.3, 4.4 and 4.4 was felt widely in northern and western Mexico in San Luis Potosi and Guanajuato States of Mexico. NEIC reported maximum intensity V in Ahualulco and IV in San Felipe, Zaragoza, Edina and II-III in Escalerillas, San Luis Potosi, Soledad, Leion Jauregui and Juarez. The only other event of M>=4.4 within about 250 km of this epicenter in the past 30 years was an M 4.4 about 250 km north of this on June 4, 2004. This series began yesterday with an M 4.3 and an M 4.1. These events are located at 103 degrees from the South Sandwich Islands M 8.1 of August 12 and were probably promoted  from that source. Forecast 136767 had expected enhanced seismicity south of this around September 7." (September 6-7, 2021)

 

The forecast noted here referenced a possible moderate to strong quake about

100 km north of today's Mexico quake as:

 

 

O: 05SEP2021 11:07:43  21.7N  101.0W ML=4.3  EMSC   GUANAJUATO, MEXICO

O: 06SEP2021 04:49:49  21.7N  101.1W ML=4.4  EMSC   GUANAJUATO, MEXICO

O:  6SEP2021 02:31:16  21.6N  100.9W mb=4.4  EMSC   GUANAJUATO, MEXICO           

O:  7SEP2021 08:49:02  21.7N  101.0W ML=3.8  EMSC   GUANAJUATO, MEXICO           

P:  6SEP2021 136760    18.0N  102.0W 3.5-5.4 ACAAA  Michoacan, Mexico          

P:  7SEP2021 136767    18.0N  100.0W 3.5-5.5 ACAAA  Oaxaca, Mexico             

 

Forecast 136767 had expected today's activity was likely within about 25 km  of the mainshock between September 4 and 8.

 

O: 08SEP2021 03:50:47  16.8N   99.8W ML=4.1  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 02:41:55  16.9N   99.9W ML=4.3  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 02:41:55  16.9N   99.9W ML=4.3  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 03:30:20  16.9N   99.9W ML=4.2  EMSC   GUERRERO, MEXICO

O: 08SEP2021 04:17:50  16.9N   99.9W ML=4.2  EMSC   OFFSHORE GUERRERO, MEXICO

O: 08SEP2021 04:24:15  16.9N   99.8W ML=4.2  EMSC   GUERRERO, MEXICO

O: 08SEP2021 02:18:02  17.0N   99.8W mb=4.9  EMSC   GUERRERO, MEXICO

O: 08SEP2021 00:55:24  17.1N   99.4W mb=4.2  EMSC   GUERRERO, MEXICO

O: 08SEP2021 02:58:20  17.1N   99.8W mb=4.7  EMSC   GUERRERO, MEXICO

O:  8SEP2021 03:53:33  16.0N   98.4W ML=4.1  EMSC   OFFSHORE OAXACA, MEXICO      

O:  8SEP2021 05:43:05  17.1N   99.7W mb=4.5  EMSC   GUERRERO, MEXICO             

O: 08SEP2021 01:47:46  17.0N   99.8W Mw=7.0  EMSC   GUERRERO, MEXICO

P:  4SEP2021 136767    17.0N  100.0W 3.5-5.5 BAAAA  Oaxaca, Mexico             

P:  7SEP2021 136767    18.0N  100.0W 3.5-5.5 AAAAA  Oaxaca, Mexico             

 

 

An earthquake of M 5.3-5.5 north of Afghanistan was felt in Tajikistan today in Murgob Gorno-Badakhshan and Dushanbe with intensity V and II respectively. It was also reported felt with intensity II in Faizabad, Afghanistan. This is the strongest in a series of moderate earthquake in the region which began in late August and has included nine moderate quakes of M>=4 including those of M 5.0 in the Hindu Kush, Afghanistan on September 2 and August 30. An earthquake of M 5.9  hit this area on February 12, 2021 and this is probably an aftershock of that earthquake. Similar quakes hit the area on Jun 16 and January 24, 2020. Today's event is located at 103 degrees from the M 7.0 in Vanuatu of August 18 and was probably promoted by energy from that source. This summary noted this swarm previously as:

 

 

"A moderate earthquake of M 5.0 in Afghanistan today continued moderate seismicity in that region which has been occurring over the past several days. This summary noted this in previous issues as:

 

"An unusual earthquake of M 4.5 occurred today in Central Afghanistan, accompanying the major geomagnetic storm today. This epicenter is located in the mountains west of Kabul, Afghanistan. The last earthquake within about 250 km of this epicenter in Afghanistan was an M 5.0 and 4.7 aftershock on January 15, 2007." (August 27-28, 2021)

 

Two earthquakes of larger magnitude have occurred within about 200 km of this epicenter in Afghanistan in the past year - an M 5.5 on January 16, 2021 and an M 5.2 on August 15." (August 30-31, 2021)

 

Forecast 136812 had expected today's activity within about 100 km was likely around September 6.

 

O: 07SEP2021 13:34:13  38.2N   73.3E mb=4.7  EMSC   TAJIKISTAN

O:  8SEP2021 05:20:02  38.2N   73.2E mb=5.5  EMSC   TAJIKISTAN                   

P:  6SEP2021 136812    39.0N   72.0E 3.8-5.3 AAAAA  Hindu Kush/Pakistan        

 

A strong earthquake of M 6.0 was also felt in the area of Tonga/Fiji today. NEIC reported maximum intensity V in Nuku'alofa and II-III in Suva, and Navua, Central Fiji and in Apia, Samoa.  The last shallow focus earthquake of M>=6 within about 200 km of today's epicenter was an M 6.4 on Octgober 1, 2020 and an M 6.1 on November 11, 2019. Forecast 136944 had expected today's activity within about 100 km was likely around September 8.

 

O:  7SEP2021 09:49:57  19.4S  176.1W Mw=5.8  EMSC   FIJI REGION                  

O:  7SEP2021 09:49:57  19.4S  176.1W Mw=6.0  ANSS   FIJI REGION                  

P:  8SEP2021 136944    20.0S  175.0W 4.0-5.7 AAAAA  Tonga Islands              

 

 

MODERATELY STRONG QUAKE SHAKES TAIWAN

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 6, 2021

 

A moderate earthquake of M 5.2-5.9 shook much of the area of Taiwan today.

No damage was reported with today's earthquake.  NEIC reported this earthquake of M 5.2 in Taiwan was felt with intensity III-IV in the area(s) of Taiwan at Hualien, Ilan, Taipei, Taichung, Tainan and Kaohsiung. CWB reported this earthquake was felt with intensity IV in Hualien; III in Yilan, Nantou, Taichung, Taitung, Changhua, Chiayi, Taipei, II in Hsinchu, Yunlin, Miaoli, Taoyuan, Chiayi, Kaohsiung, Tainan and I in Pingtung Counties, Taiwan. The last earthquake in Taiwan with M>=5.9 was an M 6.2 on December 10, 2020. The most

recent such event was an M 5.8 on August 4, 2021 and today's event may have been a regional aftershock of that.  Forecast 136791 had expected today's event within about 100 km was likely around September 6. Today's event occurred near local solar midnight and may have been promoted by tidal stresses associated with the new moon which arrived today as noted in previous issues of this summary:

 

"The new moon will arrive at 00:52 UT on September 7, 2021. Longitudes which are near local solar midnight at this time are in the Atlantic Ocean and western Europe near 15 West and include areas of the Central Mid-Atlantic and the South Sandwich Islands while those at local solar noon are near 165 East and include areas of the northern Kurils and the Sea of Okhotsk, Near Islands and western Aleutians as well as the Vanuatu/Loyalty Islands, Kermadec-Tonga-Fiji-New Zealand arc. These areas will see maximum tidal stresses with this new moon and are most likely to see enhanced seismicity in the next week." (September 5-6, 2021)

 

 

O:  6SEP2021 14:00:25  23.8N  122.2E Mw=5.2  EMSC   TAIWAN REGION                 

O:  6SEP2021 14:00:26  23.9N  122.1E ML=5.9  TAI    Hualien, Taiwan              

P:  6SEP2021 136791    23.0N  123.0E 4.0-5.4 AAAAA  Taiwan                     

 

An unusual earthquake also occurred in the Lac Kivu region of the Congo today. NEIC reported this earthquake of M 4.4 in DR Congo was felt with intensity IV - V in the area(s) of DR Congo at Kabare, Bukavu, Goma, Kigali, Rwanda and in Gitega, Burundi. Similar events of M 4.4-4.5 occurred in this region of the Congo on February 9 and February 25, 2021. This earthquake occurred near local solar midnight and may have been promoted by high tidal stresses from the new moon which arrived about an hour earlier. Forecast 136731 had expected this event was likely within about 25 km of this epicenter in early September. This is near the volcano Mount Nyirangongo which erupted earlier this year and may indicate additional volcanic activity in the area.

 

O:  7SEP2021 01:48:22   2.2S   28.9E mb=4.4  EMSC   LAC KIVU REGION, CONGO       

P:  2SEP2021 136731     2.0S   29.0E 3.0-4.6 BAAAA  Lake Victoria area         

 

An unusual earthquake of M 5.1 hit near the north geographic pole today in the region north of Svalbard. It was not reported felt in this region. This is the strongest earthquake in this region of the Arctic Ocean since an M 5.2 on February 18, 2020. Most earthquakes of M>=5 in the area are moderate events of M 5.0-5.5. The largest earthquake in the area in the past 30 years was an M 6.0 in a series of moderately large events on October 28, 2017. Like the event in the Yukon Territory of Canada today this event is located at 145 degrees from the South Sandwich Islands M 8.1 of August 12 and was probably promoted by energy from that source. It is also near 103 degrees from the M 7.1 in Vanuatu of August 18 and may have promoted by energy from that source. Other earthquakes at this distance from Vanuatu today included the M 5.7 in the South Sandwich Islands and moderate quakes in Mexico.

 

O:  6SEP2021 17:31:22  86.1N   33.3E mb=5.1  EMSC   NORTH OF SVALBARD            

 

The strongest earthquake in the world today was an M 5.7 in the South Sandwich Islands. This is part of a long-enduring aftershocks sequence following an M 8.1 on August 12, 2021 but is a decline in daily activity over the past several weeks. Forecast 136964 had expected today's event within about 50 km was likely around September 7.

 

O: 06SEP2021 08:19:42  58.8S   25.3W Mw=5.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  7SEP2021 01:52:55  58.5S   25.3W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

The strongest earthquake in the U.S. or Canada today was an M 3.9-4.1 in the southern Yukon Territory of Canada near southeast Alaska. It was lightly felt in southeastern Alaska. NEIC reported this earthquake of M 4.1 in Southeastern Alaska was felt with intensity II-III in the area(s) of Southeastern Alaska at Elfin Cove. A similar M 4.1 hit the region on September 5, 2021 but the last event in the area of greater magnitude occurred about 150 km to the north on May 9, 2021. Forecast 136907 had expected today's activity around September 5. Like the event in the Arctic Ocean today this event is located at 145 degrees from the South Sandwich Islands M 8.1 of August 12 and was probably promoted by energy from that source.

 

O: 06SEP2021 07:10:55  60.3N  139.6W MB=4.1  ECAN OF YAKUTAT, AK   

O: 06SEP2021 07:10:48  60.0N  140.1W mb=3.9  EMSC   SOUTHERN YUKON TERRITORY, CANADA

O: 06SEP2021 16:49:33  60.0N  140.1W ml=3.4  EMSC   SOUTHEASTERN ALASKA

O: 06SEP2021 21:10:56  60.0N  140.2W ML=3.0  EMSC   SOUTHERN YUKON TERRITORY, CANADA

O:  6SEP2021 07:30:44  60.1N  140.3W ML=3.3  EMSC   SOUTHERN YUKON TERRITORY, CANA

P:  5SEP2021 136907    59.0N  139.0W 3.0-4.6 AAAAA  Southeast Alaska           

 

MODERATELY STRONG QUAKE FELT IN TONGA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 5, 2021

 

The strongest earthquake in the world today was an M 5.9 in the Tonga Islands. NEIC reported it was felt with intensity IV in Nuku'alofa and II-III in Mu'a and Tofoa-Koloua, Tongatapu. The last earthquake within about 200 km of this epicenter in Tonga with M>=5.9 occurred more than a year ago as an M 5.9 on May 28, 2020 and prior to that an M 6.1 on June 15, 2019. Forecast 136689 and 136944 had expected this area would see enhanced seismicity in late August or early September.

 

O:  5SEP2021 17:51:44  21.9S  174.7W Mw=5.9  EMSC   TONGA                        

P:  8SEP2021 136944    20.0S  175.0W 4.0-5.7 BBAAA  Tonga Islands              

P: 28AUG2021 136689    22.0S  175.0W 4.0-5.6 CAAAA  Tonga Islands              

 

Moderate earthquakes of M 4.3, 4.4 and 4.4 was felt widely in northern and western Mexico in San Luis Potosi and Guanajuato States of Mexico. NEIC reported maximum intensity V in Ahualulco and IV in San Felipe, Zaragoza, edina and II-III in Escalerillas, San Luis Potosi, Soledad, Leion Jauregui and Juarez. The only other event of M>=4.4 within about 250 km of this epicenter in the past 30 years was an M 4.4 about 250 km north of this on June 4, 2004. This series began yesterday with an M 4.3 and an M 4.1. These events are located at 103 degrees from the South Sandwich Islands M 8.1 of August 12 and were probably promoted  from that source. Forecast 136767 had expected enhanced seismicity south of

 this around September 7.

 

O: 05SEP2021 11:07:43  21.7N  101.0W ML=4.3  EMSC   GUANAJUATO, MEXICO

O: 06SEP2021 04:49:49  21.7N  101.1W ML=4.4  EMSC   GUANAJUATO, MEXICO

O:  6SEP2021 02:31:16  21.6N  100.9W mb=4.4  EMSC   GUANAJUATO, MEXICO           

P:  7SEP2021 136767    18.0N  100.0W 3.5-5.5 ACAAA  Oaxaca, Mexico             

 

Strong aftershocks also continued today in the South Sandwich Islands. The largest of these was an M 5.4. This continues the strong and lengthy aftershock series following the M 8.1 in the region of August 12. Forecasts 136964 and 136965 had expected today's activity was likely around September 7 within about 50 km of these events. An M 4.6 event occurred within several minutes of local solar noon and was probably promoted by high tidal stresses which maximize near this hour.

 

O: 05SEP2021 13:47:43  58.6S   25.0W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 05SEP2021 09:59:01  58.7S   25.2W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 05SEP2021 10:17:53  58.8S   25.1W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 05SEP2021 10:28:59  59.3S   25.3W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  5SEP2021 21:00:42  59.4S   25.8W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

P:  7SEP2021 136965    60.0S   29.0W 4.0-5.8 AAAAA  So. Sandwich Islands       

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in Southern Alaska. NEIC reported this earthquake of M 3.5-3.8 in Southern Alaska was felt with intensity II-III in the area(s) of Southern Alaska at Homer. The last earthquake within about 100 km of this epicenter with M>=3.8 was an M 4.0 on August 14, 2021 and an M 4.2 on June 28, 2021. The last earthquake of M>4.5 in the area was an M 4.8 on June 7, 2019, an aftershock of an M 5.8 on May 27, 2019. Forecast 136912 had expected a moderate earthquake in this area was likely around September 7.

 

O: 05SEP2021 16:42:01  59.0N  152.8W ML=3.3  EMSC   SOUTHERN ALASKA

O:  5SEP2021 12:28:10  59.3N  152.4W ML=3.8  EMSC   SOUTHERN ALASKA              

P:  7SEP2021 136912    60.1N  153.4W 3.2-5.2 AAAAA  Central Alaska             

 

UNUSUAL HIGH LATITUDE QUAKES ASSOCIATED WITH EARLIER GEOMAGNETIC STORM

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 4, 2021

 

The strongest earthquake in the U.S. or Canada was an M 4.4 in Baffin Bay. While an M 3.3 hit near this epicenter on September 1, 2021, the last event in the region within about 200 km with M>=4.4 since an M 4.6 on October 22, 2019 and an M 4.6 on May 22, 2017. These may be regional aftershocks of an M 6.0 in the area on July 7, 2009.  This may have been promoted by the recent geomagnetic storm which would have preferentially enhanced seismicity at high latitudes such as in the South Sandwich Islands and Baffin Bay, Canada as noted in earlier summaries:

 

"This geomagnetic storm is expected to continue through the end of August and may enhance global seismicity especially at high latitudes " (August 31, 2021)

 

O:  4SEP2021 18:58:14  73.3N   73.0W mb=4.4  EMSC   BAFFIN BAY                   

 

The strongest earthquake in the world today was once again in the South Sandwich Islands.  Forecast 136964 had expected this event within about 50 km in early September. It is an aftershock of the M 8.1 of August 12, 2021 and continues a slowly declining aftershock sequence.

 

O: 04SEP2021 13:55:59  58.1S   25.3W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 05SEP2021 02:03:21  58.7S   23.9W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 04SEP2021 16:13:02  58.9S   25.3W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 04SEP2021 07:44:28  59.0S   25.5W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  5SEP2021 05:26:32  56.8S   25.8W Mw=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  9SEP2021 136964    57.0S   25.0W 4.0-5.6 BAAAA  So. Sandwich Islands       

 

An unusual earthquake of M 4.5 occurred today in the Madeira Islands southwest of Portugal. It was not reported felt in this area. The last such earthquakes in the Madeira Islands occurred as M 4.7 events on January 1, 2021 and January 30, 2021.

 

O:  5SEP2021 06:10:44  32.6N   17.3W mb=4.5  EMSC   MADEIRA ISLANDS, PORTUGAL REGI

QUAKES IN NORTH ISLAND, NEW ZEALAND; ANTIPODAL AREAS OF OKHOTSK AND SOUTH SANDWICH IS   

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 3, 2021

 

An earthquake of M 5.0 was widely felt in the Hastings area of North Island, New Zealand today. NEIC reported it was felt with maximum intensity V in New Zealand in Otane, Hastings, Hawke's Bay and IV in Waipukurau, Dannevirke, Napier, Palmersont North and II-III in Ohakune, Wairoa, Turngi and Masterton, New Zealand. GEONET reported this earthquake was felt with moderate intensity in southeastern North Island. More than 6154 people reported feeling this earthquake. Light to moderate intensity was reported throughout much of southern and eastern North Island and northern South Island. 1513 reports of weak intensity;  2970 of light intensity; 1470 with moderate; 184 with strong shaking and 6 with severe and 11 with extreme intensity. This is the strongest earthquake in North Island within about 200 km of this epicenter since an M 5.9 on November 22, 2016. Forecasts 136957 and 136702 had expected this activity was likely within this range at the end of August or in early September, 2021.

 

 

O: 04SEP2021 04:54:27  40.0S  176.6E MS=4.9  GEONET Felt with moderate intensity

O:  4SEP2021 04:54:26  40.0S  176.7E mb=5.0  EMSC   NORTH ISLAND OF NEW ZEALAND  

P:  1SEP2021 136957    40.0S  174.0E 3.0-4.4 BABAA  North Island, N.Z.         

P: 28AUG2021 136702    40.0S  175.0E 3.0-4.4 CABAA  North Island, N.Z.         

 

The strongest earthquakes in the world today occurred at the near-antipodal areas of the South Sandwich Islands (M 5.7) and the Sea of Okhotsk, Russia (M 5.8). The earthquake in the South Sandwich Islands is not surprising as earthquakes of this size have occurred almost daily since the M 8.1 there on August 12, 2021. It was accompanied by aftershocks of M 4.5 and 4.7. Forecast 136964 had expected this event within about 100 km was likely around September 7. 

 

O: 03SEP2021 16:50:32  57.9S   24.8W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 03SEP2021 18:14:59  58.5S   25.6W mb=4.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  3SEP2021 07:49:43  59.9S   26.7W Mw=5.7  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 BAAAA  So. Sandwich Islands       

 

The earthquake of M 5.8 in the Sea of Okhotsk was reported lightly felt in this area. It occurred in the antipodal area of the South Sandwich Islands and was probably promoted by strong energy from that source. A possible precursory earthquake hit the area yesterday and was commented on in the previous summary as:

 

"The strongest earthquake felt in the world today was an M 5.2 northwest of the Kuril Islands. It was not reported felt in this region. The last earthquake of M>=5.2 within about 200 km of this epicenter was an M 5.4 on September 18, 2014 and prior to that an M 5.2 on July 9, 2008. An M 6.7 hit about 200 km northeast of today's epicenter on May 24, 2013. The event in 2013 followed an M 8.3 in the Sea of Okhotsk earlier on that date. At the time of that event, this summary noted:

 

"A great earthquake of M 8.2-8.3 hit deep under Kamchatka and the Sea of

Okhotsk, Russia today. It was preceded by major earthquakes in Northern California (M 5.7) and Tonga (M 7.4). While it was too deep to have triggered a significant tsunami, it was felt throughout the northwestern Pacific rim. Because of its size and great depth it was felt as far as Moscow, 7,000 km to the west where shaking caused evacuation of some office buildings and people fled into the streets/" (May 24, 2013)

 

These areas show deep focus earthquakes and may help trigger each other." (September 3, 2021)

 

This earthquake in the Sea of Okhotsk is the strongest within about 200 km of this epicenter in at least 30 years - since 1990. Forecast 136640 had expected enhanced seismicity in this area within about 100 km of today's epicenter was likely around August 29. This epicenter is at 103 degrees from the M 7.2 in Haiti of  August 14 and was probably promoted by strong seismic energy from that source.

 

 

O:  3SEP2021 10:14:25  49.5N  147.0E Mw=5.8  EMSC   SEA OF OKHOTSK               

P: 29AUG2021 136640    50.0N  148.0E 4.0-5.4 BAAAA  Sakhalin                   

 

MODERATE QUAKES UNDER WORLD'S OCEANS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 2, 2021

 

A series of moderately large earthquake hit under the world's oceans today. None of these were reported felt. The largest was an M 5.6 in the South Sandwich Islands but activity also continued in the Scotia Sea following a moderate quake in that area yesterday. An earthquake of M 4.6 in the Azores was the strongest within about 200 km of this epicenter since an M 4.8 on July 24, 2021 - the largest in the past year. This area may have been promoted by energy from the South Sandwich Islands as it is located at 103 degrees from those epicenters - a distance at which strong energy concentration occurs on the earth's surface following major earthquakes.

 

O:  2SEP2021 14:17:56  42.0N   29.4W mb=4.6  EMSC   AZORES ISLANDS REGION        

P:  8SEP2021 136869    41.0N   30.0W 4.0-5.8 CAAAA  No. Mid-Atlantic Ridge     

 

Many of these events occurred near local solar midnight or local solar noon and were probably promoted by high tidal stresses which maximize near this hour. These included the events in the East Pacific Rise (local midnight); the Azores (local noon) and the South Sandwich Islands (local midnight).

 

An M 5.4 also occurred in the Southeast Pacific Rise west of Central Chile.  The last similar activity within about 250 km of the events in the Southern East Pacific  Rise as an M 5.8 on December 25, 2019 and an M 5.4 on May 4, 2019 following a lull from 2014 to 2019. Forecast 136940 had expected today's activity within about 100 km of today's Pacific Rise activity in early September. This activity is at the fifth node (72 degrees) from the M 6.9 in the Vanuatu Islands and at the sixth node (60 degrees) from the Haiti quake of August 14 and was probably promoted by energy from those sources.

 

O: 03SEP2021 05:40:10  24.5S  116.1W mb=4.8  EMSC   SOUTHERN EAST PACIFIC RISE

O:  3SEP2021 05:22:57  24.3S  116.0W Mw=5.4  EMSC   SOUTHERN EAST PACIFIC RISE   

P:  8SEP2021 136940    24.0S  115.0W 4.0-5.6 BAAAA  So. East Pacific Rise      

 

O:  2SEP2021 17:58:55  60.4S   48.8W mb=4.7  EMSC   SCOTIA SEA                   

 

O: 02SEP2021 08:47:25  58.9S   25.5W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 02SEP2021 12:01:52  59.2S   24.9W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 03SEP2021 00:56:41  59.4S   25.7W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  3SEP2021 00:06:16  58.8S   25.8W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 BAAAA  So. Sandwich Islands       

 

The strongest earthquake felt in the world today was an M 5.2 northwest of the Kuril Islands. It was not reported felt in this region. The last earthquake of M>=5.2 within about 200 km of this epicenter was an M 5.4 on September 18, 2014 and prior to that an M 5.2 on July 9, 2008. An M 6.7 hit about 200 km northeast of today's epicenter on May 24, 2013. The event in 2013 followed an M 8.3 in the Sea of Okhotsk earlier on that date. At the time of that event, this summary noted:

 

"A great earthquake of M 8.2-8.3 hit deep under Kamchatka and the Sea of

Okhotsk, Russia today. It was preceded by major earthquakes in Northern California (M 5.7) and Tonga (M 7.4). While it was too deep to have triggered a significant tsunami, it was felt throughout the northwestern Pacific rim. Because of its size and great depth it was felt as far as Moscow, 7,000 km to the west where shaking caused evacuation of some office buildings and people fled into the streets/" (May 24, 2013)

 

These areas show deep focus earthquakes and may help trigger each other. Forecast 136640 expected today's activity in this area was likely around August 29.

 

O:  2SEP2021 20:26:14  50.5N  150.5E Mw=5.2  EMSC   NORTHWEST OF KURIL ISLANDS   

P: 29AUG2021 136640    50.0N  148.0E 4.0-5.4 BABAA  Sakhalin                    

 

A moderate earthquake of M 4.8 shook the Caucasus region of Russia today. NEIC reported this earthquake of M 4.8 in the Caucasus, Russia was felt with intensity II-III in the area(s) of  Georgia at Telari, Kakheti and Tbilisi.

The last earthquake within about 200 km of this epicenter with larger magnitude was an M 4.9 on August 10, 2019 and an M 5.3 on June 5, 2018. Forecast 136846 had expected activity to the south of this around September 3.

 

O:  3SEP2021 03:34:49  42.4N   46.1E mb=4.8  EMSC   CAUCASUS REGION, RUSSIA      

P:  3SEP2021 136846    38.0N   44.0E 3.5-5.0 ACBAA  Turkey                     

 

The strongest earthquakes in the U.S. or Canada today were an M 4.6 south of Alaska in the Alaska Peninsula area and an M 4.7 in the Unimak Island region of Alaska. These events were not reported felt in the area. The M 4.7 in the Unimak Island area was the strongest in that region since an M 5.1 on January 11, 2021.  Forecast 136908 had expected enhanced seismicity in the Unimak Islands was likely around September 2.

 

O:  3SEP2021 03:55:44  53.5N  163.6W mb=4.7  EMSC   UNIMAK ISLAND REGION, ALASKA 

P:  2SEP2021 136908    54.6N  163.6W 3.5-5.0 ABAAA  Unimak Islands, Aleutians  

 

The earthquake of M 4.6 South of Alaska was the strongest within about 150 km  of that epicenter since an M 6.1 on July 29, 2021. Forecast 136890 had expected enhanced seismicity in this area was likely around September 2.

 

O:  2SEP2021 08:08:34  54.5N  159.7W mb=4.6  EMSC   SOUTH OF ALASKA              

P:  2SEP2021 136890    54.7N  156.9W 3.5-5.1 AABAA  Alaska Peninsula           

 

An M 4.2 in western Texas today was accompanied by a strong series of foreshocks and aftershocks.  NEIC reported this earthquake of M 4.2 in Western Texas was felt with intensity II-III in the area(s) of New Mexico at Carlsbad, Artesia, Alamogordo, Roswell, Capitan. Several aftershocks were felt lightly in Roswell, New Mexico.  This area has seen a long series of moderate earthquakes this year including events of M 4.3, 4.4 and 4.5 on March 17, 2021, June 25, 2021 and July 28, 2021. This series began with an M 5.0 on March 26, 2021 after nine years of quiet at this magnitude in the area. Forecast 136827 had expected enhanced seismicity in this area was likely around September 3.

 

O: 02SEP2021 07:23:05  31.7N  104.4W ML=2.0  EMSC   WESTERN TEXAS

O: 02SEP2021 09:37:00  31.7N  104.0W ML=2.4  EMSC   WESTERN TEXAS

O: 02SEP2021 12:20:45  31.7N  104.4W ML=2.1  EMSC   WESTERN TEXAS

O: 03SEP2021 00:42:59  31.7N  104.4W ML=3.4  EMSC   WESTERN TEXAS

O: 03SEP2021 01:31:49  31.7N  104.4W ML=3.0  EMSC   WESTERN TEXAS

O: 03SEP2021 05:41:14  31.7N  104.4W ML=4.2  EMSC   WESTERN TEXAS

O: 03SEP2021 05:45:49  31.7N  104.4W ML=2.8  EMSC   WESTERN TEXAS

O:  3SEP2021 06:29:06  31.7N  104.4W ML=2.6  EMSC   WESTERN TEXAS                

P:  3SEP2021 136827    32.5N  104.6W 2.0-3.9 AAAAA  SW U.S.A                   

 

 

MODERATE QUAKE SHAKES ROMANIA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 1, 2021

 

An earthquake of M 4.4 in Romania today was widely felt.  NEIC reported this earthquake of M 4.4 in Romania  was felt with intensity II-III in the area(s) of Romania at Stantu (VI); Pocsani, Galati, Bucherest (V) and IV in Brasov, Ploesti, Iasi and in Chiainau, Moldavia. Similar earthquakes of M 4.4 have shook Romania in the past year on August 11, 2021; April 9, 2021 and October 29, 2020 but the last of larger magnitude in Romania was an M 4.9 on April 24, 2020. Forecast 136615 had expected today's event was likely at the end of August within about 50 km of this epicenter.

 

O:  1SEP2021 10:32:11  45.7N   26.5E mb=4.4  EMSC   ROMANIA                      

P: 29AUG2021 136615    46.0N   27.0E 3.0-4.9 AAAAA  Romania/NW Turkey          

 

A moderate M 5.6-5.8 was felt in the area of Atacama, Chile today. NEIC reported this earthquake of M 5.6 in Atacama, Chile was felt with intensity II-III in the area(s) of Atacama, Chile at Copiapo (VI), Diego de Almagro (IV); and Vina del Mar, Quilpue, Valparaiso and Santiago, Chile.  GUC reported this earthquake was felt with intensity  III in  Tarapaca at Alto Hospicio and Iquique and in Antofagasta with III in Quillagua, Chile. This is the strongest earthquake in the area of Atacama within about 200 km of this epicenter since an M 6.0 about 150 km southwest of this on July 4, 2021. The last such event closer to this epicenter was an M 6.8 and aftershocks on September 1, 2020 exactly one year ago. Today's event may be an aftershock of that earthquake. Aftershocks at one year after mainshocks are statistically more likely than at other times and may be related to local weather conditions or ocean or atmospheric loading.  Forecasts 136678, 136679 and 136936 had expected enhanced seismicity in this area of Chile was likely at the end of August or in early September. This epicenter is located near 103 degrees from the M 7.1 in Vanuatu of August 18 and was probably promoted by energy from that source. Other events at this distance from Vanuatu today occurred as an M 5.6 in the South Sandwich Islands, Oacaxa and Guerrero, Mexico, Texas, Afghanistan.

 

O:  1SEP2021 18:36     27.7S   71.1W mb=5.8  GUC    Tarapaca at Alto Hospicio and

O:  1SEP2021 18:35:44  27.7S   71.2W Mw=5.6  EMSC   OFFSHORE ATACAMA, CHILE      

P: 26AUG2021 136679    28.0S   71.0W 4.0-5.4 BAAAA  Coast Central Chile        

P: 30AUG2021 136678    28.0S   68.0W 4.0-5.5 AACAA  Argentina                  

P:  4SEP2021 136936    29.0S   72.0W 4.0-5.5 BBAAA  Coast Central Chile        

 

Moderately strong earthquakes occurred today in the Central Mid-Atlantic Ridge. These events were not reported felt in these remote areas. They occurred as Hurricane Larry was forming to the north and may have been promoted by energy from that storm as noted in this summary:

 

"Hurricane Larry formed today in the mid-Atlantic with winds up to 75 kts. It is expected to track to the west over the next week but not to make landfall. Some minor seismic enhancement in the Virgin Islands may occur around September 6-9." (September 1, 2021)

 

Both of these occurred near local solar noon or midnight and were probably promoted by strong tidal stresses at this hour. The largest was an M 5.7 within minutes of local solar noon in the central Mid-Atlantic. This is the largest quake in the world today. The last earthquake within about 250 km of this epicenter with M>=5.7 was an M 6.5 on November 30, 2017. Forecast 136448 had expected today's event was likely within about 25 km of this epicenter at the end of August or early September. This activity is at 142 - 144 degrees from strong shocks in the Kermadec Islands (M 8.1, March 4) and Mindanao, Philippines (M 7.1, August 11) and at the sixth and seventh nodes (60 and 52 degrees) and may have been promoted by strong seismic energy from those sources.

 

O:  1SEP2021 13:50:13   1.1S   24.3W Mw=5.7  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 28AUG2021 136448     1.0S   24.0W 4.0-5.6 BAAAA  Central Mid-Atlantic       

 

An M 5.3 also occurred to the east of the M 5.7 in the area of the Atlantic north of Ascension Island. A similar M 5.3 hit within about 250 km of this epicenter on June 6, 2021 but the last event of larger magnitude in this area was an M 6.3 about 200 km to the east on October 23, 2019. Forecast 136726 had expected this event within about 100 km was likely around September 3.

 

O:  1SEP2021 22:51:35   1.6S   15.5W Mw=5.3  EMSC   NORTH OF ASCENSION ISLAND    

P:  3SEP2021 136726     1.0S   16.0W 4.0-5.4 AAAAA  Central Mid-Atlantic       

 

An earthquake of M 5.0 in Afghanistan today continues a series of moderate quakes in the area over the past week. NEIC reported this earthquake of M 5.0 in Afghanistan was felt with intensity II-III in the area(s) of Tajikistan at Boshkengash. It is at 103 degrees from the M 7.1 in Vanuatu of August 18 and may have been promoted by energy from that source. Forecast 136812 had expected enhanced seismicity in this area of Hindu Kush was likely around September 2.

 

O:  2SEP2021 04:50:06  37.5N   70.3E mb=5.0  EMSC   HINDU KUSH REGION, AFGHANISTAN

P:  2SEP2021 136812    36.0N   71.0E 3.8-5.5 ABAAA  Hindu Kush/Pakistan        

 

The strongest earthquakes in the world today again occurred in the South Sandwich Islands with events of M 5.6, 5.1, 5.0 and 4.9 recorded. These events were not reported felt in this remote area. These continue almost daily aftershocks at this magnitude level since the mainshock of M 8.1 on August 12, 2021. Forecast 136964 had expected this activity in early September within about 25 km of today's activity.

 

O: 01SEP2021 10:02:18  59.0S   25.6W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 02SEP2021 06:05:17  59.0S   25.6W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 02SEP2021 06:17:16  59.0S   25.5W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O:  1SEP2021 09:01:14  59.1S   25.7W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  7SEP2021 136964    59.0S   26.0W 4.0-5.6 CAAAA  So. Sandwich Islands       

 

SEISMICITY IN WESTERN U.S. UP FOLLOWING HURRICANE IDA LANDFALL

 

EARTHQUAKE SUMMARY FOR AUGUST 31, 2021

 

A series of unusual, moderate earthquakes were felt in California and Nevada today following an M 4.4 off the coast of Oregon yesterday. These were concentrated in northern and central California and Nevada with the largest an M 4.7 in northern Nevada. Other moderate regional events occurred in the area south of San Francisco in the Paicines area and off the coast of Northern California with M 4.0 and 4.2. This may be related to landfall of Hurricane Ida on the coast of Louisiana over the past two days - one of the strongest hurricanes to make landfall in the U.S. in several hundred years. This summary noted this hurricane in previous issues as:

 

"Hurricane Ida continued over Kentucky today with winds up to 30 kts. It made landfall today with winds up to 160 kts, a category 4 hurricane, one of the strongest ever to make landfall in the U.S. Much damage occurred in southern Louisiana but only one death was initially reported. It is expected to track to the north into Tennessee August 30-31 as a category 2 hurricane. Seismicity in Guatemala and Honduras is likely to remain high due to atmospheric downloading with the low pressures in Ida. A further moderate quake in this region is possible in the next several days. Regional seismicity in the southeastern U.S. may be enhanced with landfall in the next two days. A light M 2.7 in Tennessee near the eye of Ida today may have been promoted by loading effects with this storm. Damage is currently estimated at $200 billion." (August 29-31, 2021)

 

A moderate earthquake of M 4.7 was felt in northeastern Nevada today. This was the strongest event in the U.S. or Canada today. NEIC reported maximum intensity V in Jackpot, Nevada and IV in Deeth and Well with II-III in Spring Creek, Elko, Carlin, Crescent Valley, Ely, Battle Mountain and Eureka, Nevada. The only earthquakes of equal or greater magnitude within about 100 km of this epicenter

during the past 30 years was an M 6.0 on February 21, 2008 and prior to that an M 4.7 on November 23, 2003. At the time of the event on February 21, 2008 - of which this is the strongest aftershock to date - this summary noted:

 

 

"NEIC reported that the earthquake in Nevada near Wells was felt with maximum intensity VI and caused damage in the area. It was felt throughout the Great Basin and Rocky Mountains area of the Unites States within about 1000 km of the epicenter.

 

... This is the strongest earthquake ever recorded by NEIC in this region of Nevada (39-42N 113-116W). UUSN scientists stated that no earthquake of this size had hit the region in the past 150 years. The historic district, largely unoccupied now, in Wells was heavily damaged. At least 20-25 buildings were heavily damaged according to reports from the area. Brick facades fell from several buildings and windows broke. Some vehicles were damaged by falling debris. The town's 140 years old brothel was badly damaged. Wells formed in the late 19th century as deep clear springs attracted travelers going west to California and has often been used in western and road movies. The historic district may need to be demolished after the quake according to local officials. All commercial establishments were closed. The town of Wells was closed to all but residents numbering more than 1000. At least three injures were reported. a broken arm, head lacerations and breathing difficulties. Two buildings partially collapsed and two water mains ruptured. Train traffic was temporarily suspended but schools continued.  There were no problems found in underground gold mines in the region although 40 miners were underground at the time of the quake.  More than two feet of snow in the area will hinder geological investigation until spring. While Nevada is the third most seismic state in the U.S. after Alaska and California, the University of Nevada reported just two days ago that the state had seen the third lowest seismic in recent history in the year 2007." (February 22, 2008)

 

This epicenter is at 106 degrees from the M 7.1 in Mindanao, Philippines of August 11, 2021 and was probably promoted by concentrated energy from that source. Forecasts 136854 and 136582 had expected seismic enhancement in this area at the end of August or early September within about 100 km of this epicenter.

 

O: 31AUG2021 17:21:10  41.0N  114.9W Mw=4.7  EMSC   NEVADA                       

P:  2SEP2021 136854    40.2N  114.6W 2.5-4.7 AAAAA  California/Nevada area     

P: 30AUG2021 136582    39.6N  111.9W 2.0-4.4 ABBAA  Utah area                  

 

The M 4.7 in Nevada followed an M 4.1 in  the Pinnacles area of Central California. NEIC reported this event was felt with intensity IV in Paicines, Soledad, Greenfield and II-III in Gonzales, Hollister, Salnas, King City and San Juan Bautista, Central California. This is the strongest earthquake within about 50 km of this epicenter since an M 4.3 on January 2, 2021 and an M 4.7 on October 15, 2019. Forecasts 136526 and 136803 had expected today's event within about 25 km was likely between August 31 and September 3. This event is at 103 degrees from the M 7.1 in Mindanao of August 11, 2021 and was probably promoted by energy from that source.

 

O: 31AUG2021 16:09:55  36.6N  121.1W Mw=4.1  EMSC   CENTRAL CALIFORNIA           

P:  3SEP2021 136803    36.4N  121.0W 2.5-4.6 BAAAA  Central California         

P: 26AUG2021 136526    36.7N  121.4W 2.5-4.6 BAAAA  Central California         

 

An M 4.0 also occurred off the coast of Northern California earlier in the day. NEIC reported it was felt with intensity II-III in Whitethorn, Carberville, Leggett and Willits, California. Larger earthquakes in this area occurred on July 18 and July 21, 2021 with M 4.4 and M 5.1 and this may be an aftershock of those events. Forecast 136608 had expected today's activity within about 25 km was likely around August 31.

 

O: 31AUG2021 08:01:11  40.3N  124.4W ML=3.4  EMSC   OFFSHORE NORTHERN CALIFORNIA 

O: 31AUG2021 08:01:11  40.3N  124.4W ML=4.0  ANSS   OFFSHORE NORTHERN CALIFORNIA 

P: 31AUG2021 136608    40.2N  124.2W 2.5-4.4 AAAAA  Off Coast of No. Calif     

 

A moderate earthquake of M 5.4 was felt strongly in northern Vanuatu today. NEIC reported intensity VIII in Sola Torba, Vanuatu for this event. This may be a regional aftershock of an M 6.9-7.1 which occurred about 150 km to the south of this on August 18. Forecasts 136933 and 136676 had expected today's activity within about 50 km at the end of August.

 

O: 31AUG2021 13:26:58  13.7S  167.5E Mw=5.4  EMSC   VANUATU                      

P:  2SEP2021 136933    13.0S  167.0E 4.0-5.4 AAAAA  Vanuatu Islands            

P: 28AUG2021 136676    14.0S  168.0E 4.0-5.4 BAAAA  Vanuatu Islands            

 

The strongest earthquakes in the world today occurred beneath the world's oceans. These included the strongest - an M 5.6 in the South Sandwich Islands; a series of events of M 4.7, 4.8 and 5.0 in the Northern Mid-Atlantic Ridge and an M 5.2 in the Scotia Sea west of the South Sandwich Islands. The activity in the northern mid-Atlantic Ridge is the strongest within about 150 km of that  epicenter since an M 5.2 on October 29, 2016. It was possibly promoted by stresses associated with Tropical Storm Kate which is currently located to the southwest of this epicenter as noted in previous summaries:

 

"TS Kate continued today in the North Atlantic east of Florida with winds up to 35 kts." (August 31, 2021)

 

Forecasts 135783 and 136506 had expected this activity was likely at the end of August or in early September within about 100 km of these epicenters. This activity is at 142-144 degrees from the M 8.1 in the Kermadec Islands of March 4, 2021  and the M 7.1 in Mindanao, Philippines of August 11, 2021.

 

O: 31AUG2021 22:54:49  29.8N   42.7W mb=4.8  EMSC   NORTHERN MID-ATLANTIC RIDGE

O: 31AUG2021 22:02:47  29.9N   42.8W mb=4.7  EMSC   NORTHERN MID-ATLANTIC RIDGE

O: 31AUG2021 22:24:23  29.8N   42.7W mb=5.0  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P:  4SEP2021 136783    29.0N   43.0W 4.0-5.5 BAAAA  Mid-Atlantic Ridge         

P: 26AUG2021 136506    29.0N   44.0W 4.0-5.5 BAAAA  Mid-Atlantic Ridge         

 

The M 5.6 in the South Sandwich Islands today continued similar activity on a nearly daily basis which has followed the M 8.1 of August 12. Forecast 136710 had expected today's event at the end of August.

 

O: 31AUG2021 14:24:27  57.0S   25.2W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 25AUG2021 136710    59.0S   26.0W 4.0-5.7 CBAAA  So. Sandwich Islands       

 

The earthquake of M 5.2 in the Scotia is the strongest in that region since an M 5.5 on April 14, 2018. An event of M 5.9 hit about 100 km to the northeast on May 6, 2017. Forecast 136712 had expected today's event within about 20 km east of today's epicenter around August 28.  This event is at 102 degrees from the M 7.1 in Vanuatu August 18, 2021 and was probably promoted by energy from that source. Other activity in the world today near 103 degrees from the Vanuatu event was located southern Texas, Oaxaca, Mexico, the South Sandwich Islands.

 

 

O: 31AUG2021 22:40:28  61.2S   39.0W mb=5.2  EMSC   SCOTIA SEA                    

P: 28AUG2021 136712    61.0S   34.0W 4.0-5.5 BABAA  Southern  Ocean            

 

An unusual earthquake of M 5.1 was also felt in central Turkey today. NEIC reported maximum intensity V in Turkey at Insanye, Afyon and IV in Afyonkarahisar. This is the strongest earthquake within about 200 km of this epicenter since an 5.8 about 150 km to the southwest of this on August 8, 2019. Forecasts 136580 and 136606 had expected enhanced seismicity in this area was likely at the end of August.

 

O: 31AUG2021 11:04:26  39.0N   30.2E Mw=5.1  EMSC   WESTERN TURKEY               

P: 26AUG2021 136580    39.0N   28.0E 3.5-5.1 BABAA  Turkey                     

P: 31AUG2021 136606    41.0N   31.0E 3.5-5.2 ABAAA  No. Turkey/Black Sea       

 

STRONG AFTERSHOCK IN KERMADEC ISLANDS, NEW ZEALAND

 

EARTHQUAKE SUMMARY FOR AUGUST 30, 2021

 

The strongest earthquake in the world today was an M 6.3 in the Kermadec Islands, New Zealand. NEIC reported it may have been felt in North Island, New Zealand with light intensity. The last aftershock of the M 8.1 in the Kermadec Islands of March 4, 2021 with larger magnitude occurred on June 20, 2021 and April 1, 2021 both with M 6.5. Today's event was preceded by an M 4.9 foreshock near local solar noon and may have been enhanced by strong tidal stresses which maximize near this hour. Forecasts 136682 and 136699 had expected this activity in the Kermadec Islands was likely at the end of August.

 

O: 30AUG2021 23:14:01  30.7S  178.0W mb=4.9  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 31AUG2021 02:52:49  30.0S  177.4W Mw=6.3  EMSC   KERMADEC ISLANDS, NEW ZEALAND

P: 22AUG2021 136682    29.0S  176.0W 4.0-5.4 CAAAA  No. Kermadec Islands       

P: 27AUG2021 136699    32.0S  180.0W 4.0-5.4 BBBAA  So. Kermadec Islands       

 

A moderate earthquake of M 5.0 in Afghanistan today continued moderate seismicity in that region which has been occurring over the past several days. This summary noted this in previous issues as:

 

"An unusual earthquake of M 4.5 occurred today in Central Afghanistan, accompanying the major geomagnetic storm today. This epicenter is located in the mountains west of Kabul, Afghanistan. The last earthquake within about 250 km of this epicenter in Afghanistan was an M 5.0 and 4.7 aftershock on January 15, 2007." (August 27-28, 2021)

 

Two earthquakes of larger magnitude have occurred within about 200 km of this epicenter in Afghanistan in the past year - an M 5.5 on January 16, 2021 and an M 5.2 on August 15. Forecast 136535 had expected today's event within about 50 km was likely around August 30. This activity is at 103 degrees from the Vanuatu quake of M 7.1 of August 18 and may have been promoted by energy from that event. Other activity at this distance from Vanuatu today occurred in the South Sandwich Islands and Tennessee among others.

 

O: 30AUG2021 08:18:59  36.6N   70.9E mb=4.2  EMSC   HINDU KUSH REGION, AFGHANISTAN

O: 30AUG2021 18:23:28  36.4N   69.0E mb=5.0  EMSC   HINDU KUSH REGION, AFGHANISTAN

P: 30AUG2021 136535    36.0N   69.0E 3.8-5.5 AAAAA  Hindu Kush/Pakistan        

 

A light earthquake in eastern Tennessee today of M 2.7 was lightly felt today. NEIC reported it was felt in Tennessee at Englewood, Etowah, Madisonville, Telico Plains, Athens, Delano, Reliance, Sweetwater, Riceville and Niota. This event was probably promoted by the passage of Hurricane Ida near the time of this event as noted in this and previous issues of this report:

 

"Hurricane Ida continued over Tennessee today with winds up to 30 kts. It made landfall today with winds up to 160 kts, a category 4 hurricane, one of the strongest ever to make landfall in the U.S. Much damage occurred in southern Louisiana but only one death was initially reported. It is expected to track to the north into Tennessee August 30-31 as a category 2 hurricane. Seismicity in Guatemala and Honduras is likely to remain high due to atmospheric downloading with the low pressures in Ida. A further moderate quake in this region is possible in the next several days. Regional seismicity in the southeastern U.S. may be enhanced with landfall in the next two days. A light M 2.7 in Tennessee near the eye of Ida today may have been promoted by loading effects with this storm. Damage is currently estimated at $200 billion." (August 29-31, 2021)

 

The last earthquake within about 100 km of this epicenter of M>=2.7 was an M 2.8 on May 26, 2021. Forecast 136537 had expected today's activity within about  50 km was likely at the end of August. This event is at 103 degrees from the Vanuatu Islands and may have been promoted by energy from that source.

 

O: 30AUG2021 13:13:26  35.4N   84.4W mb=2.5  EMSC   EASTERN TENNESSEE            

O: 30AUG2021 13:13:26  35.4N   84.4W mb=2.7  ANSS   EASTERN TENNESSEE            

P: 23AUG2021 136537    35.0N   84.0W 2.0-4.2 CAAAA  Kentucky/Tennessee/NC      

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 off the coast of Oregon. A series of moderate earthquake hit last within about 200 km of this epicenter on June 4, 2021 with events of M 5.9, 5.9 and 4.7. Today's activity is probably enhanced by effects from the strong geomagnetic storm of the past several days as noted in this and previous summaries:

 

"The geomagnetic field saw active conditions today. The AP level was 20.  High latitude geomagnetic field saw stormy conditions with AP 41. This geomagnetic storm is expected to continue through the end of August and may enhance global seismicity especially at high latitudes and near the geomagnetic equator during this period. This is the strongest geomagnetic storm in more than three months - the last with high latitude AP>40 was on May 12, 2021 and the last of global AP>20 was May 20, 2021 when AP reached 24. The storm on May 20 was followed on May 21 by an M 7.5 in Qinghai, China." (August 27, 2021)

 

Forecast 136610 had expected today's event within about 100 km was likely around August 27.

 

O: 30AUG2021 11:31:18  43.5N  127.4W mb=4.4  EMSC   OFF COAST OF OREGON          

P: 27AUG2021 136610    44.1N  128.8W 3.0-4.6 BAAAA  Off Coast of Oregon        

 

PRECURSORY? MINOR EARTHQUAKES CONTINUE IN HAWAII

 

EARTHQUAKE SUMMARY FOR AUGUST 29, 2021

 

The current series of minor earthquakes continued today in the area of Hawaii. The strongest of these today was an M 3.7 which was felt in Hawaii with intensity II-III in Pahoa, Volcano, Mountain View, Kurtistown, Keaau, Papakou, Pepeekeo, Hakalau and Laupahoehoe. These may be precursory to another eruption of Kilauea volcano and the Hawaii Volcano Observatory (HVO) has raised the alert level to a watch. Forecast 136479 had expected enhanced seismicity in this region of Hawaii was likely at the end of August. This activity is located at the seventh node (51 degrees) from the Vanuatu quake of August 18, 2021 and may have been promoted by energy from that source.

 

O: 30AUG2021 04:02:58  19.3N  155.4W ML=3.4  EMSC   ISLAND OF HAWAII, HAWAII

O: 30AUG2021 00:16:50  19.3N  155.1W ML=3.8  EMSC   ISLAND OF HAWAII, HAWAII     

P: 27AUG2021 136479    19.2N  155.2W 3.0-4.5 AAAAA  Hawaii                     

 

Seismicity at moderate levels continued today in the South Sandwich Islands region. The maximum size of these events today was an M 5.4 in the east-centrl South Sandwich Islands – the largest earthquake in the world today. These events were not reported felt in this area. Forecasts 136710 and 136709 had expected the area would continue at enhanced conditions at the end of August.

 

O: 29AUG2021 23:32:45  58.2S   23.7W Mw=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 29AUG2021 13:04:03  58.4S   24.8W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 29AUG2021 23:43:30  59.3S   23.7W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 29AUG2021 14:53:27  57.0S   25.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 25AUG2021 136710    59.0S   26.0W 4.0-5.7 BBAAA  So. Sandwich Islands       

P: 29AUG2021 136709    55.0S   29.0W 4.0-5.8 ABBAA  So. Sandwich Islands       

 

The strongest earthquake in the U.S. or Canada today was an M 4.3 in the Fox Islands, Aleutians. It was not reported felt in the area. Larger earthquakes in the Fox Islands have most recently occurred on August 17 (M 4.5) and July 3 (M 4,7). Forecast 136633 had expected enhanced seismicity to the west of today's event in the Fox Islands was likely around August 28.

 

O: 29AUG2021 08:30:15  52.8N  168.2W ml=4.3  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 28AUG2021 136633    52.5N  169.2W 3.5-5.1 AAAAA  Fox Islands, Aleutians     

 

The swarm of light to moderate earthquakes in the northern Baja/Gulf of California, Mexico region continued today with events of M 3.2, 3.3 and 3.7. This follows an M 4.3 on August 27. This summary noted this at the time as:

 

 

"A series of moderate quakes also occurred south of California today in the northern Gulf of California. The strongest of these was an M 4.3 but was not reported felt. The last earthquake in this region of M>4.3 was an M 4.4 on December 12, 2019. Forecast 136502 had expected today's activity within about 50 km was likely around August 26. This activity may be related to stresses associated with Hurricane Nora currently in the Gulf of California as noted in this summary:

 

"Hurricane Nora (TD 14E) continued today in the region south of the Gulf of California Mexico with winds up to 90 kts. It is expected to track to the northwest possibly into the Gulf of California. Some seismicity enhancement in western Mexico may occur with this storm in the area." (August 26-29, 2021)

 

O: 29AUG2021 21:16:55  30.5N  114.8W ML=3.3  EMSC   BAJA CALIFORNIA, MEXICO

O: 29AUG2021 21:32:09  30.5N  114.9W ML=3.2  EMSC   BAJA CALIFORNIA, MEXICO

O: 29AUG2021 21:03:46  30.4N  114.4W ML=3.7  EMSC   GULF OF CALIFORNIA           

P: 26AUG2021 136502    30.0N  114.0W 3.5-4.9 BAAAA  Gulf of California         

 

An unusual earthquake of M 2.9 struck the region of Southern Texas today. Seismicity in this area began in November 2020 and has continued off and on  since that time. The last earthquake of M>=2.9 in the area was an M 3.2 on June 18, 2021. The strongest event in the region in the past 30 years was an M 3.5 on April 3, 2005, the only such event in the past 30 years in this area recorded prior to November 21, 2020. Forecast 136509 had expected today's event in the region was likely around August 24.

 

O: 29AUG2021 14:39:59  28.5N  100.3W ML=2.9  EMSC   SOUTHERN TEXAS               

P: 24AUG2021 136509    28.0N   98.0W 3.0-4.6 BABAA  Northern Mexico            

 

An unusual earthquake of M 5.1 occurred today in Veracruz, Mexico. NEIC reported this earthquake of M 5.1 in Veracruz, Mexico was felt with intensity II-III in the area(s) of Veracruz, Mexico at Cordoba and Coatepec and in Oaxaca at Teotitlan den Valle, Huayapam, Oaxaca and in Tlanepantla. This is the strongest earthquake in Veracurz, Mexico since an M 5.4 on January 30, 2019  and the first located north of 18 North latitude since an M 5.7 on October 29, 2009. Forecast 136473 had expected activity in this area was likely around August 28. This may be related to the landfall of Hurricane Ida to the north as was noted in previous issues of this summary:

 

"Hurricane Ida continued over Louisiana today with winds up to 105 kts. It is expected to track to the north reaching the southeastern U.S. near New Orleans around August 29-30 as a category 4 hurricane. Seismicity in Guatemala and Honduras is likely to remain high due to atmospheric downloading with the low pressures in Ida. A further moderate quake in this region is possible in the next several days. Regional seismicity in the southeastern U.S. may be enhanced with landfall." (August 28-29, 2021)

 

This epicenter is at 102-103 degrees from the M 7.1 in Vanuatu of August 18, 2021 and at the sixth node (60 degrees) from the M 8.2 in the Alaska Peninsula quake of July 29, 2021 and may have been promoted by energy from those sources.

Other moderate quakes near 103 degrees from Vanuatu today occurred in Afghanistan, the Southern Indian Ocean, South Sandwich Islands, Coquimbo, Chile and Tennessee.

 

O: 29AUG2021 19:29:26  18.0N   94.9W Mw=5.1  EMSC   VERACRUZ, MEXICO             

P: 28AUG2021 136473    17.0N   95.0W 3.5-5.1 AAAAA  Chiapas, Mexico             

 

 

MODERATE QUAKES IN STRAIT OF GIBRALTAR AND PAPUA, INDONESIA

 

EARTHQUAKE SUMMARY FOR AUGUST 28, 2021

 

The strongest earthquake in the world today was an M 5.8 in Papua, Indonesia. NEIC reported it was felt with intensity V at Jaya Pura, Papua, Indonesia. NEIC reported the aftershock of M 5.0 in Indonesia was felt with intensity II-III in the area(s) of Indonesia at Aberpura. This is an active area with the last events of M>=5.8 on January 18, 202 and an M 6.1 on June 24, 2019. This epicenter is at 103 degrees from the Los Angeles area of Southern California and major earthquakes in the area have been followed by enhanced seismicity in that area. Today's event is probably too small to have more than minor effects on the seismicity of that area. Forecast 136459  had expected today's event about 150 km to the north in Papua, Indonesia was likely around August 25. This epicenter is at 144 degrees from the Haiti  quake of M 7.2 on August 14 and may have been promoted by energy from that source.

 

O: 28AUG2021 21:00:14   3.6S  140.2E mb=5.0  EMSC   PAPUA, INDONESIA

O: 28AUG2021 12:27:23   3.5S  140.1E Mw=5.8  EMSC   PAPUA, INDONESIA             

P: 25AUG2021 136459     2.0S  140.0E 4.0-5.4 BBAAA  Papua New Guinea           

 

An earthquake of M 5.1-5.3 also occurred today in the Strait of Gibraltar. NEIC reported it was felt with maximum intensity V in Ceuta, Spain, IV in Benamccarra, Velez-Malaga and Melila, Spain and II-III in Spain at Torremolinos and Granada and in Gibraltar and in Morocco at Al Hoceima and Inzouren. This area became active in January, 2016 with a maximum sized event of M 6.3 on

January 25, 2016. Today's M 5.3 is the strongest aftershock in the region since an M 5.6 on March 15, 2016 although smaller regional events have been occurring over the past several months including an M 4.1 on August 7 and an M 4.6 on July 20, 2021. Forecast 136541 had expected today's activity within about 50 km of this epicenter was likely around August 25.

 

O: 28AUG2021 11:20:50  35.5N    3.6W mb=5.3  ANSS   STRAIT OF GIBRALTAR          

O: 28AUG2021 11:20:50  35.5N    3.6W mb=5.1  EMSC   STRAIT OF GIBRALTAR          

P: 25AUG2021 136541    35.0N    4.0W 3.5-5.4 BAAAA  Morocco/Spain              

 

The strongest earthquake in the U.S. or Canada today was an M 3.4 in western

Montana.  NEIC reported this earthquake of M 3.4 in Western Montana was felt with intensity II-III in the area(s) of Western Montana at Canyon Creek, Lincoln and Clancy.  The M 3.4 was followed by a regional aftershock of M 2.9 about 75 km southeast of that epicenter. NEIC reported this earthquake of M 2.9 in Montana was felt with intensity II-III in the area(s) of Montana at Winston, Clancy, Missoula. The M 3.4 is the strongest event in the region of western Montana since an M 3.4 on August 23, 2019 about 150 km to the southeast of today's epicenter. Forecast 136624 had expected today's activity within about 50 km around August 27.

 

O: 28AUG2021 23:10:48  46.4N  111.8W ML=2.9  EMSC   WESTERN MONTANA              

O: 28AUG2021 15:55:02  46.9N  112.5W Ml=3.4  EMSC   WESTERN MONTANA              

P: 27AUG2021 136624    46.4N  111.4W 2.0-4.0 AAAAA  Yellowstone/Wyoming        

 

STRONGEST GEOMAGNETIC STORM SINCE MAY, 2021 MAY ENCHANCE GLOBAL SEISMICITY

 

EARTHQUAKE SUMMARY FOR AUGUST 27, 2021

 

A strong geomagnetic storm occurred today and is expected to continue for several more days. This summary noted this storm as:

 

"The geomagnetic field saw active conditions today. The AP level was 20.  High latitude geomagnetic field saw stormy conditions with AP 41. This geomagnetic storm is expected to continue through the end of August and may enhance global seismicity especially at high latitudes and near the geomagnetic equator during this period. This is the strongest geomagnetic storm in more than three months - the last with high latitude AP>40 was on May 12, 2021 and the last of global AP>20 was May 20, 2021 when AP reached 24. The storm on May 20 was followed on May 21 by an M 7.5 in Qinghai, China." (August 27, 2021)

 

An unusual earthquake of M 4.5 occurred today in Central Afghanistan, accompanying the major geomagnetic storm today. This epicenter is located in the mountains west of Kabul, Afghanistan. The last earthquake within about 250 km of this epicenter in Afghanistan was an M 5.0 and 4.7 aftershock on January 15, 2007. Forecasts 136517 and 136535 had expected today's activity in Afghanistan was likely around August 30. This epicenter is near 103 degrees from the M 7.1 in Vanuatu of August 18, 2021 and was probably promoted by energy from that source. Other earthquakes at this distance from Vanuatu today occurred in the South Sandwich Islands, eastern Mexico and Guatemala, and Central Chile among others.

 

O: 28AUG2021 03:57:36  35.0N   64.3E mb=4.5  EMSC   CENTRAL AFGHANISTAN          

P: 30AUG2021 136517    33.0N   60.0E 3.8-5.6 ABCAA  Afghanistan                

P: 30AUG2021 136535    36.0N   69.0E 3.8-5.5 AACAA  Hindu Kush/Pakistan        

 

The strongest earthquake in the world today was an M 5.6 in Mindanao, Philippines. NEIC reported with maximum intensity VI in southern Mindanao at Cablalan, V in Baiton, Glan, Buayan, IV in Sult, Koronadal and II-III in Malsbong, Digos, Kisante and Davao. NEIC reported the aftershock of M 4.5 in Southern Mindanao, Philippines was felt with intensity II-III in the area(s) of Southern Mindanao, Philippines at Sarangani. This is probably a regional aftershock of the M 7.1 of August 11, 2021 but the last event of M>=5.6 within about 100 km of this epicenter occurred on December 15, 2020 with M 6.1. The mainshock coincided with the beginning of the major geomagnetic storm today and occurred near the local geomagnetic equator. It was probably promoted by geomagnetic effects. Forecast 136441 had expected this activity within about 100 km was likely around August 29.

 

O: 27AUG2021 11:36:27   5.6N  125.2E ML=4.4  EMSC   MINDANAO, PHILIPPINES

O: 27AUG2021 07:15:18   5.7N  126.7E ML=4.3  EMSC   MINDANAO, PHILIPPINES

O: 27AUG2021 10:22:26   5.7N  125.2E Mw=5.6  EMSC   MINDANAO, PHILIPPINES

O: 27AUG2021 11:07:02   5.7N  125.2E mb=4.5  EMSC   MINDANAO, PHILIPPINES

O: 27AUG2021 14:49:50   5.5N  125.2E ML=4.1  EMSC   MINDANAO, PHILIPPINES        

P: 29AUG2021 136441     6.0N  124.0E 4.0-5.4 AAAAA  Mindanao, Philippines      

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in Central California north of Los Angeles. NEIC reported it was felt with maximum intensity IV in Bodfish, Lake Isabella, and Caliente and II-III in Sequoia Natinal Forecst, Weldon, Wofford Heights, Kernville, Onyx, Techachapi and Bakersfield. This earthquake is the strongest in the region near Bakersfield, California since an M 4.3 on April 19, 2014. It was likely promoted by stresses associated with the major geomagnetic storm today as it began as that storm began. Forecasts 136568 and 136570 had expected today's event within about 25 km  was likely between August 24 and 30. This continues elevated seismicity in California as noted in the previous issues of this summary:

 

"This is the strongest aftershock to date of the M 6.0 west of this on July 8, 2021. This activity may be related to the landfall of Hurricane Henri in the northeastern U.S. over the past several days. This summary had noted this possibility in previous issues as:

 

 

"Seismicity is likely to be enhanced with landfall of Hurricane Henri in the northeastern U.S. in the next two days. In addition to enhanced seismicity in the region of landfall, it is also possible to see increased earthquake activity at the antipode south of Western Australia. This summary had noted these possibilities as: (August 26, 2021)

 

"TS Henri continued in the north Atlantic today east of Georgia with winds up to 70 kts.  It is expected to track to the north reaching New England around August 23 where it may help trigger minor seismicity upon landfall. In addition to local seismic enhancement, unusual hurricane landfalls in the Northeastern U.S. are often accompanied within a few days by a moderately strong to strong earthquake on the North American western rim. These often occur in the Vancouver or Queen Charlotte Islands area of British Columbia, but with the current track of Henri appears to be most likely this time in the region of Southern California. The area is under a cautionary seismic watch for the next week." (August 20-22, 2021)

 

O: 27AUG2021 12:34:50  35.5N  118.4W Mw=3.9  EMSC   CENTRAL CALIFORNIA           

P: 24AUG2021 136570    35.7N  118.1W 2.5-4.4 BAAAA  So. California             

P: 30AUG2021 136568    35.3N  118.6W 2.5-4.5 BAAAA  So. California             

 

A series of moderate quakes also occurred south of California today in the northern Gulf of California. The strongest of these was an M 4.3 but was not reported felt. The last earthquake in this region of M>4.3 was an M 4.4 on December 12, 2019. Forecast 136502 had expected today's activity within about 50 km was likely around August 26. This activity may be related to stresses associated with Hurricane Nora currently in the Gulf of California as noted in this summary:

 

"Hurricane Nora (TD 14E) continued today in the region south of the Gulf of California Mexico with winds up to 90 kts. It is expected to track to the northwest possibly into the Gulf of California. Some seismicity enhancement in western Mexico may occur with this storm in the area." (August 26-27, 2021)

 

O: 27AUG2021 08:59:22  29.9N  114.3W ML=3.5  EMSC   GULF OF CALIFORNIA

O: 27AUG2021 09:01:26  30.0N  114.2W ML=4.3  EMSC   GULF OF CALIFORNIA

O: 27AUG2021 08:58:00  30.1N  114.4W ML=3.5  EMSC   GULF OF CALIFORNIA

O: 27AUG2021 09:05:52  30.2N  114.3W ML=3.8  EMSC   GULF OF CALIFORNIA

O: 27AUG2021 07:10:53  30.7N  114.3W ML=3.6  EMSC   GULF OF CALIFORNIA           

P: 26AUG2021 136502    30.0N  114.0W 3.5-4.9 AAAAA  Gulf of California         

 

 

An unusual earthquake of M 3.6-3.8 was lightly felt in the Maniwaki, Quebec, Canada area today. The last earthquake within about 200 km of this epicenter with M>3.6 was an M 3.9 on May 9, 2020 and before that an M 4.4 and 4.1 on May 17, 2013. Forecast 136326 had expected today's event was likely within about 50 km of this epicenter around August 19.

 

O: 27AUG2021 15:49:30  46.7N   76.6W MB=3.8  ECAN Maniwaki, QC. Felt             

O: 27AUG2021 15:49:29  46.8N   76.5W ML=3.6  EMSC   SOUTHERN QUEBEC, CANADA      

P: 19AUG2021 136326    47.0N   76.0W 2.0-3.9 CAAAA  New York State             

 

MODERATE AFTERSHOCK ON NEVADA-CALIFORNIA BORDER

 

EARTHQUAKE SUMMARY FOR AUGUST 26, 2021

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 aftershock in western Nevada near the California border. NEIC reported it was felt with intensity II-III in California at Topaz, Coleville, South Lake Tahoe, Sonora, Camino and in Nevada at Wellington, Gardnerville, Glenbrook, Carson City, and Reno. This is the strongest aftershock to date of the M 6.0 west of this on July 8, 2021. This activity may be related to the landfall of Hurricane Henri in the northeastern U.S. over the past several days. This summary had noted this possibility in previous issues as:

 

 

"Seismicity is likely to be enhanced with landfall of Hurricane Henri in the northeastern U.S. in the next two days. In addition to enhanced seismicity in the region of landfall, it is also possible to see increased earthquake activity at the antipode south of Western Australia. This summary had noted these possibilities as:

 

"TS Henri continued in the north Atlantic today east of Georgia with winds up to 70 kts.  It is expected to track to the north reaching New England around August 23 where it may help trigger minor seismicity upon landfall. In addition to local seismic enhancement, unusual hurricane landfalls in the Northeastern U.S. are often accompanied within a few days by a moderately strong to strong earthquake on the North American western rim. These often occur in the Vancouver or Queen Charlotte Islands area of British Columbia, but with the current track of Henri appears to be most likely this time in the region of Southern California. The area is under a cautionary seismic watch for the next week." (August 20-22, 2021)

 

Forecast 136523 had expected enhanced seismicity in this area was likely at the end of August. This activity is at 103 degrees from the M 7.1 in Mindanao, Philippines of August 11 and may have been promoted by energy from that source.

 

O: 27AUG2021 01:23:12  38.6N  119.4W ml=2.6  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 01:27:22  38.6N  119.4W ML=2.1  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 01:35:59  38.6N  119.4W ml=2.3  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 01:47:25  38.6N  119.4W Mw=3.5  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 01:51:28  38.6N  119.4W ml=2.1  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 01:54:20  38.6N  119.4W ML=2.7  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 02:45:25  38.6N  119.4W ml=2.2  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 04:47:45  38.6N  119.4W Mw=4.2  EMSC   NEVADA

O: 27AUG2021 04:47:45  38.6N  119.4W Mw=4.6  ANSS   NEVADA

O: 27AUG2021 04:55:18  38.6N  119.4W ML=3.0  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 04:57:39  38.6N  119.4W ml=2.2  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:06:38  38.6N  119.4W Md=2.1  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:16:05  38.6N  119.4W ml=2.0  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:19:33  38.6N  119.4W ML=2.6  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:28:58  38.6N  119.4W Md=2.0  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:32:07  38.6N  119.4W Md=2.2  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:37:23  38.6N  119.4W ml=2.2  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 05:41:30  38.6N  119.4W ml=2.9  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 06:03:45  38.6N  119.4W Md=2.0  EMSC   CENTRAL CALIFORNIA

O: 27AUG2021 04:59:09  38.5N  119.4W Md=2.1  EMSC   CENTRAL CALIFORNIA           

P: 30AUG2021 136523    38.5N  119.6W 2.5-4.6 BAAAA  California/Nevada area     

 

A series of light to moderate quakes also occurred in Baja California south of the California border. These events are about 150 km south of the swarm in Southern California which has been occurring. The last earthquakes in  this region of M>3.5 occurred on April 26 and May 5, 2021. Forecast 136560  had expected this activity was likely around August 24.

 

O: 26AUG2021 07:16:18  31.4N  115.5W ML=3.5  EMSC   BAJA CALIFORNIA, MEXICO

O: 26AUG2021 09:55:34  31.4N  115.4W ML=3.4  EMSC   BAJA CALIFORNIA, MEXICO

O: 26AUG2021 21:57:00  31.4N  115.5W ML=3.5  EMSC   BAJA CALIFORNIA, MEXICO

O: 26AUG2021 21:01:10  31.2N  115.3W ML=3.3  EMSC   BAJA CALIFORNIA, MEXICO      

P: 24AUG2021 136560    31.9N  116.3W 2.5-4.8 AAAAA  So. California             

 

 

The strongest earthquakes in the world today continued in the South Sandwich Islands. While this aftershock series appears to be winding down, moderate quakes of M 5.1 and 5.3 occurred in the area today. These were not felt in this remote area. Forecast 136710 had expected this activity in the South Sandwich Islands was likely around August 23-25.

 

O: 26AUG2021 12:26:00  57.3S   25.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 09:02:32  58.8S   25.2W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 08:02:05  59.9S   26.3W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 09:13:02  59.9S   26.2W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 07:34:45  60.4S   25.2W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 20:18:15  57.2S   25.5W Mw=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 23AUG2021 136710    58.0S   25.0W 4.0-6.8 BAAAA  So. Sandwich Islands       

P: 25AUG2021 136710    59.0S   26.0W 4.0-5.7 ABAAA  So. Sandwich Islands       

 

MORE STRONG SEISMICITY IN SOUTH SANDWICH ISLANDS

 

EARTHQUAKE SUMMARY FOR AUGUST 25, 2021

 

The strongest activity in the world continued today in the area of the South Sandwich Islands. This event was accaompanied by 10 other moderate quakes including two of M 5.4. Forecast 136709 had expected today's event was likely around August 23.

 

O: 26AUG2021 00:30:06  57.1S   25.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 00:30:06  57.1S   25.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 25AUG2021 21:26:34  57.2S   25.4W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 25AUG2021 10:43:16  58.6S   25.1W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 03:20:21  58.8S   25.5W Mw=5.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 05:16:39  58.8S   25.3W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 25AUG2021 19:31:45  59.4S   25.8W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 26AUG2021 06:37:21  59.7S   26.2W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 25AUG2021 22:51:40  55.6S   26.7W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 23AUG2021 136709    56.0S   27.0W 4.0-5.8 AAAAA  So. Sandwich Islands       

 

A moderate earthquake of M 4.8 was felt with moderate intensity in northern Venezuela today. NEIC reported maximum intensity VI at Araure and IV in Acangua and Barquisimeto, Lara, Venezuela. It was also felt with intensit II-III in Venezuela at Cabudare, Los Rostrojos, Tacarigua, Valera, El Limon, Palo Negro and Capua, Aragua. The only similar earthquake in northern Venezuela in the past year was an M 5.1 on June 3, 2021. Forecast 136444 had expected today's event was likely within  about 100 km of this epicenter around August 26.

 

O: 26AUG2021 01:40:50   9.6N   69.3W mb=5.2  EMSC   PORTUGUESA, VENEZUELA        

P: 26AUG2021 136444     9.0N   70.0W 4.0-5.7 AAAAA  Venezuela                  

 

A moderate quake of M 5.2 also hit the region of Honduras today. NEIC  reported this earthquake was felt with intensity V in Villanueva and IV in Cuyamel, Armenta, Pena Blanca, Zapotal del Norte, San Pedro Sula, Nuevo Chamelecon, Trinidad and III in Choloma Honduras and in Puerto Barrios Izabel, Guatemala.   An M 4.6 hit offshore Honduras on August 24 but no events of M>=5 have occurred in Honduras in the past year. Forecast 136487 had expected enhanced activity south of this in the area of Honduras was likely around August 28.

 

O: 25AUG2021 21:04:20  15.5N   88.3W Mw=5.2  EMSC   HONDURAS                     

P: 28AUG2021 136487    14.0N   88.0W 3.5-5.1 BBAAA  Nicaragua                   

 

An M 5.5 also shook the region of Sulawesi, Indonesia today. This appears to be an aftershock of an M 6.2-6.5 on July 26, 2021. Forecast 136466 had expected a major aftershock was likely within about 50 km of this epicenter around August 26. NEIC reported this earthquake of M 5.5 in Indonesia was felt with intensity II-III in the area(s) of Indonesia at Luwuk, Sulawesi.

 

O: 26AUG2021 02:14:21   0.8S  121.6E Mw=5.5  EMSC   SULAWESI, INDONESIA          

P: 26AUG2021 136466     1.0S  122.0E 4.0-5.4 AAAAA  Sulawesi area              

 

An M 5.4 aftershock was also felt in the Qinghai region of China today. This follows the M 7.5 there on May 21. Today's event was felt in northern Qinghai at Xining. A similar M 5.4 occurred in northern Qinghai on June 16, 2021 but no earthquakes of M>5.4 have hit northern Qinghai, China in the past year. Forecast 136585 had expected regional aftershock activity was likely southwest of this around August 27.

 

O: 25AUG2021 23:38:19  38.9N   95.6E mb=5.4  EMSC   NORTHERN QINGHAI, CHINA      

P: 27AUG2021 136585    36.0N   94.0E 3.8-5.2 ACBAA  Xizang                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 in the Rat Islands. It was not reported felt in this remote area. An M 5.4 occurred about 150 km to the west of this on August 8, 2021 and about 100 km west on July 11 and to the east on May 17, 2021, the last events in the Rat Islands of equal or greater magnitude. Forecast 136639 had expected today's event was likely around August 25.

 

O: 25AUG2021 10:15:42  52.0N  178.3E mb=4.6  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 25AUG2021 136639    50.0N  178.0E 4.0-5.8 ABAAA  Rat Islands                

 

An earthquake of M 4.5 also occurred in western Greenland today. It was not reported felt but may have been promoted by high tidal stresses near local solar noon. This is the strongest earthquake within about 300 km of this epicenter since an M 4.7 on September 26, 2015. Forecasts 136637 and 136645 had expected to see enhanced seismicity in the area to the ast of this was likely at the end of August. This epicenter is at the third node (120 degrees) from the recent major activity in the South Sandwich Islands and may have been promoted by energy from that source.

 

O: 25AUG2021 16:30:20  60.6N   43.4W mb=4.5  EMSC   WESTERN GREENLAND            

P: 29AUG2021 136637    57.0N   32.0W 4.0-5.7 BCDAA  North Mid-Atlantic Ridge   

P: 31AUG2021 136637    61.0N   58.0W 2.5-4.2 CADAA  Baffin/Davis Strait, Canada

 

MODERATELY LARGE QUAKES IN GUATEMALA, GUAM, KERMADEC ISLANDS

 

EARTHQUAKE SUMMARY FOR AUGUST 24, 2021

 

The strongest earthquakes in the world today occurred in the Kermadec Islands (M 5.8); Guatemala (M 5.6) and Guam (M 5.6). The earthquake in Guatemala of M 5.6 was felt with intensity III in La Gomera, Esciuntla. This is the strongest earthquake in Guatemala since events of M 5.6 and 5.9 on May 12, 2021. The only other such event in Guatemala in the past year was an M 5.9 on January 15, 2021. Forecast 136477 had expected activity in Guatemala within bout 150 km of today's epicenter was likely around August 24-28. This epicenter is at 103 degrees from the M 6.9 on August 18 and may have been promoted by energy from this source.

 

 

O: 24AUG2021 09:33:57  13.5N   91.9W mb=4.0  EMSC   OFFSHORE GUATEMALA

O: 24AUG2021 16:16:48  13.4N   91.6W Mw=5.6  EMSC   OFFSHORE GUATEMALA           

P: 24AUG2021 136477    15.0N   92.0W 3.5-5.4 ABAAA  Guatemala                  

P: 28AUG2021 136477    13.0N   90.0W 3.5-5.3 BABAA  Guatemala                  

 

The earthquake in Guam of M 5.4-5.6 was reported by NEIC to have been felt with intensity IV in Guam at Yigo, Dededo, II-III in Inarajan, Yona, Santa Rita, Tamuning. This is the strongest earthquake in the area of Guam during the past year. An M 5.9 hit the area on June 23, 2020. It is likely that this event may have been promoted by the passage of Tropical Storm 16W earlier this week as noted at the time:

 

"TS 16W continued in the area of northern Pacific east of Guam today with winds up to 30 kts. It is expected to track to the west in the North Pacific and may enhance seismicity slightly near Guam in the next several days." (August 18-20, 2021)

 

Forecast 136495 had expected this activity in Guam around August 24. This epicenter is at the sixth node (60 degrees) from the M 8.2 in the Alaska Peninsula and was probably promoted by energy from strong quakes in that area.

 

O: 24AUG2021 14:47:24  12.8N  145.2E Mw=5.4  EMSC   GUAM REGION                  

P: 24AUG2021 136495    12.0N  143.0E 4.0-5.4 AABAA  So. Marianas/Guam          

 

The M 5.7 in the Kermadec Islands is an aftershock of the M 8.1 of March 4, 2021 somewhat to the east of this epicenter. It was not reported felt in this remote region. It is the strongest event in the Kermadec Islands since an M 6.1 and 5.8 on July 24 and 25, 2021. Like the events in July, today's activity appears to have been promoted by tidal stresses associated with the full moon of August 22. The tidal forecast for seismicity with this full moon had been noted in previous issues of this summary as:

 

 

"The Full Moon  arrived at 12:02 UT on August 22. Longitudes which were at local solar noon at this time area near 0 East while those at local solar midnight are near 180 E (or W) longitudes. Regions subject to enhanced seismicity in the next week include western Europe and the Atlantic Ocean in the west as well as the South Sandwich Islands aftershock zone where a major aftershock is possible at this time and in the Aleutians, and the Tonga/Fiji/New Zealand arc at this time. A moderate to large earthquake is possible in these areas at this time but a major earthquake appears unlikely with this full moon." (August 20-24, 2021)

 

Forecast 136682  had expected today's event was likely around August 22.

 

O: 25AUG2021 05:58:02  29.7S  177.6W mb=5.7  EMSC   KERMADEC ISLANDS, NEW ZEALAND

P: 22AUG2021 136682    29.0S  176.0W 4.0-5.4 BAAAA  No. Kermadec Islands       

 

The Hawaii Volcano Observatory (HVO) has raised the volcanic warning level at Kilauea to "WATCH". This was done after a strong series of minor earthquakes began yesterday and continued today under this volcano. These earthquakes, including the largest of M 3.4 have been reported by NEIC to have been felt with IV in Pahoa and III in Volcano and Hawaii National Park, Hawaii. A change in tilt at the volcano also indicated magma movements at this time. While Kilauea is not in eruption now, this activity suggests that an eruption may be far behind. Forecast 136579 had expected today's enhanced activity was likely around August 24.

 

O: 25AUG2021 04:37:52  19.4N  155.3W ML=3.0  EMSC   ISLAND OF HAWAII, HAWAII

O: 25AUG2021 05:34:34  19.4N  155.3W ML=3.0  EMSC   ISLAND OF HAWAII, HAWAII

O: 24AUG2021 11:36:02  19.4N  155.3W Ml=3.4  EMSC   ISLAND OF HAWAII, HAWAII     

P: 24AUG2021 136479    18.8N  155.2W 3.0-4.5 AAAAA  Hawaii                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.5-4.9 aftershock in the Alaska Peninsula. NEIC reported it was felt with intensity IV in Chignik Lagoon, Alaska. This is the strongest aftershock in the Alaska Peninsula area since the M 7.0 of August 14, 2021. It occurred near local solar noon and may have been promoted by tidal stresses. Forecast 136625 had expected enhanced seismicity within about 50 km of this epicenter was likely around August 24.

 

O: 24AUG2021 23:30:11  55.2N  157.5W ML=3.2  EMSC   ALASKA PENINSULA

O: 25AUG2021 01:31:27  55.6N  158.6W mb=4.9  EMSC   ALASKA PENINSULA             

P: 24AUG2021 136625    54.8N  158.7W 3.5-4.9 AAAAA  Alaska Peninsula           

 

Seismicity in the South Sandwich Islands continued today at moderate levels for the current aftershock series. The largest regional event today was an M 5.2 and 5.1. Forecasts 136710 and 136711 expected today's activity within about 50 km was likely around August 25.

 

O: 24AUG2021 07:19:10  59.0S   25.7W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 24AUG2021 14:52:00  59.3S   25.3W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 25AUG2021 00:49:57  59.7S   26.5W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 24AUG2021 23:26:54  59.8S   25.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 25AUG2021 00:39:02  58.5S   23.7W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 25AUG2021 136710    59.0S   26.0W 4.0-5.7 AAAAA  So. Sandwich Islands       

 

O: 24AUG2021 18:48:39  60.6S   24.8W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 21AUG2021 136711    60.0S   24.0W 4.0-6.6 BAAAA  So. Sandwich Islands       

 

STRONG QUAKE IN KURIL ISLANDS

 

EARTHQUAKE SUMMARY FOR AUGUST 23, 2021

 

The strongest earthquake in the world today was an M 6.1 in the Kuril Islands. This occurred as Tropical Storm Omais passed near this epicenter and may have been promoted by stresses associated with that storm. This summary had noted this possibility in previous issues of this summary as:

 

"TS Omais (16W) continued today in the area of Yellow Sea with winds up to 35 kts. It is expected to track to the west of Honshu, Japan and may enhance seismicity slightly in the area in the next several days as it dissipates." (August 22-23, 2021)

 

The last earthquake within about 300 km of this epicenter with M>=6.1 occurred as an M 7.5 about 300 km east of this on March 25, 2020. The last within about 200 km was an M 6.5 on November 16, 2012. Forecasts 136339 and 136618 had expected this activity between August 17 and 26 in the Kuril Islands to the south.

 

O: 24AUG2021 05:37:50  48.8N  154.9E Mw=6.1  EMSC   KURIL ISLANDS                

P: 17AUG2021 136339    47.0N  154.0E 3.5-5.4 CBAAA  So. Kurils                 

P: 26AUG2021 136618    47.0N  151.0E 3.5-5.6 ABBAA  So. Kurils                 

 

The strongest earthquake in the U.S. or Canada today was an M 4.0 in Southern California near Westmorland. NEIC reported it was felt with intensity II-III in Westmorland, Brawley, Imperial, Holtville, Calexico, Borrego Springs, San Diego, Rancho Cucamonga and Walnut, California. An earthquake of M 5.3 hit this area on June 5. 2021 but today's event is the strongest aftershock of this mainshock since June 12, 2021 when an M 4.1 and 4.3 occurred.  This event may be related to the landfall of Hurricane Henri in the Northeastern U.S. today. This summary had previously suggested this landfall event might enhance seismicity in southern California as:

 

"TS Henri continued in the area of Connecticut today with winds up to 30 kts.  It is expected to track to the north reaching New England around August 23 where it may help trigger minor seismicity upon landfall. In addition to local seismic enhancement, unusual hurricane landfalls in the Northeastern U.S. are often accompanied within a few days by a moderately strong to strong earthquake on the North American western rim. These often occur in the Vancouver or Queen Charlotte Islands area of British Columbia, but with the current track of Henri appears to be most likely this time in the region of Southern California. The area is under a cautionary seismic watch for the next week." (August 22-23, 2021)

 

Forecast 136561 had expected today's activity within about 25 km was likely around August 24-25.

 

O: 23AUG2021 14:57:23  33.1N  115.7W ML=3.9  EMSC   SOUTHERN CALIFORNIA

O: 23AUG2021 14:57:23  33.1N  115.7W ML=4.0  ANSS   SOUTHERN CALIFORNIA

O: 23AUG2021 14:59:25  33.1N  115.8W Ml=2.3  EMSC   SOUTHERN CALIFORNIA

O: 23AUG2021 16:15:51  33.1N  115.6W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O: 23AUG2021 18:17:03  33.1N  115.6W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O: 23AUG2021 21:05:43  33.1N  115.0W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

O: 23AUG2021 21:55:43  33.1N  115.7W ML=2.9  EMSC   SOUTHERN CALIFORNIA

O: 23AUG2021 22:51:52  33.1N  115.6W Ml=2.4  EMSC   SOUTHERN CALIFORNIA

O: 24AUG2021 05:48:29  32.4N  115.3W Ml=2.4  EMSC   BAJA CALIFORNIA, MEXICO      

P: 24AUG2021 136561    32.8N  116.0W 2.5-4.8 AAAAA  So. California             

P: 25AUG2021 136561    32.9N  115.6W 2.5-4.9 AAAAA  So. California             

 

 

Seismicity in the South Sandwich Islands today was way down from the past 11 days. The earthquakes which were recorded of M 5.2 and 4.5 occurred within minutes of local solar noon, a time when tidal stresses maximize, especially with the full moon and were probably promoted by stresses from tides.  Forecast 136711 had expected today's events within about 50 km of these epicenters. The sudden reduction in regional seismicity in the South Sandwich Islands may indicate that the M 7.1 there yesterday essentially used up the available stress in the area and that the immediate aftershock sequence of large earthquake is nearly over.

 

O: 23AUG2021 13:29:28  59.8S   26.2W mb=4.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 23AUG2021 14:28:49  60.6S   24.8W Mw=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 21AUG2021 136711    60.0S   24.0W 4.0-6.6 AAAAA  So. Sandwich Islands       

 

An unusual earthquake of M 5.1 occurred in the Bay of Bengal, India today. NEIC reported it was felt with intensity IV in India at Tamil Nadu at Chetpel, Pammal, and II-III in Tanuku, Andhra Pradesh, and in Tamil Nado at Madras, Anakaputhur, Alandur, Peningudi, Saint Thomas, Madippakkam and Avadi. This is the strongest earthquake within about 300 km of this epicenter in at least 30 years. The only similar or larger earthquake within about 400 km of this in the past 30 years was an M 5.1 on September 25, 2001.

 

O: 24AUG2021 07:05:55  14.5N   83.0E mb=5.1  EMSC   BAY OF BENGAL                

 

TIDAL TRIGGERING NEAR GREENWICH MERIDIAN AND IDL

 

EARTHQUAKE SUMMARY FOR AUGUST 22, 2021

 

A series of earthquakes occurred today in locations and at times which indicated

a strong influence from tidal stresses associated with today's full moon. In addition to a major quake of M 7.1 in the South Sandwich Islands other such events occurred in the Greenland Sea (M 4.2); the western Andreanof Islands (M 4.9). The tidal forecast for seismicity previously published in this summary had noted the areas most likely to see such effects were near the Greenwich Meridan (GM 0 E) and the IDL (International Date Line - 180E) as:

 

"The Full Moon  arrived at 12:02 UT on August 22. Longitudes which were at local solar noon at this time area near 0 East while those at local solar midnight are near 180 E (or W) longitudes. Regions subject to enhanced seismicity in the next week include western Europe and the Atlantic Ocean in the west as well as the South Sandwich Islands aftershock zone where a major aftershock is possible at this time and in the Aleutians, and the Tonga/Fiji/New Zealand arc at this time. A moderate to large earthquake is possible in these areas at this time but a major earthquake appears unlikely with this full moon." (August 20-22, 2021)

 

The strongest earthquake in the world today was an M 7.0-7.1 in the South Sandwich Island, the strongest aftershock to date of the August 12, 2021 M 8.1 and is approximately the size of the earthquake in Haiti of August 14 (M 7.2). It was accompanied by a strong series of earthquakes including an M 5.8.  Tidal stresses (see above) were near their maximum in the South Sandwich Islands today with the full moon and probably helped enhance this activity. Forecasts 136711 and 136710 had expected today's activity within about 50 km of these epicenter was likely around August 21-23.

 

O: 22AUG2021 19:20:03  59.8S   26.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 19:20:03  59.8S   26.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 23AUG2021 06:02:57  60.2S   23.9W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 21:33:20  60.3S   25.0W Mw=7.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 23AUG2021 03:05:37  60.5S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 21AUG2021 136711    60.0S   24.0W 4.0-6.6 AAAAA  So. Sandwich Islands       

 

O: 22AUG2021 11:20:30  57.5S   25.2W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 13:14:04  57.5S   24.9W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 15:21:57  58.3S   25.0W Mw=5.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 23AUG2021 00:56:31  58.3S   23.6W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 13:55:38  58.4S   25.5W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 21:21:12  58.4S   24.9W mb=4.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 22AUG2021 12:36:41  57.1S   25.5W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 23AUG2021 136710    58.0S   25.0W 4.0-6.8 AAAAA  So. Sandwich Islands       

 

 

An earthquake of M 4.2 occurred in the Greenland Sea within about 20 km of the GM today. This is probably an aftershock of the M 5.5 near this epicenter of July 23, 2021 which occurred with the previous full moon of July 24. Today's event also appears to have been triggered by tidal effects as it occurred near local solar noon, a time when such stresses area maximized. Forecast 136661 had expected today's event within about 50 km of this epicenter around August 24.

 

O: 22AUG2021 13:42:55  79.6N    3.2E mb=4.2  EMSC   GREENLAND SEA                

P: 24AUG2021 136661    79.0N    7.0E 4.0-5.4 AAAAA  Arctic Ocean Region        

 

The strongest earthquake in the U.S. or Canada today occurred in the western Andreanof Islands, Aleutians, Alaska. NEIC reported it was felt with intensity II in Adak, Alaska. Like other moderate earthquakes around the world today, this event occurred in close temporal association with the full moon, occurring within about 10 minutes of local solar midnight, a time when tidal stresses from the full moon are maximized. It also occurred near the longitude of maximum tidal stress with this full moon as previously noted in this summary. Forecast 136627 had expected today's event in the Andreanof Islands within about 50 km of this epicenter was likely around August 24.

 

O: 22AUG2021 11:46:08  51.3N  178.3W ML=4.1  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

O: 22AUG2021 11:45:03  51.5N  178.4W mb=4.9  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 24AUG2021 136627    51.8N  178.0W 3.5-5.0 AAAAA  Andreanoff Isls, Aleutians 

 

 

MAJOR ACTIVITY IN SOUTH SANDWICH ISLANDS WITH FULL MOON

 

EARTHQUAKE SUMMARY FOR AUGUST 21, 2021

 

The strongest earthquake in the world today was another major event in the South Sandwich  Islands. This earthquake of M 6.9 was reported by NEIC to have been felt in Tierra del Fuego, Argentina with light intensity. This is the third major aftershock of the M 8.1 which hit that area on August 12. The M 6.9 today occurred within about 30 minutes of local solar midnight and was probably promoted by high tidal stresses with the full moon that arrived today as reported in previous issues of this summary:

 

"The Full Moon  arrived at 12:02 UT on August 22. Longitudes which were at local solar noon at this time area near 0 East while those at local solar midnight are near 180 E (or W) longitudes. Regions subject to enhanced seismicity in the next week include western Europe and the Atlantic Ocean in the west as well as the South Sandwich Islands aftershock zone where a major aftershock is possible at this time and in the Aleutians, and the Tonga/Fiji/New Zealand arc at this time. A moderate to large earthquake is possible in these areas at this time but a major earthquake appears unlikely with this full moon." (August 20-22, 2021)

 

and

 

"The full moon will arrive August 22 and stresses will be highest at longitudes near the South Sandwich Islands. The expected enhancement with this new moon ..." (August 20-21, 2021)

 

Forecast 136711 had expected today's M 6.9 was likely within about 50 km of this epicenter around August 21.

 

O: 22AUG2021 00:45:08  60.2S   24.4W Mw=6.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 21AUG2021 136711    60.0S   24.0W 4.0-6.6 AAAAA  So. Sandwich Islands       

 

O: 22AUG2021 03:37:59  57.5S   24.9W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 14:55:00  58.4S   23.4W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 15:34:20  58.7S   23.8W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 15:53:06  58.7S   24.1W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 09:33:15  58.9S   23.9W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 13:48:46  59.6S   23.9W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 11:04:03  57.0S   25.1W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 23AUG2021 136710    58.0S   25.0W 4.0-6.8 AAAAA  So. Sandwich Islands       

 

An aftershock of M 4.4 in Haiti today was reported with intensity II in Les Cayes Sud, Haiti. This is an aftershock of the M 7.2 in Haiti of August 14, 2021. The current tolls from that mainshock stand at 2189 deaths and 333 still missing. Residents are frustrated at the lack of speedy help and have in some cases attacked trucks carrying relief supplies.  Forecast 136494 had expected enhanced regional aftershocks around August 22.

 

O: 21AUG2021 14:19:05  18.3N   73.5W ML=3.4  EMSC   HAITI REGION

O: 21AUG2021 18:47:31  18.4N   73.5W mb=4.4  EMSC   HAITI REGION

O: 22AUG2021 00:25:11  19.2N   73.2W ML=3.7  EMSC   HAITI REGION                 

P: 22AUG2021 136494    19.0N   73.0W 3.4-5.4 AAAAA  Haiti                      

 

The strongest seismicity outside the South Sandwich Islands today was an M 5.3 and M 5.2 off the east coast of Honshu, Japan.  NEIC reported this earthquake of M 5.3 off the coast of Eastern Honshu, Japan  was felt with intensity II-III in the area(s) of Eastern Honshu, Japan at Miyagi (IV), Fukushima, Ibarki, and Kanagawa.  The area has been relatively quiet in recent months with the only earthquake of greater magnitude since May, 2021 an M 5.8 on August 3, 2021. Forecast 136554 had expected today's activity was likely around August 21.  This activity may have been excited by the passage of Tropical Storm Omais through the region as reported in this and previous issues of this summary:

 

"TS Omais (16W) continued today in the area of Yellow Sea and Ryukyu Islands with winds up to 55 kts. It is expected to track to the west in the North Pacific and may enhance seismicity slightly in the area in the next several days. An unusual earthquake in the Yellow Sea today may have been promoted by stresses associated with this storm." (August 20-22, 2021)

 

O: 21AUG2021 21:55:40  36.0N  142.4E Mw=5.2  EMSC   OFF EAST COAST OF HONSHU, JAPA

O: 22AUG2021 02:24:35  37.6N  141.7E mb=5.3  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 21AUG2021 136554    37.0N  142.0E 4.0-5.4 AAAAA  Off East Coast Honshu      

 

The strongest earthquake in the U.S. or Canada today was an M 3.4 off the coast of Oregon. This may be related to stresses from Hurricane Henri which is expected to make landfall today in the Northeast U.S. and was reported in this summary as:

 

"TS Henri continued in the north Atlantic today east of New Jersey with winds up to 75 kts.  It is expected to track to the north reaching New England around August 23 where it may help trigger minor seismicity upon landfall. In addition to local seismic enhancement, unusual hurricane landfalls in the Northeastern U.S. are often accompanied within a few days by a moderately strong to strong earthquake on the North American western rim. These often occur in the Vancouver or Queen Charlotte Islands area of British Columbia, but with the current track of Henri appears to be most likely this time in the region of Southern California. The area is under a cautionary seismic watch for the next week.." (August 21, 2021)

 

Forecast 136609 had expected today's activity off the coast of Oregon was likely to the south around August 22.

 

O: 21AUG2021 16:49:01  44.7N  126.8W mb=3.4  EMSC   OFF COAST OF OREGON          

P: 22AUG2021 136609    42.5N  126.8W 3.0-4.8 ACAAA  Off Coast of Oregon        

 

HURRICANE HENRI COULD ENHANCE REGIONAL AND GLOBAL SEISMICITY

 

EARTHQUAKE SUMMARY FOR AUGUST 20, 2021

 

The strongest earthquakes in the world today continued as aftershocks in the South Sandwich Islands. These followed the M 8.1 mainshock of August 12, 2021 and had been noted in the previous summary as:

 

 

"This earthquake with M 8.1 is more in keeping with the strong far-field global activity following it including major earthquakes in the regions of Mindanao, Vanuatu, the Alaska Peninsula and Haiti as well as several local  major aftershocks. Far-field seismic enhancement is likely to continue at least through the next week but at a somewhat reduced level." (August 20, 2021)

 

The full moon will arrive August 22 and stresses will be highest at longitudes near the South Sandwich Islands. The expected enhancement with this new moon are noted in this summary as:

 

"The Full Moon will arrive at 12:02 UT on August 22. Longitudes which are at local solar noon at this time area near 0 East while those at local solar midnight are near 180 E (or W) longitudes. Regions subject to enhanced seismicity in the next week include western Europe and the Atlantic Ocean in the west as well as the South Sandwich Islands aftershock zone where a major aftershock is possible at this time and in the Aleutians, and the Tonga/Fiji/New Zealand arc at this time. A moderate to large earthquake is possible in these areas at this time but a major earthquake appears unlikely with this full moon." (August 20-21, 2021)

 

O: 20AUG2021 15:07:46  57.1S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 18:59:14  57.2S   25.1W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 21AUG2021 02:50:56  57.8S   24.7W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 15:56:51  58.7S   23.2W Mw=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 11:16:13  58.9S   24.8W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 15:07:46  57.1S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 BBAAA  So. Sandwich Islands       

 

O: 20AUG2021 22:25:54  58.0S   25.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 BBAAA  So. Sandwich Islands       

 

Seismicity is likely to be enhanced with landfall of Hurricane Henri in the northeastern U.S. in the next two days. In addition to enhanced seismicity in the region of landfall, it is also possible to see increased earthquake activity at the antipode south of Western Australia. This summary had noted these possibilities as:

 

"TS Henri continued in the north Atlantic today east of Georgia with winds up to 70 kts.  It is expected to track to the north reaching New England around August 23 where it may help trigger minor seismicity upon landfall. In addition to local seismic enhancement, unusual hurricane landfalls in the Northeastern U.S. are often accompanied within a few days by a moderately strong to strong earthquake on the North American western rim. These often occur in the Vancouver or Queen Charlotte Islands area of British Columbia, but with the current track of Henri appears to be most likely this time in the region of Southern California. The area is under a cautionary seismic watch for the next week." (August 20-21, 2021)

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 in the eastern Andreanof Island, Aleutians, Alaska. The last earthquake within about 200 km of this epicenter with M>=4.7 was an M 4.8 on June 30, 2021 and prior to that an M 5.0 on May 22, 2021. Forecast 136350 had expected today's earthquake in this area was likely in mid-August. It occurred within about 30 minutes of local solar midnight and was probably promoted by high tidal stresses which maximize near this hour.

 

O: 20AUG2021 12:20:19  52.0N  173.3W mb=4.7  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 16AUG2021 136350    52.1N  174.4W 3.5-5.1 BAAAA  Andreanoff Isls, Aleutians 

 

A moderate earthquake of M 4.6 occurred today in the Yellow Sea east of northeastern China. NEIC reported this earthquake of M 4.6 in the Yellow Sea was felt with intensity V-VI in the area(s) of South Korea at Taeain, Kunsan, IV in Mokpo, and II-III in Yonggwang, Taechion, Seoul, Eujeongbu, Pusan and Hitachi, Japan.  This is an unusual earthquake with the last event within about 200 km of this epicenter with M>=4.6 an M 5.0 on March 31, 2014. An unusual Tropical Storm

(Omais) may have helped promote today's earthquake by stressing the area.  This summary had noted this storm in previous issues as:

 

"TS Omais (16W) continued today in the area of Yellow Sea and Ryukyu Islands with winds up to 55 kts. It is expected to track to the west in the North Pacific and may enhance seismicity slightly in the area in the next several days. An unusual earthquake in the Yellow Sea today may have been promoted by stresses associated with this storm." (August 20-21, 2021)

 

Forecast 136323 had expected enhance regional activity in northeast China in mid-August.

 

O: 21AUG2021 00:40:42  35.8N  124.6E mb=4.6  EMSC   YELLOW SEA                   

P: 16AUG2021 136323    41.0N  129.0E 3.5-5.5 BCCAA  NE China                   

 

STRONG AFTERSHOCKS AFTER RECALCULATED M 8.1 IN SOUTH SANDWICH ISLANDS

 

EARTHQUAKE SUMMARY FOR AUGUST 19, 2021

 

The strongest earthquakes in the world today continued in the South Sandwich Islands. The largest of these were M 5.3 and 5.4. These are aftershocks of the M 8.1 that hit the area on August 12, 2021, likely the strongest earthquake ever recorded in the South Atlantic Ocean. A strong series of earthquakes around the world has followed that event and were probably promoted by strong energy from that source. Forecasts 136431 and 136432 had expected this activity around August 16-17.

 

O: 20AUG2021 01:09:51  57.0S   25.1W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

 

O: 19AUG2021 16:34:08  60.5S   26.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 BAAAA  So. Sandwich Islands       

P: 17AUG2021 136432    60.0S   29.0W 4.0-5.7 AABAA  So. Sandwich Islands       

 

O: 19AUG2021 08:28:26  58.0S   25.7W Mw=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 03:21:33  58.0S   25.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 21:26:31  58.5S   23.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 03:13:51  58.6S   23.2W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 08:02:02  58.8S   25.3W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 16:14:34  59.4S   26.0W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 02:42:30  59.4S   24.8W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 16:27:41  59.7S   26.2W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 20AUG2021 03:41:19  59.8S   26.6W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 10:23:30  59.9S   23.5W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 16:34:08  60.5S   26.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 BAAAA  So. Sandwich Islands       

P: 17AUG2021 136432    60.0S   29.0W 4.0-5.7 AABAA  So. Sandwich Islands       

 

 

The USGS has recalculated the magnitude of the mainshock of March 12, 2021 in the South Sandwich Islands. It is now cataloged as MW 8.1. While an M 8.3 was reported in the South Sandwich Islands on June 27, 1929 the magnitude is uncertain and this is probably the strongest earthquake ever recorded in the South Atlantic Ocean. It is now given with parameters:

 

MO DA HR MN SC YEAR  S LAT W LON DEO MW

08 12 18 35 20 2021 -58.4  -25.3  60 8.1

 

This earthquake with M 8.1 is more in keeping with the strong far-field global activity following it including major earthquakes in the regions of Mindanao, Vanuatu, the Alaska Peninsula and Haiti as well as several local major aftershocks. Far-field seismic enhancement is likely to continue at least through the next week but at a somewhat reduced level.

 

 

The strongest earthquake in the U.S. or Canada today was an M 4.3 in the Destruction Bay area of Canada's Yukon Territory. It was felt lightly in the area according to Earthquakes Canada.  NEIC reported this earthquake of M 4.1 in Southern Alaska was felt with intensity II-III in the area(s) of Southern Alaska at Cooper Center. This appears to be an aftershock of an M 4.9 of May 9, 2021, the only such event in the area of larger magnitude in the past year Forecasts 136373 and  136363 had expected today's activity was likely around August 16. This activity is near 144 degrees from the South Sandwich Islands and was probably promoted by energy from that source.

 

O: 20AUG2021 05:39:28  61.6N  141.3W ML=3.6  EMSC   SOUTHERN ALASKA

O: 20AUG2021 01:48:15  61.6N  141.3W mb=4.3  EMSC   SOUTHERN ALASKA              

O: 20AUG2021 01:48:22  61.5N  140.2W MB=4.3  ECAN OF DESTRUCTION BAY, YT         

P: 16AUG2021 136373    63.0N  144.6W 3.2-5.1 BBBAA  Central Alaska             

P: 16AUG2021 136363    59.0N  137.0W 3.0-4.6 BCBAA  Southeast Alaska           

 

The swarm in the area of Southern California continued today. This included earthquakes of M 4.0 and 3.8 as reported in the previous issue of this summary:

 

"A moderate series of earthquakes occurred today in southern California with mainshocks of M 4.0 and 3.8 which NEIC reported were felt with intensity II-III in Thermal, Imperial, Holtville, Descanso, Campo, Warner Springs, El Centro, Jacumba, La Quinta, Palm Desert and San Diego and in Mexicali, Baja California.

NEIC reported the aftershock of M 3.3 in Southern California was felt with intensity II-III in the area(s) of Southern California at Thermal. This epicenter is at the third node (120 degrees) from the recent major earthquakes in the South Sandwich Islands and at the tenth node (36 degrees) from the M 8.2 in the Alaska Peninsula and was probably promoted by energy from those sources. The mainshocks occurred near local solar noon and may also have been promoted by energy associated with the high tidal stresses at this hour. Forecast 136287 had expected today's activity in the region was likely around August 20.  Seismicity has been active about 50 km east of this in recent months included an M 5.3 on June 5, 2021 but activity closer than that to the epicenter today last saw an event of M>=4 on May 10, 2020 when an M 4.5 was registered in the area." (August 18-19, 2021)

 

Forecast 136285 had expected today's series was likely within about 15 km of this epicenter in mid-August.

 

O: 18AUG2021 18:01:01  33.1N  116.0W Ml=2.8  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:15:49  33.1N  116.0W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:21:15  33.1N  116.0W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:34:26  33.1N  116.0W Ml=2.5  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:41:41  33.1N  116.0W Ml=2.3  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:35:38  33.1N  116.0W Ml=2.2  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:36:45  33.1N  116.0W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:45:13  33.1N  116.0W Mw=3.9  EMSC   SOUTHERN CALIFORNIA

O: 19AUG2021 23:57:05  33.1N  116.0W Ml=2.0  EMSC   SOUTHERN CALIFORNIA          

P: 15AUG2021 136285    33.0N  115.9W 2.5-4.9 BAAAA  So. California              

 

MAJOR EARTHQUAKE FELT IN VANUATU

 

EARTHQUAKE SUMMARY FOR AUGUST 18, 2021

 

A major earthquake of M 6.9-7.0 was felt strongly in northern Vanuatu today. NEIC reported it was felt with damage and intensity VIII in Vanuatu at Port Olry; VI in Luganville, Sanma, IV in Vila Shefa and III in Lakatoro, Malampa. This earthquake is located at 104 degrees from the South Sandwich Islands where major earthquakes have occurred in the past week and was probably triggered by strong energy enhancement from that source. This event of M 6.9 is the strongest within Vanuatu within about 200 km of this epicenter since an M 6.9 on  April 3, 2017 and prior to that events of M 7.1 on October 20, 2015 and May 27, 2010. Forecast 136401 had expected today's event within about 100 km was likely around

August 15.

 

O: 18AUG2021 10:10:05  14.9S  167.2E Mw=6.9  EMSC   VANUATU                      

P: 15AUG2021 136401    14.0S  167.0E 4.0-5.5 BAAAA  Vanuatu Islands            

 

The earthquake in Vanuatu may be near the end of the global enhancement of seismicity following the M 8.2 in the Alaska Peninsula of July 29, 2021. Immediate global triggering from great quakes does not often last more than 20 days after the mainshock and it has now been 20 days from the Alaska event. In this period, seven events of M>=6.9 have been recorded worldwide. During the period of 70 days from May 21, 2021 when an M 7.3 hit the Qinghai area of China through the Alaska Peninsula event of July 29, no events of M 6.8 or greater occurred in the world. The seven in the past 20 days, including six different regions - Mindanao, Philippines; northern and southern South Sandwich Islands, the Alaska Peninsula, Haiti, the south Atlantic Ocean and today's in Vanuatu - are therefore highly significant and are located at epicenters at harmonic distances from recent major earthquakes. 

 

Strong seismicity also continued today in the South Sandwich Islands. This began with an M 4.9 within minutes of local solar noon and probably enhanced by strong tidal stresses which maximize near this time and included an M 5.9 later in the day. This follows strong earthquakes in the South Sandwich Islands of M 6.9 on August 16, 2021 and of M 8.1 and M 7.5 on August 12, 2021. Forecasts 136431 and 136432 had expected this activity in the South Sandwich Islands around August 16-17.

 

O: 18AUG2021 21:02:32  58.6S   23.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 18AUG2021 23:30:33  58.7S   23.3W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 18AUG2021 21:49:52  59.7S   26.4W Mw=5.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 18AUG2021 20:29:00  59.9S   26.5W Mw=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 19AUG2021 05:23:48  58.4S   25.0W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 18AUG2021 14:04:35  60.1S   27.3W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

P: 17AUG2021 136432    60.0S   29.0W 4.0-5.7 AAAAA  So. Sandwich Islands       

 

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Island of Hawaii.  NEIC reported this earthquake of M 4.1-4.4 in Hawaii was felt with intensity II-III in the area(s) of Hawaii with IV in Pahala, Mountain View and in Hawaii National Park, Naalehu, Volcano, Captain Cook, Hilo, Kurtistown, Holualoa, and Papaikou.  The last earthquake of M 4.4 or larger within Hawaii occurred on June 18, 2021. An M 5.2 occurred north of Hawaii on June 5, 2021. Forecast 136221 had expected today's activity was likely within about 25 km around August 18. This activity may have been promoted by energy from Hurricane Linda which is bearing down on the region of Hawaii as reported in this summary:

 

"Hurricane Linda continued east of Hawaii today with winds up to 110 kts. It is expected to track into the Pacific and may energize seismicity in Hawaii as it approaches and passes by. (August 18-19, 2021)

 

O: 18AUG2021 12:01:57  19.2N  155.4W ML=4.4  EMSC   ISLAND OF HAWAII, HAWAII     

P: 18AUG2021 136221    19.4N  155.1W 3.0-4.4 AAAAA  Hawaii                     

 

An M 4.3 aftershock also occurred today in the Alaska Peninsula. It was not reported felt in the area. Forecast 136346 had expected today's activity in mid-August.

 

O: 19AUG2021 02:22:28  56.7N  157.3W mb=4.3  EMSC   ALASKA PENINSULA             

P: 13AUG2021 136346    55.7N  157.9W 3.5-5.4 CAAAA  Alaska Peninsula           

P: 16AUG2021 136346    54.7N  156.9W 3.5-5.4 BBAAA  Alaska Peninsula           

 

A moderate series of earthquakes occurred today in southern California with mainshocks of M 4.0 and 3.8 which NEIC reported were felt with intensity II-III in Thermal, Imperial, Holtville, Descanso, Campo, Warner Springs, El Centro, Jacumba, La Quinta, Palm Desert and San Diego and in Mexicali, Baja California. NEIC reported the aftershock of M 3.3 in Southern California was felt with intensity II-III in the area(s) of Southern California at Thermal.  This epicenter is at the third node (120 degrees) from the recent major earthquakes in the South Sandwich Islands and at the tenth node (36 degrees) from the M 8.2 in the Alaska Peninsula and was probably promoted by energy from those sources. The mainshocks occurred near local solar noon and may also have been promoted by energy associated with the high tidal stresses at this hour. Forecast 136287 had expected today's activity in the region was likely around August 20.  Seismicity has been active about 50 km east of this in recent months included an M 5.3 on June 5, 2021 but activity closer than that to the epicenter today last saw an event of M>=4 on May 10, 2020 when an M 4.5 was registered in the area.

 

O: 18AUG2021 18:01:01  33.1N  116.0W Ml=2.8  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:15:49  33.1N  116.0W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:21:15  33.1N  116.0W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:34:26  33.1N  116.0W Ml=2.5  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 18:41:41  33.1N  116.0W Ml=2.3  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:35:38  33.1N  116.0W Ml=2.2  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:36:45  33.1N  116.0W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:45:13  33.1N  116.0W Mw=3.9  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:45:14  33.1N  116.0W Mw=4.0  ANSS   SOUTHERN CALIFORNIA

O: 18AUG2021 21:50:22  33.1N  116.0W Mw=3.8  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 21:53:27  33.1N  116.0W Ml=2.4  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 22:24:59  33.1N  116.0W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O: 18AUG2021 22:40:26  33.1N  116.0W Ml=2.5  EMSC   SOUTHERN CALIFORNIA

O: 19AUG2021 02:14:40  33.1N  116.0W ML=2.7  EMSC   SOUTHERN CALIFORNIA

O: 19AUG2021 04:21:35  33.0N  115.9W Ml=2.1  EMSC   SOUTHERN CALIFORNIA          

O: 19AUG2021 04:29:46  33.1N  116.0W Ml=3.2  EMSC   SOUTHERN CALIFORNIA          

P: 20AUG2021 136287    33.7N  116.1W 2.5-4.8 AAAAA  So. California              

 

Moderate activity continued today in the region of Haiti where an M 7.2 occurred earlier this week and killed more than 2189 while injuring more than 10,000 people. Local officials admitted the country is devastated and may not recover for some time. This earthquake and landslides and motions associated with Hurricane Grace were followed today by moderate quakes of M 4.8 and 4.8 today. The first of these at 16:57 UT (local solar time 11:57 ) occurred within minutes of noon and was probably promoted by high tidal stresses which maximize near this hour. The second event of M 4.8 occurred within and hour of local solar midnight and was also probably promoted by high tidal stresses. These are the strongest aftershocks since the mainshocks of M 7.2 on August 14 and M 5.8 of August 15, 2021. Today's activity was probably also enhanced by passage of Tropical Storm Grace over the last several days as noted in previous summaries:

 

“TS Grace continued over Haiti today with winds up to 40 kts. This may help enhance seismicity in the northern Caribbean over the next week. It is expected to track to the northwest passing over Haiti around August 16 where it may trigger a moderate to strong aftershock of the M 7.2 there of August 14. It is expected to track along behind TS Fred reaching the Florida Keys in about 5 days.

 

 

And

 

 ... moderate to large earthquakes in the area are probably not yet over. The passage of Tropical Storm Grace over the area in the last two days is likely to bring a moderate aftershock of M>=4.5 in the next two days." (August 18, 2021)

 

Forecast 136239 had expected enhanced seismicity in Haiti in mid-August.

 

O: 18AUG2021 16:47:53  18.2N   73.5W mb=4.8  EMSC   HAITI REGION

O: 19AUG2021 03:57:38  18.5N   73.5W mb=4.8  EMSC   HAITI REGION

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 CBAAA  Bahamas/No. Caribbean      

 

 

SOUTHERN OCEAN SEISMICITY CONTINUES UNABATED

 

EARTHQUAKE SUMMARY FOR AUGUST 17, 2021

 

Strong earthquakes continued in the southern Oceans today. This included strong earthquakes in Fiji and in the South Sandwich Islands.  Strong seismicity continued in the South Sandwich Islands. Aftershocks in this region today occurred with maximum magnitude M 6.1 and 5.8. This activity continued from north to south throughout the region but was concentrated in the southern area and had been expected to continued at an enhanced rate as noted in previous issues of this summary:

 

"This history suggest more major earthquakes may be in store in the next week

in this region, or at the least a number of additional strong earthquakes may be coming. This is a seventh harmonic distance and probably relates a triggering situation from Alaska." (August 12-13, 14, 2021

 

Forecast 136431 had expected today's activity was likely around August 16-17 within about 150 km of these epicenters.

 

O: 17AUG2021 17:53:28  58.0S   25.6W Mw=6.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 17AUG2021 08:17:21  58.8S   24.6W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 18AUG2021 00:19:20  59.1S   25.6W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 17AUG2021 21:47:43  59.4S   25.3W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 18AUG2021 02:48:55  59.6S   26.3W Mw=5.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 17AUG2021 19:40:34  59.7S   26.4W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 17AUG2021 20:06:13  59.7S   26.2W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 17AUG2021 20:06:13  59.7S   26.2W Mw=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 17AUG2021 20:19:41  59.7S   26.0W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

O: 18AUG2021 00:06:46  56.7S   25.7W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 AAAAA  So. Sandwich Islands       

 

An M 5.8 in the Fiji Islands was felt lightly with intensity II-III in Tonga at Tofoa-Koloua and Nuku'alofa, Tongatapu. The last earthquake within about 200 km of this epicenter in Fiji of equal or larger magnitude was an M 6.5 on April 25, 2021. But the last within about 150 km of today's epicenter occurred more than a year ago with an M 5.9 about 150 km south of today's epicenter on June 2, 2020. The last event in the region with M>=6 was an M 6.4 on September 26, 2017. Forecast 136413 had expected today's activity was likely within about 100 km around August 20. This activity in Fiji is near 100 degrees from the South Sandwich Islands and was probably promoted by energy from that source.

 

O: 17AUG2021 12:29:45  21.0S  178.7W mb=4.8  EMSC   FIJI REGION                  

O: 17AUG2021 17:24:47  23.2S  177.0W Mw=5.8  EMSC   SOUTH OF FIJI ISLANDS        

P: 20AUG2021 136413    24.0S  178.0W 4.0-5.4 BAAAA  Tonga Islands              

 

The strongest earthquake in the U.S. or Canada today was an M 4.5 in the Fox Islands, Aleutians. NEIC reported it was felt with intensity II in Unalaska, Alaska. The last earthquake in the Fox Islands with equal or larger magnitude was an M 4.7 on July 3, 2021. Forecast 136356 had expected today's activity was likely within about 100 km around August 17.

 

O: 17AUG2021 17:10:51  52.9N  167.6W mb=4.0  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 17AUG2021 17:10:51  52.9N  167.6W mb=4.5  ANSS   FOX ISLANDS, ALEUTIAN ISLANDS

P: 17AUG2021 136356    53.7N  167.0W 3.5-4.9 AAAAA  Fox Islands, Aleutians     

 

An M 2.7 earthquake in North Carolina was widely felt in the region. NEIC reported intensity II-III was felt in North Carolina at Morganton, Valdese, Hudson, Lenoir, Collettsville, Granite Falls, Nebo, Conneleys Springs, Hildebran and Casar. It was also reported lightly felt in Maryland, Pennsylvania, Florida, Mississippi, Arkansas, New York. The epicenter of this earthquake was directly under the eye of Tropical Storm Fred as it moved to the north. This summary had noted this in the previous issues as:

 

"TS Fred continued in the Florida Panhandle today with winds up to 40 kts.  It is expected to track north into Georgia and North Carolina and to dissipate in the next several days." (August 16-17, 2021)

 

This is the strongest earthquake in North Carolina since an M 3.2 on October 25, 2020. Forecast 136268 had expected today's event within about 100 km was likely in North Carolina around August 11. This epicenter is located at 103 degrees from the major activity in the South Sandwich Islands and was probably promoted by energy from that source.

 

O: 17AUG2021 13:19:28  35.8N   81.7W mb=2.7  EMSC   NORTH CAROLINA               

P: 11AUG2021 136268    36.0N   83.0W 2.0-4.0 CAAAA  Kentucky/Tennessee/NC      

 

An unusually large earthquake of M 4.2 occurred today in Sicily, Italy. The last earthquake of M>=4.2 in Sicily occurred within a volcanic eruption of Etna in late December, 2020 and included an M 4.6 and 4.2. The last such event in Sicily within about 100 km of today's epicenter was an M 4.4 on October 24, 2020. Forecast 136270 had expected today's event within this area was likely around August 12. This epicenter is at 103 degrees from the major activity in  the South Sandwich Islands and was probably enhanced by energy from that source. Similar activity at 103 degrees from the South Sandwich Islands today occurred at Mt. Merapi, a volcano in Java, Indonesia, Sumatra, North Carolina.

 

O: 17AUG2021 10:21:43  38.7N   14.6E mb=4.2  EMSC   SICILY, ITALY                

P: 12AUG2021 136270    38.0N   14.0E 3.0-4.6 BAAAA  Mediterranean/Sicily       

 

Moderate seismicity continued in the area of Haiti today. At least seven events of M>=3.3 were reported in the area today. But moderate to large earthquakes in the area are probably not yet over. The passage of Tropical Storm Grace over the area in the last two days is likely to bring a moderate aftershock of M>=4.5 in the next two days. At this time at least 1900 have been recognized as dead from the earthquake while more than 10,000 were injured. Many of the local people do not expect any governmental assistance according to reports in the New York Times. NASA reported many landslides with the passage of Tropical Storm Grace and travel throughout the area is difficult due to this and damage from the earthquake. Forecast 136239 had expected seismic enhancement in this area in mid-August.

 

O: 18AUG2021 03:39:57  18.3N   73.6W ML=3.3  EMSC   HAITI REGION

O: 18AUG2021 00:32:21  18.4N   74.1W ML=3.5  EMSC   HAITI REGION

O: 18AUG2021 01:17:00  18.4N   73.9W ML=3.5  EMSC   HAITI REGION

O: 18AUG2021 01:17:00  18.4N   73.9W ML=3.5  EMSC   HAITI REGION

O: 18AUG2021 03:14:27  18.4N   73.8W ML=3.3  EMSC   HAITI REGION

O: 18AUG2021 02:53:46  18.2N   74.0W ML=3.4  EMSC   HAITI REGION                 

O: 18AUG2021 02:17:50  18.3N   74.1W ML=3.5  EMSC   HAITI REGION                 

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 CBAAA  Bahamas/No. Caribbean      

 

MAJOR EARTHQUAKES CONTINUE IN SOUTH ATLANTIC

 

EARTHQUAKE SUMMARY FOR AUGUST 16, 2021

 

A further major earthquake of M 6.9 occurred today in the South Atlantic Ocean east of the South Sandwich Islands. It was reported lightly felt in southern South America. It was accompanied by a number of moderately large earthquakes in the aftershock zone in the South Sandwich Islands but was not part of the classical aftershock series as it occurred outside the extensive aftershock zone to the west. It may have been promoted by regional stress redistribution and by tidal effects as it occurred near local solar noon, a time when such tidal stresses are maximized.  This summary had expected additional strong seismicity in the area at this time in previous issues as:

 

"This history suggest more major earthquakes may be in store in the next week  in this region, or at the least a number of additional strong earthquakes  may be coming. This is a seventh harmonic distance and probably relates a triggering situation from Alaska." (August 12-13, 14, 2021

 

Forecast 136431 had expected today's activity was likely around August 16-17 within about 150 km of these epicenters.

 

O: 17AUG2021 03:10:50  58.1S   24.1W Mw=5.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 11:10:36  58.4S   23.5W Mw=6.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 13:41:57  58.6S   23.4W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 11:52:28  58.7S   23.8W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 14:08:11  57.9S   23.9W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 15AUG2021 136432    61.0S   22.0W 4.0-5.8 ABAAA  Southern  Ocean            

 

O: 16AUG2021 23:37:23  59.5S   26.2W Mw=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 08:46:14  59.7S   26.5W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 10:23:22  60.0S   26.6W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 19:17:05  60.2S   26.7W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 20:50:34  60.3S   24.8W Mw=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

O: 16AUG2021 14:35:59  57.8S   25.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 ABAAA  So. Sandwich Islands       

 

A strong volcanic eruption occurred today at Mt. Merapi in Indonesia. This continues an eruption in the area which began last year and saw a considerable lava flow today. Merapi is located at 7.5S 110.5E in Java, Indonesia. Merapi is located at 103-104 degrees from the major earthquakes in the South Sandwich Islands of August 12, 2021 and the M 6.9 east of this in the South Atlantic Ocean today. Mount Merapi is at 103-104 degrees from the major earthquakes in the South Sandwich Islands of the past several days. This is a distance at which seismic energy is concentrated following major earthquake. Such energy often activates enhanced seismicity at this distance. A moderate M 4.6-4.8 in Croatia (see below) was also at this distance from the South Sandwich Islands today.

 

Forecast 136205 had expected enhanced seismicity near Mt. Merapi around August 19.

 

O: 17AUG2021 06:00:00   7.5S  110.5E ML=5.0  VOLC   MT MERAPI ERUPTION, JAVA, INDO

P: 19AUG2021 136205     9.0S  111.0E 4.0-5.4 ABAAA  So. of Java                

 

Three volcanoes are also erupting in the Aleutians of Alaska at this time. This is the first time three volcanoes have erupted simultaneously in this area since

2014. Volcanoes in eruption are the Great Sitkin volcano, Mount Pavlof and Semisopochnoi. Lava is flowing  from Great Sitkin. These may have been triggered by stresses associated with the M 8.2 in the Alaska Peninsula of July 29. Increased seismicity is also occurring near Mount Cleveland and the volcanic region near Atka where small earthquakes and explosions have been reported.

 

An earthquake of M 4.6-4.8 in Croatia was widely felt today. NEIC reported maximum intensity V in Petrinja and Sisak; IV in Gradici, Sesvete and II-III in Kutina, Zagreb, Dutrava, Lucko, Jezovec and Vrbovec, Croatia. This is the strongest earthquake in Croatia since an M 5.0 on January 6, 2021 aftershock of the M 6.4 quake of December 29, 2020. Today's event is an aftershock of the December 29, 2020 mainshock. Forecast 136314 had expected today's activity in this area was likely around August 12. This epicenter is at 103-104 degrees from the major earthquakes in the South Sandwich Islands of the past several days and was probably promoted by strong seismic energy from those sources, as was the eruption of Mount Merapi in Indonesia (see above).

 

O: 16AUG2021 23:58:55  45.4N   16.3E mb=4.7  EMSC   CROATIA                      

P: 12AUG2021 136314    44.0N   16.0E 3.0-5.3 BBAAA  Italy                      

 

An earthquake of M 4.1 shook the area of Austria several hours before the event in Croatia.  NEIC reported this earthquake of M 3.8-4.1 in Austria was felt with intensity II-III in the area(s) of Austria in Wattens (IV), Worgi, Hopfgarten, Kirchbichi, Fugen, Jenback Tirol, Austria and Ortisel, Italy. The only event of larger or similar magnitude in Austria within about 200 km of this epicenter in the past year was an M 4.2 to the east of this on January 20, 2021. The last events in Austria of significantly larger magnitude were of M 4.5 on October 25, 2020 and June 9, 2012. Like the epicenter in Croatia, this epicenter is also near 104 degrees from the activity in the South Sandwich Islands and was probably promoted by energy from that source. Forecast 136308 had expected today's event in Austria was likely around August 14.

 

O: 16AUG2021 21:15:39  47.5N   12.1E ML=4.1  EMSC   AUSTRIA                      

O: 16AUG2021 21:15:39  47.5N   12.1E ML=3.8  ANSS   AUSTRIA                      

P: 14AUG2021 136308    46.0N   13.0E 3.0-5.1 ABAAA  Austria                    

 

Moderate aftershocks continued in the region of Haiti today where an M 7.2 earthquake hit on August 14, 2021. While new numbers are not yet available preliminary death tolls count more than 1300 fatalities and thousands of injured. This earthquake was about 10 times more powerful than that of  January, 2010 - an event of M 7.0 which killed more than 200,000 and left the country in economic and physical ruin. That earthquake occurred in a more populated region - a fact that accounts for most of the higher casualties, but improvements in building are also partially responsible for the mitigated destruction and deaths. Forecast 136239 had expected a moderate quake in Haiti around August 12, 2021.

 

O: 16AUG2021 11:24:58  18.4N   73.7W ML=4.0  EMSC   HAITI REGION

O: 16AUG2021 11:35:55  18.4N   73.5W ML=3.7  EMSC   HAITI REGION

O: 16AUG2021 10:42:50  18.5N   73.6W ML=4.1  EMSC   HAITI REGION

O: 16AUG2021 18:35:40  18.5N   73.6W ML=4.1  EMSC   HAITI REGION

O: 16AUG2021 09:17:31  18.6N   73.6W ML=4.0  EMSC   HAITI REGION

O: 16AUG2021 12:53:43  18.6N   73.6W ML=4.1  EMSC   HAITI REGION

O: 16AUG2021 15:16:30  18.2N   73.6W ML=3.0  EMSC   HAITI REGION                 

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 BBAAA  Bahamas/No. Caribbean      

 

The strongest earthquake in the U.S. or Canada today was an M 4.3 aftershock in the Alaska Peninsula of the M 8.2 and 7.0 mainshocks of July 29 and August 13. It was not reported felt in this area. Forecast 136346 had expected this event within about 50 km was likely around August 16.

 

O: 16AUG2021 16:24:03  55.3N  157.5W Mw=4.3  EMSC   ALASKA PENINSULA

O: 17AUG2021 00:22:10  56.6N  157.1W ML=3.4  EMSC   ALASKA PENINSULA

O: 16AUG2021 12:19:41  55.2N  157.1W ML=3.4  EMSC   ALASKA PENINSULA             

P: 16AUG2021 136346    54.7N  156.9W 3.5-5.4 AAAAA  Alaska Peninsula           

 

An unusual earthquake of M 5.0 occurred today in the South Indian Ocean south of India today. The last earthquake within about 300 km of this epicenter with M>=5 was an M 5.7-5.8 on March 14, 2010. This epicenter is near 100-103 degrees from the Alaska Peninsula and the South Sandwich Islands and may have been promoted by energy from those sources.

 

O: 16AUG2021 13:13:03   4.3S   82.3E mb=5.0  EMSC   SOUTH INDIAN OCEAN            

 

EARTHQUAKE DEATH TOLL IN HAITI PASSES 1300

 

EARTHQUAKE SUMMARY FOR AUGUST 15, 2021

 

The death toll in the earthquake in Haiti passed 1300 today and continued to climb. A frantic population sought shelter in crushed buildings and collapsed structures as Tropical Storm Grace passes through the area today. Medical services were lacking and the thousands of injured people found difficulty finding assistance.  Moderate aftershocks continued to be felt in Haiti today following the M 7.2 there on August 14. Today's activity was felt with intensity II-III within the aftershock zone and including aftershocks of M 4.8 and 4.5 among others. Following is a listing of aftershocks of M>=4.0. A more complete listing of aftershocks of M>=3 can be found in the "AMERICA" section below. Forecast 136239 had expected this activity in Haiti was likely around August 12.

 

O: 15AUG2021 07:01:41  18.5N   73.7W mb=4.0  EMSC   HAITI REGION

O: 15AUG2021 12:05:43  18.5N   73.7W mb=4.8  EMSC   HAITI REGION

O: 15AUG2021 16:05:05  18.5N   73.6W mb=4.1  EMSC   HAITI REGION

O: 15AUG2021 19:46:44  18.5N   73.5W ML=4.1  EMSC   HAITI REGION

O: 15AUG2021 22:48:42  18.5N   73.5W ML=4.5  EMSC   HAITI REGION

O: 15AUG2021 14:07:24  18.6N   73.7W ML=4.0  EMSC   HAITI REGION

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 BBAAA  Bahamas/No. Caribbean      

 

The strongest earthquakes in the world today continued in the area of the South Sandwich Islands. This included an M 5.8 aftershock along with a score of other moderate to moderately large events.  This summary had expected additional strong seismicity in the area at this time in previous issues as:

 

"This history suggest more major earthquakes may be in store in the next week

in this region, or at the least a number of additional strong earthquakes may be coming. This is a seventh harmonic distance and probably relates a triggering situation from Alaska." (August 12-13, 14, 2021

 

Forecast 136431 had expected today's events at the northern and southern end

of the aftershock zone was likely around August 16-17.

 

O: 16AUG2021 05:46:20  56.9S   25.7W Mw=5.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 10:31:34  57.8S   25.5W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 10:44:00  57.9S   24.8W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 11:26:36  57.9S   25.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 11:42:35  58.1S   23.9W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 22:30:43  58.5S   25.1W Mw=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 12:44:39  56.5S   25.6W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 AAAAA  So. Sandwich Islands       

 

O: 15AUG2021 15:04:04  58.6S   25.5W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 08:52:15  58.8S   23.7W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 17:20:22  58.8S   25.1W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 07:44:23  58.9S   24.7W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 21:38:26  59.5S   26.3W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 19:00:47  60.0S   26.8W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 16:34:51  60.4S   28.1W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 16AUG2021 06:44:12  60.7S   26.9W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

The long swarm of light to moderate earthquakes continued in the Gulf of California today. This included an M 4.0 as well as several others of M3.4-3.6.

Forecast 136284 had expected this activity was likely within about 25 km  around August 14.

 

O: 15AUG2021 09:12:17  30.7N  114.2W ML=4.0  EMSC   GULF OF CALIFORNIA

O: 15AUG2021 09:17:44  30.7N  114.1W ML=3.4  EMSC   GULF OF CALIFORNIA

O: 15AUG2021 20:16:23  30.7N  114.3W ML=3.5  EMSC   GULF OF CALIFORNIA

O: 15AUG2021 09:22:03  30.5N  114.4W ML=3.6  EMSC   GULF OF CALIFORNIA           

P: 14AUG2021 136284    30.9N  114.3W 2.5-4.8 AAAAA  So. California             

 

MAJOR EARTHQUAKE IN HAITI DEADLY, DAMAGING

 

PRELIMINARY EARTHQUAKE SUMMARY FOR AUGUST 14, 2021

 

A major earthquake hit the region of Haiti today. This event of M 7.2 was initially reported to have killed more than 225 people but hundreds more are missing or injured. The mainshock was reported by NEIC to have been felt with intensity IV in Haiti at Saint-Louis-du-Sud, Torbeck, VIII in Asile Grande, Petit-Trou-de-Nippes, Jeremie Grand; VII in Port-au-Prince, VI in Grand-Goave; V in Saint-Marc, Petot-Goave, Cavaillon. It was reported to have been felt lightly as far as Rhode Island, New Jersey, Maryland, South Carolina, Florida, Colombia, Trinidad and Tobago, Jamaica, Puerto Rico, Cuba, A strong M 5.8 aftershock occurred and was felt with intensity IX in Haiti at Chardonnieres; IV in Kenscoff and Kingston and II-III in Petit Goave, Port-au-Prince, Petionville, Port-de=Paix, Haiti and in Santiago de Cuba, Cuba Kingston, Jamaica and Caracas, Venezuela. Internet photos show damaged and collapsed buildings in Haiti. The most damage probably occurred in the area of the towns of Les Caves and Jeremie, Petit Trou de Nipes which was near the epicenter. Many buildings collapsed in the earthquake and hospitals were overwhelmed. A tsunami warning was issued but later withdrawn. An earthquake of M 7.0 hit Haiti on January, 12, 2010 killing more than 200,000 people and causing massive dislocation and loss of property and infrastructure. It was followed months later by a cholera epidemic which killed more than 10,000 and affected nearly a million people. Multiple international attempts at reconstruction have largely failed. At the time of the 2010 event this summary noted in part:

 

"This is the worst earthquake to hit Haiti in at least 200 years and may be the worst in modern history.

 

Associated Press reported that the capital Port-au-Prince has been largely destroyed by the earthquake. Casualties are severe and widespread and bodies and blood are everywhere. Many who were gravely injured are lying in the streets. In public squares survivors are often found holding hands and singing hymns. Thousands are thought to have died in the earthquake which destroyed or did massive damage to the Presidential Palace, the World Bank, government buildings and a cathedral. Roads and bridges are in ruins. All modes of communications are disrupted and most of the electricity is out. The area has a population of about two million and tolls will not be forthcoming for some time in the current chaos which has ensued. Initial estimates of costs from the earthquake range from hundreds of millions of U.S. Dollars to billions." (January 13, 2010)

 

The only earthquake in historical record in Haiti of M>=7.2 was an M 7.2 in 1887 but the date is not known. A similar event may have occurred with M 7.2 in 1770 and in October 1751. More recently earthquakes in the region of Puerto Rico, Dominican Republic and Haiti occurred north of Puerto Rico with M 7.3 on April 21, 1948; M 8.1 and 7.9 in August, 1946 and M 7.9 on July 29, 1943. Earthquakes in northern Puerto Rico also occurred in the 1900's on October 11, 1918 with M 7.5 and with M 7.2 on April 24, 1916. This suggest such event occur in clusters and more such events in the next several years in the area are likely.

 

Several factors probably combined in bringing today's earthquake at this time. The passage of Tropical Storm Fred through Haiti over the past several days may have been the main contributing stress producer but a series of major earthquakes around the world - in Alaska, the Philippines, the South Sandwich Islands in the past several days also probably contributed to the timing and magnitude of today's event. In particular about 32 minutes before the M 7.2 in Haiti, an earthquake of M 7.0 hit the Alaska Peninsula aftershock zone. The epicenter in Haiti is located exactly at the fifth node (72.0 degrees) from the event in Alaska. Surface waves from that source travel this distance in about 32 minutes. That means the surface waves from the aftershock in Alaska would have coincided in Haiti with the M 7.2 there.  Examples of such clear seismic wave triggering abound but few are as clearly obvious as this. The earthquake in Haiti is also at the fourth node (90 degrees) from the M 7.5 of August 12 in the South Sandwich Islands and was also probably affects by energy from that source as well as high tidal stress from the recent new moon which was expected to maximize in the Atlantic area. There was some foreshock activity before the main Haitian shock today.

 

In the previous issue of this summary it had been noted:

 

"The area of Puerto Rico and Haiti were showing elevated seismicity today following the M 7.5 in the South Sandwich Islands yesterday. An M 3.2 in Puerto Rico was reported by NEIC to have been felt with intensity III in Ponce, in the active aftershock zone in southwestern Puerto Rico. Tropical Storm Fred was probably the major triggering factor for these earthquakes however. This summary had noted that this storm was likely to enhance regional seismicity in Haiti as noted in  the previous issue of this report:

 

 

"TS Fred continued over the Dominican Republic today with winds up to 35 kts. This is the area of a strong M 6.7 and a long aftershock series over the past two years and the low pressures associated with this storm may help promoted enhanced aftershocks at this time." (August 12-13, 2021)

 

This region is also at the fourth harmonic (90 degrees) from the southern end of the major earthquakes yesterday in the South Sandwich Islands. It is also at the fifth harmonic (72 degrees) from the M 8.2 in the Alaska Peninsula and is probably being promoted by energy from that source as noted at the time in this summary" (August 13-14, 2021)

 

Following is a listing of aftershocks in the first six hours of the M 7.2 in

Haiti. A more complete listing can be found under the "AMERICA" section of this summary. Forecast 136239 had expected today's activity within about 100 km in mid-August. This activity may also have been promoted by energy from Mindanao, Philippines of M 7.1 which is at 147 degrees from Haiti.

 

O: 15AUG2021 02:37:53  18.6N   73.6W mb=5.1  EMSC   HAITI REGION

O: 15AUG2021 03:20:45  18.4N   74.1W Mw=5.8  EMSC   HAITI REGION

O: 15AUG2021 06:23:19  18.4N   73.5W ML=4.1  EMSC   HAITI REGION

O: 14AUG2021 20:14:43  18.5N   73.8W ML=4.1  EMSC   HAITI REGION

O: 14AUG2021 20:18:38  18.5N   74.0W ML=4.1  EMSC   HAITI REGION

O: 14AUG2021 22:10:53  18.5N   74.0W mb=4.1  EMSC   HAITI REGION

O: 14AUG2021 22:14:06  18.5N   74.0W mb=4.5  EMSC   HAITI REGION

O: 14AUG2021 22:26:56  18.5N   73.6W ML=4.0  EMSC   HAITI REGION

O: 15AUG2021 03:26:09  18.5N   74.0W ML=4.1  EMSC   HAITI REGION

O: 15AUG2021 03:27:35  18.5N   74.1W ML=4.2  EMSC   HAITI REGION

O: 15AUG2021 04:00:02  18.5N   74.1W mb=4.0  EMSC   HAITI REGION

O: 15AUG2021 07:01:43  18.5N   73.7W mb=4.0  EMSC   HAITI REGION

O: 14AUG2021 12:49:38  18.9N   73.7W mb=5.2  EMSC   HAITI REGION                 

O: 14AUG2021 13:30:29  18.3N   73.9W ML=4.0  EMSC   HAITI REGION

O: 14AUG2021 12:29:09  18.4N   73.5W Mw=7.2  EMSC   HAITI REGION

O: 14AUG2021 12:56:58  18.4N   73.8W ML=4.6  EMSC   HAITI REGION

O: 14AUG2021 13:45:47  18.4N   73.5W ML=4.1  EMSC   HAITI REGION

O: 14AUG2021 14:05:15  18.4N   73.7W ML=5.3  EMSC   HAITI REGION

O: 14AUG2021 14:23:31  18.4N   73.4W ML=4.1  EMSC   HAITI REGION

O: 14AUG2021 15:46:18  18.4N   73.6W ML=4.0  EMSC   HAITI REGION

O: 14AUG2021 16:04:48  18.4N   73.6W ML=4.0  EMSC   HAITI REGION

O: 14AUG2021 16:08:02  18.4N   73.8W mb=5.1  EMSC   HAITI REGION

O: 14AUG2021 16:44:19  18.4N   73.6W ML=4.3  EMSC   HAITI REGION

O: 14AUG2021 18:11:10  18.4N   73.6W mb=5.1  EMSC   HAITI REGION

O: 14AUG2021 13:14:15  18.5N   73.5W mb=4.4  EMSC   HAITI REGION

O: 14AUG2021 13:18:07  18.5N   73.6W ML=4.0  EMSC   HAITI REGION

O: 14AUG2021 13:22:12  18.5N   74.1W ML=4.3  EMSC   HAITI REGION

O: 14AUG2021 14:02:35  18.5N   73.6W mb=4.2  EMSC   HAITI REGION

O: 14AUG2021 14:12:21  18.5N   73.6W ML=4.2  EMSC   HAITI REGION

O: 14AUG2021 14:28:51  18.5N   73.5W mb=4.6  EMSC   HAITI REGION

O: 14AUG2021 14:40:46  18.5N   73.7W mb=4.2  EMSC   HAITI REGION

O: 14AUG2021 14:57:34  18.5N   73.6W mb=4.6  EMSC   HAITI REGION

O: 14AUG2021 15:08:11  18.5N   73.6W mb=4.2  EMSC   HAITI REGION

O: 14AUG2021 16:23:18  18.5N   73.6W ML=4.2  EMSC   HAITI REGION

O: 14AUG2021 16:59:42  18.5N   73.6W ML=4.0  EMSC   HAITI REGION

O: 14AUG2021 17:05:18  18.5N   73.6W Mw=4.7  EMSC   HAITI REGION

O: 14AUG2021 13:32:22  18.6N   73.4W ML=4.0  EMSC   HAITI REGION

O: 14AUG2021 17:05:19  18.5N   73.6W mb=5.2  ANSS   ESE of Barad├¿res Haiti      

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 AAAAA  Bahamas/No. Caribbean      

 

Among the regional aftershocks was an M 4.1 in Puerto Rico. NEIC reported this earthquake of M 4.1 in southwestern Puerto Rico was felt with intensity IV in Puerto Rico at Sabana Grande, Ponce, Cabo Rojo and II-III in the area(s) of southwestern Puerto Rico in Guanica, Lajas, Yauco, Sabana Grande, Ponce, Las Marias.  Forecasts 136235 and 136238 had expected today's event was likely in  mid-August in this region (see above).

 

O: 15AUG2021 03:39:49  17.8N   66.9W ML=4.1  EMSC   PUERTO RICO REGION           

P: 10AUG2021 136235    18.0N   67.0W 3.4-5.3 BAAAA  Puerto Rico                

P: 14AUG2021 136238    20.0N   67.0W 3.0-4.7 ACAAA  Bahamas/No. Caribbean      

 

A moderately strong M 5.4 earthquake also occurred south of Haiti today in the area of the border of Peru and Ecuador. The last event of larger magnitude within about 200 km of this epicenter was an M 7.5 on February 22, 2019. An M 5.4 also occurred on June 7, 2020 near today's epicenter.  NEIC reported this earthquake of M 5.4 in the Peru-Ecuador border was felt with intensity VI in the area(s) of Ecuador at Gualaquiza Morona and II-III in Zamora and Loza.  Forecast 136194  had expected to see strong enhancement in this area around August 17.

 

O: 15AUG2021 05:40:03   3.7S   77.1W Mw=5.4  EMSC   PERU-ECUADOR BORDER REGION   

P: 17AUG2021 136194     4.0S   80.0W 4.0-5.4 AACAA  Ecuador                     

 

The strongest earthquake in the rest of the world today was an M 7.0 aftershock in the region of the Alaska Peninsula. As noted above, this occurred at 72 degrees (node 5) from Haiti and 32 minutes prior to that event and probably helped trigger the Haitian quake. The event in Alaska is the strongest aftershock to date in the area. In previous summaries, this had been noted as an area where re-activation was occurring as in the previous issue:

 

 

"The strongest earthquake in the U.S. or Canada today was an M 4.4 in the aftershock in the Alaska Peninsula. This is the third event of M>=4 in as many days. This re-energizing of the area may have been activated by a series of large earthquakes at harmonic distances from Alaska. Forecast 136346 had expected today's activity was likely around August 13-16." (August 13, 2021)

 

 

O: 14AUG2021 15:20:49  54.7N  156.8W ML=3.5  EMSC   SOUTH OF ALASKA

O: 14AUG2021 13:06:39  55.0N  157.7W ML=4.2  EMSC   ALASKA PENINSULA

O: 14AUG2021 14:55:01  55.0N  157.6W ML=3.3  EMSC   ALASKA PENINSULA

O: 14AUG2021 12:14:51  55.2N  157.6W ml=3.9  EMSC   ALASKA PENINSULA

O: 14AUG2021 12:34:54  55.3N  157.8W ml=3.6  EMSC   ALASKA PENINSULA

O: 14AUG2021 14:20:56  55.3N  157.9W ML=3.2  EMSC   ALASKA PENINSULA

O: 14AUG2021 18:44:40  55.3N  157.6W mb=4.5  EMSC   ALASKA PENINSULA

O: 14AUG2021 11:57:42  55.4N  157.8W Mw=7.0  EMSC   ALASKA PENINSULA             

P: 13AUG2021 136346    55.7N  157.9W 3.5-5.4 AAAAA  Alaska Peninsula           

 

A light earthquake of M 3.9-4.0 was also felt in the area of Hawaii today. It was reported with maximum intensity IV in Holualoa and II-III in Pahala, Hawaii National Park, Naalehu, Captain Cook, Volcano, Mountain View, Pahoa, Kealakekua and Keaau, Hawaii. The last earthquake of M>=3.9 within about 100 km of this epicenter in Hawaii occurred as an M 4.5 on June 18, 2021. Forecast 136221 had expected today's event was likely around August 15.

 

O: 14AUG2021 23:42:53  19.2N  155.5W ML=4.0  EMSC   ISLAND OF HAWAII, HAWAII     

P: 15AUG2021 136221    18.8N  155.2W 3.0-4.7 AAAAA  Hawaii                     

 

A light earthquake in Maryland today of M 1.7 also occurred in the region of Maryland today. It is notable because it occurred exactly at local solar midnight and was probably promoted by high tidal stresses which maximize near this hour. Forecast 136325 had expected today's event within about 100 km of this epicenter was likely around August 14. This epicenter is at 103 degrees from the northern end of the South Sandwich Islands series and may have been promoted by energy from that source.

 

O: 15AUG2021 05:06:04  39.3N   76.7W ml=1.7  ANSS   NE of Woodlawn Maryland      

P: 14AUG2021 136325    40.0N   76.0W 2.0-4.3 AAAAA  New York State             

 

Strong earthquakes also continued today in the South Sandwich Islands today, the site of major activity in the past several days. This included an M 7.5 - the strongest earthquake in that area in decades on August 12, 2021. Forecast 136431 had expected today's activity in the South Sandwich Islands was likely around August 16-17.

 

O: 14AUG2021 21:42:06  56.6S   25.7W Mw=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 10:23:24  57.5S   25.2W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 09:57:20  56.0S   26.3W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

 

O: 14AUG2021 21:57:19  56.7S   26.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 23:36:18  57.8S   23.6W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 04:17:45  57.9S   25.1W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 22:41:41  58.1S   25.3W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 02:07:21  58.1S   25.1W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 19:03:31  58.3S   25.7W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 03:32:22  58.3S   23.9W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 03:38:01  58.6S   25.0W mb=4.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 05:49:06  58.6S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 03:58:37  58.7S   25.1W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 20:28:41  59.2S   25.2W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 23:53:43  59.2S   25.1W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 22:27:15  59.3S   25.2W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 02:01:36  60.0S   26.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 21:57:19  56.7S   26.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 23:36:18  57.8S   23.6W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 04:17:45  57.9S   25.1W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 22:41:41  58.1S   25.3W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 02:07:21  58.1S   25.1W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 19:03:31  58.3S   25.7W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 03:32:22  58.3S   23.9W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 03:38:01  58.6S   25.0W mb=4.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 05:49:06  58.6S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 03:58:37  58.7S   25.1W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 20:28:41  59.2S   25.2W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 23:53:43  59.2S   25.1W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 22:27:15  59.3S   25.2W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 15AUG2021 02:01:36  60.0S   26.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 09:46:36  58.5S   25.4W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 19:03:30  58.5S   25.5W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 07:07:27  59.3S   25.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 11:33:07  59.7S   25.9W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 18:11:56  59.7S   26.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 10:30:07  60.1S   26.8W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 14:49:29  60.4S   26.8W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 10:00:08  60.4S   27.0W mb=5.7  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 AAAAA  So. Sandwich Islands       

 

 

STRONG AFTERSHOCK SHAKES MINDORO, PHILIPPINES

 

EARTHQUAKE SUMMARY FOR AUGUST 13, 2021

 

A strong aftershock of M 5.8-5.9 hit the region of Mindoro, Philippines today. This is  the strongest aftershock to date of the M 6.7 of July 23, 2021. NEIC reported it was felt with maximum intensity V in Southern Tagalog at Talaga and IV in Santa Clara and Matabag with intensity III in Bauan, San Isidro, Kinalagiagan, Tagaylay, Bitangan, Putin Kahoy and Silang. This epicenter is located at the fifth node (72 degrees) from the M 8.2 in the Alaska Peninsula of July 29 and was probably promoted by energy from that source as noted in previous issues of this summary. It is also at the seventh harmonic from the South Sandwich Islands (128 degrees) and may have been promoted by energy from that source. This event occurred near local solar midnight and may have been promoted by strong tidal stresses which maximize near this hour. Forecast 136223 had expected enhanced activity within about 150 km of this epicenter around August 14.

 

O: 13AUG2021 15:08:30  13.7N  120.8E Mw=5.8  EMSC   MINDORO, PHILIPPINES         

P: 14AUG2021 136223    13.0N  122.0E 3.5-5.1 AAAAA  Luzon, Philippines         

 

Strong seismicity also continued today in the South Sandwich Islands region. The strongest earthquake in the area today was an M 6.3 but more than a score of moderate events of M>=5 were also recorded. This activity follows the M 7.5 in the region yesterday. This was discussed in the previous issue of this summary in detail. In part, that read:

 

"A major earthquake of M 7.5 in the South Sandwich Islands today was followed by a series of large and moderately large aftershocks. Four earthquakes of M>=7 have occurred in the South Sandwich Islands in the past 30 years - events of M 7.1-7.3 occurred December 27, 1991; July 15, 2013; May 28, 2106 and December 11, 2018. But the last earthquake of M>=7.5 in the South Sandwich Islands was an M 7.6 on September 8, 1961 following events of M 7.5 on September and an an M 7.7 on September 5, 1961. The only other event of M>7.5 in the historical catalog for the region was an M 8.3 on June 27, 1929. An M 7.5 also occurred southeast of the South Sandwich Islands about 500 km southeast of today's epicenters on October 6, 1973. These earthquakes occurred at 154 degrees from the M 8.2 in the Alaska Peninsula of July 29, 2021. This history suggest more major earthquakes may be in store in the next week in this region, or at the least a number of additional strong earthquakes may be coming. This is a seventh harmonic distance and probably relates a triggering situation from Alaska." (August 12-13, 2021

 

Forecast 136431 had expected today's activity in mid-August.

 

O: 13AUG2021 09:01:24  57.1S   25.6W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 11:45:38  57.3S   25.5W mb=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 08:46:29  57.4S   25.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 07:08:36  57.8S   24.0W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 10:11:18  57.8S   23.9W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 03:34:04  57.8S   25.3W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 08:25:00  58.4S   25.0W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 21:51:11  58.4S   23.5W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 03:31:30  58.4S   24.9W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 14:51:48  58.5S   23.7W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 00:23:33  58.5S   24.9W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 05:20:16  58.5S   25.0W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 07:13:56  58.7S   25.3W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 02:32:23  58.7S   25.1W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 07:04:35  58.8S   24.8W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 03:04:46  58.8S   24.8W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 12:39:22  58.9S   25.4W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 08:33:13  59.3S   24.8W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 13:12:19  59.8S   26.5W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 00:16:34  59.8S   26.4W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 05:14:36  59.8S   26.3W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 18:11:39  60.1S   26.8W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 11:25:03  60.2S   24.9W mb=4.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 16:21:20  60.4S   26.2W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 10:34:28  60.5S   27.2W Mw=6.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 20:49:55  60.5S   24.8W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 14AUG2021 03:23:40  60.5S   27.0W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 23:32:41  60.6S   26.6W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 15:52:43  57.0S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

 

An unusual regional aftershock of M 4.9 also occurred in the Southwestern Atlantic Ocean today. It was not felt in this remote area. This is the strongest earthquake within about 250 km of this epicenter in more than 30 years. Most regional activity occurs about 300 km to the north of today's epicenter. Forecast 136432 had expected today's activity in this region was likely to the north around August 15.

 

O: 13AUG2021 16:20:48  63.3S   19.7W mb=4.9  EMSC   SOUTHWESTERN ATLANTIC OCEAN  

P: 15AUG2021 136432    61.0S   22.0W 4.0-5.8 ABAAA  Southern  Ocean            

 

 

The area of Puerto Rico and Haiti were showing elevated seismicity today following the M 7.5 in the South Sandwich Islands yesterday. An M 3.2 in Puerto Rico was reported by NEIC to have been felt with intensity III in Ponce, in the active aftershock zone in southwestern Puerto Rico. Tropical Storm Fred was probably the major triggering factor for these earthquakes however. This summary had noted that this storm was likely to enhance regional seismicity in Haiti as noted in the previous issue of this report:

 

 

"TS Fred continued over the Dominican Republic today with winds up to 35 kts. This is the area of a strong M 6.7 and a long aftershock series over the past two years and the low pressures associated with this storm may help promoted enhanced aftershocks at this time." (August 12-13, 2021)

 

This region is also at the fourth harmonic (90 degrees) from the southern end of the major earthquakes yesterday in the South Sandwich Islands. It is also at the fifth harmonic (72 degrees) from the M 8.2 in the Alaska Peninsula and is probably being promoted by energy from that source as noted at the time in this summary:

 

 

"Following up on this forecast this summary reported notable seismicity from the Alaska Peninsula followed at nodal distances as:

 

Node 5 (72 degrees)

 

Alaska Peninsula to Mindoro, Philippines, Samoa, Nicaragua, New Britain, Solomon Islands, Dominican Republic, Galapagos, Mindanao, Philippines, Fiji, England, Samoa, Philippines, New Guinea to Fox Islands, Xizang, China," (July 29, 2021)

 

Forecasts 136235 and 136239 had expected today's activity in the northern

Caribbean was likely in mid-August.

 

O: 14AUG2021 02:17:34  17.9N   66.3W Md=3.2  EMSC   PUERTO RICO REGION

O: 14AUG2021 05:26:26  17.9N   66.9W Md=3.1  EMSC   PUERTO RICO REGION

O: 13AUG2021 13:13:34  18.0N   67.1W Md=3.1  EMSC   PUERTO RICO REGION

O: 14AUG2021 02:01:56  18.0N   66.3W Md=3.2  EMSC   PUERTO RICO REGION

O: 14AUG2021 01:46:55  17.8N   66.8W Md=3.2  EMSC   PUERTO RICO REGION           

P: 10AUG2021 136235    18.0N   67.0W 3.4-5.3 BAAAA  Puerto Rico                

 

O: 14AUG2021 04:38:50  18.3N   72.0W ML=2.8  EMSC   HAITI REGION                  

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 ABAAA  Bahamas/No. Caribbean      

 

O: 13AUG2021 15:16:15  18.9N   69.5W ML=3.0  EMSC   DOMINICAN REPUBLIC           

P: 14AUG2021 136235    18.0N   69.0W 3.4-5.3 AAAAA  Puerto Rico                

 

O: 13AUG2021 09:57:46  19.6N   71.3W ML=2.9  EMSC   DOMINICAN REPUBLIC

O: 13AUG2021 09:23:47  19.7N   71.3W ML=3.0  EMSC   DOMINICAN REPUBLIC

O: 13AUG2021 08:32:56  19.6N   71.3W ML=2.9  EMSC   DOMINICAN REPUBLIC           

P: 12AUG2021 136239    20.0N   73.0W 3.0-4.6 AAAAA  Bahamas/No. Caribbean      

P: 14AUG2021 136239    20.0N   71.0W 3.0-4.6 AAAAA  Bahamas/No. Caribbean      

 

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in the Alaska Peninsula aftershock zone. This region may be due for a significant aftershock as noted in the previous issue of this summary:

 

 

"The strongest earthquake in the U.S. or Canada today was an M 4.4 in the aftershock in the Alaska Peninsula. This is the third event of M>=4 in as many days. This re-energizing of the area may have been activated by a series of large earthquakes at harmonic distances from Alaska. Forecast 136346 had expected today's activity was likely around August 13-16." (August 13, 2021)

 

O: 13AUG2021 17:28:42  55.2N  157.6W ML=3.8  EMSC   ALASKA PENINSULA             

P: 13AUG2021 136346    55.7N  157.9W 3.5-5.4 AAAAA  Alaska Peninsula           

 

MAJOR EARTHQUAKE IN THE SOUTH SANDWICH ISLANDS

 

EARTHQUAKE SUMMARY FOR AUGUST 12, 2021

 

A major earthquake of M 7.5 in the South Sandwich Islands today was followed by a series of large and moderately large aftershocks. Four earthquakes of M>=7 have occurred in the South Sandwich Islands in the past 30 years - events of M 7.1-7.3 occurred December 27, 1991; July 15, 2013; May 28, 2106 and December 11, 2018. But the last earthquake of M>=7.5 in the South Sandwich Islands was an M 7.6 on September 8, 1961 following events of M 7.5 on September and an an M 7.7 on September 5, 1961. The only other event of M>7.5 in the historical catalog for the region was an M 8.3 on June 27, 1929. An M 7.5 also occurred southeast of the South Sandwich Islands about 500 km southeast of today's epicenters on October 6, 1973. These earthquakes occurred at 154 degrees from the M 8.2 in the Alaska Peninsula of July 29, 2021. This history suggest more major earthquakes may be in store in the next week in this region, or at the least a number of additional strong earthquakes may be coming. This is a seventh harmonic distance and probably relates a triggering situation from Alaska. The seventh harmonic seismicity elevation from Alaska was detailed in the previous issue of this summary as:

 

 

"The activity at 78 degrees is part of the 7th harmonic activation following the Alaska Peninsula earthquake. This has included significant enhancement at 25.7, 51.4, 77.1, 102.8, 128.5 and 154.2 degrees from the Alaska epicenter. This includes nodes and antinodes of the 7th harmonic (51.4 degrees) with M 1 and 2 or with the 14th harmonic (25.7 degrees). Significant seismicity has occurred at these distances from Alaska since July 29 in the Galapagos, South Sandwich Islands (154 degrees); North of Australia, Gulf of Aden, Java, South Indian Ocean, South Island, New Zealand, Southeast Pacific, Sumatra, Nicobar Islands, Southern Peru (103 degrees); Uzbekistan, Virgin Islands, New Guinea, Mindanao, Caucasus, Hindu Kush, Afghanistan, Northern Mid-Atlantic, Tonga, Vanuatu, Myanmar and Tajikistan (77-78 degrees); Alaska Peninsula to Quebec, Ohio, Newfoundland, Western Mexico (51.4 degrees)." (August 11-12, 2021)

 

 

A series of foreshocks in the South Sandwich Islands began shortly after the Alaska Peninsula quake and were detailed in this summary on August 7, 2021 as:

 

"The strongest earthquake of the day was an M 5.9 in the South Sandwich Islands. It was not reported felt in this remote area. This event is located at the seventh node (154 degrees) from the M 8.2 in the Alaska Peninsula of July 29 and was probably promoted by energy from that source. This is with m=3, n=7. Other seventh node distances are at 103 and 51.5 degrees from the Alaska Peninsula. These have all seen enhanced seismicity since the Alaska event.      This is the strongest earthquake in the South Sandwich Islands within about 200 km of this epicenter since an M 6.3 a year ago on July 26, 2020 shortly after the first M 7.6 earthquake in the Alaska Peninsula of July 22, 2020. At the time this summary noted in this regard:

 

"This is the strongest earthquake recorded in the South Sandwich Islands within  about 300 km of this epicenter since an M 6.6 northwest of today's event on August 27, 2019.  Earthquakes about 250 km to the north also occurred as an M 6.5 on April 9, 2019 and an M 7.1 on December 11, 2018, the only other such regional events since July 15, 2013. The mainshock was followed by an M 5.2 aftershock. The mainshock occurred within about an hour of local solar midnight and may have also been promoted by strong tidal effects.

 

... The mainshock was located in the antipodal area of the Alaska Peninsula event (60S vs 56N and 25W vs 158W) and was probably enhanced by that event." (July 26, 2020, August 7, 2021)

 

This activity in the South Sandwich Islands was also near the maximum tidal stress longitude with the past new moon. The longitude of the mainshock was at exactly local solar noon at the new moon where tidal stresses were maximized. This was probably a factor in the excessive magnitude of today's event as detailed in previous issues of this summary:

 

 

"The new moon arrived at 13:50 UT on August 8, 2021. Longitudes which were at local solar noon near this time are in the Central Atlantic including Iceland and the mid-Atlantic Ridge. Those at local solar midnight are near 160 East and include areas of Kamchatka and the Kurils and the Solomon Islands and the Vanuatu and Tonga/Kermadec/New Zealand chain. These areas are most likely to see enhanced tidal stresses and potential seismic triggering in the next week. A strong earthquake in the southwest Pacific is possible at this time. Seismicity in Japan is likely to be enhanced at this time as well." (August 6-11, 2021)

 

Forecast 136431 had expected today's activity in the South Sandwich Islands was likely in mid-August. Following is a listing of aftershocks in the area which extends from 56 South to 61 South latitude of M>=5. A more extensive listing of events of M>=4 can be found under the "OCEANS" section of this summary.

 

O: 12AUG2021 19:07:52  57.2S   25.5W mb=5.9  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 19:37:30  57.2S   26.2W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 03:53:16  57.3S   24.8W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 05:43:58  57.4S   25.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 18:32:54  57.6S   25.4W Mw=7.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 02:33:44  57.7S   23.8W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 04:03:57  57.8S   23.5W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 05:24:55  57.8S   24.9W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 04:53:09  57.9S   23.9W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 21:48:24  58.0S   25.3W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 03:43:22  58.0S   25.5W mb=5.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 22:08:39  58.1S   25.3W mb=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 01:47:37  58.3S   24.3W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 06:34:34  58.3S   23.9W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 06:41:47  58.3S   25.2W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 23:50:15  58.4S   24.4W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:06:32  58.5S   25.5W mb=5.8  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 01:26:38  58.6S   25.1W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 23:32:57  58.7S   25.3W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 23:23:40  58.8S   25.1W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 03:38:25  58.9S   24.7W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 00:42:25  59.0S   27.2W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 19:39:22  59.1S   25.0W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 00:04:15  59.2S   25.1W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 05:41:20  59.4S   25.1W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:38:07  59.5S   26.0W mb=5.4  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 06:14:11  59.5S   24.4W mb=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 23:08:15  59.7S   26.3W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 19:29:18  59.8S   26.5W mb=5.7  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 19:43:42  59.8S   26.4W mb=6.0  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:15:16  59.8S   26.1W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:15:16  59.8S   26.1W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:36:18  59.8S   26.4W mb=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 21:07:02  59.8S   26.6W mb=5.6  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 22:13:10  59.8S   26.5W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 19:44:48  59.9S   26.3W Mw=6.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:49:54  59.9S   26.5W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 13AUG2021 00:46:18  59.9S   25.0W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 18:49:51  57.2S   25.2W mb=5.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 17AUG2021 136431    56.0S   26.0W 4.0-5.8 BAAAA  So. Sandwich Islands       

 

O: 12AUG2021 21:19:51  60.3S   26.5W mb=5.2  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 19:59:04  60.4S   27.4W mb=5.5  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 21:56:55  60.5S   26.4W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

O: 12AUG2021 20:28:40  60.0S   26.6W mb=5.0  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 16AUG2021 136431    60.0S   26.0W 4.0-5.6 BAAAA  So. Sandwich Islands       

 

 

Another factor leading to enhanced seismicity at this time in the South Sandwich Islands was energy from the M 7.1 in Mindanao, Philippines which occurred yesterday.  It is near the third node (120 degrees) from that event and could have been affected by energy from that source. Aftershocks also continued in Mindanao, Philippines today. The largest of these was an M 5.7 which was felt in the same general area of southeastern Mindanao as the M 7.1 in the region yesterday.  NEIC reported this earthquake of M 5.7 in Mindanao, Philippines was felt with intensity II-III in the area(s) of Mindanao, Philippines at Manay, Buayan, Canocotan, and Davao. The M 5.7 was probably enhanced by tidal stresses as it occurred within minutes of local solar midnight, a time when such stresses are maximized. Following is a listing of aftershocks of M>=5 in this area today. A more extensive listing of M>=4 can be found in the "INDONESIA" section of this report.

 

O: 12AUG2021 20:17:09   6.0N  127.1E mb=5.3  EMSC   PHILIPPINE ISLANDS REGION

O: 12AUG2021 20:28:39   6.0N  127.2E mb=5.3  EMSC   PHILIPPINE ISLANDS REGION

O: 12AUG2021 21:03:46   6.0N  127.1E mb=5.3  EMSC   PHILIPPINE ISLANDS REGION

O: 12AUG2021 15:42:30   6.1N  127.2E mb=5.1  EMSC   PHILIPPINE ISLANDS REGION

O: 12AUG2021 15:53:30   6.4N  127.3E Mw=5.7  EMSC   PHILIPPINE ISLANDS REGION    

P: 11AUG2021 136186     6.0N  124.0E 4.0-5.5 AACAA  Mindanao, Philippines      

P: 14AUG2021 136180     8.0N  125.0E 4.0-5.4 ABBAA  Central Philippines        

 

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the aftershock in the Alaska Peninsula. This is the third event of M>=4 in as many days. This re-energizing of the area may have been activated by a series of large earthquakes at harmonic distances from Alaska. Forecast 136346 had expected today's activity was likely around August 13-16.

 

O: 13AUG2021 06:02:53  55.1N  157.5W ML=3.1  EMSC   ALASKA PENINSULA

O: 12AUG2021 09:54:34  55.2N  157.3W mb=4.4  EMSC   ALASKA PENINSULA

O: 13AUG2021 00:54:42  55.4N  158.1W ML=3.0  EMSC   ALASKA PENINSULA

O: 12AUG2021 22:00:49  54.9N  156.9W ML=3.7  EMSC   SOUTH OF ALASKA              

P: 13AUG2021 136346    55.7N  157.9W 3.5-5.4 AAAAA  Alaska Peninsula           

P: 16AUG2021 136346    54.7N  156.9W 3.5-5.4 BAAAA  Alaska Peninsula           

 

 

 

 

 

 

MAJOR EARTHQUAKE SHAKES MINDANAO, PHILIPPINES

 

EARTHQUAKE SUMMARY FOR AUGUST 11, 2021

 

A major earthquake of M 7.1 shook the region of Mindanao, Philippines today.

NEIC reported intensity IX (with major damage) in southern Mindanao at Tibanban, Talsay; VIII in Pundaguitan, Tamisan; V in Davao, Tagum, Mawab, Ising; IV in Lasang, and III in Canocotan. PHIVOLCS reported this earthquake was felt with intensity V in Governor Generoso, City of Mati, Baganga and Lupon, Davao Oriental; Cithy of Tagum, City of Panabo, Carmen and Nabunturan, Davao del Norte; General Santo City; Alabel and Malungon, Sarangani; IV in City of Davao; Kiblawan, Davao del Sur, City of Koronadal, Tampakan, Tupi and Polomolok, South Cotabato, Glan, Malapatana dn Kiamba, Sarangani; Monkayo, Davao de Oro; III in Kabacan, Cotabato, Bayugan, Agusan del Sur, II ion Cagayan de Oro City, Maasim, Sarangani; Arakan and Banisilan, Cotabato and I in Mambajao, Camiguin Island, Philippines. BMG reported it was felt with intensity IV in Talaud; II-IIII in Sangihe, and Bitung, Indonesia. No major damage was reported and the risk of a significant tsunami was considered minimal. A minor tsunami was reported by PTWC with height 0.05 m in Bitung Indonesia and 0.04 m in Davao, Philippines. The last non-deep focus earthquake of M>=7.1 in the region of Mindanao occurred as an M 7.2 on March 5, 2002 but the last of equal or larger magnitude within about 250 km of today's epicenter occurred as an M 7.4 twenty years ago on January 1, 2001 and  an M 7.3 and 7.1 on May 17, 1992. Deep focus earthquake hit about 350 km to the east of today's epicenter with M 7.6 on July 23, 2010 and an M 7.1 on February 5, 2005.

 

Today's event is at 77-78 degrees from the epicenter of the M 8.2 in Alaska Peninsula of July 29. Shortly after that event it became clear that this distance had been activated by energy from that source. This was emphasized in this summary on

August 2-3 as:

 

 

"The strongest earthquake in the world today was an M 6.1 in New Guinea. BMG reported it was felt with intensity IV in Kaimana, Indonesia. This epicenter is at node 9 (80 degrees) from the epicenter of the M 8.2 in the Alaska Peninsula of July 29. This continues enhanced seismicity at this distance from Alaska which was emphasized several days ago in this summary as:

 

"An M 5.3 also occurred today in the Central East Pacific Rise. It was not reported felt in this epicentral area. This event, like that in the northern mid-Atlantic Ridge occurred at 78 degrees from the Alaska epicenter. Other moderate earthquakes today occurred at this distance from Alaska in Tonga, Vanuatu, Myanmar and Tajikistan. This may represent a free-earth concentration of energy at this distance." (July 30, 2021, August 2, 2021)

 

The activity at 78 degrees is part of the 7th harmonic activation following the Alaska Peninsula earthquake. This has included significant enhancement at 25.7, 51.4, 77.1, 102.8, 128.5 and 154.2 degrees from the Alaska epicenter. This includes nodes and antinodes of the 7th harmonic (51.4 degrees) with M 1 and 2 or with the 14th harmonic (25.7 degrees). Significant seismicity has occurred at these distances from Alaska since July 29 in the Galapagos, South Sandwich Islands (154 degrees); North of Australia, Gulf of Aden, Java, South Indian Ocean, South Island, New Zealand, Southeast Pacific, Sumatra, Nicobar Islands, Southern Peru (103 degrees); Uzbekistan, Virgin Islands, New Guinea, Mindanao, Caucasus, Hindu Kush, Afghanistan, Northern Mid-Atlantic, Tonga, Vanuatu, Myanmar and Tajikistan (77-78 degrees); Alaska Peninsula to Quebec, Ohio, Newfoundland, Western Mexico (51.4 degrees).

 

It also seems likely that this event in Mindanao was promoted by high tidal stresses associated with the new moon of August 8. It occurred near local solar noon, an hour when tidal stresses maximize. Also note that the 103 degrees distance from Mindanao passes through Southern and Central California where enhanced seismicity should be anticipated in the near future. The tidally enhanced forecast with this new moon had read:

 

"The new moon arrived at 13:50 UT on August 8, 2021. Longitudes which were at local solar noon near this time are in the Central Atlantic including Iceland and the mid-Atlantic Ridge. Those at local solar midnight are near 160 East and include areas of Kamchatka and the Kurils and the Solomon Islands and the Vanuatu and Tonga/Kermadec/New Zealand chain. These areas are most likely to see enhanced tidal stresses and potential seismic triggering in the next week. A strong earthquake in the southwest Pacific is possible at this time. Seismicity in Japan is likely to be enhanced at this time as well." (August 8-11, 2021)

 

Forecasts 136185 and 136186 had expected today's activity in mid-August within  about 150 km of this epicenter in Mindanao, Philippines.

 

O: 11AUG2021 18:28:23   5.9N  126.9E ML=4.8  EMSC   MINDANAO, PHILIPPINES

O: 11AUG2021 23:34:27   6.0N  127.2E mb=4.4  EMSC   PHILIPPINE ISLANDS REGION

O: 11AUG2021 18:23:44   6.1N  127.0E ML=4.3  EMSC   MINDANAO, PHILIPPINES

O: 11AUG2021 19:28:34   6.2N  126.9E mb=4.9  EMSC   MINDANAO, PHILIPPINES

O: 12AUG2021 02:26:10   6.2N  127.3E mb=5.2  EMSC   PHILIPPINE ISLANDS REGION

O: 12AUG2021 04:39:09   6.3S  131.2E ML=4.4  EMSC   KEP. TANIMBAR REGION, INDONESIA

O: 11AUG2021 18:44:01   6.4N  127.1E ML=4.6  EMSC   PHILIPPINE ISLANDS REGION

O: 11AUG2021 18:54:50   6.5N  127.3E ML=4.4  EMSC   PHILIPPINE ISLANDS REGION

O: 11AUG2021 17:46:14   6.6N  126.8E Mw=7.1  EMSC   MINDANAO, PHILIPPINES

O: 11AUG2021 19:25:24   7.0N  126.0E ML=4.4  EMSC   MINDANAO, PHILIPPINES

O: 11AUG2021 19:40:17   7.2N  127.4E ML=4.3  EMSC   PHILIPPINE ISLANDS REGION    

P: 11AUG2021 136186     6.0N  124.0E 4.0-5.5 ABCAA  Mindanao, Philippines      

P: 20AUG2021 136185     8.0N  127.0E 4.0-5.6 CAAAA  Halmahera                  

 

 

The second largest earthquake in the world today - an M 5.5 in Fiji - was also located at 77 degrees from the Alaska Peninsula epicenter. The last earthquake of M>=5.5 within about 200 km of this epicenter was an M 6.1 on May 7, 2021. Forecast 136399 expected today's activity was likely within about 100 km around August 12.

 

O: 12AUG2021 03:47:01  18.3S  178.0W Mw=5.5  EMSC   FIJI REGION                  

P: 12AUG2021 136399    19.0S  178.0W 4.0-5.5 AAAAA  Tonga Islands              

 

UNUSUAL QUAKE IN NEW ZEALAND SUGGESTS TRIGGERING FROM ALASKA

 

EARTHQUAKE SUMMARY FOR AUGUST 10, 2021

 

An unusual earthquake of M 4.2 hit in South Island, New Zealand today. It was reported in Canterbury at Timaru, and Oamaru. This is an unusual epicenter (thanks to reader PB for calling this to our attention and for information from local sources for this event). GEONET reported it was felt with light intensity in the area southeast of Christchurch, South Island. 742 reports of felt intensity came from the area west and north of the epicenter. More than 742 people reported feeling this earthquake with 278 reporting weak shaking and 382 light intensity; 78 with moderate intensity and 4 with strong shaking. This epicenter is at 103 degrees from the epicenter of the M 8.2 in the Alaska Peninsula of July 29 and was probably promoted by energy from that source.

This is the strongest earthquake within about 100 km of this epicenter since an M 4.3 on May 27, 2011. The largest such event in the past 30 years was an M 5.0 on February 8, 1998. Forecast 136170 had expected today's event to the north was likely around August 8.

 

O: 10AUG2021 13:03:53  44.4S  170.9E mb=4.2  EMSC   SOUTH ISLAND OF NEW ZEALAND  

O: 10AUG2021 13:03:53  44.4S  170.9E MS=4.1  GEONET Felt with light intensity

P:  8AUG2021 136170    43.0S  171.0E 3.0-4.9 ABAAA  So. Island, N.Z.           

 

An unusual earthquake of M 4.2 also occurred today north of Australia. It was not reported felt in this remote epicentral region. The last event of M>=4.2 within about 250 km of this epicenter was an M 5.3 on April 17, 2011, more than ten years ago. It may have been promoted by antipodal effects from Tropical Storm Fred which made landfall in southern Puerto Rico today at the exact antipode of this event north of Australia. This storm was accompanied by an M 3.7 event in the Dominican Republic. The likely effects of TS Fred  been noted in this summary as:

 

"TS Fred formed south of Puerto Rico today with winds up to 40 kts. This is the area of a strong M 6.7 and a long aftershock series over the past two years and the low pressures associated with this storm may help promoted enhanced aftershocks at this time. It is expected to track to the northwest reaching the region of Southern Florida around August 15. It is then expected to hit the Tampa, Florida area and north to the Florida Panhandle as a Tropical Storm." (August 10-11, 2021)

 

This epicenter may also have been affected by energy from the M 8.2 in the

Alaska Peninsula of July 29 as it lies at 105 degrees from that event - a distance at which triggering is expected from large surface disturbances.

 

O: 10AUG2021 23:22:23  19.7S  112.9E ML=4.2  EMSC   NORTHWEST OF AUSTRALIA       

 

O: 10AUG2021 07:22:21  18.8N   69.9W ML=3.7  EMSC   DOMINICAN REPUBLIC            

P: 14AUG2021 136235    18.0N   69.0W 3.4-5.3 BAAAA  Puerto Rico                

 

The strongest seismicity in the world today was a series of moderate earthquakes of M 5.0 in the Kuril Islands. Today's activity was not reported felt in these remote areas. The Kuril Islands have been relatively quiet in recent months. No strong quakes have hit the region in the past year. The last of M>=5.0 was an M 5.4 on August 2, 2021. This summary had suggested the Kuril Islands might see enhanced seismicity with the new moon in previous issues as:

 

"The new moon arrived at 13:50 UT on August 8, 2021. Longitudes which were at local solar noon near this time are in the Central Atlantic including Iceland and the mid-Atlantic Ridge. Those at local solar midnight are near 160 East and include areas of Kamchatka and the Kurils and the Solomon Islands and the Vanuatu and Tonga/Kermadec/New Zealand chain. These areas are most likely to see enhanced tidal stresses and potential seismic triggering in the next week. A strong earthquake in the southwest Pacific is possible at this time. Seismicity in Japan is likely to be enhanced at this time as well." (August 6-10, 2021)

 

Forecasts 136324 and 136056 had expected today's activity within about 100 km  was likely in early to mid-August.

 

O: 10AUG2021 16:27:55  47.7N  154.4E mb=5.0  EMSC   KURIL ISLANDS                

P: 13AUG2021 136324    47.0N  156.0E 3.5-5.4 BABAA  NE Pacific                 

 

O: 10AUG2021 12:08:44  44.1N  148.4E mb=5.0  EMSC   KURIL ISLANDS                 

P:  9AUG2021 136056    44.0N  147.0E 3.5-5.8 AAAAA  Hokkaido, Japan            

 

Moderate earthquakes also shook two ocean ridges today. An M 5.0 in the Gulf of Aden and an M 4.9-5.0 in the Northern Mid-Atlantic Ridge were not reported felt in these remote areas. An M 5.3 also occurred in the active Loyalty Islands today.

 

Forecasts 135944 and 136213 had expected the activity ini the Gulf of Aden within about 100 km of this epicenter around August 9-13.

 

This epicenter may also have been affected by energy from the M 8.2 in the

Alaska Peninsula of July 29 as it lies at 106 degrees from that event - a distance at which triggering is expected from large surface disturbances.

 

O: 10AUG2021 15:25:12  13.2N   49.6E mb=5.0  EMSC   GULF OF ADEN                  

P:  9AUG2021 135944    13.0N   51.0E 3.5-4.9 AABAA  Gulf of Aden               

P: 13AUG2021 136213    14.0N   49.0E 3.5-4.9 BAAAA  Arabian Sea                

 

The M 4.9 in the Northern Mid-Atlantic had been expected within about 100 km of this epicenter to occur around August 11.

 

O: 10AUG2021 18:58:22  28.3N   43.8W mb=4.9  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P: 11AUG2021 136245    29.0N   43.0W 4.0-5.4 AAAAA  Mid-Atlantic Ridge         

 

Forecast 136405 had also expected enhanced activity in the Loyalty Islands around August 13.

 

O: 10AUG2021 21:21:53  23.3S  171.6E mb=5.2  EMSC   SOUTHEAST OF LOYALTY ISLANDS 

P: 13AUG2021 136405    23.0S  169.0E 4.0-5.8 BABAA  Loyalty Islands            

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 aftershock in the Alaska Peninsula of the M 8,2 of July 29. It was reported by NEIC to have been lightly felt in the epicentral area. Aftershocks of this magnitude are not uncommon in  the sequence. However, the last event in the aftershock zone of M>=4.4 occurred July 30, 2021 so this is the strongest such event in nearly two weeks. Forecast 136346 had expected today's event within about 15 km of this epicenter was likely in mid-August.

 

O: 11AUG2021 05:46:13  54.7N  156.9W ml=3.7  EMSC   SOUTH OF ALASKA

O: 11AUG2021 05:43:34  54.8N  157.0W mb=4.4  EMSC   SOUTH OF ALASKA

O: 10AUG2021 08:59:46  55.0N  157.3W ML=3.4  EMSC   SOUTH OF ALASKA

O: 10AUG2021 19:24:45  55.3N  157.4W ML=3.5  EMSC   ALASKA PENINSULA

O: 11AUG2021 05:51:01  54.6N  156.8W ml=3.7  EMSC   SOUTH OF ALASKA              

P: 16AUG2021 136346    54.7N  156.9W 3.5-5.4 BAAAA  Alaska Peninsula           

 

An unusual earthquake of M 4.2 also occurred today in the region of southern

Manitoba, Canada. It was not reported felt in this area. The last earthquake with equal or greater magnitude within about 250 km of this epicenter in Manitoba or North Dakota occurred as an M 4.4 about 50 km northwest of today's epicenter on April 14, 2010 and was the only such event in the area in the past 30 years.

 

O: 11AUG2021 04:34:30  50.5N  101.6W mb=4.2  EMSC   MANITOBA, CANADA             

 

ANTIPODAL PAIR IN NEAR ISLANDS, ALEUTIANS; SOUTH ATLANTIC

 

EARTHQUAKE SUMMARY FOR AUGUST 9, 2021

 

Antipodal earthquakes of M 5.2 each occurred in the Near Islands, Aleutians, Alaska and then in the Southern Mid-Atlantic Ridge today. These were note reported felt in these remote areas. The earthquakes in the Southern Mid-Atlantic followed a pair of M 5.0 events reported in this summary in the previous issue as:

 

 

"Two similar events occurred in the southern Mid-Atlantic Ridge with M 5.0. It occurred near local solar midnight and also was probably promoted by tidal stresses associated with today's new moon. A strong M 6.6 hit about 200 km southwest of today's epicenter on April 3, 2021." (August 9, 2021)

 

The M 5.2 today occurred within about half an hour of local solar noon and was also probably promoted by high tidal stresses associated with the new moon. This summary had forecast seismicity with this new moon in previous issues as:

 

"The new moon arrived at 13:50 UT on August 8, 2021. Longitudes which were at local solar noon near this time are in the Central Atlantic including Iceland and the mid-Atlantic Ridge. Those at local solar midnight are near 160 East and include areas of Kamchatka and the Kurils and the Solomon Islands and the Vanuatu and Tonga/Kermadec/New Zealand chain. These areas are most likely to see enhanced tidal stresses and potential seismic triggering in the next week. A strong earthquake in the southwest Pacific is possible at this time. Seismicity in Japan is likely to be enhanced at this time as well." (August 6-9, 2021)

 

O: 09AUG2021 13:18:36  56.7S    6.0W mb=5.0  EMSC   SOUTHERN MID-ATLANTIC RIDGE

O: 09AUG2021 21:50:31  56.8S    6.3W mb=5.0  EMSC   SOUTHERN MID-ATLANTIC RIDGE

O:  9AUG2021 12:54:35  56.7S    6.1W Mw=5.2  EMSC   SOUTHERN MID-ATLANTIC RIDGE  

 

The M 5.2 in the Near Islands, Alaska was the strongest event in the Near Islands since an M 5.3 on April 15, 2021. The last event in the Near Islands of significantly larger magnitude was an M 6.2 on March 27, 2017. Today's event follows an M 5.4 in the Rat Islands to the east of this on August 8. That event had been noted in also in the previous issue of this summary as:

 

 

"The strongest earthquake in the U.S. or Canada today was an M 5.4 in the Rat Islands, Alaska. It was preceded by an M 4.3 aftershock. Like much of the other significant activity in the world today (see above) this began near local solar midnight and was probably promoted by high tidal stresses associated with the new moon which arrived within minutes of these events. The last event in the Rat Islands of larger magnitude occurred as an M 6.4 on April 2, 2019. Similar events of M 5.4 hit the Rat Islands about 250 km to the east and west of today's epicenter on October 26, 2019 and May 17, 2021.

 

The geomagnetic storm at high latitudes yesterday may also have helped trigger this activity at this time as noted in the previous issue of this summary:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 11.  High latitude geomagnetic field saw active conditions with AP 22. Seismicity at high latitudes may be enhanced following this geomagnetic activity through August 11." (August 7-9, 2021)

 

Today's event in the Near Islands had been expected in forecast 136097 to occur around August 7 within about 50 km of this epicenter.

 

O:  9AUG2021 09:41:58  53.5N  170.1E Mw=5.2  EMSC   NEAR ISLANDS, ALEUTIAN ISLANDS

P:  7AUG2021 136097    54.0N  170.0E 4.0-5.6 AAAAA  Near Islands               

 

Light earthquakes of M 3.5 each were also felt in the Texas Panhandle and to the northeast in northern Kansas. The event in the Texas Panhandle follows an M 2.7 at this epicenter on August 8, 2021 and is the strongest within about 100 km in this area in at least a year. Forecast 136040 had expected regional activity around August 8. The foreshock was discussed in the previous issue of this summary as:

 

 

"NEIC reported this earthquake of M 2.8 in the Texas Panhandle was felt with intensity II-III in the area(s) of the Texas Panhandle at Wheeler." (August 8-9, 2021)

 

The only event within about 100 km of this Texas Panhandle event of M>=3.5 in the past 30 years was an M 3.7 about 50 km northwest of this on October 14, 2008.

 

NEIC reported this earthquake of M 3.5 in the Texas Panhandle was felt with intensity II-III in the area(s) of the Texas Panhandle at Wheeler and Briscoe (IV) and in Mobeetie, Canadian, Sayre, Clarendon.

 

O:  9AUG2021 12:24:41  35.5N  100.3W mb=3.5  EMSC   TEXAS PANHANDLE REGION       

P:  8AUG2021 136040    36.0N   97.0W 2.0-4.0 AACAA  Southern Plains            

 

The M 3.5 in northern Kansas occurred within about half an hour of local solar noon and was probably promoted by tidal stresses associated with the new moon. An M 3.8 occurred on May 6, 2021 about 50 km east of this epicenter and an M 4.5 about 100 km southwest of this on June 22, 2019.A small foreshock at this epicenter  occurred on July 29, 2021. At the time this summary noted this as:

 

 

"An aftershock of M 3.2 hit near the Nebraska-Kansas border today. NEIC reported this earthquake of M 3.2 in Northern Kansas was felt with intensity II-III in the area(s) of Northern Kansas at Mankato and in Omaha, Nebraska. This follows a smaller foreshock which hit several hours before the M 8.2 in Alaska and may have been precursory to that event. In the previous issue of this summary it was noted in this regard:

 

"An M 2.9 in northern Kansas preceded the earthquake in Alaska today. It was reported lightly felt in the epicentral areas. Unusual earthquakes in the central plains of the U.S. often precede strong quakes in Alaska. A series of light earthquakes occurred east of this epicenter on May 6, 2021 with maximum size of M 3.8. Forecast 135779 had expected regional enhancement of seismicity in this area was possible around July 28." (July 29, 2021)

 

Forecast 136040 had expected today's event in northern Kansas was likely in  early August within about 100 km of today's epicenter.

 

NEIC reported this earthquake of M 3.5 in Kansas was felt with intensity II-III in the area(s) of Kansas at Mankato, Cawker, Burr Oak, Jewell, Abilene and Manhattan.

 

O:  9AUG2021 19:29:31  39.7N   98.4W Mw=3.5  EMSC   KANSAS                       

P:  4AUG2021 136040    39.0N   99.0W 2.0-4.1 BAAAA  Southern Plains            

 

NEW MOON ACTIVE IN TIDAL TRIGGERING

 

EARTHQUAKE SUMMARY FOR AUGUST 8, 2021

 

A series of earthquakes occurred today in the Vanuatu region of the South  Pacific. These began with an M 4.3 in Vanuatu within about 5 minutes of the passage of the new moon over the area and was followed by two additional moderate quakes in the area in the next hour. These were probably promoted by  today’s new moon tidal stresses. The seismicity associated with this new moon had been noted in previous issues of this summary as:

 

"The new moon will arrive at 13:50 UT on August 8, 2021. Longitudes which are at local solar noon near this time are in the Central Atlantic including Iceland and the mid-Atlantic Ridge. Those at local solar midnight are near 160 East and include areas of Kamchatka and the Kurils and the Solomon Islands and the Vanuatu and Tonga/Kermadec/New Zealand chain. These areas are most likely to see enhanced tidal stresses and potential seismic triggering in the next week. A strong earthquake in the southwest Pacific is possible at this time. Seismicity in Japan is likely to be enhanced at this time as well." (August 7-8, 2021)

 

Forecast 136144 had expected today's activity in the Vanuatu area was likely in early August.

 

O:  8AUG2021 14:37:22  19.1S  168.7E mb=4.8  EMSC   VANUATU                      

P:  3AUG2021 136144    19.0S  169.0E 4.0-5.6 BAAAA  Vanuatu Islands            

 

O:  8AUG2021 14:51:10  12.1S  166.8E mb=4.8  EMSC   SANTA CRUZ ISLANDS           

P:  5AUG2021 136144    13.0S  167.0E 4.0-5.4 BAAAA  Vanuatu Islands            

 

O:  8AUG2021 13:56:07  14.5S  167.6E mb=4.3  EMSC   VANUATU                      

P:  5AUG2021 136144    13.0S  167.0E 4.0-5.4 BBAAA  Vanuatu Islands            

 

The largest earthquake in the world today occurred south of Vanuatu at 160 East longitude in the Macquarie Islands region. This event of M 5.5 is the strongest within about 250 km of this epicenter since an M 5.6 on August 3, 2020. The last of significantly larger magnitude was an M 5.9 on February 9, 2012. Today's event occurred near local solar noon. 

 

O:  8AUG2021 22:19:10  59.8S  159.5E Mw=5.5  EMSC   MACQUARIE ISLAND REGION      

 

Two similar events occurred in the southern Mid-Atlantic Ridge with M 5.0. It occurred near local solar midnight and also was probably promoted by tidal stresses associated with today's new moon. A strong M 6.6 hit about 200 km southwest of today's epicenter on April 3, 2021.

 

 

O: 08AUG2021 23:03:37  56.7S    6.0W mb=5.0  EMSC   SOUTHERN MID-ATLANTIC RIDGE

O:  9AUG2021 01:54:02  56.6S    6.1W mb=5.0  EMSC   SOUTHERN MID-ATLANTIC RIDGE  

 

Another experimental explosion was made today off the coast of Florida. It was reported lightly felt in the epicentral area off eastern Florida. Similar explosions off Florida occurred with M 3.9 on June 18, 2021 and on July 16, 2021. The purpose of these experiments has not been revealed.

 

O:  8AUG2021 19:55:17  30.1N   79.6W ML=3.9  EMSC   OFF EAST COAST OF UNITED STATE

 

 

A series of light earthquakes occurred today in central an northern California.

Two of these - an M 2.1 in the San Francisco, California area and an M 2.6  in northern California occurred within 15 minutes of local solar noon and were probably promoted by today's new moon tidal stresses. Forecasts 135993 and 135996 had expected today's activity in Central California was likely within about 25 km of these epicenter around August 9.

 

O: 08AUG2021 16:07:21  37.4N  122.2W Md=2.4  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 08AUG2021 20:31:23  37.4N  121.7W Md=2.1  EMSC   NORTHERN CALIFORNIA

O:  8AUG2021 10:24:57  37.3N  122.0W Md=2.3  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P:  9AUG2021 135993    37.2N  122.1W 2.5-4.6 AAAAA  Central California         

P:  9AUG2021 135993    37.4N  121.8W 2.5-4.7 AAAAA  Central California         

 

O: 08AUG2021 19:48:26  39.7N  122.9W Md=2.6  EMSC   NORTHERN CALIFORNIA

O: 08AUG2021 20:21:59  39.7N  122.9W Md=2.5  EMSC   NORTHERN CALIFORNIA

O:  8AUG2021 17:31:21  39.7N  122.9W Md=2.5  EMSC   NORTHERN CALIFORNIA          

P:  4AUG2021 135996    39.4N  123.3W 2.5-4.6 BAAAA  Central California         

 

The strongest earthquake in the U.S. or Canada today was an M 5.4 in the Rat Islands, Alaska. It was preceded by an M 4.3 aftershock. Like much of the other significant activity in the world today (see above) this began near local solar midnight and was probably promoted by high tidal stresses associated with the new moon which arrived within minutes of these events. The last event in the Rat Islands of larger magnitude occurred as an M 6.4 on April 2, 2019. Similar events of M 5.4 hit the Rat Islands about 250 km to the east and west of today's epicenter on October 26, 2019 and May 17, 2021. Forecast 136102 had expected today's event was likely within about 50 km around August 8. The geomagnetic storm at high latitudes yesterday may also have helped trigger this activity at this time as noted in the previous issue of this summary:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 11.  High latitude geomagnetic field saw active conditions with AP 22. Seismicity at high latitudes may be enhanced following this geomagnetic activity through August 11." (August 7-8, 2021)

 

O:  8AUG2021 13:22:00  51.6N  175.7E mb=4.3  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

O: 08AUG2021 14:50:27  51.6N  175.9E Mw=5.4  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P:  8AUG2021 136102    51.0N  176.0E 4.0-5.9 AAAAA  Rat Islands                

 

 

RIDGES ACTIVE

 

EARTHQUAKE SUMMARY FOR AUGUST 7, 2021

 

The strongest seismicity in the world today occurred on mid-Ocean ridges. The largest of these was an M 5.3 in the Prince Edward Islands region south of Africa. Other moderate sub-oceanic seismicity occurred in the South Sandwich Islands with events of M 4.7 and 4.8. These follow an M 5.9 that hit the area yesterday in the southern South Sandwich area. An event of M 5.0 also occurred in the northern East Pacific Rise area near the Galapagos. None of these events were reported felt. Forecasts 136176 had expected the activity in the South Sandwich Islands was likely around August 6. This activity is at 154 degrees from the Alaska Peninsula epicenter of July 29, 2021 - a seventh harmonic - and was probably promoted by energy from that source.

 

O:  7AUG2021 13:42:30  45.1S   34.6E Mw=5.3  EMSC   PRINCE EDWARD ISLANDS REGION 

 

O:  8AUG2021 02:55:27  56.1S   27.6W mb=4.7  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  6AUG2021 136176    57.0S   27.0W 4.0-5.8 AAAAA  So. Sandwich Islands       

 

O:  7AUG2021 09:58:26  59.6S   25.8W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  6AUG2021 136176    57.0S   27.0W 4.0-5.8 ACAAA  So. Sandwich Islands       

 

O:  8AUG2021 00:49:31   2.2N  101.4W Mw=5.0  EMSC   GALAPAGOS TRIPLE JUNCTION REGI

 

An earthquake of M 5.3 also occurred today in the Solomon Islands. It was not reported felt in this remote area. Recent similar earthquakes hit the area on May 21, 2021 and January 9, 2021 with M 5.3 and 5.4. The last event of larger magnitude within about 200 km of this epicenter was an M 5.6 to the north on October 30, 2020. This event was closely associated with the M 7.4 in the Alaska Peninsula of October 19 as noted at the time in this summary:

 

"An earthquake of M 5.6 in the Solomon Islands preceded the M 7.0 in the Dodecanese Islands today. This event was reported felt with intensity IV in Honiara, Guadalcanal, Solomon Islands. This epicenter is at the fifth node (72 degrees) from the M 7.5 in the Alaska Peninsula of October 19 and may have been promoted by energy from that source. SS phases from the Solomon Islands would have been present in the Dodecanese Islands when that subsequent quake occurred and may have helped trigger it. This event occurred near local solar midnight and may have been promoted by high tidal stresses with the full moon which are maximized near this time. This is the strongest quake within about 200 km of this epicenter since an M 5.8 about 150 km to the south on July 18, 2020." (October 30, 2020)

 

 

O:  7AUG2021 14:51:30  10.0S  161.1E Mw=5.3  EMSC   SOLOMON ISLANDS              

P:  8AUG2021 136134    10.0S  160.0E 4.0-5.6 AAAAA  No. of Santa Cruz Islands  

 

An unusual earthquake of M 2.4 occurred in eastern Colorado today. The last earthquake within about 100 km of this epicenter with M>=2.4 occurred on September 11, 2018 about 100 km northwest of today's event.  Forecast 135999 had expected activity in Colorado in early August to the west of today's epicenter.

 

O:  7AUG2021 21:46:20  38.4N  103.5W mb=2.4  EMSC   COLORADO                     

P:  5AUG2021 135999    38.8N  107.4W 2.0-3.9 AACAA  Colorado area              

 

 

STRONG QUAKE IN SOUTH SANDWICH ISLANDS

 

EARTHQUAKE SUMMARY FOR AUGUST 6, 2021

 

The strongest earthquake of the day was an M 5.9 in the South Sandwich Islands. It was not reported felt in this remote area. This event is located at the seventh node (154 degrees) from the M 8.2 in the Alaska Peninsula of July 29 and was probably promoted by energy from that source. This is with m=3, n=7. Other seventh node distances are at 103 and 51.5 degrees from the Alaska Peninsula. These have all seen enhanced seismicity since the Alaska event.      This is the strongest earthquake in the South Sandwich Islands within about 200 km of this epicenter since an M 6.3 a year ago on July 26, 2020 shortly after the first M 7.6 earthquake in the Alaska Peninsula of July 22, 2020. At the time this summary noted in this regard:

 

"This is the strongest earthquake recorded in the South Sandwich Islands within  about 300 km of this epicenter since an M 6.6 northwest of today's event on August 27, 2019.  Earthquakes about 250 km to the north also occurred as an M 6.5 on April 9, 2019 and an M 7.1 on December 11, 2018, the only other such regional events since July 15, 2013. The mainshock was followed by an M 5.2 aftershock. The mainshock occurred within about an hour of local solar midnight and may have also been promoted by strong tidal effects. ... The mainshock was located in the antipodal area of the Alaska Peninsula event (60S vs 56N and 25W vs 158W) and was probably enhanced by that event." (July 26, 2020)

 

Forecast 136176 had expected today's activity in the South Sandwich Islands was likely around August 6.

 

O:  6AUG2021 19:22:03  59.6S   26.2W Mw=5.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  6AUG2021 136176    57.0S   27.0W 4.0-5.8 ACAAA  So. Sandwich Islands       

 

The strongest earthquakes felt today were a pair of events of M 5.3 aftershock of the M 6.1 in Taiwan of August 4. Today's events was reported by NEIC to have been felt with intensity V in Ilan, II-III in Tainan and Taichung and Taipei, Taiwan. CWB reported the mainshock of 5.5 were felt with intensity IV in Taipei, Yilan, III in Hualien, Keelung City, Taoyuan, Hsinchu, Nantou, Miaoli, Taichung, Yunlin, Hsinchu, Changhua, Chiayi, Taitung, Penghu, Kaohsiung, Tainan, Pingtung, and Kinmen Counties, Taiwan. The quake of M 5.4 was reported felt with intensity IV in Hualien; II in Nantou, Taitung, Kaohsiung, Chiayi, Tainan, Yunlin, Chiayi and I in Pingtung, Changhua, Miaoli, Yilan and Hsinchu Counties, Taiwan. These earthquakes occurred as Tropical Storm Lupit moved through the area  of Taiwan and were probably promoted by stresses from that storm as noted in previous issues of this summary:

 

"TS Lupit (13W) continued in the South China Sea today with winds up to 45 kts. It is expected to track to the northeast and could affect seismicity near Taiwan in the next several days." (August 3-4, 2021) NEIC reported this earthquake of M  in  was felt with intensity II-III in the area(s) of 

 

Forecast 135979 had expected today's activity was likely in early August.

 

O:  6AUG2021 08:11:04  24.8N  122.2E ML=5.5  TAI    Hualien, Taiwan              

O:  7AUG2021 05:43:59  24.8N  122.3E ML=4.2  TAI    Hualien, Taiwan              

O:  6AUG2021 11:12:30  23.2N  121.3E ML=5.4  TAI    Hualien, Taiwan              

O:  6AUG2021 11:37:30  23.1N  121.3E ML=4.1  TAI    Hualien, Taiwan              

O:  6AUG2021 11:39:13  23.2N  121.3E ML=4.6  TAI    Hualien, Taiwan              

O: 06AUG2021 11:12:30  23.1N  121.4E Mw=5.3  EMSC   TAIWAN

O: 06AUG2021 11:37:30  23.1N  121.3E ML=4.1  EMSC   TAIWAN

O: 06AUG2021 11:39:15  23.2N  121.3E mb=4.6  EMSC   TAIWAN

O: 06AUG2021 11:40:15  23.2N  121.3E ML=4.2  EMSC   TAIWAN

O: 06AUG2021 12:28:52  23.2N  121.3E ML=4.2  EMSC   TAIWAN

O: 06AUG2021 08:11:04  24.8N  122.3E Mw=5.3  EMSC   TAIWAN REGION

P:  3AUG2021 135979    24.0N  121.0E 4.0-5.4 AAAAA  Taiwan                     

 

An M 5.3 in the Sunda Strait in Indonesia was reported felt with intensity IV in Pringsewu, Lampung, Indonesia as reported by NEIC. This is the strongest earthquake in the Sunda Strait since a similar M 5.3 on January 16, 2021. Forecast 135930 had expected today's event was likely around August 7.

This epicenter is near 103 degrees from the Alaska Peninsula M 8.2 and was probably promoted by energy from that source.

 

O:  6AUG2021 11:08:18   6.1S  104.8E Mw=5.3  EMSC   SUNDA STRAIT, INDONESIA      

P:  7AUG2021 135930     7.0S  106.0E 4.0-5.4 AAAAA  So. of Java                

 

An M 5.1 also occurred in the Dodecanese Islands of Greece. NEIC reported it was felt with intensity II-III in Kefalos, Kardamaina, Limin and in Datoa, Turkey. This continues activity in this area which began on July 31, 2021 shortly after the M 8.2 in the Alaska Peninsula of July 29 and linked to that event in this summary at the time and included an M 5.7. A similar series of earthquakes in the Dodecanese Islands near this epicenter followed the M 7.6 of October 29, 2020 in the Alaska Peninsula and included an M 7.0 mainshock. Forecast 135983 had expected today's event was likely around August 2 within about 25 km of this epicenter.

 

O: 06AUG2021 10:52:39  36.3N   27.0E ML=4.2  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 06AUG2021 19:57:06  36.3N   27.1E mb=4.2  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 06AUG2021 20:41:58  36.3N   27.0E ML=4.1  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 07AUG2021 01:39:45  36.3N   27.1E Mw=5.1  EMSC   DODECANESE IS.-TURKEY BORDER REG

O:  6AUG2021 09:16:47  36.3N   27.1E mb=4.3  EMSC   DODECANESE IS.-TURKEY BORDER R

P:  2AUG2021 135983    36.0N   27.0E 3.0-4.4 BAAAA  Aegean Sea                 

 

A moderate earthquake of M 3.9 was felt in South Island, New Zealand today.

GEONET reported this earthquake was felt with light intensity in the area southwest of Haast, South Island. 30 reports of felt intensity came from the area east and north of the epicenter. More than 30 people reported feeling this earthquake with 14 reporting weak shaking and 15 light intensity; 1 with moderate intensity and none with strong, severe or extreme shaking. This epicenter is at 103 degrees from the epicenter of the M 8.2 in the Alaska Peninsula of July 29 and was probably promoted by energy from that source. An unusual earthquake of M 4.9 also hit the Indian Ocean south of Sumatra and an M 5.3 in the Sunda Strait today at 103 degrees from the Alaska Peninsula.

Forecast 136171 had expected this activity within about 100 km was likely around August 4.

 

O:  7AUG2021 06:51:20  44.1S  169.2E ML=3.9  EMSC   SOUTH ISLAND OF NEW ZEALAND  

O: 07AUG2021 06:51:20  44.1S  169.2E MS=3.9  GEONET Felt with light intensity

P:  4AUG2021 136171    44.0S  168.0E 3.0-5.1 BAAAA  So. Island, N.Z.           

P:  7AUG2021 136171    45.0S  167.0E 3.0-4.9 AABAA  So. Island, N.Z.           

 

The strongest earthquake in the region of the U.S. or Canada today was an M 4.0 in the northern Gulf of California. This continues an ongoing series of events generally to the northwest of this epicenter which began in mid-July. The only event of larger magnitude in this area of the Gulf of California in the past year was an M 4.7 on April 1, 2021 - an M 4.3 also hit the area on February 13, 2020. Forecast 136019 had expected today's activity was likely within about 50 km around August 8.

 

NEIC reported this earthquake of M 3.6 in Baja California was felt with intensity II-III in the area(s) of Baja California at Puebla.

 

O:  7AUG2021 00:23:56  30.1N  113.8W ML=4.0  EMSC   GULF OF CALIFORNIA           

P:  8AUG2021 136019    30.0N  114.3W 2.5-4.6 AAAAA  So. California             

 

 

QUIET RETURNS TO GLOBAL SEISMICITY

 

EARTHQUAKE SUMMARY FOR AUGUST 5, 2021

 

The active conditions in global seismicity which followed the M 8.2 in the Alaska Peninsula of July 29 discontinued today. There were no significant earthquakes today. The strongest earthquake in the world today was an M 5.3 south of the Fiji Islands. It is likely this event which occurred within about 30 minutes of local solar midnight was promoted by high tidal stresses which maximize near this hour. Forecast 136157 had expected this event was likely to the southeast around August 3.

 

O:  5AUG2021 11:20:17  23.1S  179.4W Mw=5.3  EMSC   SOUTH OF FIJI ISLANDS        

P:  3AUG2021 136157    24.0S  177.0W 4.0-5.6 AACAA  Tonga Islands              

 

The strongest seismicity in the U.S. or Canada today continued in the Alaska Peninsula aftershock zone. An M 4.3 occurred along with five events of M>=3.  This activity had been expected within about 25 km of this epicenter was likely around August 4.

 

O: 05AUG2021 21:42:52  54.8N  155.3W ML=3.5  EMSC   SOUTH OF ALASKA

O: 05AUG2021 07:15:31  55.0N  157.7W mb=3.8  EMSC   ALASKA PENINSULA

O: 05AUG2021 16:45:41  55.0N  155.1W ml=3.0  EMSC   SOUTH OF ALASKA

O: 05AUG2021 18:00:19  55.1N  157.1W ml=4.3  EMSC   ALASKA PENINSULA

O:  5AUG2021 21:23:24  55.3N  155.9W ml=3.4  EMSC   SOUTH OF ALASKA              

P:  4AUG2021 136087    55.1N  157.3W 3.5-5.4 AAAAA  Alaska Peninsula           

 

The strongest earthquake in the U.S. or Canada outside the Alaska Peninsula aftershock zone today was an M 3.9 off the coast of Northern California. NEIC reported it was felt with intensity III in Fort Bragg, California. Forecast 136072 had expected this activity within about 25 km was likely around August 3.

 

O:  5AUG2021 15:21:42  40.5N  125.3W ML=3.0  EMSC   OFFSHORE NORTHERN CALIFORNIA 

O:  5AUG2021 15:21:42  40.5N  125.3W ML=3.9  ANSS   OFFSHORE NORTHERN CALIFORNIA 

P:  3AUG2021 136072    40.6N  124.9W 2.5-4.6 AAAAA  Off Coast of No. Calif     

 

 

STRONG QUAKE SHAKES TAIWAN - ASSOCIATED WITH TS LUPIT

 

EARTHQUAKE SUMMARY FOR AUGUST 4, 2021

 

The strongest earthquake in the world today was an M 5.8-6.1 in the area of Taiwan. NEIC reported it was felt with intensity IV in Taiwan in Taipei, and III in Ilan, and Taoyuan. CWB reported the mainshock was felt with intensity IV in Taipei, Yilan, III in Hualien, Keelung City, Taoyuan, Hsinchu, Nantou, Miaoli, Taichung, Yunlin, Hsinchu, Changhua, Chiayi, Taitung, Penghu, Kaohsiung, Tainan, Pingtung, and Kinmen Counties, Taiwan. This earthquake occurred as Tropical Storm Lupit was passing by Taiwan and was probably promoted by stresses associated with that storm as noted in previous issues of this summary:

 

"TS Lupit (13W) continued in the South China Sea today with winds up to 45 kts. It is expected to track to the northeast and could affect seismicity near Taiwan in the next several days." (August 3-4, 2021)

 

The last earthquake in Taiwan with M>=6.1 was an M 6.2 near this epicenter on December 10, 2020; the last of M>=5.8 was an M 5.8 on April 18, 2021. Forecast 135979 had expected today's activity was likely within about 100 km around August 3.

 

O:  4AUG2021 21:56:26  24.7N  122.2E ML=5.2  TAI    Hualien, Taiwan              

O:  4AUG2021 21:54:33  24.8N  122.3E ML=4.3  TAI    Hualien, Taiwan              

O:  4AUG2021 21:53:20  24.8N  122.3E ML=4.5  TAI    Hualien, Taiwan              

O:  4AUG2021 21:50:44  24.8N  122.5E ML=6.1  TAI    Hualien, Taiwan              

O: 05AUG2021 02:14:08  24.4N  122.9E mb=4.4  EMSC   TAIWAN REGION

O: 04AUG2021 21:56:27  24.7N  122.3E mb=5.1  EMSC   TAIWAN REGION

O: 04AUG2021 21:50:46  24.8N  122.4E Mw=5.8  EMSC   TAIWAN REGION

P:  3AUG2021 135979    24.0N  121.0E 4.0-5.4 AAAAA  Taiwan                     

 

The strongest earthquake in North America today was an M 4.8 off the coast of Veracruz, Mexico. NEIC reported it was felt with maximum intensity V in Veracruz at El Tejar and IV in Boca del Rio, Veracruz and Ixtaczoquitlan, and II-III in Cordoba, Coatepec, Tenango de Rio Blanco, Tlalnepantla. This is far to the north of the normal seismicity in this region. The only such event within about 100 km of this epicenter in the past 30 years was an M 5.7 on October 29, 2009. This epicenter is located at the sixth node (60 degrees) from the Alaska Peninsula

M 8.2 of July 29 and was probably promoted by energy from that source. Forecast 135696 had expected activity in this area was likely around July 31.

 

O:  4AUG2021 09:58:25  19.3N   95.8W mb=4.7  EMSC   OFFSHORE VERACRUZ, MEXICO    

O:  4AUG2021 09:58:25  19.3N   95.8W mb=4.8  ANSS   OFFSHORE VERACRUZ, MEXICO    

P: 31JUL2021 135696    17.0N   96.0W 3.5-5.1 BCAAA  Oaxaca, Mexico             

 

A moderate earthquake of M 4.2-4.7 occurred in the Cook Strait, New Zealand today. NEIC reported this earthquake of M 4.2 in Cook Strait, New Zealand was felt with intensity II-III in the area(s) of Cook Strait, New Zealand with IV in Kapiti and III in Porirua, Makara-Ohariu, Lower Hutt, Wellington, Levin, Blenheim, Wanganui and Nelson. GEONET reported this earthquake was felt with moderate intensity in Cook Strait and Southern North Island. 5906  people reported feeling this event; 1745 with weak intensity; 3184 with light shaking; 917 moderate; 50 strong; 4 with severe and 6 with extreme shaking. The last earthquake of M>=4.7 in the Cook Strait of New Zealand occurred as an M 4.7 on March 12, 2021. Forecast 136170 had expected this event was likely within about 50 km around August 4. This epicenter is near 100 degrees from the Alaska Peninsula and may have been promoted by energy from that source.

 

O:  4AUG2021 15:51:20  40.9S  174.6E Mw=4.2  EMSC   COOK STRAIT, NEW ZEALAND     

O: 04AUG2021 15:51:21  40.9S  174.6E ML=4.7  GEONET Felt with moderate intensity

P:  4AUG2021 136170    41.0S  174.0E 3.0-4.9 AAAAA  So. Island, N.Z.           

 

A new epicenter was active in New Mexico today. This site saw two light earthquakes today - an M 3.1 and an aftershock of M 2.5. This is the first such activity in New Mexico in at least 30 years. It may be related to the series in northern Mexico of recent days which has included an M 5.2 about 150 km southwest of this on July 31, 2021. Forecast 136020 had expected activity in the area in early August. This activity is located at the ninth node (40 degrees) from the M 8.2 in Alaska of July 29 and was probably promoted by energy from that source.

 

O: 05AUG2021 00:46:34  31.7N  108.7W ML=3.1  EMSC   NEW MEXICO

O:  5AUG2021 05:46:00  31.7N  108.7W ML=2.5  EMSC   NEW MEXICO                   

P:  4AUG2021 136020    32.5N  104.6W 2.0-4.1 AABAA  SW U.S.A                   

 

An M 5.5 aftershock also continued activity in the Nicobar Islands, India today. This follows the M 6.1 in this region of August 3, 2021. Forecast 135911 had expected this activity within about 100 km was likely around August 6.

 

O:  4AUG2021 17:57:40   8.8N   94.1E Mw=5.5  EMSC   NICOBAR ISLANDS, INDIA REGION

P:  6AUG2021 135911     8.0N   94.0E 4.0-5.6 AAAAA  Nicobar Islands            

 

STRONG QUAKE IN TOKYO, JAPAN OLYMPIC VENUE

 

EARTHQUAKE SUMMARY FOR AUGUST 3, 2021

 

The strongest earthquake of the day was an M 5.9 off the east coast of Honshu, Japan near Tokyo. NEIC reported it was felt with intensity VIII in Chiba and II in Fukushima, Saitama, Tokyo, Kanagawa, and Miyagi, Japan. Foreshocks of M 5.1, 4.5 and 4.9 were also felt in this area of Japan today. This earthquake was reported by JMA to have been lightly felt throughout much of the Olympic Venue near Tokyo. This activity in eastern Honshu, Japan was probably promoted by landfall of Tropical Storm Nepartak which made landfall at this epicenter in late July as noted at the time in this summary:

 

"TS Nepartak continued today in the region (of) northern  Honshu, Japan with winds up to 40 kts. It is expected to track to the northwest reaching an area north of Tokyo, Honshu near the Olympic venue around July 27-28. Some enhanced seismicity in this area is likely in the Honshu, Japan area as it makes landfall." (July 28- August 2, 2021)

 

Moderate foreshocks of M 4.4, 4.5 and 4.7 hit the area yesterday as reported in this summary.

 

Today's M 5.8 is the strongest earthquake within about 150 km of this epicenter in more than a year. An M 5.9 hit south of this epicenter on June 24, 2020 and near this epicenter  with M 5.8 on May 10, 2020. Forecast 136015 had expected today's events within about 50 km of this activity was likely around August 4. Like many of the unusual quakes following the Alaska Peninsula of July 29 this epicenter is located at 45 degrees from that epicenter. As noted in earlier issues of this summary, this distance has seen elevated seismicity in recent days at:

 

 

"Node 8 (45 degrees)

 

Alaska Peninsula to Honshu, Japan, Oklahoma, Texas, Gulf of California,  Sonora, Mexico, Siberia," (July 29-August 3, 2021)

 

 

O: 03AUG2021 06:02:51  36.4N  141.9E mb=4.5  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O:  2AUG2021 15:35:33  36.2N  141.9E Mw=4.7  EMSC   NEAR EAST COAST OF HONSHU, JAP

O:  2AUG2021 21:39:14  36.4N  141.8E mb=4.4  EMSC   NEAR EAST COAST OF HONSHU, JAP

P:  4AUG2021 136015    36.0N  142.0E 4.0-5.4 AAAAA  Off East Coast Honshu      

 

O: 03AUG2021 07:28:21  36.2N  142.0E mb=4.6  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 10:29:16  36.2N  141.9E Mw=5.1  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 20:33:33  36.2N  142.1E Mw=5.8  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 20:43:11  36.2N  142.1E Mw=5.1  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 21:17:56  36.2N  142.1E mb=4.4  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 22:10:54  36.2N  142.1E mb=4.9  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O: 04AUG2021 01:09:58  36.2N  142.0E mb=4.3  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 04AUG2021 02:56:24  36.2N  142.0E mb=4.9  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O: 04AUG2021 04:11:50  36.2N  142.4E mb=4.5  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O: 04AUG2021 04:40:24  36.2N  141.9E Mw=5.4  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 04AUG2021 06:14:54  36.2N  141.9E mb=4.8  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 11:16:47  36.3N  141.9E mb=4.6  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 20:39:30  36.3N  141.9E ML=4.7  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 22:49:04  36.3N  141.9E mb=4.5  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 04AUG2021 06:08:25  36.3N  141.9E mb=4.9  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 20:53:25  36.7N  141.6E mb=4.4  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 12:38:30  36.9N  141.8E ML=4.3  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 03AUG2021 13:20:21  37.4N  142.2E mb=4.7  EMSC   OFF EAST COAST OF HONSHU, JAPAN

O:  4AUG2021 00:53:32  36.0N  142.3E mb=4.4  EMSC   OFF EAST COAST OF HONSHU, JAPA

P:  4AUG2021 136015    36.0N  142.0E 4.0-5.4 AAAAA  Off East Coast Honshu      

 

A light earthquake of M 2.1 was widely felt in the area of New Jersey today. NEIC reported it was felt with intensity II-III in Maryland  at Clarks, Highland, Fulton, Dayton, Columbia, Ashton, Brinklow, Ellicott City, Glenelg, Laurel. It was also reported felt lightly in Alabama, New Hampshire, North Carolina, Pennsylvania, New York, Delaware, District of Columbia, Virginia. A similar earthquake hit this epicenter with M 2.6 on June 25, 2021. At the time this summary noted this as:

 

 

"An unusual earthquake of M 2.6 was reported widely felt in the region of northern Maryland today. NEIC reported maximum intensity IV in Maryland at Baltimore with II-III in Gwynn, Catonsville, Windsor, Pikesville.

The last earthquake of M>=2.6 within about 100 km of this epicenter was an M 2.8

on September 15, 2019. The largest event in the region in the past 30 years

occurred as an M 4.6 on January 16,  1994. This was followed hours later by

the M 6.7 in Northridge, California of the same date. It may have been precursory

to that event. At the time of the M 4.1 on November 30, 2017 this summary noted in this regard:

 

"The Delaware earthquake of M 4.1-4.5 was reported felt with maximum intensity V in Clayton, Delaware; Newport New Jersey, and IV in Delaware at Dover, Magnolia, Camden Wyoming, Marydel, in Maryland at Galena, Sudlersville, and in general within about 50 km of the epicenter. It was felt with intensity II-III throughout much of the central eastern coast of the U.S. including in New Jersey, Delaware, Pennsylvania, Virginia, New York, Washington D.C, Connecticut, West Virginia, Massachusetts, Rhode Island, North Carolina, Vermont, Ohio, Kentucky, South Carolina, Illinois, Florida, Mississippi, Missouri, and Maryland, The earthquake in Delaware is one of the strongest recorded in that State. Earthquake in this area are often followed within days by a strong quake in southern or central California, such as occurred in the Northridge quake of M 6.7 on January 17, 1994 (preceded by an M 4.6 in southern Pennsylvania on January 16, 1994) and the Morgan Hill quake of April 24, 1984 preceded by an M 4.4 in Pennsylvania on April 23, 1984.  The events in August 2011 were later found to occur at the time of one of the strongest cosmic ray events known, possibly associated with a gravity wave and other effects which may have triggered this series. A similar relation may be found with today's events, but these areas usually not announced until extensive data anaylsis. As this list includes the largest events in the Delaware area in the past 50 years and some of the strongest earthquakes in Central and southern California in the same period, it may be significant. This correlation is strongest with moderate starting quakes in the region of Delaware. The area of southern California near Northridge is currently at the 23-year cycles of large quakes in the area. A moderate earthquake in the region west of Los Angeles and north to San Francisco is considered possible in the next four days. At the least, residents should check their earthquake preparedness kits to see if they are ready for a moderate quake at this time." (December 1, 2017) (June 25, 2021)

 

O:  4AUG2021 06:10:57  39.2N   77.0W ML=2.1  EMSC   MARYLAND                     

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 near Aillik, Newfoundland. This is the largest earthquake within about 200 km of this epicenter in the past 30 years. Recent quakes in Newfoundland within about 350 km of this epicenter occurred on May 20, 2021 (M 4.5); November 4, 2020 and February 3, 2020 (M 4.3-4.4) after 12 years of inactivity in the area. Forecast 135110 had expected today's activity was likely in early August.

 

O:  3AUG2021 06:13:49  56.9N   56.3W MB=3.9  ECAN Aillik, NL                     

P:  6AUG2021 136110    61.0N   58.0W 2.5-4.1 BCAAA  Baffin/Davis Strait Canada 

 

Unusual earthquakes also continued in the Ocean Ridges today. A further moderate quake of M 5.0 occurred at the antipode of the Alaska Peninsula in the area southwest of Africa. This follows several moderate quakes in this area following the M 8.2 in the Alaska Peninsula of July 29 and is probably related to focused seismic energy at the antipode of that epicenter. Forecast 136174 had expected  today's activity south of Africa was likely within about 50 km of this epicenter in early August.

 

O:  3AUG2021 08:30:45  52.7S   18.4E mb=5.0  EMSC   SOUTHWEST OF AFRICA          

P:  7AUG2021 136174    53.0S   19.0E 4.0-5.7 BAAAA  Atlantic-Indian Ridge      

 

An earthquake of M 4.6 also occurred in the southeast Central Pacific Ocean west of northern Chile. It was not reported felt in this remote area. No earthquakes of M>=4.6 have been recorded within about 300 km of this epicenter in the past 30 years. This earthquake was probably triggered by energy from the M 8.2 in the Alaska Peninsula of July 29. It is located at 101-102 degrees from that epicenter, a distance at which seismic energy is concentrated and often sees enhanced seismicity following large earthquakes. Other earthquakes at this distance from Alaska today occurred in Sumatra and  northern Chile.

 

O:  3AUG2021 07:49:12  22.3S   81.1W mb=4.6  EMSC   SOUTHEAST CENTRAL PACIFIC OCEA

 

 

STRONG QUAKES HIT SUMATRA AND NICOBAR ISLANDS, INDIA

 

EARTHQUAKE SUMMARY FOR AUGUST 2, 2021

 

The strongest earthquake in the world today was an M 6.1 in the Nicobar Islands, India. NEIC reported it was felt with intensity II in Port Blair, Andaman and Nicobar Islands and possibly in Sumatra, Indonesia at Sabang Aceh and Banda Aceh. It followed a strong foreshock sequence felt in the same area.   This event of M 6.1 is the strongest in the Nicobar Islands within about 200 km of this epicenter since an M 6.4 about 200 km to the south on November 8, 2015. Forecast 135911 had expected today's event was likely within about 100 km  around August 6.

 

O: 03AUG2021 03:42:08   8.8N   94.0E mb=5.3  EMSC   NICOBAR ISLANDS, INDIA REGION

O: 03AUG2021 01:51:13   8.9N   93.9E Mw=5.3  EMSC   NICOBAR ISLANDS, INDIA REGION

O: 03AUG2021 03:42:35   8.9N   94.0E Mw=6.1  EMSC   NICOBAR ISLANDS, INDIA REGION

O: 03AUG2021 03:43:55   9.4N   94.2E mb=5.8  EMSC   NICOBAR ISLANDS, INDIA REGION

O:  3AUG2021 00:57:10   8.7N   94.1E mb=4.6  EMSC   NICOBAR ISLANDS, INDIA REGION

P:  6AUG2021 135911     8.0N   94.0E 4.0-5.6 BAAAA  Nicobar Islands            

 

The Nicobar Islands earthquake followed a series which included an M 5.8 south of Sumatra in the Kep. Mentawai region. BMG reported this earthquake of M 5.8 in Sumatra was felt with intensity III in the area(s) of  Sumatra at Mukomuko and Curup, Indonesia. This group of earthquakes occurred near 103 degrees of the M 8.2 in the Alaska Peninsula and was probably promoted by strong energy concentration from that source. This distance often sees strong enhancement of seismicity following major earthquakes. This event is the strongest within about 250 km of this epicenter since an M 5.9 on November 17, 2020. A series also occurred near this epicenter on February 2, 2019. Forecasts 135674, 135931 and 135932 had expected this activity in late July or early August.

 

O: 02AUG2021 20:35:04   3.2S  100.3E mb=4.5  EMSC   KEP. MENTAWAI REGION, INDONESIA

O: 02AUG2021 23:00:40   3.2S  100.3E mb=4.6  EMSC   KEP. MENTAWAI REGION, INDONESIA

O: 02AUG2021 23:01:00   3.2S  100.4E mb=5.2  EMSC   KEP. MENTAWAI REGION, INDONESIA

O: 03AUG2021 01:57:50   3.2S  100.2E ML=4.1  EMSC   KEP. MENTAWAI REGION, INDONESIA

O:  2AUG2021 22:48:50   3.1S  100.3E Mw=5.8  EMSC   KEP. MENTAWAI REGION, INDONESI

P:  3AUG2021 135931     2.0S   99.0E 4.0-5.4 ABAAA  So. of Sumatera            

P:  4AUG2021 135932     4.0S  103.0E 4.0-5.4 AACAA  So. of Sumatera            

P: 23JUL2021 135674     2.0S  100.0E 4.0-5.4 CBAAA  So. of Sumatera            

 

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in the Kodiak Island region of southern Alaska. The Kodiak region has been active to the south of this epicenter about 250 km from today's epicenter but the last earthquake of M>=3.9 within about 200 km of today's event in the Kodiak Island area was an M 4.4 on March 4, 2021. Forecast 136112 had expected regional seismic enhancement around August 3. NEIC reported this earthquake of M 3.9 in Kodiak, Alaska was felt with intensity II-III in the area(s) of Kodiak, Alaska.

 

O:  2AUG2021 21:13:10  58.0N  151.7W mb=3.9  EMSC   KODIAK ISLAND REGION, ALASKA 

P:  3AUG2021 136112    60.1N  153.4W 3.2-5.3 ACAAA  Central Alaska             

 

The antipodal area of the M 8.2 in the Alaska Peninsula continued to see elevated seismicity today. An M 5.1 southwest of Africa in the Indian Ocean there today was within about 250 km of that antipode. Antipodal activity is common following great earthquakes as the seismic energy is focused at this point due to the near-spherical shape of the earth. Forecasts 136174 and 135897 had expected today's event southwest of Africa was likely between July 30 and August 7.

 

O:  3AUG2021 06:43:00  52.7S   18.5E mb=5.1  EMSC   SOUTHWEST OF AFRICA           

P:  7AUG2021 136174    53.0S   19.0E 4.0-5.7 BAAAA  Atlantic-Indian Ridge      

P: 30JUL2021 135897    53.0S   19.0E 4.0-5.6 BAAAA  Atlantic-Indian Ridge      

 

A series of minor earthquakes occurred in northern California today. The strongest event in this series was an M 3.7.  NEIC reported these earthquakes of M 3.7 and 2.9 in Northern California were felt with intensity II-III in the area(s) of Northern California at Willows, Elk Creek, Ukiah.  Forecasts 135996 and 135805 had expected this activity within about 50 km was likely around August 2.

 

O: 02AUG2021 14:50:16  39.7N  122.9W Md=2.3  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 15:04:29  39.7N  122.8W ML=2.5  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 15:48:49  39.7N  122.9W Md=2.2  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 18:20:39  39.7N  122.9W Md=2.0  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 18:28:53  39.7N  122.8W Mw=3.7  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 18:38:51  39.7N  122.9W Md=2.9  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 18:49:52  39.7N  122.9W Md=2.2  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 19:02:06  39.7N  122.9W Md=2.2  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 19:25:54  39.7N  122.9W Md=2.1  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 19:58:47  39.7N  122.9W Ml=3.1  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 20:15:28  39.7N  122.9W Md=2.7  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 21:05:53  39.7N  122.9W Md=2.6  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 22:20:19  39.7N  122.9W Md=2.5  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 22:28:46  39.7N  122.9W Md=2.3  EMSC   NORTHERN CALIFORNIA

O: 02AUG2021 23:03:02  39.7N  122.8W Md=2.1  EMSC   NORTHERN CALIFORNIA

O: 03AUG2021 06:10:04  39.7N  122.8W ML=2.7  EMSC   NORTHERN CALIFORNIA

O:  3AUG2021 01:02:36  39.5N  122.0W Md=2.9  EMSC   NORTHERN CALIFORNIA           

P:  2AUG2021 135996    39.8N  123.5W 2.5-4.4 AABAA  Central California         

P: 26JUL2021 135805    40.4N  122.2W 2.5-4.8 CAAAA  Northern California        

 

 

STRONG ENHANCEMENT CONTINUES AT NODAL DISTANCES FROM ALASKA PENINSULA

 

EARTHQUAKE SUMMARY FOR AUGUST 1, 2021

 

The strongest earthquake in the world today was an M 6.1 in New Guinea. BMG reported it was felt with intensity IV in Kaimana, Indonesia. This epicenter is at node 9 (80 degrees) from the epicenter of the M 8.2 in the Alaska Peninsula of July 29. This continues enhanced seismicity at this distance from Alaska which was emphasized several days ago in this summary as:

 

"An M 5.3 also occurred today in the Central East Pacific Rise. It was not reported felt in this epicentral area. This event, like that in the northern mid-Atlantic Ridge occurred at 78 degrees from the Alaska epicenter. Other moderate earthquakes today occurred at this distance from Alaska in Tonga, Vanuatu, Myanmar and Tajikistan. This may represent a free-earth concentration of energy at this distance." (July 30, 2021)

 

The last earthquake within about 200 km of this epicenter with M>=6.1 was an M 6.5-6.6 on October 12, 2012. Today's event had been expected in forecasts 135677 and 135934 to occur in late July or early August.

 

O:  2AUG2021 05:01:21   4.5S  134.0E Mw=6.1  EMSC   NEAR S COAST OF PAPUA, INDONES

O: 02AUG2021 05:51:13   3.9S  133.9E ML=4.2  EMSC   PAPUA, INDONESIA

P:  3AUG2021 135934     5.0S  135.0E 4.0-5.9 AAAAA  West Irian, PNG            

P: 26JUL2021 135677     3.0S  135.0E 4.0-5.4 CBAAA  West Irian, PNG            

 

An M 5.6 earthquake also occurred in the Kermadec Islands, New Zealand today. It was not reported felt in this remote epicentral area. This epicenter occurred at the fourth node (90 degrees) from the M 8.2 Alaska Peninsula quake of July 29. In the previous issue of this summary it had been noted that this node was especially active at this time as:

 

"The strongest earthquake in the world today was an M 5.5-5.7 in the Dodecanese Islands, Greece. NEIC reported it was felt with maximum intensity IV in Afantou and II-III in Kefalos, Kardamaina, Pillon, Ziparion, Kos, Lardos, Kremasti, Iailsos and Kosovo, Serbia and Montenegro. This epicenter is near the fourth node (90 degrees) from the epicenter of the M 8.2 in the Alaska Peninsula of July 29. This node has been active in the past several days since the Alaskan mainshock and has included an M 6.1 in northern Peru as well as moderate quakes in Gibraltar, Algeria, Vanuatu, the Banda Sea, Indonesia, and the south Pacific Ocean among other areas." (August 1, 2021)

 

Today's event is not a classical aftershock of the M 8.1 in the Kermadec Islands of March 4, 2021 as it occurred about 250 km southwest of that epicenter. It is probably an aftershock of an M 6.5 which shook the same area on June 20, 2021.  Forecast 135875 and 126162 had expected enhanced seismicity in this region in  late July or early August.

 

O:  2AUG2021 01:27:36  30.6S  177.7W Mw=5.6  EMSC   KERMADEC ISLANDS, NEW ZEALAND

P:  7AUG2021 136162    30.0S  179.0W 4.0-5.4 BAAAA  No. Kermadec Islands       

P: 25JUL2021 135875    29.0S  176.0W 4.0-5.6 CBBAA  No. Kermadec Islands       

P: 27JUL2021 135875    28.0S  177.0W 4.0-5.4 BCAAA  No. Kermadec Islands       

 

Strongly enhanced seismicity also occurred in the region of Iceland today. This began within hours of the event in the Alaska Peninsula and reached maximum magnitudes of M 5.2 today. In the previous issues of this summary it had been noted as:

 

"A strong series of earthquakes also occurred today in southwestern Iceland.

This was probably promoted by energy from the Alaska Peninsula. A similar series of events in Iceland occurred following the M 7.5 on July 22, 2020 in the Alaska Peninsula and the day after the M 7.8 on October 19, 2020. That event was an M 5.5, slightly larger than today's maximum magnitude in Iceland. This event occurred on October 20 and was noted in this summary as:

 

"This (of M 5.5) is the strongest earthquake in southern Iceland within about 200 km of this epicenter since an M 6.3 more than 12 years ago on May 29, 2008. Other  such events occurred in 1998 and 2000. It is likely that this was triggered by energy from the Alaska Peninsula quake of M 7.5 yesterday" (October 20, 2020; August 1, 2021)

 

Forecast 136099 had expected today's activity within about 100 km was likely

at the beginning of August.

 

O: 01AUG2021 10:24:09  62.9N   24.0W mb=4.1  EMSC   ICELAND REGION

O: 01AUG2021 12:06:36  62.9N   25.3W mb=4.5  EMSC   ICELAND REGION

O: 01AUG2021 13:03:09  62.9N   25.4W mb=4.7  EMSC   ICELAND REGION

O:  1AUG2021 10:40:27  62.7N   25.2W Mw=5.2  EMSC   ICELAND REGION               

P:  2AUG2021 136099    62.0N   25.0W 4.0-5.8 AAAAA  North Mid-Atlantic Ridge   

 

O:  1AUG2021 10:40:20  65.2N   16.3W ML=3.6  EMSC   ICELAND                      

P:  5AUG2021 136117    65.0N   18.0W 3.0-4.6 BAAAA  Iceland area               

 

Moderate aftershocks continued today in the Alaska Peninsula following the M 8.2 there of July 29. The largest of today's aftershocks were M 4.5 and 4.6. Forecast 136087 had expected today's activity at the beginning of August.

 

O: 01AUG2021 08:58:55  55.3N  155.2W mb=4.5  EMSC   SOUTH OF ALASKA

O: 01AUG2021 15:27:42  55.5N  158.7W mb=4.6  EMSC   ALASKA PENINSULA

P:  2AUG2021 136087    54.8N  158.7W 3.5-4.9 AAAAA  Alaska Peninsula           

P: 31JUL2021 135821    54.7N  156.9W 3.5-5.3 AAAAA  Alaska Peninsula           

 

A moderate earthquake of M 5.0-5.1 occurred under North Island, New Zealand today. GEONET Felt with moderate intensity northeast of Rotorua and in northwestern North Island. Light to moderate intensity was reported throughout much of northern and western North Island. More than 2790 people reported feeling this earthquake with 1639 reports of weak intensity; 1039 of light intensity; 104 with moderate intensity; 5 with strong intensity; and 0 of severe intensity and 3 of extreme shaking. A similar M 5.1-5.2 hit the area within about 100 km of this epicenter occurred on January 24, 2021 and on February 4, 2020. Forecasts 135888 and 136163 had expected this activity in late July or early August.

 

O:  1AUG2021 13:04:53  38.3S  175.9E Mw=5.0  EMSC   NORTH ISLAND OF NEW ZEALAND  

O: 01AUG2021 13:04:54  38.3S  176.0E ML=5.1  GEONET Felt with moderate intensity

P:  2AUG2021 136163    39.0S  174.0E 3.0-4.4 AABAA  North Island, N.Z.         

P: 29JUL2021 135888    39.0S  174.0E 3.0-4.6 BABAA  North Island, N.Z.         

 

MODERATELY STRONG QUAKE IN DODECANESE ISLANDS, GREECE

 

EARTHQUAKE SUMMARY FOR JULY 31, 2021

 

The strongest earthquake in the world today was an M 5.5-5.7 in the Dodecanese Islands, Greece. NEIC reported it was felt with maximum intensity IV in Afantou and II-III in Kefalos, Kardamaina, Pillon, Ziparion, Kos, Lardos, Kremasti, Iailsos and Kosovo, Serbia and Montenegro. This epicenter is at the fourth node (90 degrees) from the epicenter of the M 8.2 in the Alaska Peninsula of July 29. This node has been active in the past several days since the Alaskan mainshock and has included an M 6.1 in northern Peru as well as moderate quakes in Gibraltar, Algeria, Vanuatu, the Banda Sea, Indonesia, and the South Pacific Ocean among other areas. This summary on July 29 suggested enhanced seismicity was likely in many of these areas after the Alaskan event at this node as:

 

"Node 4 (90 degrees): Alaska Peninsula to Canary Islands, Dodecanese Islands, Northern Peru, Banda Sea, Iran, Crete, Lebanon, Pakistan, Kermadec Islands" (July 29, 2021)

 

With M 5.7 today's event is the strongest aftershock to date of the M 7.0 in the

Dodecanese Islands of October 30, 2020 which followed the M 7.5 in the Alaska Peninsula of October 19, 2020 and with that event shows the strong effect of major earthquakes in the Alaska Peninsula on the seismicity in the Dodecanese Islands as noted in this summary on October 30, 2020:

 

"Today's activity in the Dodecanese Islands is at the fourth node (90 degrees) from the Alaska Peninsula event of M 7.5 of October 19 and may have been promoted by energy from that source." (October 30, 2020)

 

Forecast 135722 had expected moderate seismicity in this region in late July.

 

O: 01AUG2021 05:12:34  36.4N   27.0E Mw=4.1  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 31JUL2021 19:57:55  36.4N   27.0E mb=4.6  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 31JUL2021 23:25:41  36.4N   27.0E mb=4.2  EMSC   DODECANESE IS.-TURKEY BORDER REG

O:  1AUG2021 04:31:27  36.3N   27.0E mb=5.5  EMSC   DODECANESE IS.-TURKEY BORDER R

O:  1AUG2021 04:31:27  36.3N   27.0E mb=5.7  ANSS   DODECANESE IS.-TURKEY BORDER R

P: 27JUL2021 135722    38.0N   26.0E 3.0-4.6 BBAAA  Aegean Sea                 

 

The strongest earthquake in North America today was an M 5.5 in the Gulf of California. NEIC reported it was felt in Baja California with intensity V in Santa Rosalia, Baja and IV in Sonora at Guaymas, and II-III in Empalme, Obregon, Hermosilo, and Canos. This activity is near the eighth node (45 degrees) from the Alaska Peninsula (half of 90 degrees, node 4 which has also been active following that Alaskan event). This is the strongest earthquake in the Gulf of California within about 200 km of this epicenter since an M 6.3 about 150 km to the southeast of January 19, 2018. Forecast 135707 had expected today's event within about 100 km was likely around July 31.

 

 

O: 31JUL2021 20:27:28  27.5N  111.5W ML=4.3  EMSC   GULF OF CALIFORNIA

O: 31JUL2021 21:07:57  27.5N  111.5W ML=4.3  EMSC   GULF OF CALIFORNIA

O: 31JUL2021 16:13:09  27.6N  111.5W ML=4.0  EMSC   GULF OF CALIFORNIA

O: 31JUL2021 15:39:20  27.5N  111.3W Mw=5.5  EMSC   GULF OF CALIFORNIA           

P: 31JUL2021 135707    28.0N  112.0W 3.5-5.3 AAAAA  Gulf of California         

 

A strong series of earthquakes also occurred today in southwestern Iceland.  This was probably promoted by energy from the Alaska Peninsula. A similar series of events in Iceland occurred following the M 7.5 on July 22, 2020 in the Alaska Peninsula and the day after the M 7.8 on October 19, 2020. That event was an M 5.5, slightly larger than today's maximum magnitude in Iceland. This event occurred on October 20 and was noted in this summary as:

 

"This (of M 5.5) is the strongest earthquake in southern Iceland within about 200 km of this epicenter since an M 6.3 more than 12 years ago on May 29, 2008. Other such events occurred in 1998 and 2000. It is likely that this was triggered by energy from the Alaska Peninsula quake of M 7.5 yesterday" (October 20, 2020)

 

O: 01AUG2021 01:25:52  62.8N   25.2W Mw=5.0  EMSC   ICELAND REGION

O: 01AUG2021 00:18:21  62.9N   24.9W mb=4.3  EMSC   ICELAND REGION

O: 01AUG2021 00:55:31  62.9N   25.1W Mw=4.9  EMSC   ICELAND REGION

O: 01AUG2021 00:33:44  63.0N   25.2W mb=4.6  EMSC   ICELAND REGION

O:  1AUG2021 00:51:15  62.7N   25.2W mb=4.8  EMSC   ICELAND REGION               

 

Moderate aftershocks also continued in the Alaska Peninsula following the M 8.2 in that region of July 29. The strongest of these were of M 4.9 and 4.5. Forecast 135821 had expected enhanced seismicity in the area was likely around July 31.

 

O: 31JUL2021 15:40:52  55.7N  156.0W mb=4.9  EMSC   SOUTH OF ALASKA

O: 31JUL2021 18:04:15  56.2N  156.3W mb=4.5  EMSC   ALASKA PENINSULA             

P: 31JUL2021 135821    54.7N  156.9W 3.5-5.3 AAAAA  Alaska Peninsula           

 

STRONG QUAKE DAMAGING IN PERU

 

EARTHQUAKE SUMMARY FOR JULY 30, 2021

 

The strongest earthquake in the world today was an M 6.1 in northern Peru near the border with Ecuador. NEIC reported the mainshock was felt with minor damage and intensity VII in Peru at Sulland and IV in Oura, Taiara, Lambayeque, and III in Ecuador at Canamanga, Loja, Puebloviego, Cuenca Azuay, Guayaquil and Eloy Alfaro. News sources indicate the quake caused some panic in the epicentral area and injured at least one person - an elderly woman trapped by a collapsed wall. Some cars were also damaged by falling debris. An ancient church - the Piura cathedral, from the 16th century - was also damaged when portions of the cornice on the facade fell off. Several other churches were also damaged. This epicenter is near 90 degrees (88 degrees) (node 4) from the epicenter of the M 8.2 in the Alaska Peninsula of July 29 and was probably promoted by strong seismic waves from that source. Aftershocks of M 4.3 were felt with light intensity in Sullana, Pura, Peru. The last earthquake within about 250 km of today's epicenter with M>=6.1 occurred on March 15, 2014 with M 6.3. More recent activity about 350 km to the northeast has included an M 7.5 on February 22, 2019. Forecast 135669 had expected today's activity in Northern Peru was likely towards the end of July.

 

O: 30JUL2021 20:14:08   4.9S   80.8W ML=4.4  EMSC   PERU-ECUADOR BORDER REGION

O: 31JUL2021 04:33:02   5.1S   80.8W mb=4.3  EMSC   NEAR COAST OF NORTHERN PERU

O: 30JUL2021 17:10:19   4.9S   80.7W Mw=6.1  EMSC   PERU-ECUADOR BORDER REGION   

P: 24JUL2021 135669     6.0S   79.0W 4.0-5.5 CBBAA  No. Peru                   

 

Other abnormal seismicity near the fourth node (90 degrees) from the Alaska epicenter also occurred today in Algeria (M 4.3) and the Strait of Gibraltar (M 4.8) as well as the East Pacific Rise (M 5.1) and the Kermadec Islands (M 4.7).

The M 4.5 in Northern Algeria was preceded by an M 3.9 to the east of this epicenter. The last earthquake within about 200 km of the epicenter in  Northern Algeria with M>=4.5 occurred as an M 4.7 oln April 23, 2018. Forecast 135784 had expected this activity in northern Algeria was likely around July 28.

 

NEIC reported this earthquake of M 4.3 in Algeria was felt with intensity III-IV in the area(s) of Algeria at Oued Fodda and Ayn ad-Daflah.

 

O: 30JUL2021 16:31:35  36.6N    6.4E mb=3.9  EMSC   NORTHERN ALGERIA             

O: 31JUL2021 02:01:45  36.3N    1.7E mb=4.5  EMSC   NORTHERN ALGERIA             

P: 28JUL2021 135784    37.0N    5.0E 3.0-4.6 BACAA  Western Mediterranean      

 

The strait of Gibraltar has been active in recent weeks. Today's event of M 4.6 and an aftershocks of M 4.3 are located at the same epicenter as the recent activity and were probably promoted by energy from the Alaska Peninsula quake. The only activity within about 200 km of today's epicenter in the past four years with M>=4.6 occurred as an M 4.7 on June 19, 2021 and on July 25, 2020 with M 4.8. Forecast 135495 had expected today's activity within about 50 km was likely at the end of July.

 

NEIC reported this earthquake of M 4.6 in Gibraltar was felt with intensity II-III in the area(s) of Gibraltar.

 

O: 30JUL2021 08:38:52  35.5N    3.6W ML=4.0  EMSC   STRAIT OF GIBRALTAR

O: 30JUL2021 09:13:03  35.5N    3.7W mb=4.3  EMSC   STRAIT OF GIBRALTAR

O: 30JUL2021 08:58:50  35.4N    3.7W mb=4.6  EMSC   STRAIT OF GIBRALTAR          

P: 21JUL2021 135495    35.0N    4.0W 3.5-5.0 CAAAA  Morocco/Spain              

 

Aftershocks also continued today in the Alaska Peninsula area following the M 8.2 there on July 29, the largest earthquake in the U.S. or Canada since 1964 when the area of Anchorage, Alaska was rocked by the strongest quake ever recorded in North America (M>9). Following is a listing of aftershocks today of M>=4.9. A more extensive listing of today's aftershocks can be found in the "ALASKA" regional section of this summary. Forecast 135821 had expected today's aftershock were likely in late July.

 

O: 30JUL2021 07:24:37  55.2N  156.4W Mw=4.6  EMSC   SOUTH OF ALASKA

O: 30JUL2021 09:58:07  55.2N  157.7W ML=4.3  EMSC   ALASKA PENINSULA

O: 30JUL2021 14:41:52  55.2N  157.6W mb=4.0  EMSC   ALASKA PENINSULA

O: 31JUL2021 03:25:21  55.3N  157.4W ML=4.3  EMSC   ALASKA PENINSULA

O: 30JUL2021 07:49:10  55.4N  157.3W mb=4.5  EMSC   ALASKA PENINSULA

O: 30JUL2021 13:28:19  55.4N  157.5W mb=4.3  EMSC   ALASKA PENINSULA

O: 30JUL2021 14:58:22  55.4N  157.3W ML=4.2  EMSC   ALASKA PENINSULA

O: 30JUL2021 21:44:22  55.5N  156.1W mb=4.2  EMSC   SOUTH OF ALASKA

O: 30JUL2021 22:11:36  55.8N  154.5W Mw=4.9  EMSC   SOUTH OF ALASKA

P: 31JUL2021 135821    54.7N  156.9W 3.5-5.3 AAAAA  Alaska Peninsula           

 

An M 4.7 earthquake also shook the antipode of the M 8.2 in Alaska today. This event occurred South of Africa within about 250 km of the exact antipode of the event at 54N 156W in Alaska. Seismic energy is focused near the antipode of great quakes and can help trigger unusual seismicity in the antipodal area.

The last earthquake in this area with M>=4.7 occurred on February 9, 2021 and before that on October 19, 2020 both with M 4.9. This earthquake occurred on the same date as the M 7.5 foreshock in the Alaska Peninsula and had been noted in that summary as:

 

 

"An M 4.9 near the antipode of the Alaskan Peninsula occurred eight hours earlier in the area South of Africa. This area became active in early and mid-August with an M 4.7 on August 3 and an M 4.9 on August 17. When the earthquake on August 17 occurred this summary noted in this regard:

 

"An earthquake of M 4.9 occurred today south of Africa within several km of the exact antipode of the M 7.8 in the Alaska Peninsula of July 22, 2020. This continues a series of events in this region which have occurred with moderate to large magnitude since the Alaska Peninsula quake. The area was expected to see enhanced activity at this time due to antipodal energy focusing from Alaska. Today's event is the nearest of these event to the exact antipode (compare 54N 158W and 53S 26E)." (August 17, 2020)" (October 20, 2020)

 

O: 30JUL2021 15:35:27  52.5S   26.4E mb=4.7  EMSC   SOUTH OF AFRICA              

 

The M 7.5 in the Alaska Peninsula or October 19, 2020 had also been accompanied by strong reported activity in British Columbia and Iceland (like the current situation) which had been reported in this summary at the time as:

 

 

"An earthquake in Queen Charlotte Island, Canada of M 4.6 was reported by Earthquakes Canada four minutes after the Alaska Peninsula M 7.5. It may be a ghost event created by misreading of an automatic earthquake algorithm or a real event triggered by energy from Alaska." (October 20, 2021)

 

and

 

"Similarly an M 3.8 in Iceland ten minutes after the Alaska Peninsula event recorded by EMSC may or may not have occurred." (October 20, 2020)

 

UNUSUAL SEISMICITY FOLLOWS M 8.2 IN ALASKA PENINSULA

 

EARTHQUAKE SUMMARY FOR JULY 29, 2021

 

The strongest earthquake in the world today outside the Alaska Peninsula aftershock zone was an M 5.5 in Myanmar. NEIC reported it was felt with maximum intensity VII in Myanmar at Mogok Mandalay; V in Kyaukse and IV in Mandalay and II in Pyinimana and in Thailand at Chiang Mai and Bankok with intensity II. This earthquake is at 78 degrees from the M 8.2 in Alaska yesterday, a distance at which some triggering is expected. This is the strongest earthquake within about 250 km of this epicenter since an M 5.6 which accompanied the Solar Eclipse of June 21, 2020. The last sizable earthquakes in northern Iceland also occurred with the Myanmar quake. The same combination occurred today with an M 5.0 in Iceland. Forecast 135469 had expected the activity in Myanmar was likely in late July.

 

O: 29JUL2021 08:39:26  22.9N   96.0E mb=5.5  EMSC   MYANMAR                      

P: 21JUL2021 135469    24.0N   94.0E 4.0-5.5 CBBAA  Myanmar                    

 

An M 5.0 earthquake occurred in the region of Iceland today. This epicenter is at 56 degrees from the epicenter of the M 8.2 in Alaska and occurred 13 minutes after that event. This is the time it takes the S-wave from Alaska to reach Iceland. This seismic phase probably triggered the event in Iceland. Forecast 135594 had expected today's event in Iceland was likely within about 50 km in mid- to late-July.

 

O: 29JUL2021 06:25:11  66.3N   17.3W ML=5.0  EMSC   ICELAND REGION                

O: 29JUL2021 19:20:14  63.6N   19.1W ML=3.5  EMSC   ICELAND                      

P: 18JUL2021 135594    66.0N   17.0W 3.0-4.4 AAAAA  Iceland area               

 

An unusually large earthquake was widely felt in South Africa today. This event of M 4.2 was reported by NEIC to have been felt with maximum intensity IV in Boksburg and Pretoria and II-IIII in Gauteng at Alberton, Brakpan, Springs, Benoni, Johannesburg, Morand, Tembisa and Verwoerdburg, South Africa. Two earthquakes of M>=4.2 have occurred within about 300 km of this epicenter in South Africa in the past year - an M 4.4 on June 3, 2021 and an M 4.8 on December 6, 2020. Forecast 135877 had expected enhanced seismicity in this region was possible around July 31. This epicenter is at 150 degrees from the M 8.2 in Alaska and may have been promoted by energy from that epicenter.

 

O: 30JUL2021 04:34:51  26.3S   28.2E ML=4.2  EMSC   SOUTH AFRICA                 

P: 31JUL2021 135877    22.0S   33.0E 4.0-5.6 ACCAA  So. Indian Ocean            

 

An unusual earthquake of M 5.0 also occurred in the Southern East Pacific Rise today. It was not reported felt in this remote area. This earthquake occurred near 100 degrees from the Alaska epicenter of M 8.2 - a distance at which seismic energy is concentrated due to internal earth reflections and refractions. It may have been triggered by this concentrated energy. The last earthquake within about 250 km of this epicenter with M>=5 occurred on April 23, 2018 with M 5.0. A strong earthquake of M 6.7 occurred about 300 km northeast of this on May 19, 2021.

 

O: 29JUL2021 20:55:52  35.7S  112.1W mb=5.0  EMSC   SOUTHERN EAST PACIFIC RISE   

 

A second oceanic event of M 4.6 hit later in the northern mid-Atlantic Ridge. This earthquake had been expected in late July within about 100 km of this epicenter (forecast 135752). The last earthquake of larger magnitude within about 250 km of this epicenter occurred with M 5.4 on October 6, 2020.

 

O: 30JUL2021 03:19:47  31.7N   40.8W mb=4.6  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P: 24JUL2021 135752    31.0N   41.0W 4.0-5.7 AAAAA  No. Mid-Atlantic Ridge     

 

An M 5.3 also occurred today in the Central East Pacific Rise. It was not reported felt in this epicentral area. This event, like that in the northern mid-Atlantic Ridge occurred at 78 degrees from the Alaska epicenter. Other moderate earthquakes today occurred at this distance from Alaska in Tonga, Vanuatu, Myanmar and Tajikistan. This may represent a free-earth concentration of energy at this distance. The last earthquakes in the area of M>=5.3 occurred in this area on February 10, 2021 with M 5.7 and previous to that an M 5.9 on July 27, 2015.

 

O: 29JUL2021 09:40:43  13.4S  112.2W mb=5.3  EMSC   CENTRAL EAST PACIFIC RISE    

 

A pair of moderate earthquakes in British Columbia, Canada followed the M 8.2 in

Alaska today. The strongest of these was an M 4.6 near Kitimat, BC and was lightly felt in the epicentral area. This epicenter at 16 degrees from the  Alaska epicenter saw the earthquake seven minutes after the Alaska earthquake. The P-phase from Alaska would have been at this epicenter at the time the earthquake occurred and may have helped trigger seismic activity at this time. Forecast 135826 had expected activity within about 50 km of this epicenter around July 23.     The last earthquake of M>=4.6 in this area occurred on September 27, 2014. The strongest earthquake every recorded in Canada hit this area as an M 7.8 on October 28, 2012. This occurred as Hurricane Sandy was making landfall in the eastern U.S.  - one of the most powerful hurricanes in the eastern U.S. in recent years.

 

O: 29JUL2021 06:19:22  53.1N  129.7W ML=4.6  EMSC   BRITISH COLUMBIA, CANADA     

O: 29JUL2021 06:19:22  53.1N  129.7W MB=4.6  ECAN OF KITIMAT, BC   

P: 23JUL2021 135826    53.0N  131.0W 3.0-5.3 CAAAA  British Colombia           

 

The second of these events - the M 3.8 near Port Alice, Vancouver Island, Canada followed the Alaska quake by 47 minutes and may have been promoted by the ScS seismic phase from that earthquake. Forecast 135816 had expected activity in the Vancouver Island was likely around July 28.

 

O: 29JUL2021 06:59:09  49.5N  127.8W MB=3.8  ECAN Port Alice, BC   

O: 29JUL2021 06:59:09  49.5N  127.8W ML=3.8  EMSC   VANCOUVER ISLAND, CANADA REGIO

P: 28JUL2021 135816    47.9N  129.1W 2.8-5.3 ABAAA  Vancouver Island area      

 

Moderate aftershocks including two of M>6 and an M 5.5 and M 5.8 continued today in the Alaska Peninsula area. These were lightly felt in this remote area near Perryville, Alaska. Forecast 135821 had expected today's activity was likely around July 31 within the aftershock zone. This forecast was first published more than a week ago. Following is a listing of aftershocks in the Alaska Peninsula area today of M>=4.5. A more complete listing can be found in the "ALASKA" section of this summary.

 

O: 29JUL2021 10:26:52  54.8N  157.1W mb=4.5  EMSC   SOUTH OF ALASKA

O: 29JUL2021 06:45:12  55.0N  157.5W ml=4.5  EMSC   SOUTH OF ALASKA

O: 29JUL2021 07:32:34  55.0N  157.4W ml=4.5  EMSC   SOUTH OF ALASKA

O: 29JUL2021 21:00:05  55.0N  158.1W mb=4.7  EMSC   SOUTH OF ALASKA

O: 29JUL2021 06:19:25  55.1N  158.1W mb=6.1  EMSC   ALASKA PENINSULA

O: 29JUL2021 06:47:23  55.1N  157.8W mb=5.4  EMSC   ALASKA PENINSULA

O: 29JUL2021 08:15:49  55.1N  157.0W mb=4.6  EMSC   ALASKA PENINSULA

O: 29JUL2021 07:31:15  55.2N  156.8W mb=4.6  EMSC   SOUTH OF ALASKA

O: 29JUL2021 09:53:41  55.2N  157.1W mb=4.7  EMSC   ALASKA PENINSULA

O: 29JUL2021 09:58:24  55.2N  155.6W mb=4.5  EMSC   SOUTH OF ALASKA

O: 29JUL2021 16:09:08  55.2N  156.9W mb=5.2  EMSC   SOUTH OF ALASKA

O: 29JUL2021 20:32:41  55.2N  156.8W Mw=5.4  EMSC   SOUTH OF ALASKA

O: 29JUL2021 21:39:14  55.2N  157.2W mb=4.6  EMSC   ALASKA PENINSULA

O: 29JUL2021 06:32:34  55.3N  156.9W mb=5.8  EMSC   SOUTH OF ALASKA

O: 29JUL2021 08:09:45  55.3N  157.3W mb=4.8  EMSC   ALASKA PENINSULA

O: 29JUL2021 08:40:16  55.3N  157.3W mb=4.5  EMSC   ALASKA PENINSULA

O: 29JUL2021 09:55:20  55.3N  155.7W mb=5.0  EMSC   SOUTH OF ALASKA

O: 29JUL2021 11:08:48  55.3N  157.5W mb=4.5  EMSC   ALASKA PENINSULA

O: 29JUL2021 22:18:26  55.3N  157.3W Mw=4.7  EMSC   ALASKA PENINSULA

O: 29JUL2021 23:38:16  55.3N  157.1W mb=4.5  EMSC   ALASKA PENINSULA

O: 29JUL2021 07:50:01  55.4N  157.6W mb=4.8  EMSC   ALASKA PENINSULA

O: 29JUL2021 06:15:50  55.5N  158.0W Mw=8.2  EMSC   ALASKA PENINSULA

O: 29JUL2021 06:23:31  55.5N  157.5W mb=6.3  EMSC   ALASKA PENINSULA

O: 29JUL2021 09:28:24  55.5N  157.6W mb=4.9  EMSC   ALASKA PENINSULA

O: 29JUL2021 19:11:27  55.5N  156.7W mb=4.8  EMSC   SOUTH OF ALASKA

O: 29JUL2021 20:30:33  55.5N  157.0W mb=5.0  EMSC   SOUTH OF ALASKA

O: 29JUL2021 08:25:19  55.6N  156.2W mb=4.8  EMSC   SOUTH OF ALASKA

O: 30JUL2021 01:26:35  55.6N  155.8W mb=4.5  EMSC   SOUTH OF ALASKA

O: 30JUL2021 03:52:15  55.6N  157.1W Mw=5.5  EMSC   ALASKA PENINSULA

O: 29JUL2021 13:17:50  55.8N  156.1W mb=4.8  EMSC   SOUTH OF ALASKA

P: 31JUL2021 135821    54.7N  156.9W 3.5-5.3 AAAAA  Alaska Peninsula           

 

An aftershock of M 3.2 hit near the Nebraska-Kansas border today. NEIC reported this earthquake of M 3.2 in Northern Kansas was felt with intensity II-III in the area(s) of Northern Kansas at Mankato and in Omaha, Nebraska. This follows a smaller foreshock which hit several hours before the M 8.2 in Alaska and may have been precursory to that event. In the previous issue of this summary it was noted in this regard:

 

"An M 2.9 in northern Kansas preceded the earthquake in Alaska today. It was reported lightly felt in the epicentral areas. Unusual earthquakes in the central plains of the U.S. often precede strong quakes in Alaska. A series of light earthquakes occurred east of this epicenter on May 6, 2021 with maximum size of M 3.8. Forecast 135779 had expected regional enhancement of seismicity in this area was possible around July 28." (July 29, 2021)

 

O: 29JUL2021 12:57:47  39.7N   98.4W mb=3.2  EMSC   KANSAS                       

P: 28JUL2021 135779    37.0N   97.0W 2.0-4.1 AAAAA  Southern Plains