UNPRECEDENTED M 6.7 IN MAURITIUS-REUNION AREA TRIGGERED BY ANTIPODAL EFFECTS

 

EARTHQUAKE SUMMARY FOR  MAY 12, 2021

 

The strongest earthquake in the world today was an M 6.7 in the Mauritius-Reunion area in the South Indian Ocean. NEIC reported it was as far as 1000 km from the epicenter in Mauritius at Laimatie Flaco, Bois des Amourettes, Grand Port, Curepipe Plaines Wilheim, Quatre Bornes Paines Wilheim and in Antananarivo, Madagascar and at Male, Maldives. The last earthquake in the world of larger magnitude was an M 7.0 on March 20, 2021 off the coast of eastern Honshu. A smaller event off Honshu of M 6.7-6.8 occurred more recently on May 1, 2021. The only earthquake ever recorded of M>=6.7 within about 300 km of this epicenter was an M 6.6 on July 26, 2012. Today's earthquake is at the exact antipode of the eye of Tropical Storm Andres which is south of western Mexico at this time. The possibility of such an event at this time had been suggested in this summary in the previous summary as:

 

"Tropical storm Andres continued in the area south of Jalisco, Mexico with winds up to 85 kts.  The M 5.1 in Michoacan today was probably promoted by stresses from this storm. The antipode of this storm is at 17S 67E in the South Indian Ridge. A moderate to strong earthquake in this area is possible at this time. This longitude is also near the maximum tidal stress with the current new moon as noted in previous issues of this summary:

 

"The new moon will arrive on May 11, 2021 at 19:00 UT. Longitudes which are at local solar noon at this hour are near 105 West and those at local solar midnight near 75 East longitude. In the west these include areas of central and Western U.S. and Canada and western Mexico as well as portions of the East Pacific Rise. In the east area near 75E include Afghanistan, India, Hindu Kush, Iran and eastern Indonesia and portions of the mid-Indian ridges. These regions are expected to see enhanced seismicity during the coming week. Other tidally promoted seismicity may occur elsewhere and is most likely near local solar midnight and noon when tidal stresses are generally maximized." (May 9-12, 2021)

 

A third factor which probably enhanced global seismicity today was a strong geomagnetic storm which began about the time of M 6.7 in the Mauritius-Reunion area (about 14:00 UT). Most of the strong activity today occurred near the geomagnetic equator or at high latitude as expected with strong geomagnetic triggering. As described in this summary, this storm is the strongest recorded since September 1, 2019:

 

"The geomagnetic field saw stormy conditions today. The AP level was 41.  High latitude geomagnetic field also saw strong storm conditions with AP 47. Strong, sudden commencement storms such as this can enhance seismicity especially near the geomagnetic equator or near the polar auroral regions. This is the strongest geomagnetic storm since AP reached 45 on September 1, 2019 more than 1.5 years ago.." (May 12-13, 2021)

 

An M 6.7 in Fiji accompanied the strong geomagnetic storm on September 1, 2019. Moderately strong earthquakes in Panama, Peru and Halmahera today followed with this storm and lie near the geomagnetic equator. They were probably promoted by geomagnetic effects associated with today's storm.

 

The M 6.6-6.7 on July 26, 2012 was also apparently triggered by a similar storm south of Mexico as noted in this summary at the time as:

 

"A strong M 6.7 earthquake occurred today off the Indian Ocean islands of Mauritius, The epicenter was about 400 km north of the island of Rodrigues. There were no immediate reports of damage or injury. No tsunami warning was issued. Mauritius is a popular tourist area and a tsunami would do major damage. This earthquake is located on the mid-Indian ridge near the volcanic centers at Reunion and could be associated with a volcanic epicenter. Earthquakes on mid-Ocean ridges, no matter how large, seldom produce appreciable tsunamis.  This epicenter is antipodal to the region of western Mexico where Socorro and Revilla Gigedo Islands are located. A series of hurricanes has been passing over this area in the past two weeks. Microseismics from these could have helped promote the antipodal activity in the Indian Ocean as we suggested at the time. It is also possible that the earthquake near Mauritius will trigger renewed activity in the region of western Mexico near its antipode. We discussed this possibility in our summary of July 8 where we stated in this regard on the occurrence of the M 5.0 foreshock to today's earthquake in Mauritius:

 

"A moderate earthquake hit the region of Mauritius and Reunion in the South Indian Ocean today with M 5.0. This is at the antipode of the current location of Hurricane Daniel which is a major hurricane south of Mexico. Microseisms from this hurricane will focus at this location in the south Indian Ocean and could help promote seismicity in the area. This has been seen in the case of major hurricanes on a number of occasions in the past and appears to be another way to promote regional seismicity. A more detailed study of this is probably called for." (July 8, 2012)  - note since that time three other hurricanes have taken the same path, an unprecedented series in this region.

 

This event is the strongest in this region of the South Indian Ocean ever recorded. The last of M>=6 was an M 6.3 on August 16, 2010 and the last of M>=6.5 was an M 6.5 on September 17, 1995 and November 5, 1991. These last two were the largest previously recorded in the area." (July 26, 2012)

 

Forecast 133641 had expected this event within about 300 km was likely in the South Indian Ocean around May 9.

 

O: 12MAY2021 14:05:16  17.3S   66.5E Mw=6.7  EMSC   MAURITIUS - REUNION REGION   

P:  9MAY2021 133641    14.0S   66.0E 4.0-5.4 BCAAA  So. Indian Ocean           

 

 

A strong earthquake of M 5.9 also occurred near El Salvador today. NEIC reported

this event was felt with maximum intensity V in San Salvador at La Libertad; IV in Antiguo Cuscatlan, El Salvador and II-III in Armenia, Nueva San Salvador, Nuevo Cuscatlan, Opico, San Marcos, San Salvador and Ilopango and in Guatemala at Masagua Escuintla. This event followed a smaller M 5.7 foreshock reported in the previous summary as:

 

 

"A moderately strong earthquake occurred near El Salvador today with M 5.6. NEIC reported it was felt with maximum intensity VIII in El Salvador at Acajuatla; IV in Nuevo Cuscatlan, Antiguo Cuscatlan, and II-III in Opico, and in Guatemala at Masagua, Mixco, Guatemala City, Antigua Guatemala, Santa Catarina Pinula. This earthquake occurred within minutes of local solar midnight and was probably promoted by high tidal stresses which maximize near this hour. It is also near the maximum tidal longitude for the current new moon. It also occurred near the origination point of Tropical Storm Andres which is now south of Jalisco, Mexico and may have helped trigger the M 5.1 in Michoacan yesterday as well as the activity in El Salvador today." (May 12, 2021)

 

 

Forecasts 133447 and 133760 had expected this activity was likely between May 5 and 13 within about 100 km of this epicenter. No major damage was reported with this earthquake and no tsunami was expected nor observed. This epicenter is at 103 degrees from the M 7.7 in the Loyalty Islands of February 10, 2021 and was probably promoted by energy from that source. Today's event of M 5.9 is the strongest within about 200 km of this epicenter since an M 5.9 on December 19, 2019 and an M 5.9 on July 31, 2019. A strong M 6.6 hit the area about 100 km to the east on May 30, 2019.  Forecasts 133760 and 133758 had expected today's event within about 100 km was likely around May 13-14.

 

O: 12MAY2021 08:45:48  13.3N   90.2W Mw=5.9  EMSC   OFFSHORE EL SALVADOR         

P: 13MAY2021 133760    13.0N   91.0W 3.5-5.6 AAAAA  Guatemala                  

P: 14MAY2021 133758    13.0N   89.0W 3.5-5.2 AAAAA  Coast of Central America   

 

An M 6.0 also occurred south of Panama and west of Colombia today. NEIC reported this earthquake was felt with intensity II-III in Panama in Chiriqui at Los Lomas and Boquete and in Santa Fe, Veraguas, Panama. When an M 5.7 near the antipode of this epicenter occurred on May 5, 2021 this summary noted this relation could bring about a strong earthquake at this time in the area of Colombia or Ecuador at this time as:

 

"The antipode of this epicenter is in southern Colombia and Ecuador at 2N 80W - an area which is currently active and could see triggered antipodal seismicity with strong events in this area of Indonesia." (May 5, 2021)

 

This is the strongest earthquake within about 200 km of this epicenter since

an M 6.2 about 200 km to the north on June 26, 2019 and an M 6.6 about 150 km to the south on  January 7, 2015. Forecast 133721 had expected seismic enhancement in this region was likely around May 11.

 

O: 13MAY2021 09:42:10   6.7N   82.4W Mw=6.0  EMSC   SOUTH OF PANAMA               

P: 11MAY2021 133721     8.0N   83.0W 3.5-5.4 ABAAA  Costa Rica                 

 

 

An earthquake of M 5.5-5.6 shook the area of Central Peru today. NEIC reported it was felt with intensity V in Ica, Peru at Ica and Santiago; IV in Arequipa and II-III in the Lima area at Nuevo Imperial, Mala, San Luis, Santa Maria and Lima. This epicenter is located on the geomagnetic equator and was probably promoted by today's geomagnetic storm. The last earthquake within about 200 km of this epicenter with M>=5.6 occurred on October 28, 2020 with M 5.6 and prior to that on May 8, 2019. A strong M 7.1 hit about 150 km southeast of this on January 14, 2018. Forecast 133932 had expected today's event was likely within about 100 km around May 17. This earthquake occurred within about an hour of local solar noon, a time when tidal and geomagnetic stresses are maximized.

 

O: 12MAY2021 15:56:57  14.1S   75.6W mb=5.6  EMSC   NEAR COAST OF CENTRAL PERU   

P: 17MAY2021 133932    15.0S   76.0W 4.0-5.7 BAAAA  Central Peru                

 

The M 5.6 followed an M 5.3 which occurred earlier in the day in southern

Peru. NEIC reported this earthquake was felt with maximum intensity VII in Tarata, Tacna, Peru and in La Paz, Bolivia. Forecast 133937 had expected today's event was likely within about 200 km around May 15.

 

O: 12MAY2021 07:53:23  17.2S   70.0W mb=5.3  EMSC   SOUTHERN PERU                

P: 15MAY2021 133937    17.0S   72.0W 4.0-5.5 BABAA  So. Peru/Bolivia           

 

An earthquake of M 5.5 also occurred today north of Halmahera, Indonesia. It was felt lightly in the epicentral region. It was preceded by an M 5.3 about three hours earlier. This event occurred within about 15 minutes of local solar midnight, a time when tidal and geomagnetic stresses are maximized and was probably promoted by them. Forecast 133406 had expected this event within about 100 km was likely around May 10.

 

 

O: 12MAY2021 15:45:31   4.0N  128.7E mb=5.3  EMSC   NORTH OF HALMAHERA, INDONESIA

O: 12MAY2021 18:20:28   4.0N  128.7E Mw=5.5  EMSC   NORTH OF HALMAHERA, INDONESIA

P: 10MAY2021 133406     4.0N  128.0E 4.0-5.4 AAAAA  Halmahera                  

 

The strongest earthquake in the U.S. or Canada today was an M 5.1 in the Rat Islands, Aleutians. It followed an M 4.8 foreshock but neither of these events were reported felt in this remote area. These occurred near local solar midnight and noon about 12 hour apart. The M 5.1 is the strongest in the Rat Islands

since an M 5.3 on February 4, 2020 and April 14, 2019. It was probably promoted by the major geomagnetic storm today.  Forecast 133906 had expected today's events within about 100 km of these epicenters were likely mid-May.

 

O: 12MAY2021 22:00:34  51.8N  176.3E mb=5.1  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

O: 12MAY2021 09:32:35  51.3N  176.7E mb=4.8  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 17MAY2021 133906    52.0N  175.0E 4.0-5.6 BAAAA  Rat Islands                

 

MODERATE QUAKES WITH NEW MOON IN MICHOACAN, MEXICO; KERMADEC ISLANDS

 

EARTHQUAKE SUMMARY FOR  MAY 10, 2021

 

The generally quiet conditions in the world seismicity continued today. The largest earthquakes of the day were and M 5.3 in the Kermadec Islands aftershock zone and an M 5.1 in Michoacan, Mexico.

 

The event in Michoacan occurred in conjunction with the passage of the first Tropical Storm (Andres) to the south of this epicenter and was likely promoted by stresses from this storm as noted in previous issues of this summary:

 

"Tropical storm Andres continued in the area south of Michoacan, Mexico with winds up to 85 kts.  Little impact on regional seismicity is expected with this storm but an M 5.1 in Michoacan today was probably promoted by stresses from this storm.

 

This is the strongest earthquake in the Mexican State of Michoacan in at least

a year. The last such event of M>=5.1 occurred more than three years ago as an M 5.8 on February 9, 2018 and before that as an M 5.5 on September 30, 2015.

Tidal stresses with the new moon today had been expected to maximize near 105 West longitude in western Mexico (see below) and probably helped promote today's event. Forecast 133454 had expected today's activity in Michoacan was likely around May 7.

 

"The new moon will arrive on May 11, 2021 at 19:00 UT. Longitudes which are at local solar noon at this hour are near 105 West and those at local solar midnight near 75 East longitude. In the west these include areas of central and Western U.S. and Canada and western Mexico as well as portions of the East Pacific Rise. In the east area near 75E include Afghanistan, India, Hindu Kush, Iran and eastern Indonesia and portions of the mid-Indian ridges. These regions are expected to see enhanced seismicity during the coming week. Other tidally promoted seismicity may occur elsewhere and is most likely near local solar midnight and noon when tidal stresses are generally maximized." (May 9-11, 2021)

 

NEIC reported this earthquake of M 5.1 in Michoacan, Mexico was felt with intensity II-III in the area(s) of  Michoacan at Aguilla (VII), Uruapan (IV) and in Artega, Pihuamo, Paizcuaro, Zamora, Zapotitic, Jalisco.  This epicenter is near 100 degrees from the recent strong quakes in Honshu, Japan and may have been promoted from that source as well. An unusual M 4.5 in the Madeira Islands off Portugal today shared this distance from Japan.

 

O: 11MAY2021 04:37:12  18.9N  102.6W Mw=5.1  EMSC   MICHOACAN, MEXICO            

P:  7MAY2021 133454    19.0N  101.0W 3.5-5.8 BAAAA  Michoacan, Mexico          

 

An unusual M 4.1 also occurred north of Michoacan, Mexico today in the state of Coahuila, Mexico. It was not reported felt in this area. It, too, was probably promoted by tidal stresses with the new moon. The last earthquake within  about 200 km of this epicenter with M>=4.1 occurred as an M 4.7 on December 5, 1993, the only such event in this region in the past 30 years. An M 5.7 about 300 km northwest of this occurred on April 14, 1995.

 

 

O: 10MAY2021 16:40:59  27.5N  102.4W ML=4.1  EMSC   COAHUILA, MEXICO             

 

Another unusual earthquake at this longitude (120W) also occurred today in the region of the Texas Panhandle. NEIC reported an earthquake of M 3.2 in Texas Panhandle was felt with intensity II-III in the area(s) of Texas Panhandle in Hartley.  The last earthquake within about 100 km of this epicenter in the Texas Panhandle with M>=3.2 occurred on  January 6, 2014 with an M 3.5. An M 4.3 hit the area about 150 km northeast of this on April 14 with the new moon. At the time this summary noted in this regard:

 

"Two unusual earthquakes occurred today in the region of northern Texas.

This activity is at 100-104 degrees from the major and great eartquakes

in the Loyalty Islands, Kermadec Islands and North Island, New Zealand of

February and March , 2021 and was likely promoted by energy from that source.

The largest of these, and the strongest in the U.S. or Canada was an M 4.3 which hit the Texas Panhandle today. NEIC reported it was felt with intensity IV in Miami, Texas and II-III in Borger, Skellytown, Pampa, Perryton, Groom, Amarillo, and possibly as far as Axtell, Nebraska. This is the strongest earthquake within about 200 km of this epicenter in at least 30 years. The only earthquake in this area of larger magnitude in the past 50 years was an M 4.5-4.6 on February 15, 1974. The strongest quake in this area on record is an M 5.0 on July 30, 1925." (April 14-15, 2021)

 

Forecast 133506 had expected enhanced activity in this area was likely around May 8. This activity is at 101-103 degrees from recent large events in the Loyalty Islands and New Zealand and was probably promoted by energy from those sources.

 

O: 10MAY2021 11:46:31  35.7N  102.5W ml=3.2  ANSS   W of Channing Texas           

P:  8MAY2021 133506    37.0N  105.2W 2.0-4.2 AAAAA  Colorado area              

 

The aftershock of M 5.3 in the Kermadec Islands was the largest event located in the world today. This is the strongest aftershock of the M 8.1 of March 4, 2021 in this area since an M 5.9 on April 29, 2021 which occurred near the full moon with a series of moderate to strong  earthquakes from April 27-29. Today's event occurred near local solar midnight and was also probably promoted by tidal stresses. Forecast 133663 had expected this activity was likely around May 7. More such activity is expected in the next several days as tidal effects linger.

 

O: 10MAY2021 14:10:20  29.2S  176.1W mb=5.3  EMSC   KERMADEC ISLANDS REGION      

P:  7MAY2021 133663    29.0S  178.0W 4.0-5.4 BABAA  No. Kermadec Islands       

 

Seismicity was also up in the region of central Asia today in the areas of Hindu Kush, Afghanistan, Kyrgyzstan and Kazakshstan where moderate earthquakes occurred. This is consistent with tidal triggering in these areas as expected in the tidal forecast for the upcoming new moon of May 11 as noted in  previous issues of this summary (see above).

 

Forecasts 133563 and 133509 had expected today's activity in early May. This activity is at the third node (120 degrees) from the quakes in New Zealand of March 4 and was probably promoted by energy from those sources.

 

O: 10MAY2021 08:04:24  36.5N   71.2E mb=4.3  EMSC   HINDU KUSH REGION, AFGHANISTAN

P:  7MAY2021 133509    37.0N   72.0E 3.8-5.4 BAAAA  Hindu Kush/Pakistan        

 

O: 10MAY2021 10:00:54  42.3N   76.3E mb=3.9  EMSC   KYRGYZSTAN                   

P:  9MAY2021 133563    40.0N   75.0E 4.0-5.5 ACAAA  Kirgizstan/Xinjiang        

 

O: 10MAY2021 16:51:42  47.1N   83.1E mb=4.3  EMSC   KAZAKHSTAN-XINJIANG BORDER REG

P:  5MAY2021 133563    42.0N   83.0E 4.0-5.4 BCAAA  Kirgizstan/Xinjiang        

 

 

MODERATE QUAKES IN KURIL ISLANDS

 

EARTHQUAKE SUMMARY FOR  MAY 9, 2021

 

It was a quiet day in global seismicity. The largest earthquakes of the day were located with M 5.0 in the Kuril Islands and Tonga. The events in the Kuril Islands were the most active in the world today with four other additional moderate quakes in the area. These were not reported felt. The M 5.0 in the Kuril Islands is the strongest in the Kurils since an M 5.1 on March 20, 2021. Forecasts 133585, 133559 and 133570 expected this activity was likely in early May.

 

O: 09MAY2021 16:05:00  47.4N  151.6E mb=4.4  EMSC   KURIL ISLANDS

O:  9MAY2021 23:33:37  46.6N  152.1E mb=5.0  EMSC   KURIL ISLANDS                

P:  4MAY2021 133585    48.0N  154.0E 3.5-5.8 BABAA  So. Kurils                  

 

O: 10MAY2021 00:39:51  43.9N  146.7E mb=4.5  EMSC   KURIL ISLANDS                

P:  8MAY2021 133559    44.0N  145.0E 3.5-5.6 AAAAA  Hokkaido, Japan            

 

O:  9MAY2021 16:23:45  49.4N  155.8E mb=4.8  EMSC   KURIL ISLANDS                

P:  7MAY2021 133570    49.0N  155.0E 3.5-5.8 AAAAA  NE Pacific                 

 

The M 5.0 in the Tonga Islands was reported felt in that area. NEIC reported this earthquake of M 5.0 in Tonga was felt with intensity II-III in the area(s) of Tonga in Neiafu, Vavau. This area has been active in the past week and has included events of M 6.1 and 5.5 in the past week. Today's M 5.0 is not a classical aftershock of the M 6.1 on May 7 as it occurred about 400 km northeast of that event. Forecast 133647 expected the M 5.0 in Tonga today was likely around May 8. 

 

O: 10MAY2021 01:59:17  17.8S  173.6W mb=5.0  EMSC   TONGA                        

P:  8MAY2021 133647    18.0S  178.0W 4.0-5.7 AACAA  Tonga Islands              

 

Two light earthquakes were felt today in the Los Angeles, California area. These occurred within about half an hour of each other. These began with an M 3.2  near local solar midnight and was followed half an hour later by an M 2.5 in the Santa Monica Bay area of California. The may signal a more active period in  the Los Angeles area and resembles some of the precursory activity in the area prior to the Northridge quake of January, 1994. Forecasts 133536 and 133531 expected this activity in early May in this area.

 

NEIC reported the earthquake of M 2.5 in Santa Monica Bay, California was felt with intensity II-III in the area(s) of Santa Monica Bay, California at Hermosa Beach, Manhattan Beach, Redondo Beach, El Segundo, Torrance, Lawndale, Hawthorne and Palos Verdes.  NEIC reported the earthquake of M 3.2 in eastern Los Angeles, California was felt with intensity II-III in the area(s) of eastern Los Angeles, California at Loma Linda, Grand Terrace, Colton, Redlands, San Bernardino, Moreno Valley, Highland.

 

O:  9MAY2021 09:37:57  33.9N  118.5W Ml=2.5  EMSC   SANTA MONICA BAY, CALIFORNIA 

O:  9MAY2021 09:09:33  34.0N  117.2W ML=3.2  EMSC   GREATER LOS ANGELES AREA, CALI

P:  5MAY2021 133535    34.1N  117.4W 2.5-4.8 BAAAA  So. California             

P:  7MAY2021 133531    33.8N  117.7W 2.5-4.7 AAAAA  So. California             

 

 

MODERATE QUAKE SHAKES YUKON TERRITORY, CANADA

 

EARTHQUAKE SUMMARY FOR  MAY 8, 2021

 

The strongest earthquake in the U.S. or Canada today was an M 4.6-4.9 in the Yukon Territory, Canada. This is the strongest earthquake within about 250 km of this epicenter since an M 5.3 about 250 km northwest of today's epicenter occurred on February 13. 2017. An M 6.0 hit about 100 km south of this on July 17, 2014. Forecast 133621 had expected elevated seismicity in this region was likely around May 6. This earthquake was located at the seventh node (51.4 degrees) from the M 7.1, 7.2 and 6.8 in Honshu Japan in March and April and was probably promoted by energy from those sources.  It is also located at 104 degrees from the M 7.3 off North Island, New Zealand of March 4 and was probably promoted by energy from that source.

 

O:  9MAY2021 02:03:44  61.4N  141.0W MB=4.6  ECAN  BEAVER CREEK, YT            

O:  9MAY2021 02:03:46  61.5N  140.6W mb=4.9  EMSC   SOUTHERN YUKON TERRITORY, CANA

O:  9MAY2021 02:03:46  61.5N  140.5W mb=4.9  ANSS   SOUTHERN YUKON TERRITORY, CANA

P:  6MAY2021 133621    62.8N  143.8W 3.2-5.3 BBBAA  Central Alaska             

 

The strongest earthquake in the U.S. or Canada today outside Alaska was and M 4.4 in western Nevada. NEIC reported it was felt with intensity II-III in Nevada at Glenbrook and Fallon and in Carson City. A similar M 4.4 occurred about 25 km west of this on March 30, 2021 but the last event in the area of larger magnitude was an M 4.7 on December 14, 2020. Forecast 133495 expected enhanced activity in this area was likely around May 4 to May 7, 2021. This event is located at the fourth node (90 degrees) from the M 7.7 in the Loyalty Islands of February 10 and at the fifth node (72 degrees) recent major events off eastern Honshu, Japan and was probably promoted by energy from those sources.

 

O: 08MAY2021 13:07:02  38.2N  117.9W ml=2.3  EMSC   NEVADA

O: 08MAY2021 13:07:02  38.2N  117.9W ml=2.3  EMSC   NEVADA

O: 08MAY2021 15:31:26  38.2N  117.9W ml=2.0  EMSC   NEVADA

O:  8MAY2021 08:13:52  38.2N  117.9W Mw=4.1  EMSC   NEVADA                       

O:  8MAY2021 08:13:52  38.2N  117.9W Mw=4.4  ANSS   NEVADA                       

P:  4MAY2021 133495    38.0N  118.8W 2.5-4.6 BAAAA  California/Nevada area     

P:  7MAY2021 133495    37.5N  118.6W 2.5-4.6 AAAAA  California/Nevada area     

 

An M 3.8 also occurred today off the coast of Oregon. It may have been felt lightly on the coast of Oregon at Hillsboro. This continues the enhanced seismicity in this area which began with an M 4.1 on April 26, 2021 with an M 5.4, 5.3 and 5.2 on April 29. Forecast 133578 expected this event was likely around 133578 around May 9.

 

O:  8MAY2021 08:37:00  44.2N  129.2W mb=3.8  EMSC   OFF COAST OF OREGON          

P:  9MAY2021 133578    44.5N  129.8W 3.0-4.5 AAAAA  Off Coast of Oregon        

 

The strongest earthquake in the world today was an M 5.1 in the South Sandwich Islands. It was not reported felt in this remote region. While earthquakes of M 5.0 and M 5.3 occurred about 200 km southeast of this on May 7 and April 26, 2021, the last event of M>=5.1 within this distance of today's epicenter occurred on February 23, 2021 with M 5.2. The last of significantly large magnitude in this area was an M 5.4 on May 8, 2020 exactly one year ago. Forecast 133712 had expected today's event within about 50 km in early May.

 

O:  8MAY2021 18:17:38  55.6S   29.2W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  3MAY2021 133712    55.0S   29.0W 4.0-6.0 BAAAA  So. Sandwich Islands       

P:  9MAY2021 133712    57.0S   27.0W 4.0-6.0 ABBAA  So. Sandwich Islands       

 

An earthquake of M 4.5 continued the aftershocks in Gabon, West Africa today.

NEIC reported this earthquake of M 4.5 in Lambarene, Gabon was felt with intensity II-III in the area(s) of Lambarene, Gabon. The mainshocks in this area were an 5.2 on March 6 and an M 5.4 on March 9, 2021. Aftershocks of M 5.4 and 4.7 occurred on April 27. At the time this summary noted in this regard:

 

"A pair of moderate aftershocks occurred in the region of Gabon, West Africa today. These are aftershocks of the M 5.2 and 5.4 in the area of March 6 and 9, 2021 and are the largest since those events occurred. They occurred near local solar midnight and may have been promoted by high tidal stresses with the full moon. The activity in Gabon is near 144 degrees from the M 8.1 in the Kermadec  Islands of March 5 and is probably promoted by energy from that source." (April 26, 2021)

 

 

O:  9MAY2021 01:30:07   1.2S   10.1E mb=4.5  EMSC   GABON                        

 

 

 

 

 

STRONG FIJI QUAKE PROMOTED BY LARGEST FLARE IN HALF A YEAR

 

EARTHQUAKE SUMMARY FOR  MAY 7, 2021

 

The largest earthquake in the world today was an M 6.1 near the geomagnetic equator in Fiji. This event followed the strongest solar flare observed by SWPC since an M4.4 on November 29, 2020 and was measured by SWPC at M3.9.  The parameters for this flare given by SWPC are:

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

 640       1843   1904      1919   M3.9      (May 7, 2021)   4.5E-02  

 

The earthquake of M 6.1 in Fiji occurred within minutes of local solar noon a time when solar and tidal effects are maximized and was probably triggered by the M3.9 flare. Forecast 133647 expected today's event in Fiji was likely within about 100 km around May 8. An M 6.5 occurred within about 150 km of this epicenter on April 24, 2021 (also near local solar noon) with the previous such quake of M 6.1 on November 11, 2019. When the M 6.5 occurred in late April, this summary noted in this regard:

 

"The strongest earthquake in the world today was an M 6.5  in Central Tonga. NEIC reported it was felt with intensity VI in Tofoa-Koloua, Tonga  and II in Neiafu, Vavau, Tonga. The last earthquake with M>=6.5 in the world was an M 6.6 on April 3, 2021 in the South Atlantic. The only other event of this magnitude or greater in the world in the past month was an M 6.5 aftershock in the Kermadec Islands aon April 1, 2021. This earthquake occurred near local solar noon in an area near the regional geomagnetic equator. It was preceded about an hour earlier by an M 5.3 about 150 km to the south, an earthquake which occurred within about 30 minutes of local solar noon. It was probably promoted effects from the strong geomagnetic storm and solar flares of the past several days which maximize near this hour. The M 6.5 is the strongest earthquake within about 250 km of this epicenter since an M 6.6 on November 4, 2019." (April 24, 2021)

 

O:  7MAY2021 23:35:15  18.9S  177.6W Mw=6.1  EMSC   FIJI REGION                  

P:  8MAY2021 133647    18.0S  178.0W 4.0-5.7 AAAAA  Tonga Islands              

 

The series of moderate earthquakes of the past several days in California continued today. Moderate earthquakes in the northern Gulf of California and Baja California continued with a series of events of M 3.5-4.2 today. This summary reported in the previous issue on this series as:

 

 

"A pair of moderate earthquakes of M 4.1 and 4.2 also occurred in the Gulf of California today. Earthquakes of M>=4.2 have most recently occurred within about 100 km of these epicenters on April 1, 2021 (M 4.7) and February 13, 2020 (M 4.3). Forecast 133527 had expected this activity within about 25 km was likely to occur in early May." (May 6-7, 2021)

 

Moderate activity in this region can precede enhanced regional seismicity in Southern California within days as stresses migrate to the northwest.

 

O: 07MAY2021 08:53:20  30.1N  113.9W ML=4.0  EMSC   GULF OF CALIFORNIA

O: 07MAY2021 08:58:35  30.1N  113.8W ML=3.8  EMSC   GULF OF CALIFORNIA

O: 07MAY2021 09:00:14  30.1N  113.7W ML=3.9  EMSC   GULF OF CALIFORNIA

O: 07MAY2021 09:27:03  30.1N  113.9W ML=3.8  EMSC   GULF OF CALIFORNIA

O:  7MAY2021 08:49:02  30.0N  114.0W ML=4.1  EMSC   GULF OF CALIFORNIA           

P:  1MAY2021 133527    30.2N  114.1W 2.0-4.1 BAAAA  SW U.S.A                   

 

An earthquake of M 6.0 in the Macquarie Islands today followed an M 5.4 to the southeast of this on May 5. This summary noted that event at the time as:

 

An "M 5.4 in the area west of the Macquarie Island area and an M 5.1 in the

Southwest Indian Ridge. An M 6.1 hit the area west of Macquarie Island on March 20, 2021 about 400 km southeast of today's epicenter but the last of similar or larger magnitude within about 200 km of today's epicenter occurred as an M 5.7 on November 8, 2016 and prior to that as an M 5.5 on December 24, 2014. The antipode of this event is at 57N 33W in the Reykjanes Ridge in the north Atlantic Ridge  south of Iceland. Some seismic enhancement in this region is possible following today's event in the Macquarie Island area." (May 6, 2021)

 

O:  7MAY2021 15:21:14  54.5S  144.1E Mw=6.0  EMSC   WEST OF MACQUARIE ISLAND     

 

A moderate sized earthquake in the Northern Mid-Atlantic today of M 5.5 did occur along with today's M 6.0 in the Macquarie Islands. It was located east of The Leeward Islands in the eastern Caribbean. This is among the largest earthquakes in this area of the North Atlantic (within about 200 km) in the past 30 years. A set of three moderate to large  quakes last hit the area in November,  2018 which included the largest event in this area in the past 30 years and were the last events of M>=5.5 in the area. Forecast 133455 had expected activity in this area of the North Atlantic Ridge was likely around May 8.

 

O:  7MAY2021 11:45:25  14.1N   48.3W Mw=5.5  EMSC   NORTH ATLANTIC OCEAN         

P:  8MAY2021 133455    15.0N   46.0W 4.0-5.5 AABAA  Mid-Atlantic Ridge         

 

MODERATE QUAKE SHAKES TAHOE, CALIFORNIA AREA

 

EARTHQUAKE SUMMARY FOR  MAY 6, 2021

 

A moderate earthquake of M 4.7 was widely felt in the area of Tahoe on the northern border of California and Nevada today. This was the strongest earthquake in the U.S. or Canada today. It was accompanied by several felt foreshocks and aftershocks. NEIC reported it was felt with maximum intensity IV in California at Sierraville, Truckee, Soda Springs, Norden, Loyalton, Kings Beach and with lesser intensity in Tahoe National Park, Calpine, and Carnelian Bay among other localities. An M 2.5 regional foreshock occurred and was felt with intensity II in Incline Village, Nevada. This is the strongest earthquake in the Tahoe region within about 150 km of this epicenter since an M 4.8 on August 4, 2016 about 75 km northeast of today's epicenter. An M 5.0 hit about 150 km west of this on January 30, 2016. A moderately larger M 5.7 occurred about 100 km northwest of today's epicenter on May 24, 2013 - that was the  strongest in the area in the past 30 years at least.

 

When an M 3.7 hit the area about 50 km south of this epicenter near Reno, Nevada and Tahoe, California on April 25, 2021 this summary noted:

 

"A moderate earthquake of M 3.7 was widely felt in the area of Reno, Nevada near the California-Nevada border. NEIC reported it was felt with intensity IV in Tahoe City, Olympic Valley, Homewood, Kings Beach and III in Tahoe Vista, Tahoma, Carnelian Bay and in Nevada with II-III in Carson City, Glenbrook. 

This is the strongest earthquake in this region within about 100 km since an M 4.5 in Nevada about 50 km to the east of today's epicenter. An M 3.7-3.8 also  occurred about 100 km east of this on December 12, 2020. Forecast 133197 had expected today's quake within about 25 km was likely around April 24. This epicenter is at the fourth node (90 degrees) from the M 7.7 in the Loyalty Islands of February 10 and at the fifth node (72 degrees) from the recent major earthquakes off eastern Honshu, Japan of March 20 and may have been promoted by energy from those sources." (April 25-26, 2021)

 

Forecasts 133496 and 133503 had expected today's activity was likely within about 25 km of these epicenters to occur around May 6-9 with magnitude up to M 4.6.

 

O: 07MAY2021 04:35:13  39.5N  120.3W Mw=4.7  EMSC   NORTHERN CALIFORNIA

O: 07MAY2021 04:37:37  39.5N  120.3W ML=3.1  EMSC   NORTHERN CALIFORNIA

O: 07MAY2021 05:03:57  39.5N  120.3W Md=2.2  EMSC   NORTHERN CALIFORNIA

O:  7MAY2021 04:26:30  39.5N  120.3W ML=3.3  EMSC   NORTHERN CALIFORNIA           

P:  6MAY2021 133496    39.3N  120.0W 2.5-4.5 AAAAA  California/Nevada area     

P:  9MAY2021 133503    39.8N  120.6W 2.5-4.6 AAAAA  Central California         

 

O:  6MAY2021 13:18:34  39.1N  120.0W MD=2.5  EMSC   NORTHERN CALIFORNIA          

P:  6MAY2021 133496    39.3N  120.0W 2.5-4.5 AAAAA  California/Nevada area     

 

A pair of moderate earthquakes of M 4.1 and 4.2 also occurred in the Gulf of California today. Earthquakes of M>=4.2 have most recently occurred within about 100 km of these epicenters on April 1, 2021 (M 4.7) and February 13, 2020 (M 4.3). Forecast 133527 had expected this activity within about 25 km was likely to occur in early May.

 

O: 07MAY2021 02:03:48  30.1N  113.8W ML=4.1  EMSC   GULF OF CALIFORNIA

O:  6MAY2021 17:05:52  30.1N  113.9W ML=4.2  EMSC   GULF OF CALIFORNIA           

P:  1MAY2021 133527    30.2N  114.1W 2.0-4.1 BAAAA  SW U.S.A                   

 

A series of light earthquakes also occurred today in the region of northern

Kansas. This included an M 3.8 and afterhocks of M 3.0, 3.1 and 3.1.  An M 3.8 in northern Kansas today was widely felt.  NEIC reported this earthquake and aftershocks of M 3.1 in Kansas was felt with intensity IV in the area(s) of Kansas at Formoso, Courtland, Burr Oak, Hope and II-III in Jewel, Randall, Webber, Mankato, Belleville, Concordia, and Bend, Herington and Ramona. Other aftershocks of M 3.1 and 3.0 in Kansas were felt with intensity IV in Formoso and possibly in Sylvan Grove and in Peru, Nebraska.  This is the strongest earthquake within about 100 km of this epicenter in the past year. An M 4.5 occurred about 150 km southeast of this in Kansas on January 19, 2020. Forecast 133547 had expected today's activity in northern Kansas was likely around May 4. This activity is at 101-103 degrees from the major quakes in February and March, 2020 in the Kermadec and Loyalty Islands and was probably promoted by energy from those sources. Other events at this distance from these quakes occurred as an M 4.7 in Siberia, southern Alaska and Panama.

 

 

O: 06MAY2021 13:04:24  39.7N   98.0W mb=3.0  EMSC   KANSAS

O: 06MAY2021 11:35:32  39.8N   98.0W mb=3.8  EMSC   KANSAS

O:  7MAY2021 06:30:18  38.7N   97.0W mb=3.1  EMSC   KANSAS                       

O:  6MAY2021 18:20:33  39.8N   98.0W mb=3.1  EMSC   KANSAS                       

P:  4MAY2021 133547    39.0N   99.0W 2.0-4.3 AAAAA  Southern Plains            

 

An M 3.8 occurred in the region of southwestern Puerto Rico near Ponce today. NEIC reported this earthquake of M 3.8 in Southwest Puerto Rico was felt with intensity II-III in the area(s) of Southwest Puerto Rico with IV in Lajas, Sabana Grande and lesser shaking at Guanica, San German, Cabo Rojo, Yauco, Ponce and Guaynaco.  The last earthquake in this aftershock zone of larger magnitude occurred on December 24, 2020 with a series including an M 4.7 and M 4.8. Forecast 133463 had expected today's event was likely within about 10 km of the M 3.8 to occur around May 5.

 

O: 06MAY2021 13:02:30  17.9N   67.0W ML=3.4  EMSC   PUERTO RICO REGION

O: 06MAY2021 13:06:07  18.0N   67.0W Md=3.2  EMSC   PUERTO RICO REGION

O: 06MAY2021 13:08:56  18.0N   67.0W ML=3.8  EMSC   PUERTO RICO REGION

O: 06MAY2021 13:13:31  18.0N   67.0W Md=3.2  EMSC   PUERTO RICO REGION

O: 06MAY2021 13:25:34  18.0N   67.0W Md=3.1  EMSC   PUERTO RICO REGION

O:  6MAY2021 21:43:10  18.0N   67.0W Md=3.1  EMSC   PUERTO RICO REGION           

P:  5MAY2021 133463    18.0N   67.0W 3.4-5.0 AAAAA  Puerto Rico                

 

The strongest earthquake in the world today was an M 5.3 in Central Vanuatu.

It was not reported felt in this area. A similar M 5.3-5.4 quake hit about 100 km northeast of this on May 1, 2021 but the last of larger magnitude in the region was  an M 5.8 about 150 km south of this on February 28, 2020. Forecast 133649 had expected today's event was likely within about 75 km around May 3.

 

O:  6MAY2021 12:20:37  16.6S  167.5E mb=5.3  EMSC   VANUATU                      

P:  3MAY2021 133649    17.0S  167.0E 4.0-5.6 BAAAA  Vanuatu Islands            

 

 

 

 

 

MODERATE SEISMICITY IN OCEAN RIDGES

 

EARTHQUAKE SUMMARY FOR  MAY 5, 2021

 

Moderate activity  occurred today in the ocean ridges. This included an M 5.4 in the area west of the Macquarie Island area and an M 5.1 in the Southwest Indian Ridge. An M 6.1 hit the area west of Macquarie Island on March 20, 2021 about 400 km southeast of today's epicenter but the last of similar or larger magnitude within about 200 km of today's epicenter occurred as an M 5.7 on November 8, 2016 and prior to that as an M 5.5 on December 24, 2014. The antipode of this event is at 57N 33W in the Reykjanes Ridge in the north Atlantic Ridge south of Iceland. Some seismic enhancement in this region is possible following today's event in the Macquarie Island area.

 

O:  5MAY2021 19:20:09  57.0S  147.5E Mw=5.4  EMSC   WEST OF MACQUARIE ISLAND     

 

The last event of M>=5.1 within about 200 km of today's epicenter in the Southwest Indian Ridge occurred on March 6, 2020. Forecast 133697 expected this event within this area was likely around May 3. The antipode of this epicenter is located at 31N 121W off the coast of southern California, an area which may see increased seismicity in coming days. This event occurred at 103 degrees from the M 6.8 in Honshu, Japan of May 2 and was probably promoted by energy from that source. Other events at this distance from Honshu, Japan today occurred in Chiapas, Mexico, the Macquarie Island area and in the Azores.

 

O:  5MAY2021 21:22:59  30.9S   59.3E mb=5.1  EMSC   SOUTHWEST INDIAN RIDGE       

P:  3MAY2021 133697    32.0S   59.0E 4.0-5.7 ABAAA  So. Indian Ocean           

 

The strongest earthquakes in the U.S. or Canada today occurred in the Aleutians of Alaska. These were and M 4.8 in the Alaska Peninsula near Unimak Island and  an M 4.5 in the Near Islands in the western portion of the Aleutians. Neither of these event were reported felt in these areas. The only earthquake of M>=4.5 in this area of the Near Islands in the past year was an M 4.6 on November 30, 2020. Earthquakes about 200 km to the west of today's Near Islands epicenter occurred in the past year with M 5.3 on April 15, 2021 and on December 9, 2020. Forecast 133609 had expected today's event was likely around May 2. 

 

 

O:  5MAY2021 17:15:49  52.2N  173.6E mb=4.5  EMSC   NEAR ISLANDS, ALEUTIAN ISLANDS

P:  2MAY2021 133609    51.0N  176.0E 4.0-5.9 BBBAA  Rat Islands                

 

The last earthquake in the Alaska Peninsula within about 200 km of today's epicenter with M>=4.8 occurred as an M 4.9 on February 6, 2021. The last in the Unimak Island area with greater or equal magnitude than M 4.8 occurred as an M 5.1 on January 11, 2021. Other earthquakes in the Unimak Island area of larger magnitude in the past year occurred as an M 5.6 on August 13, 2020 and an M 5.0 on November 4, 2020. Forecast 133614 had expected today's event was likely within about 15 km to occur around May 5.

 

O:  6MAY2021 00:19:42  54.5N  161.6W mb=4.8  EMSC   ALASKA PENINSULA             

P:  5MAY2021 133614    54.5N  161.8W 3.5-5.3 AAAAA  Unimak Islands, Aleutians  

 

MODERATE QUAKES CONTINUE IN SOUTHERN SUMATRA, INDONESIA

 

EARTHQUAKE SUMMARY FOR  MAY 4, 2021

 

An M 5.7 earthquake in the Mentawai Region off southern Sumatra, Indonesia was the strongest in the world today.  BMG reported it was felt with intensity III-IV in the epicentral area of Mentawai. This area has been active since an M 6.3  on November 17, 2020, The last in this area of equal or larger magnitude in the Mentawai area. The last event near this was an M 5.6 on May 2, 2021. At that time this summary noted in this regard:

 

"An earthquake of M 5.6 (EMSC) -5.7 (BMG)  also occurred today in the area of Sumatra near Mentawai. BMG reported it was felt with intensity III-IV in the epicentral area of Mentawai. The last earthquake of M>=5.6 in this area was an M 5.6 north of this of March 5 following the M 8.1 in the Kermadec Islands of March 4, 2021 and prior to that an M 5.9 on November 17, 2020. Forecast 133431 had expected today's event within about 100 km was likely around May 4." (May 3, 2021)

 

Forecast 133431 had expected today's earthquake was likely within about 100 km  around May 4. The antipode of this epicenter is in southern Colombia and Ecuador at 2N 80W - an area which is currently active and could see triggered antipodal seismicity with strong events in this area of Indonesia.

 

 

O:  5MAY2021 01:24:35   1.9S   99.8E Mw=5.7  EMSC   KEP. MENTAWAI REGION, INDONESI

P:  4MAY2021 133431     2.0S   99.0E 4.0-5.4 AAAAA  So. of Sumatera            

 

A series of earthquakes of M 5.0, 5.2 and 5.5 occurred today in central Tonga. These were not reported felt in this remote area. The last earthquake within  about 150 km of this epicenter with M>=5.5 occurred as an M 5.5 September 6, 2020 but the last such quake of larger magnitude in ths area was an M 6.1 on June 15, 2019. Forecast 133672 had expected today's event within about 100 km of this epicenter was likely around May 4. This activity is at the fifth node (72 degrees) from the M 6.8 in Japan of May 3 and may have been promoted by energy from that source.

 

O: 05MAY2021 01:17:28  20.6S  173.8W mb=5.2  EMSC   TONGA

O: 05MAY2021 05:16:35  20.7S  173.3W mb=5.0  EMSC   TONGA

O:  4MAY2021 19:51:43  20.8S  173.8W Mw=5.5  EMSC   TONGA                        

P:  4MAY2021 133672    20.0S  174.0W 4.0-5.5 AAAAA  Tonga Islands              

 

The strongest earthquake in the U.S. or Canada today was an M 4.9 in the Fox Islands, Aleutians. It was not reported felt in this remote area. This is the largest earthquake within about 200 km of this epicenter this year and since an M 6.4 about 200 km to the east on December 1, 2020. The last within about 100 km of this epicenter was an M 5.8 on August 15, 2020 and a following event of M 5.6 on September 27, 2020. Forecast 133597 had expected today's event was likely within about 50 km around May 4.

 

O:  4MAY2021 16:47:43  52.4N  170.6W mb=4.9  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P:  4MAY2021 133597    52.1N  171.3W 3.5-5.1 AAAAA  Andreanoff Isls, Aleutians 

 

A regional aftershock occurred in Siberia today about 300 km west of the M 5.7 on the Russia-Mongolia earthquake that occurred yesterday. The last earthquake within about 200 km of today's epicenter with M>=4.7 was an M 4.7 and 5.0 on September 13, 2019. An M 7.3 earthquake hit this area on September 27, 2003. Forecast 133611 had expected today's event within about 100 km was likely around May 1.

 

O:  5MAY2021 06:57:55  49.9N   86.7E mb=4.7  EMSC   RUSSIA-KAZAKHSTAN BORDER REGIO

P:  1MAY2021 133611    50.0N   88.0E 3.0-4.6 BAAAA  So. Siberia                

 

Two large asteroids will make a near approach to the earth this week. A meteor shower is also likely to occur. Asteroid 2021 AFB passed nearby at 12:14 UT today (May 4) with magnitude 20.2. The Eta Aquariids Meteor shower is also visible on the morning of May 5-6 especially in the southern Hemisphere. These phenomena are not expected to impact global seismicity.

 

MODERATE QUAKE FELT IN MONGOLIA AND SIBERIA

 

EARTHQUAKE SUMMARY FOR  MAY 3, 2021

 

The strongest earthquake in the world today was an M 5.6 on the Russia-Mongolia border. NEIC reported it was felt with intensity III in Irkutsk, Russia and in Mongolia at Zuumharaa and Ulaanbaatar. This is the first earthquake within about 200 km of this epicenter with M>=5.6 since an M 6.7 on January 11, 2021 and is probably an aftershock of that event, the largest in the area in at least 30 years. An M 5.6 occurred about 300 km to the northeast of this event on September 21, 2020, the first in this larger region since an M 6.2 on August 27, 2008. At the time of the event in January, 2021, this summary noted in this regard:

 

"The only earthquake within about 300 km of this epicenter of equal or larger magnitude in this region near the Russia-Mongolia border was an M 6.7 about 300 km to the west on February 26, 2012 - the only such event in this region in the past 30 years. This epicenter is at the seventh node (52 degrees) from both the Dodecanese Islands of October 30, 2020 and from the M 7.6 in the Alaska Peninsula of October 19, 2020. It was probably promoted by energy from these sources. One of the strongest earthquakes in this area in recent times occurred as an M 7.5 on January 12, 1862 .." (January 12, 2021)

 

Forecast 133611 had expected today's event in southern Siberia within about

150 km of this epicenter was likely around May 1. 

 

O: 03MAY2021 08:58:52  51.4N  100.4E mb=4.0  EMSC   RUSSIA-MONGOLIA BORDER REGION

O: 03MAY2021 14:11:38  51.4N  100.4E mb=4.2  EMSC   RUSSIA-MONGOLIA BORDER REGION

O:  3MAY2021 08:46:38  51.3N  100.5E Mw=5.6  EMSC   RUSSIA-MONGOLIA BORDER REGION

P:  1MAY2021 133611    51.0N   98.0E 3.0-4.7 AABAA  So. Siberia                

 

STRONG QUAKE NORTHEAST OF TAIWAN FELT IN OKINAWA, JAPAN AND TAIWAN

 

EARTHQUAKE SUMMARY FOR  MAY 2, 2021

 

The strongest earthquake in the world today was an M 5.5 (EMSC) - M 6.4 (CWB) which occurred northeast of Taiwan in the Ryukyu Islands of Japan. NEIC reported it was felt in Taiwan in Taipei and Taoyuan and in Okinawa, Japan at Chatan, Okinawa and Ishikawa. CWB reported this earthquake was felt with intensity II in Hualien and Taitung, I in Tainan, Yunlin, Chiayi, Changhua, Miaoli, Taichung, Nantou, Hsinchu, Yilan Counties, Taiwan. An earthquake of M 5.9 hit about 150 km northeast of this on March 25, 2021 with another of M 6.1 about 200 km southwest of this on December 10, 2020 but the last within about 150 km of this with M>=5.5 was an M 5.7 on February 2, 2016. A major earthquake of M 7.4 hit southwest of today's event exactly 23 years ago on May 3, 1998. It generated a local tsunami (see history section of this summary). The last event in the general area of M>=6.4 was an M 6.4 on May 31, 2016. Forecast 133486 had expected today's event in this area was likely around May 3. This earthquake occurred near local solar noon at a longitude which was expected to see maximum tidal stresses with the past full moon and may have been promoted by those tides.  The seismic forecast in this summary regarding this full moon had read:

 

"The full moon arrived on April 27, 2021 at 03:31 UT. Longitudes which were sub-solar (local solar noon) at this time were near 130 East Longitude while those near local solar midnight area near 50 West longitude. Those in the west include the Atlantic Ocean as far as the eastern Caribbean and the Shetland and South Sandwich Islands and in the east in western Japan, Taiwan, the Philippines and Central Indonesia. These areas may see enhanced seismicity within about 3 days of the full moon." (April 27, 2021)

 

 

O:  3MAY2021 05:07:29  25.8N  123.9E Mw=5.5  EMSC   NORTHEAST OF TAIWAN          

O:  3MAY2021 05:07:31  25.5N  123.9E ML=6.4  TAI    Hualien, Taiwan              

P:  3MAY2021 133485    24.0N  124.0E 4.0-5.5 ABAAA  Taiwan                     

 

An earthquake of M 5.6 (EMSC) -5.7 (BMG)  also occurred today in the area of Sumatra near Mentawai. BMG reported it was felt with intensity III-IV in the epicentral area of Mentawai. The last earthquake of M>=5.6 in this area was an M 5.6 north of this of March 5 following the M 8.1 in the Kermadec Islands of March 4, 2021 and prior to that an M 5.9 on November 17, 2020. Forecast 133431 had expected today's event within about 100 km was likely around May 4.

 

O:  2MAY2021 17:46:41   2.3S   99.8E Mw=5.6  EMSC   KEP. MENTAWAI REGION, INDONESI

P:  4MAY2021 133431     2.0S   99.0E 4.0-5.4 AAAAA  So. of Sumatera            

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in the Alaska Peninsula west of the aftershocks of the M 7.6 of October, 2020.  The last earthquake equal or greater magnitude in this region occurred hours before the M 7.3 near North Island New Zealand and the 8.1 in the Kermadec Islands on March 3, 2021 with M 4.3 and 3.9. Forecasts 133319 and 133614 had expected this activity was likely in the Unimak Islands within about 50 km of this epicenter in late April or early May. 

 

O: 03MAY2021 00:28:53  54.2N  161.3W mb=3.8  EMSC   ALASKA PENINSULA

O:  3MAY2021 00:16:47  54.2N  161.3W mb=3.4  EMSC   ALASKA PENINSULA             

P:  2MAY2021 133614    54.1N  164.4W 3.5-5.1 AABAA  Unimak Islands, Aleutians  

P: 24APR2021 133319    54.7N  161.2W 3.5-5.1 CAAAA  Unimak Islands, Aleutians  

 

An unusual earthquake of M 2.9 occurred in southeastern Brazil near Minas Gerais today where it was lightly felt. This is the first earthquake within about 500 km of this epicenter reported by NEIC since an M 4.2 on May 19, 2012 and prior to that an M 4.1 on May 22, 1990 about 400 km to the northwest of today's epicenter.

 

O:  2MAY2021 13:53:34  19.7S   44.0W ML=2.9  EMSC   MINAS GERAIS, BRAZIL         

 

MODERATELY STRONG QUAKE SHAKES COQUIMBO, CHILE

 

EARTHQUAKE SUMMARY FOR  MAY 1, 2021      

 

The strongest earthquake in the world today was an M 5.8 in the region of Coquimbo, Chile. NEIC reported maximum intensity VI in Coquimbo and V in La Serena and Ovalle with light shaking in Valparaiso, Copiapo, Atacama, Lampa, Puente Alto, Santiago, Chile. GUC reported this earthquake was felt with intensity  VI in  Coquimbo at Vicuna, Combarbalo, V at Andacollo, Coquimbo, Paiguano, IV in Canela, Monte Patria, Ovalle, Punitaqui, Rio Hurtado, Salamanca, III in Illapel; IV in Santiaog at Puente Alto, II in Lo Barnechea; in Valparaiso with II in Quillota, Atacama with IV in Alto del Carmen and Vallenar and III in Caldera, Copiapo, Freirina, HJuasco and Tierra Amarilla, Chile. This is the strongest earthquake within about 200 km of this epicenter in Coquimbo, Chile since an M 5.8 on October 28, 2020 and an M 6.3 on September 6, 2020, the first such events in the region since an M 6.4 on June 14, 2019. A great M 8.3 earthquake hit about 150 km south of today's epicenter on September 16, 2015 doing much regional damage. An M 5.7 hit about 800 km southeast of this in Nuquen Argentina on April 29, 2021 and may have helped promote today's event. Forecasts 133377 and 133688 had expected today's activity in Coquimbo was like in late April or early May. This epicenter is at the seventh node (51-52 degrees) from the M 6.6 in the South Atlantic of April 3, 2021 and was probably promoted by energy from that event.

 

O:  2MAY2021 06:57     30.1S   71.6W mb=5.8  GUC    Coquimbo at Vicuna, Combarbalo

O:  2MAY2021 06:57:36  30.0S   71.5W Mw=5.8  EMSC   OFFSHORE COQUIMBO, CHILE     

P:  2MAY2021 133688    30.0S   70.0W 4.0-5.6 AAAAA  Coast Central Chile        

P: 25APR2021 133377    30.0S   70.0W 4.0-5.6 CAAAA  Coast Central Chile        

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 in Southeastern Alaska. NEIC reported this earthquake was felt with maximum intensity V in Alaska at Skagway, and II-III in Gustavus, Elfin Cove, Hoonan, Haines, Yakutat, Douglas, Juneau. A foreshock of M 3.6 was felt with intensity III in Douglas, Alaska.  This is the strongest earthquake in Southeastern Alaska within about 200 km of this epicenter since an M 5.2 on December 18m 2019 and prior to that an M 5.7 on September 10, 2019. A regional foreshock occurred at this epicenter with M 2.6 following the M 4.8 near Anchorage, Alaska on April 28 suggesting stress buildup in the area. This event had been noted in this summary at the time. Forecasts 133598 and 133318 had expected today's activity was likely within about 25 km of today's epicenter in late April or early May. Activity in the area had been noted on April 26 as:

 

"A glacial surge has been occurring in southeastern Alaska. It was accompanied today by an M 2.6 Ice quake, one of the strongest in recent history. The surge is happening in Denali Park in Muldrow glacier and on April 12 reached speeds up to 100 feet per day, about 100 times as fast as normal." (April 26, 2021)

 

This activity is at the fourth node (90 degrees) from the M 8.1 in the Kermadec Islands of March 5, 2021 and was probably promoted by energy from that source. It is also near the seventh node (52 degrees) from the M 6.9 off eastern Honshu, Japan which occurred on May 1 and was probably promoted by energy from that source.

 

O: 28APR2021 04:44:39  58.5N  136.8W ML=2.6  EMSC   SOUTHEASTERN ALASKA          

P: 26APR2021 133318    58.0N  139.0W 3.0-4.8 AABAA  Southeast Alaska           

 

Today's activity is at 103 degrees from the M 7.3 off the North coast of North Island, New Zealand of March 4, 2021 and at the fourth node (90 degrees) from the Loyalty Islands M 6.6 of February 10, 2021 and was probably promoted by strong energy from those sources. Similar activity at this distance from New Zealand today occurred with an M 3.9 in Nicaragua.

 

O: 01MAY2021 13:53:03  58.2N  137.9W ML=3.6  EMSC   SOUTHEASTERN ALASKA

O: 01MAY2021 15:23:22  58.4N  138.1W mb=4.5  EMSC   SOUTHEASTERN ALASKA

O: 01MAY2021 15:23:20  58.3N  137.9W mb=4.7  ANSS   SOUTHEASTERN ALASKA

O: 01MAY2021 15:23:26  58.5N  136.8W MB=4.9  ECAN OF SKAGWAY, AK   

O: 01MAY2021 15:23:21  58.3N  137.9W MB=4.9  ECAN Yakutat, AK    

O:  1MAY2021 16:40:27  58.1N  138.0W ML=3.0  EMSC   SOUTHEASTERN ALASKA          

P: 26APR2021 133318    58.0N  139.0W 3.0-4.8 BAAAA  Southeast Alaska           

P:  3MAY2021 133598    58.3N  138.5W 3.0-4.9 AAAAA  British Colombia           

 

A moderate earthquake of M 4.3 also occurred off the coast of northern California today. This joins the regional activation which in the past two days has included event of M 5.4 off the coast of Oregon and the M 4.7-4.9 in southeastern Alaska today (see above). Today's event off western California was not reported felt but is somewhat unusual. An event of M 4.3 or greater last occurred within about 75 km of this epicenter  on January 27, 2021 with M 4.6 while a series including an M 5.5 occurred in mid May, 2020 and early May 2019 which included an M 4.8. Forecast 133281 had expected today's event was likely around April 30.

 

O:  2MAY2021 03:30:52  41.1N  127.4W mb=4.3  EMSC   OFF COAST OF NORTHERN CALIFORN

P: 30APR2021 133281    41.8N  126.9W 2.5-4.4 AAAAA  Off Coast of No. Calif     

 

STRONG QUAKE SHAKES EASTERN HONSHU, JAPAN

 

EARTHQUAKE SUMMARY FOR  APRIL 30, 2021

 

The strongest earthquake in the world today was an M 6.8 off the northern coast of Eastern Honshu, Japan. NEIC reported intensity VII in Japan in Miyagi, Prefecture in Yamoto, Tagajo, Kogota, and VI in Natori, Sendai, Kesennauma and Ishinomaki and V in Shiogama, Rifu and Iwanuma. JMA reported this earthquake with M 6.6 and noted intensity 5+ in Miyagi with intensity up to 4 throughout most of western Honshu. It was preceded by an M 4.5 to the northwest which was felt with intensity II-III in Tomisato, Oamishirasato, Chiba and in Kanagawa, Japan. No tsunami was expected with this earthquake nor were significant tsunami waves observed. Trains and some company operations were suspended following the quake but operations returned after checks revealed no major damage. While some light injuries were reported no major casualties occurred. The mainshock occurred near local solar noon and was probably promoted by strong tidal stresses related to the Full Moon of April 27 as noted in previous issues of this summary:

 

"The full moon arrived on April 27, 2021 at 03:31 UT. Longitudes which were sub-solar (local solar noon) at this time were near 130 East Longitude while those near local solar midnight area near 50 West longitude. Those in the west include the Atlantic Ocean as far as the eastern Caribbean and the Shetland and South Sandwich Islands and in the east in western Japan, Taiwan, the Philippines and Central Indonesia. These areas may see enhanced seismicity within about 3 days of the full moon." (April 27, 2021)

 

Today's event follows similar earthquakes off eastern Honshu of M 7.0 on March 20, 2021 and M 7.1 on February 13, 2021 - an event closely linked to the new moon of February 11, 2021. The last such earthquake of M>=6.8 off the coast of eastern Honshu occurred as an M 6.9 on November 32, 2016. These all appear to be aftershocks of the great M 9.3 of March 11, 2011. Far-field seismicity  may be promoted by this event as noted following previous large earthquakes in this area:

 

"Far-field triggering is possible from the M 7.1 in Japan today. Areas at 144 degrees include the South Shetland Islands, northern Chile and southern Peru; near 103 degrees in central and western Mexico, the Madeira Islands, southern Spain, Madagascar, Mayotte, at 120 degrees (node 3) at Panama and Costa Rica and Puerto Rico; at 90 degrees (node 4) at Oklahoma and Texas, South Island, New Zealand; at 72 degrees (node 5) in Central and northern California, Iceland, Croatia, eastern Europe and Turkey, Fiji, Tonga, Loyalty Islands; in  western Indonesia at 60 degrees (node 6); in Tajikistan, Indonesia, Philippines  at node 7 (51 degrees) and in New Britain, Xizang, Alaska Peninsula at node 8 (45 degrees)." (February 14, 2021)

 

Forecast 133224 had expected this activity in Japan was likely within about 100 km around April 28.

 

O: 01MAY2021 03:01:30  38.3N  141.9E ML=3.6  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 01MAY2021 06:58:30  38.2N  141.7E ML=3.8  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O:  1MAY2021 01:27:28  38.2N  141.7E Mw=6.8  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 28APR2021 133224    39.0N  142.0E 4.0-5.4 BAAAA  Off East Coast Honshu      

 

O:  1MAY2021 00:10:06  39.4N  140.6E mb=4.5  EMSC   EASTERN HONSHU, JAPAN        

P: 28APR2021 133224    39.0N  142.0E 4.0-5.4 BABAA  Off East Coast Honshu      

 

The strongest earthquake in the U.S. or Canada today was an M 4.3 in the area of Central Alaska. NEIC reported this earthquake of M  4.3 in Central Alaska was felt with intensity II-III in the area(s) of Central Alaska at Fairbanks.  This is the strongest earthquake within about 200 km of this epicenter since an M 4.3 on August 4, 2020. The last event of larger magnitude in this area was an M 4.6 on September 6, 2019. Forecast 133326 had expected today's event in Central Alaska was likely around April 28. 

 

O: 30APR2021 17:19:24  64.8N  152.4W mb=4.3  EMSC   CENTRAL ALASKA               

P: 28APR2021 133326    62.8N  151.2W 3.2-5.1 ABAAA  Central Alaska             

 

MODERATE QUAKES OFF COAST OF OREGON RELATED TO FULL MOON

 

EARTHQUAKE SUMMARY FOR  APRIL 29, 2021

 

The enhanced seismicity off the coast of Oregon of the past several days maximized today with an M 5.4 and M 5.2 in the region today. These events were felt with maximum intensity VI in Oregon at Gold Beach, and II-III in Bandon, Brookings, Portland, Seaside and Salem and in California at Fortuna and Burnt Ranch. In recent history the largest earthquakes in this area have occurred with the full moon alignment and were probably tidally promoted. In the previous issue of this summary it had been noted in this regard:

 

"The strongest earthquake in the U.S. or Canada today was an M 4.4 off the coast of Oregon. This is the strongest earthquake within about 150 km of this epicenter since an M 5.1 and  an M 4.9 on February 20, 2021. A moderate quake of M 5.7 on December 29, 2020 was the only other such earthquake in the area in the past year. Forecast 133282 had expected today's event was likely around  April 29." (April 28-29, 2021)

 

Prior to the M 5.7 of December 29, 2020, the area had not seen an event of M>=5.4 since and M 5.9 on September 5, 2019, an aftershock of an M 6.3 on August 29, 2019.

 

Similar to today's event, the earthquake of December 29, 2020 occurred with the full moon of December 30, as noted  in this summary at the time:

 

"The strongest earthquake in the U.S. or Canada today was an M 5.7 off the Coast of Oregon. NEIC reported it was felt lightly along the coast in Bandon, Langlois, Port Orford, Coquille, Coos Bay, Gold Beach, Lakeside, North Bend, Florence, and Newport, Oregon. This event occurred near local solar midnight and may have been promoted by tidal triggering associated with the full moon on December 30 " (December 30, 2020)

 

and

 

"The third promoter of today's event off Oregon was probably high astronomical tides associated with the new moon." (August 30, 2019)

 

Previous events in the region including an M 6.2 on August 22, 2018; July 17, 2019 (M 5.4); August 16, 2019 (M 5.4). These events were also noted at the time to have been closely associated with the full moon as noted at the time in this summary:

 

"The strongest earthquake in the U.S. or Canada today was an M 5.4 off the coast of Oregon. NEIC reported it may have been felt lightly in Oregon at Eugene and Medford and in Seattle, Washington. A foreshock to the southeast of the M 5.4 occurred earlier in the day near local solar midnight and may have been promoted by strong tidal stresses associated with the full moon. The last event with M>=3.9 near the foreshock occurred a month ago on July 17, 2019 and prior to that as an M 4.1 on June 26, 2019. Both the event in June and July (2019) occurred with the full moon as noted at the time" (August 17, 2019)

 

Today's events of M 5.3, 5.4 and 5.2 occurred within about 25-50 km of the  epicenter expected in forecast 133282 which expected this activity was likely around April 29. This activity is at 142 degrees from the M 6.6 in the South Atlantic of April 3, 2021, the last strong global earthquake and at the fourth node (90 degrees) from the M 7.3 in the region of North Island, New Zealand of March 4, 2021 and may have been promoted by energy from those sources. Similar events at the fourth node from New Zealand occurred today in Guerrero, Mexico (M 5.0) and in California and the Gulf of California among others.

 

O: 29APR2021 13:24:55  43.8N  128.2W mb=4.1  EMSC   OFF COAST OF OREGON

O: 29APR2021 13:33:00  43.8N  128.4W mb=3.9  EMSC   OFF COAST OF OREGON

O: 29APR2021 10:30:21  43.9N  128.5W Mw=5.4  EMSC   OFF COAST OF OREGON

O: 29APR2021 10:35:45  43.9N  128.5W Mw=5.2  EMSC   OFF COAST OF OREGON

O: 29APR2021 10:58:35  43.9N  128.1W Mw=5.3  EMSC   OFF COAST OF OREGON

O: 29APR2021 10:25:16  44.0N  128.0W mb=4.3  EMSC   OFF COAST OF OREGON

O: 29APR2021 13:24:55  43.8N  128.2W mb=4.1  EMSC   OFF COAST OF OREGON          

P: 29APR2021 133282    44.1N  128.8W 3.0-4.7 AAAAA  Off Coast of Oregon        

 

The strongest seismicity in the world today continued to occur in the aftershock

zone of the Northern Kermadec Islands following the mainshock in that area of March 4, 2021. None of these events including an M 5.9 and two of M 5.5 were reported felt in this remote area. This continues elevated seismicity in this region as discussed in the previous issue of this summary:

 

 

"The strongest earthquake in the world that was not felt today was an M 5.9 in the continuing aftershock sequence in the northern Kermadec Islands, New Zealand. This followed an M 5.4 off northern North Island, New Zealand. The last earthquake in this aftershock zone in northern Kermadec Islands with M>=5.9 occurred on April 27, 2021 also with M 5.9. Earthquakes of M 6.0 on April 7 and M 6.5 on April 1 complete the list of similar earthquakes since the immediate aftershocks of the M 8.1 on March 4.  Forecasts 133362 had expected today's activity in the aftershock zone within about 50 km of this epicenter around April 26-30." (April 28-29, 2021) 

 

O: 29APR2021 13:55:31  29.2S  176.5W mb=5.0  EMSC   KERMADEC ISLANDS REGION

O: 29APR2021 06:50:30  29.4S  176.7W Mw=5.9  EMSC   KERMADEC ISLANDS REGION

O: 29APR2021 07:06:37  29.5S  176.6W mb=5.0  EMSC   KERMADEC ISLANDS REGION

O: 29APR2021 13:54:12  29.5S  176.5W mb=4.9  EMSC   KERMADEC ISLANDS REGION

O: 29APR2021 12:25:27  29.7S  176.8W mb=5.1  EMSC   KERMADEC ISLANDS REGION

O: 29APR2021 09:19:33  29.8S  177.7W mb=4.6  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 30APR2021 02:06:15  29.8S  177.6W mb=5.5  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 29APR2021 07:44:57  29.9S  177.7W mb=4.8  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 29APR2021 21:39:04  30.6S  177.6W mb=5.0  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 29APR2021 06:53:53  29.2S  176.9W mb=5.5  EMSC   KERMADEC ISLANDS REGION      

P: 26APR2021 133362    29.0S  177.0W 4.0-5.7 BAAAA  No. Kermadec Islands       

P: 30APR2021 133362    28.0S  176.0W 4.0-5.8 ABAAA  No. Kermadec Islands       

 

MODERATELY STRONG QUAKE SHAKES MAULE, CHILE

 

EARTHQUAKE SUMMARY FOR  APRIL 28, 2021

 

The strongest earthquake felt in the world today was an M 5.7 in Neuquen, Argentina. NEIC reported it was felt with maximum intensity IV in Bio Bio, Chile at Mutchen, Los Angeles, Laja, and Chiguayante with lesser shaking in Concepcion, Talcahuano, Nacimento, Cabrero, and Chilan. GUC reported this earthquake was felt with intensity  V in  Maule at Constitucion, IV in Cauquenes, Linares, Parral, Pelluhue, III in Yerbas Buenas, Villa Alegre, Talca, San Javier, Sagrada Familia, Pencahue, Pelarco, Longavi, Curico, in O'Higgins with IV in Pumanque and III in Lolol, Palmilla, Oeralillo, Santa Cruz; and in Santiago with III in Cerro Vavia and San Bernrdo and II in El Monte and Pedro Aguirre Cerda, Chile. This unusual felt pattern is probably due to the intermediate depth (137 km) of this hypocenter. The last earthquake within about 200 km of this epicenter with M>=5.7 was an M 5.9 on May 29, 2017 about 100 km west of today's epicenter. Today's event is the largest under Argentina within about 200 km since an M 5.9-6.0 on June 7, 2021. Forecasts 133374 and 133375 had expected today's event was likely in this area around April 24-27.

 

O: 29APR2021 02:17:16  37.2S   70.8W Mw=5.7  EMSC   NEUQUEN, ARGENTINA           

O: 29APR2021 02:17     37.3S   71.2W mb=5.4  GUC    Maule at Constitucion, IV in C

P: 24APR2021 133374    36.0S   73.0W 4.0-5.6 BBBAA  Central Chile              

P: 27APR2021 133375    39.0S   73.0W 4.0-5.5 ABBAA  Central Chile              

 

The strongest earthquake in the world that was not felt today was an M 5.9 in the continuing aftershock sequence in the northern Kermadec Islands, New Zealand. This followed an M 5.4 off northern North Island, New Zealand. The last earthquake in this aftershock zone in northern Kermadec Islands with M>=5.9 occurred on April 27, 2021 - also with M 5.9. Earthquakes of M 6.0 on April 7 and M 6.5 on April 1 complete the list of similar earthquakes since the immediate aftershocks of the M 8.1 on March 4.  Forecasts 133362 had expected today's activity in the aftershock zone within about 50 km of this epicenter around April 26-30. 

 

O: 28APR2021 15:25:20  29.3S  176.8W mb=4.8  EMSC   KERMADEC ISLANDS REGION

O: 29APR2021 06:50:31  29.3S  176.7W Mw=5.9  EMSC   KERMADEC ISLANDS REGION      

P: 26APR2021 133362    29.0S  177.0W 4.0-5.7 BAAAA  No. Kermadec Islands       

P: 30APR2021 133362    28.0S  176.0W 4.0-5.8 ABAAA  No. Kermadec Islands       

 

 

A moderate earthquake of M 5.4-5.8 occurred today off the east coast of North Island, New Zealand. NEIC reported it was felt with maximum intensity IV in Gisborne, New Zealand at Ruatoria, Tolaga Bay and Gisborne and in Opotiki, Whakatane, Bay of Plenty and in Nuhaka, and Wairoa, Hawkes Bay. GEONET reported this earthquake was felt with weak intensity in North Island, New Zealand with 906 reports of which 626 reported weak shaking; 250 light, 26 moderate, 2 strong, 0 Severe and 0 extreme intensity. The last earthquake in this aftershocks zone with M>=5.8 occurred on April 5, 2021 with M 6.0. The only other such aftershock of M>=5.8 in the area since the M 7.3 on March 4 was an M 6.3 on March 6, 2021.  Forecast 133378 had expected today's event was likely around April 28.

 

O: 29APR2021 03:58:47  37.6S  179.7E ML=5.8  GEONET Felt with weak intensity

O: 29APR2021 03:58:45  37.7S  179.7E Mw=5.4  EMSC   OFF E. COAST OF N. ISLAND, N.Z

P: 28APR2021 133378    37.0S  179.0W 3.5-4.9 AAAAA  E. of North Islands N.Z.   

 

The M 5.8 off North Island was preceded by an M 4.5-4.6 about 200 km to the west earlier in the day.  GEONET reported this earthquake was felt by 216 people with weak intensity by 174 and light intensity by 39 persons and moderate intensity by 3. Strong shaking was felt by 0 with no one feeling the quake with severe and 0 with extreme intensity. This event had been expected in forecast 133380 within about 100 km to occur around April 25.

 

O: 28APR2021 19:33:35  37.2S  177.3E ML=4.5  GEONET reported felt

O: 28APR2021 19:33:32  37.3S  177.3E mb=4.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z

P: 25APR2021 133380    38.0S  178.0E 3.0-4.6 BAAAA  North Island, N.Z.         

 

Aftershocks continued today in the area of Assam, India following the M 6.4 in

that area yesterday. The strongest of these was an M 4.8 which NEIC reported was

felt with maximum intensity VII in Bondila, Arunachal Pradesh, India with IV in Assam at Sualkuch, Gauhati, Dispur, Dhekiajuli, Tezpur and III in Nagao, Raha Gaon, North Gawahati, and III in Gohpur, Rana Gaon, Nagaon, Assam, India. Forecast 133182 had expected activity in  this area to the west was likely in late April.

 

O: 28APR2021 19:50:53  26.8N   92.5E mb=4.8  EMSC   ASSAM, INDIA

O: 28APR2021 12:09:57  26.6N   92.4E ML=3.0  EMSC   ASSAM, INDIA                 

P: 24APR2021 133182    27.0N   88.0E 3.5-5.4 BACAA  Nepal                      

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 off the coast of Oregon. This is the strongest earthquake within about 150 km of this epicenter since an M 5.1 and  an M 4.9 on February 20, 2021. A moderate quake of M 5.7 on December 29, 2020 was the only other such earthquake in the area in the past year. Forecast 133282 had expected today's event was likely around  April 29.

 

O: 28APR2021 21:36:26  43.9N  127.9W mb=4.4  EMSC   OFF COAST OF OREGON          

P: 29APR2021 133282    44.1N  128.8W 3.0-4.7 AAAAA  Off Coast of Oregon        

 

An earthquake of M 2.8 was widely felt in the area of San Francisco Bay, California. NEIC reported intensity IV n Berkeley and II-III associated with this event in Oakland, and Orinda as well as other communities. This continues enhanced seismicity in the area including an M 2.6 on April 26. Earthquakes of stronger magnitude in the San Francisco Bay area have most recently occurred as an M 3.0 on April 1, 2021 and an M 4.0 on February 8, 2021. Forecast 133201 had expected today's event within about 15 km of this epicenter was likely around April 27.

 

O: 28APR2021 07:18:37  37.9N  122.2W Md=2.8  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P: 27APR2021 133201    38.0N  122.3W 2.5-4.7 AAAAA  Central California         

 

FULL MOON PROMOTES STRONG QUAKES IN INDIA, NEW GUINEA AND KERMADEC ISLANDS

 

EARTHQUAKE SUMMARY FOR  APRIL 27, 2021

 

The strongest earthquake in the world today was an M 6.0 in Assam, India. The National Center for Seismology (NCS) of India gives this event M 6.4. The mainshock was reported felt with maximum shaking and damage in Assam at Udalguri; VII in Dhekiajuly, Rangapara, Nagaon, VI in Tezpur, Tangla, Raha Gaon and North Guwahati and V in Gauhati, Assam, India. An M 4.7 aftershock was felt with intensity VII in Assam at Tezpur; VI m Gauhati, and Samdrup; V in Dohu, Palasbari, Bondila, Nagaon; IV in Dispur and Shillong, Meghalaya, India.

Cracks appeared in walls, ceilings and floors of some buildings, with some reports of collapsed ceilings and walls, but there were no immediate reports of casualties. Internet showed extensive damage in some areas. People fled their homes into the streets during the earthquake. The last earthquake within about 250 km of today's activity with M>=6.0 occurred on September 21, 2009, the only such event in this region in at least 30 years although an M 5.9-6.0 quake hit about 200 km south of this on May 8, 1997. The last event of larger magnitude in the general area of northern India was an M 6.9 at intermediate depth on April 13, 2016 in Bangladesh.  Forecast 133180 had expected today's event to the southeast was likely around April 23. This event is located at 103 degrees from the M 8.1 in the Kermadec Islands of March 4, 2021 and th M 7.3 in North Island, New Zealand of the same date. After large earthquakes reflections off the core-mantle boundary seismic energy returns to the surface in the area of 103 degrees from the epicenter of the strong quake. Seismicity at this distance often increases following and is probably promoted by energy from the strong quake as in  this case and had been expected at the time of the Kermadec quake to  occur in northern India as:

 

"Far field seismic enhancement following the events in the Kermadec area is likely to include areas of … and central Asia north of India" (March 4, 2021)

 

O: 28APR2021 02:33:00  26.7N   92.5E mb=4.9  EMSC   ASSAM, INDIA

O: 28APR2021 02:43:21  26.7N   92.4E ML=4.0  EMSC   ASSAM, INDIA

O: 28APR2021 02:21:25  26.8N   92.4E Mw=6.0  EMSC   ASSAM, INDIA

O: 28APR2021 02:21:25  26.7N   92.4E Mw=6.4  NCS    ASSAM, INDIA

O: 28APR2021 03:14:34  26.6N   92.5E ML=3.6  EMSC   ASSAM, INDIA

O: 28APR2021 05:09:12  26.6N   92.5E ML=3.4  EMSC   ASSAM, INDIA

O: 28APR2021 02:55:40  26.5N   92.5E ML=3.6  EMSC   ASSAM, INDIA                  

P: 23APR2021 133180    25.0N   95.0E 4.0-5.4 BBBAA  Myanmar                    

 

A strong M 5.9-6.1 earthquake also occurred in New Guinea today. NEIC reported it was felt with intensity V in Goroka, Eastern Highlands, Papua New Guinea. It was followed by moderate aftershocks of M 5.4 and 5.2. This activity follows an M 5.7 foreshock in the region which was noted in the previous issue of this summary as:

 

"The strongest earthquake in the world today was an M 5.7 in Papua New Guinea. It was reported with light intensity as far as Queensland, Australia. This event occurred within minutes of local solar noon and an hour of the full moon in a region where which was expected to see maximum tidal stresses with this full moon. It was likely triggered by effects related to the full moon. ...

 

 

This may also be related to the minor geomagnetic storm currently active as this  epicenter lies on the geomagnetic equator where effects of such storms are at maximum. ...

 

 

Today's event was forecast within about 150 km of this epicenter to occur around April 27. An M 6.0 near this epicenter occurred on April 10, 2021. This may be an aftershock of that event." (April 27, 2021)

 

Today's event of M 6.1 is the largest in the area since an M 6.4 on February 7, 2021 and prior to that an M 6.2 on January 17, 2019. Forecast 133126 had expected this activity was likely around April 27.

 

O: 27APR2021 10:40:49   3.4S  145.5E mb=5.4  EMSC   NEAR N COAST OF NEW GUINEA, PNG.

O: 27APR2021 11:04:24   3.4S  145.6E Mw=5.3  EMSC   NEAR N COAST OF NEW GUINEA, PNG.

O: 27APR2021 08:03:49   3.6S  145.7E mb=5.1  EMSC   NEAR N COAST OF NEW GUINEA, PNG.

O: 27APR2021 15:01:11   4.0S  145.6E ML=4.6  EMSC   NEAR N COAST OF NEW GUINEA, PNG.

O: 27APR2021 08:05:32   3.4S  145.5E Mw=5.9  EMSC   NEAR N COAST OF NEW GUINEA, PN

O: 27APR2021 08:05:32   3.4S  145.5E Mw=6.1  ANSS   NEAR N COAST OF NEW GUINEA, PN

P: 27APR2021 133126     5.0S  146.0E 4.0-5.4 AAAAA  New Ireland                

 

A series of moderate to strong aftershocks in the northern Kermadec Islands of New Zealand also continued today with the largest of M 5.9-6.0. This series had been noted in the previous issue of this summary as:

 

"The most active area of the world today was the northern Kermadec Islands. Moderately large event occurred in the area with M 5.5 and 5.7-5.8. These are aftershocks of the M 8.1 in the area that occurred on March 4, 2021. Earthquakes of M 5.0 and 5.5 in the sequence occurred near local solar midnight and local solar noon and may have been promoted by high tidal stresses associated with today's full moon. Forecast 133362 had expected today's activity withini about 50 km was likely around April 26." (April 26-27, 2021)

 

Forecasts 133370 and 133362 had expected today's activity at the end of April with magnitude up to M 5.9.

 

O: 27APR2021 13:29:11  29.4S  176.7W mb=4.8  EMSC   KERMADEC ISLANDS REGION

O: 28APR2021 02:57:25  29.4S  176.6W mb=5.1  EMSC   KERMADEC ISLANDS REGION

O: 27APR2021 18:28:57  29.5S  176.7W mb=4.9  EMSC   KERMADEC ISLANDS REGION

O: 28APR2021 04:24:32  29.5S  176.7W mb=4.9  EMSC   KERMADEC ISLANDS REGION

O: 27APR2021 16:43:10  29.6S  176.7W mb=5.1  EMSC   KERMADEC ISLANDS REGION

O: 27APR2021 17:15:48  29.6S  176.7W mb=5.0  EMSC   KERMADEC ISLANDS REGION

O: 27APR2021 17:53:07  29.7S  176.9W Mw=5.3  EMSC   KERMADEC ISLANDS REGION

O: 27APR2021 23:14:40  30.1S  179.4E ML=4.3  EMSC   KERMADEC ISLANDS REGION

O: 27APR2021 16:33:33  29.1S  176.8W Mw=5.9  EMSC   KERMADEC ISLANDS REGION      

P: 26APR2021 133370    27.0S  176.0W 4.0-5.6 AAAAA  Tonga Islands              

P: 26APR2021 133362    29.0S  177.0W 4.0-5.7 AAAAA  No. Kermadec Islands       

P: 30APR2021 133362    28.0S  176.0W 4.0-5.8 AAAAA  No. Kermadec Islands       

 

An unusual earthquake of M 4.7 occurred in the Amazon region of Brazil today. NEIC reported it was felt in Brazil at Manaus, Amazonas. This event occurred within about 30 minutes of local solar midnight and was probably promoted by strong tidal stresses associated with today's full moon. This summary had forecast tidal effects on seismicity with this full moon in previous issues as:

 

"The full moon arrived on April 27, 2021 at 03:31 UT. Longitudes which were sub-solar (local solar noon) at this time were near 130 East Longitude while those near local solar midnight area near 50 West longitude. Those in the west include the Atlantic Ocean as far as the eastern Caribbean and the Shetland and South Sandwich Islands and in the east in western Japan, Taiwan, the Philippines and Central Indonesia. These areas may see enhanced seismicity within about 3 days of the full moon." (April 27, 2021)

 

The last earthquake located within about 300 km of this epicenter in Brazil with M>=4 was an M 4.4 about 300 km to the southwest on February 8, 2005 and an M 4.2 about 250 km northwest of this epicenter on March 15, 1999. No events of M>=4.7 have been recorded in this area in at least 30 years until today.

 

O: 28APR2021 03:26:40   0.5S   61.6W mb=4.7  EMSC   AMAZONAS-RORAIMA BORDER, BRAZI

 

The strongest earthquake in the U.S. or Canada today was an M 4.8 north of Anchorage, Alaska. NEIC reported maximum intensity IV in Anchorage with III in Elmendorf AFB, Fort Richardson and Wasilla, Alaska, among other communities. An M 4.1-4.3 preceded this event about 100 km to the south. NEIC reported this event was felt with intensity IV in Fort Richardson and II-III in Seward, Moose Pass, Valdez, Girdwood, Eagle River, Anchorage. The last earthquake in the Anchorage area of M>=4.7 within about 200 km of today's epicenter was an M 5.3 on February 27, 2021 and prior to that an M 5.0 on November 7, 2020 an October 4, 2019. These are aftershocks of th M 7.0 of November 30, 2018. Forecast 133323 had expected today's activity was likely within about 100 km around April 25-27. Like the event in Assam, India, the M 4.7 is located at 102-103 degrees from the M 7.3 off North Island, New Zealand and may have been promoted by energy from that source.

 

A glacial surge has been occurring in southeastern Alaska. It was accompanied today by an M 2.6 Ice quake, one of the strongest in recent history. The surge is happening in Denali Park in Muldrow glacier and on April 12 reached speeds up to 100 feet per day, about 100 times as fast as normal.

 

O: 28APR2021 04:44:39  58.5N  136.8W ML=2.6  EMSC   SOUTHEASTERN ALASKA          

P: 26APR2021 133318    58.0N  139.0W 3.0-4.8 AABAA  Southeast Alaska           

 

O: 27APR2021 17:26:00  60.4N  147.7W mb=4.3  EMSC   SOUTHERN ALASKA              

P: 25APR2021 133323    61.2N  147.4W 3.2-5.0 AAAAA  Central Alaska             

 

O: 27APR2021 17:54:36  61.3N  150.0W Mw=4.8  ANSS   SOUTHERN ALASKA              

O: 27APR2021 17:54:34  61.3N  150.0W Mw=4.7  EMSC   SOUTHERN ALASKA              

P: 27APR2021 133323    60.5N  148.5W 3.2-5.1 AAAAA  Central Alaska             

 

An earthquake of M 2.8 was widely felt in the area of San Francisco Bay, California. NEIC reported intensity IV n Berkeley and II-III associated with this event in Oakland, and Orinda as well as other communities. This continues enhanced seismicity in the area including an M 2.6 on April 26. Earthquakes of stronger magnitude in the San Francisco Bay area have most recently occurred as an M 3.0 on April 1, 2021 and an M 4.0 on February 8, 2021. Forecast 133201 had expected today's event within about 15 km of this epicenter was likely around April 27.

 

O: 28APR2021 07:18:37  37.9N  122.2W Md=2.8  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P: 27APR2021 133201    38.0N  122.3W 2.5-4.7 AAAAA  Central California         

 

A series of light earthquakes also shook the region of Los Angeles, California near local solar noon today. These could be precursory to a larger regional event in the next week. They occurred near 100 degrees from the M 6.0 in  Papua New Guinea earlier in the day, a distance at which triggering is possible from larger earthquakes. Forecast 133234 had expected today's activity was likely within about 10 km of this epicenter around April 25.

 

O: 27APR2021 18:27:19  33.9N  118.4W Ml=2.2  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 27APR2021 19:36:08  33.9N  118.4W Ml=2.1  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 27APR2021 18:17:48  34.0N  118.4W Ml=2.2  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 27APR2021 16:38:12  33.9N  118.4W Ml=2.4  EMSC   GREATER LOS ANGELES AREA, CALI

P: 25APR2021 133234    33.9N  118.3W 2.5-4.8 AAAAA  So. California             

 

An earthquake of M 4.1 was accompanied by events of M 3.0 and 3.4 in western Texas today.  NEIC reported an earthquake of M 4.0 in Western Texas was felt with intensity II-III in the area(s) of Carlsbad, New Mexico.  This event occurred near local solar noon and was probably promoted by strong tidal stresses associated with today's full moon, which maximize near this hour.  The M 4.1 occurred near local solar noon and was probably enhanced by strong tidal stresses associated with the full moon which maximize near this hour. The only earthquake in this region of Texas in the past year with greater magnitude was an M 4.5 on March 17, 2021. These are probably aftershocks of an M 5.0 on March 26, 2020. Like today's event of M 4.0-4.1, the M 5.0 on March 26, 2020 occurred a day after the new moon tidal event. Forecast 133227 had expected today's event around April 24. Like the events in Anchorage, Alaska and Assam, India, the M 4.1 in western Texas is located near 100 degrees from the M 7.3 off North Island, New Zealand and may have been promoted by energy from that source.

 

O: 27APR2021 13:21:18  31.7N  104.2W ML=3.0  EMSC   WESTERN TEXAS

O: 27APR2021 19:42:10  31.7N  104.4W ML=4.1  EMSC   WESTERN TEXAS

O: 27APR2021 19:42:10  31.7N  104.4W ML=4.0  ANSS   WESTERN TEXAS

O: 28APR2021 02:10:42  31.7N  104.6W ML=3.4  EMSC   WESTERN TEXAS

O: 27APR2021 13:06:07  31.7N  104.2W ML=2.7  EMSC   WESTERN TEXAS                

P: 24APR2021 133227    32.6N  104.6W 2.0-3.9 BAAAA  SW U.S.A                    

 

MODERATELY STRONG QUAKE IN NEW GUINEA WITH FULL MOON AND GEOMAGNETIC STORM

 

EARTHQUAKE SUMMARY FOR  APRIL 26, 2021

 

The strongest earthquake in the world today was an M 5.7 in Papua New Guinea. It was reported with light intensity as far as Queensland, Australia.  This event occurred within minutes of local solar noon and an hour of the full moon in a region where which was expected to see maximum tidal stresses with this full moon. It was likely triggered by effects related to the full moon. This had been expected in the full moon forecast previously published in this summary as:

 

"The full moon will arrive on April 27, 2021 at 03:31 UT. Longitudes which are sub-solar (local solar noon) at this time are near 130 East Longitude while those near local solar midnight area near 50 West longitude. Those in the west include the Atlantic Ocean as far as the eastern Caribbean and the Shetland and South Sandwich Islands and in the east in western Japan, Taiwan, the Philippines and Central Indonesia. These areas may see enhanced seismicity within about 3 days of the full moon.

 

This may also be related to the minor geomagnetic storm currently active as this  epicenter lies on the geomagnetic equator where effects of such storms are at maximum. The previous issue of this summary had noted in this regard:

 

"The geomagnetic field saw active to minor storm conditions today. The AP level was 20.  High latitude geomagnetic field also saw stormy conditions with AP 40. This is a reemergence of  the strongest geomagnetic storm since AP reached 29 on March 20 and the strongest at high latitudes since AP reached 62 in polar areas on October 26, 2019. A major geomagnetic storm is expected around April 25-26. Enhanced seismicity is expected in late April near the geomagnetic equator and at high latitudes due to effects from this geomagnetic storm." (April 26, 2021)

 

Today's event was forecast within about 150 km of this epicenter to occur around April 27. An M 6.0 near this epicenter occurred on April 10, 2021. This may be an aftershock of that event. At the time this summary noted in this regard:

 

 

"The strongest earthquake in the world today was an M 6.0-6.1 off the north coast of New Guinea. NEIC reported it was felt in Papua New Guinea with intensity II-III at Madang and Mount Hagen. It was probably promoted by high tidal stresses associated with the New Moon of April 12 as noted in previous issues of this report maximize near this longitude:

 

and

 

 

This epicenter is near the geomagnetic equator and like similar events in the

Celebes Sea and in Java today may have been prompted by the now-concluded strong geomagnetic storm previously identified ...

 

The only events within about 200 km of today's epicenter within the past three years occurred as an M 6.3 on February 7, 2021 and an M 6.2 on January 17, 2019." (April 10, 2021)

 

O: 27APR2021 02:12:50   3.4S  145.5E Mw=5.7  EMSC   NEAR N COAST OF NEW GUINEA, PN

P: 27APR2021 133126     5.0S  146.0E 4.0-5.4 ABAAA  New Ireland                

 

The most active area of the world today was the northern Kermadec Islands. Moderately large event occurred in the area with M 5.5 and 5.7-5.8. These are aftershocks of the M 8.1 in the area that occurred on March 4, 2021. Earthquakes of M 5.0 and 5.5 in the sequence occurred near local solar midnight and local solar noon and may have been promoted by high tidal stresses associated with today's full moon. Forecast 133362 had expected today's activity withini about 50 km was likely around April 26.

 

O: 27APR2021 01:28:10  29.1S  178.4W mb=4.6  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 26APR2021 13:42:22  29.3S  177.6W mb=5.5  EMSC   KERMADEC ISLANDS, NEW ZEALAND

O: 26APR2021 19:57:52  29.3S  176.5W mb=5.0  EMSC   KERMADEC ISLANDS REGION

O: 26APR2021 21:12:10  29.3S  176.6W mb=5.2  EMSC   KERMADEC ISLANDS REGION

O: 26APR2021 21:07:27  29.5S  176.7W Mw=5.8  EMSC   KERMADEC ISLANDS REGION

O: 26APR2021 21:07:27  29.5S  176.7W Mw=5.7  ANSS   KERMADEC ISLANDS REGION

O: 27APR2021 00:44:54  29.5S  176.8W mb=5.0  EMSC   KERMADEC ISLANDS REGION      

P: 26APR2021 133362    29.0S  177.0W 4.0-5.7 AAAAA  No. Kermadec Islands       

 

An earthquake of M 4.0 in the Virgin Islands today was felt with intensity III in San Juan, Puerto Rico. This event was probably promoted by the full moon as it occurred within minutes of the full moon and within minutes of local solar midnight. The area had been expected to see enhanced seismicity with this full moon (see above). The last earthquake to the east of this epicenter in the Virgin Islands was an M 4.4 on April 16, 2019. Forecast 133171 had expected today's event within about 50 km was likely around April 25.

 

O: 27APR2021 03:49:20  19.2N   63.7W ML=3.4  EMSC   VIRGIN ISLANDS REGION        

O: 27APR2021 03:49:22  19.4N   63.9W ML=4.0  ANSS   VIRGIN ISLANDS REGION        

P: 25APR2021 133171    20.0N   64.0W 3.0-4.4 AAAAA  Bahamas/No. Caribbean      

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 off the coast of Oregon, NEIC reported it may have been felt with light intensity in Oregon at Port Orford and Gresham. The last earthquake of larger magnitude within about 100 km of this epicenter was an 5.4 on August 15, 2019. Forecast 133282 had expected today's event was likely within about 10 km of this epicenter around April 29. This event occurred near local solar noon and may have been promoted by high tidal stresses which maximize near this hour.

 

O: 26APR2021 22:33:42  44.2N  128.9W mb=4.1  EMSC   OFF COAST OF OREGON          

P: 29APR2021 133282    44.1N  128.8W 3.0-4.7 BAAAA  Off Coast of Oregon        

 

The area of Hawaii was active today with two events of M 3.4 and M 3.6 west of the Loi'hi Seamount area south of Hawaii and northwest of Hawaii. This later event was preceded by an M 3.1 and occurred within about 30 minutes of local solar noon and was probably promoted by high tidal stresses associated with today's full moon. Forecast 133176 had expected this event was likely around April 28. Similar events of M>=3.6 within about 100 km of this epicenter occurred as an M 3.8 on February 23, 2021 and M 3.7 on May 7, 2020. Forecast 133176 had expected today's event in this region was likely around April 28. Today's earthquake was preceded earlier in the day by an M 3.4 foreshock. This had been noted in the previous issue of this summary as:

 

 

"NEIC reported the earthquake of M 3.4 in Hawaii was felt with intensity II-III in the area(s) of Hawaii in Kailua Kona. Hawaii is located at the seventh node (52 degrees) from the M 8.1 in the Kermadec Islands of March 4 and the M 7.7 in the Loyalty Islands of February 10 and may have been promoted by energy from those sources. " (April 25-26, 2021)

 

NEIC reported the earthquake of M 3.6 in Hawaii was felt with intensity II-III in the area(s) of Hawaii at Naalehu.

 

O: 26APR2021 22:57:19  19.8N  156.8W ML=3.1  EMSC   HAWAII REGION, HAWAII

O: 26APR2021 23:05:52  19.7N  156.8W ML=3.4  EMSC   HAWAII REGION, HAWAII        

O: 26APR2021 23:05:55  19.7N  156.8W ML=3.6  ANSS   HAWAII REGION, HAWAII        

P: 28APR2021 133176    20.1N  156.1W 4.0-5.8 AAAAA  Hawaii area                 

 

The earthquake south of Hawaii of M 3.4 was the strongest this far to the southwest of the big island since an M 3.9 on May 6, 2020. This was followed on May 12, 2020 by a series of events of M 3.4-3.8 about 75 km to the east. Forecast 133151 had expected activity in this area around April 25. NEIC reported this earthquake of M 3.4 off southern Hawaii  was felt with intensity II-III in the area(s) of Hawaii in Kamuela (IV), and II in Naaleu, Captain Cook, Kailua Kona.

 

O: 26APR2021 16:18:23  18.9N  155.9W ML=3.4  EMSC   HAWAII REGION, HAWAII        

P: 25APR2021 133151    18.8N  155.2W 3.0-4.7 AAAAA  Hawaii                     

 

Two moderate earthquakes hit the South Atlantic today. These were an M 5.3 in the South Sandwich Islands and an  M 5.0 in the South Shetland Islands. These events had been expected in the epicentral areas in forecasts 133394 and 133395. They may have been related to high tidal stresses with today's full moon or with the current geomagnetic storm which can trigger events at high latitudes.

 

O: 26APR2021 19:13:10  56.2S   27.5W Mw=5.3  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 27APR2021 133394    58.0S   26.0W 4.0-6.0 ABAAA  So. Sandwich Islands       

 

O: 27APR2021 00:00:01  62.4S   58.4W mb=5.0  EMSC   SOUTH SHETLAND ISLANDS       

P: 23APR2021 133395    62.0S   58.0W 3.0-5.4 BAAAA  So. So. America            

 

A pair of moderate aftershocks occurred in the region of Gabon, West Africa today. These are aftershocks of the M 5.2 and 5.4 in the area of March 6 and 9, 2021 and are the largest since those events occurred. They occurred near local solar midnight and may have been promoted by high tidal stresses with the full moon. The activity in Gabon is near 144 degrees from the M 8.1 in the Kermadec  Islands of March 5 and is probably promoted by energy from that source.

 

O: 27APR2021 00:38:57   1.1S   10.1E mb=4.5  EMSC   GABON

O: 27APR2021 00:40:56   1.1S   10.2E mb=4.7  EMSC   GABON                        

 

SECOND STRONG EARTHQUAKE IN TONGA SIMILAR TO THAT OF APRIL 23

 

EARTHQUAKE SUMMARY FOR  APRIL 25, 2021

 

The strongest earthquake in the world today was an M 6.4-6.5 in central Tonga. NEIC reported it may have been felt as far to the north as Samoa with intensity III. This event is similar in many ways to the M 6.5 in Tonga which occurred two days ago and was reported at the time in this summary as:

 

"The strongest earthquake in the world today was an M 6.5  in Central Tonga. NEIC reported it was felt with intensity VI in Tofoa-Koloua, Tonga  and II in Neiafu, Vavau, Tonga. The last earthquake with M>=6.5 in the world was an M 6.6 on April 3, 2021 in the South Atlantic. The only other event of this magnitude or greater in the world in the past month was an M 6.5 aftershock in the Kermadec Islands on April 1, 2021. This earthquake occurred near local solar noon in an area near the regional geomagnetic equator. It was preceded about an hour earlier by an M 5.3 about 150 km to the south, an earthquake which occurred within about 30 minutes of local solar noon. It was probably promoted effects from the strong geomagnetic storm and solar flares of the past several days which maximize near this hour. The M 6.5 is the strongest earthquake within about 250 km of this epicenter since an M 6.6 on November 4, 2019. Forecasts 133354 had expected this event within about 50 km was likely around April 27. The M 5.3 to the south had been expected within about 100 km around April 28 in forecast 133369. The M 6.5 is at 103 degrees from the M 6.6 in the South Atlantic of April 3 and was probably promoted by strong energy concentration associated with that earthquake at this distance." (April 23-24, 2021)

 

Today's event is near the position of the M 5.3 on April 23 and that may have been a foreshock to today's earthquake. The parameters of that foreshock were:

 

O: 23APR2021 23:11:56  20.5S  177.7W Mw=5.3  EMSC   FIJI REGION                  

 

Note that this event was near local solar noon just as today's quake was  and both may have been promoted by high tidal stresses associated with the full moon of April 27. The last earthquake of M>=6.5 within about 200 km of today's epicenter was an M 6.6 on May 27, 2016 and an M 6.4 on May w7, 2016. These two earthquakes were similar to the two in the past three days with the first about 200 km north of the second and one day apart in time.  Forecast 133369 had expected today's event within about 100 km was likely around April 28.

 

O: 25APR2021 22:28:01  21.7S  177.1W Mw=6.5  EMSC   FIJI REGION                  

P: 28APR2021 133369    21.0S  177.0W 4.0-5.7 BAAAA  Tonga Islands              

 

An M 5.4 also occurred in southern Peru on the geomagnetic equator. NEIC reported it was felt with maximum intensity IV in Peru at Acary and II-III in Nazca, Ica and San Luis, Lima. The last earthquake within about 200 km of today's epicenter of M>=5.4 occurred on January 20, 2021 with M 5.5. These are probably aftershocks of an M 7.1 within about 50 km of today's epicenter which occurred on January 14, 2018. Forecasts 133341 and 133349 had expected today's activity in the area was likely around April 28.

 

O: 25APR2021 23:50:34  15.6S   74.5W Mw=5.4  EMSC   NEAR COAST OF SOUTHERN PERU  

P: 24APR2021 133341    14.0S   73.0W 4.0-5.4 ABBAA  Central Peru                

P: 28APR2021 133349    16.0S   72.0W 4.0-5.6 BABAA  So. Peru/Bolivia           

 

A moderate earthquake of M 3.7 was widely felt in the area of Reno, Nevada near the California-Nevada border. NEIC reported it was felt with intensity IV in Tahoe City, Olympic Valley, Homewood, Kings Beach and III in Tahoe Vista, Tahoma, Carnelian Bay and in Nevada with II-III in Carson City, Glenbrook.   This is the strongest earthquake in this region within about 100 km since an M 4.5 in Nevada about 50 km to the east of today's epicenter. An M 3.7-3.8 also  occurred about 100 km east of this on December 12, 2020. Forecast 133197 had expected today's quake within about 25 km was likely around April 24. This epicenter is at the fourth node (90 degrees) from the M 7.7 in the Loyalty Islands of February 10 and at the fifth node (72 degrees) from the recent major earthquakes off eastern Honshu, Japan of March 20 and may have been promoted by energy from those sources.

 

O: 25APR2021 15:35:48  39.1N  120.0W ML=2.4  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 15:40:03  39.1N  120.0W Md=2.4  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 15:44:58  39.1N  120.0W ML=2.7  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 15:54:52  39.1N  120.0W Md=2.5  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 16:35:23  39.1N  120.0W Md=2.4  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 17:08:39  39.1N  120.0W Md=2.1  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 17:32:24  39.1N  120.0W Md=2.4  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 18:18:40  39.1N  120.0W Md=2.5  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 15:33:22  39.1N  120.0W Mw=3.7  EMSC   NORTHERN CALIFORNIA          

P: 24APR2021 133197    39.3N  120.0W 2.5-4.6 AAAAA  California/Nevada area     

 

Light to moderate earthquakes also occurred in several other areas of the U.S. today. These included an M 3.5 in Southern Idaho, an M 3.7 in Baja California, Mexico; an M 3.4 in Hawaii.  NEIC reported the earthquake of M 3.5 in Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho in Stanley.

 

O: 25APR2021 10:23:21  44.2N  115.0W ML=3.5  EMSC   SOUTHERN IDAHO               

P: 24APR2021 133269    44.4N  115.1W 2.0-4.1 AAAAA  Montana/Idaho              

 

NEIC reported the earthquake of M 3.7 in Baja California was felt with intensity II-III in the area(s) of California at Spring Valley and El Cajon.

 

O: 26APR2021 05:12:05  31.5N  115.6W ML=3.7  EMSC   BAJA CALIFORNIA, MEXICO      

P: 27APR2021 133230    31.9N  116.3W 2.5-4.4 AAAAA  So. California             

 

NEIC reported the earthquake of M 3.4 in Hawaii was felt with intensity II-III in the area(s) of Hawaii in Kailua Kona.  Hawaii is located at the seventh node (52 degrees) from the M 8.1 in the Kermadec Islands of March 4 and the M 7.7 in the Loyalty Islands of February 10 and may have been promoted by energy from those sources.

 

O: 26APR2021 03:26:52  19.8N  156.8W ML=3.4  EMSC   HAWAII REGION, HAWAII        

P: 28APR2021 133176    20.1N  156.1W 4.0-5.8 AAAAA  Hawaii area                

 

An earthquake of M 4.9 in the northern Mid-Atlantic Ridge area today continued regionally enhanced seismicity in the area of the past several days. This event occurred near local solar noon and was probably enhanced by  the full moon of April 27 as noted in previous issues of this summary:

 

The full moon will arrive on April 27, 2021 at 03:31 UT. Longitudes which are sub-solar (local solar noon) at this time are near 130 East Longitude while those near local solar midnight area near 50 West longitude. Those in the west include the Atlantic Ocean as far as the eastern Caribbean and the Shetland and South Sandwich Islands and in the east in western Japan, Taiwan, the Philippines and Central Indonesia. These areas may see enhanced seismicity within about 3 days of the full moon.

 

The forecast had placed the maximum stress longitude near this event in the  Northern Mid-Atlantic. The last earthquake of M>=4.9 in this area was an M 4.9 on November 15, 2020 but the last of larger magnitude was an M 5.0 on April 8, 2018. Forecast 133150 had expected today's event within about 50 km of this epicenter was likely around April 26. This epicenter is at 144 degrees from the Loyalty Islands where an M 7.7 hit on February 10 and may have been promoted by energy from that source.

 

O: 25APR2021 12:29:28  17.2N   46.4W mb=4.9  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P: 26APR2021 133158    17.0N   47.0W 4.0-5.7 AAAAA  Mid-Atlantic Ridge         

 

MODERATE QUAKE IN OWEN'S FRACTURE ZONE; LIGHT QUAKE IN SAN JOSE, CALIFORNIA

 

EARTHQUAKE SUMMARY FOR  APRIL 24, 2021

 

The largest earthquake in the world today was an M 5.6 in the Owen's Fracture Zone south of Iran. It was not reported felt in this remote area. The last earthquake of equal or greater magnitude within about 300 km of today's epicenter was an M 5.6 on November 28, 2015. The last of larger magnitude was an M 5.7 on April 15, 2009. Forecast 133144 had expected a moderate earthquake within about 150 km of today's epicenter was likely around April 23. This epicenter is at the fourth node (90 degrees) from the M 6.6 in the South Atlantic of April 3 and was likely promoted by energy from that source.

 

O: 24APR2021 18:00:32  13.7N   57.1E Mw=5.6  EMSC   OWEN FRACTURE ZONE REGION    

P: 23APR2021 133144    15.0N   57.0E 3.5-5.1 ABAAA  Arabian Sea                

 

A light earthquake of M 3.6 was felt in the San Jose, California area today. NEIC reported it was felt with intensity III-IV in San Jose, Coyote, Morgan Hill, Mount Hamilton, Central California. The last earthquake within about 50 km of this epicenter with M>=3.6 occurred as an M 3.8 on February 22, 2021 and prior to that with M 3.7 on  December 15, 2020. The last event of M>=4 in the area occurred with M 4.1 on October 10, 2017 with about 10 km of today's epicenter. Forecast 133201 had expected today's event within about 25 km was likely around April 27. This activity is at the fifth node (72 degrees) from recent major earthquakes off the east coast of Honshu, Japan and was likely promoted be energy from that source.

 

O: 25APR2021 05:00:39  37.3N  121.6W Md=2.4  EMSC   NORTHERN CALIFORNIA

O: 25APR2021 04:59:27  37.3N  121.6W ML=3.4  EMSC   NORTHERN CALIFORNIA          

O: 25APR2021 04:59:27  37.3N  121.6W ML=3.6  ANSS   NORTHERN CALIFORNIA          

P: 27APR2021 133201    37.4N  121.8W 2.5-4.6 AAAAA  Central California         

 

The strongest earthquake in the U.S. or Canada today was an M 5.0 in the Rat Islands of the Aleutians, Alaska. It was reported lightly felt in the epicentral area. The last earthquake in the eastern Rat Islands within about 200 km of this epicenter with M>=5 occurred with M 5.3 on February 4, 2020 and before that as an M 5.0 on October 5, 2019. Forecast 133314 had expected today's event within about 100 km was likely around April 24.

 

O: 24APR2021 09:30:42  52.0N  178.5E Mw=5.0  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 24APR2021 133314    51.0N  178.0E 4.0-5.8 AAAAA  Rat Islands                

 

STRONG EARTHQUAKE SHAKES TONGA/FIJI

 

EARTHQUAKE SUMMARY FOR  APRIL 23, 2021

 

The strongest earthquake in the world today was an M 6.5  in Central Tonga. NEIC reported it was felt with intensity VI in Tofoa-Koloua, Tonga  and II in Neiafu, Vavau, Tonga. This is the strongest earthquake in the world in the past three weeks. The last earthquake with M>=6.5 in the world was an M 6.6 on April 3, 2021 in the South Atlantic. The only other event of this magnitude or greater in the world in the past month was an M 6.5 aftershock in the Kermadec Islands aon April 1, 2021. This earthquake occurred near local solar noon in an area near the regional geomagnetic equator. It was preceded about an hour earlier by an M 5.3 about 150 km to the south, an earthquake which occurred within about 30 minutes of local solar noon. It was probably promoted effects from the strong geomagnetic storm and solar flares of the past several days which maximize near this hour. The M 6.5 is the strongest earthquake within about 250 km of this epicenter since an M 6.6 on November 4, 2019. Forecasts 133354 had expected this event within about 50 km was likely around April 27. The M 5.3 to the south had been expected within about 100 km around April 28 in forecast 133369. The M 6.5 is at 103 degrees from the M 6.6 in the South Atlantic of April 3 and was probably promoted by strong energy concentration associated with that earthquake at this distance. Other earthquakes at this distance from the South Atlantic today occurred in Oaxaca, Mexico, the Fiji Islands (M 5.3) and in Vanuatu (M 4.7).

 

O: 24APR2021 00:23:35  18.9S  176.3W Mw=6.4  EMSC   FIJI REGION                  

O: 24APR2021 00:23:35  18.9S  176.3W Mw=6.5  ANSS   FIJI REGION                  

P: 27APR2021 133354    19.0S  176.0W 4.0-5.8 BAAAA  Tonga Islands              

 

O: 23APR2021 23:11:56  20.5S  177.7W Mw=5.3  EMSC   FIJI REGION                  

P: 28APR2021 133369    21.0S  177.0W 4.0-5.7 BAAAA  Tonga Islands              

 

A series of moderate earthquakes continued to rock the area of the central Philippines today from Mindanao on the south to the Babuyan Islands on the north. These appear to be related to the passage of Typhoon Surigao off the east coast of the Philippines over the past several days and had been expected in this summary as:

 

"Typhoon Surigae continued today in the region east of Luzon, Philippines with strong winds up to 140 kts. It is expected to track to the west possibly making landfall in the central Philippines. This storm is likely to promote elevated seismicity including the potential for a moderate to strong regional event in the region of the Philippines and Taiwan in the coming week." (April 20, 2021)

 

O: 23APR2021 23:09:24   5.2N  126.4E mb=4.5  EMSC   MINDANAO, PHILIPPINES

O: 23APR2021 21:50:54   5.3N  126.4E ML=4.2  EMSC   MINDANAO, PHILIPPINES

O: 23APR2021 12:09:11   6.7N  125.7E mb=4.3  EMSC   MINDANAO, PHILIPPINES

O: 23APR2021 18:45:33   5.2N  126.5E Mw=5.0  EMSC   MINDANAO, PHILIPPINES        

P: 23APR2021 133107     6.0N  127.0E 4.0-5.8 AAAAA  Halmahera                  

 

NEIC reported the earthquakes of M 4.5 in northern Mindanao, Philippines were felt with intensity III-IV in the area(s) of northern Mindanao, Philippines at Rosario, Caraga.

 

O: 23APR2021 08:48:17   8.4N  125.9E mb=4.5  EMSC   MINDANAO, PHILIPPINES        

O: 23APR2021 10:39:48   8.3N  126.0E mb=4.5  EMSC   MINDANAO, PHILIPPINES

P: 21APR2021 133101     9.0N  126.0E 4.0-5.4 AAAAA  Central Philippines        

 

O: 24APR2021 03:15:15  19.4N  120.4E mb=4.5  EMSC   BABUYAN ISL REGION, PHILIPPINE

P: 29APR2021 133154    19.0N  120.0E 3.5-4.9 BAAAA  Luzon, Philippines         

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in Northern California near Lake Pillsbury. NEIC reported it was felt with intensity IV in California at Potter Valley, Mendocino, and II-III in Willits. This is part of a regional activation which began on August 19, 2020 with an M 4.2 and continued on December 6, 2020 with M 4.4. The last and only such event of M>=3.9 in the area since the December event was an M 4.0 about 50 km southwest of today's epicenter on March 24, 2021. Forecast 133204 had expected enhanced seismicity in this area around April 26.

 

O: 23APR2021 11:18:39  39.6N  123.0W ML=3.4  EMSC   NORTHERN CALIFORNIA          

O: 23APR2021 11:18:39  39.6N  123.0W ML=3.9  ANSS   NORTHERN CALIFORNIA          

P: 26APR2021 133204    39.4N  123.3W 2.5-4.4 BAAAA  Central California         

 

Three earthquakes of M 5.0 occurred in the Atlantic Ocean area today. These were in the South Shetland Islands, the Central-Mid Atlantic and in the northern mid-Atlantic Oceans. The event in the South Shetland Islands of M 5.0 was not part of the aftershock sequence still continuing in that area but was at a new epicenter about 300 km to the southwest of that area. The last such event within about 250 km of this epicenter occurred July 16, 2013 with  M 5.6-5.7. It was followed by an M 4.8  in the aftershock zone of the January 23, 2021 M 7.0.  Forecast 133395 had expected continuing activity in the area would likely be enhanced around April 23. The M 5.0 occurred within about an hour of local solar noon and may have been enhanced by tidal stresses which will continue to impact the area for the next several days as noted in this summary in the tidal forecast associated with the coming full moon:

 

"The full moon will arrive on April 27, 2021 at 03:31 UT. Longitudes which are sub-solar (local solar noon) at this time are near 130 East Longitude while those near local solar midnight area near 50 West longitude. Those in the west include the Atlantic Ocean as far as the eastern Caribbean and the Shetland and South Sandwich Islands and in the east in western Japan, Taiwan, the Philippines and Central Indonesia. These areas may see enhanced seismicity within about 3 days of the full moon." (April 23-24, 2021)

 

O: 23APR2021 18:12:50  62.4S   58.4W mb=4.8  EMSC   SOUTH SHETLAND ISLANDS       

O: 23APR2021 14:56:51  63.4S   63.0W mb=5.0  EMSC   SOUTH SHETLAND ISLANDS       

P: 23APR2021 133395    62.0S   58.0W 3.0-5.4 AAAAA  So. So. America            

 

The other two events in the Atlantic area of M 5.0 today  also occurred near local solar midnight and may have affected by high tides. The event in the northern Mid-Atlantic had been forecast within about 150 km of that epicenter in forecast 133221 to occur around April 26. The event in the Central mid-Atlantic had been forecast 1330099 to occur within about 15 km of that epicenter around April 23. The event in the northern Mid-Atlantic occurred at 144 degrees from the M 8.1 in the Kermadec Islands of March 4 and was probably promoted by energy from that source.

 

O: 24APR2021 00:56:27  32.5N   40.2W mb=5.0  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P: 26APR2021 133221    31.0N   41.0W 4.0-5.4 ABAAA  No. Mid-Atlantic Ridge     

 

O: 23APR2021 22:15:52   7.9N   38.1W mb=5.0  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 23APR2021 133099     8.0N   38.0W 4.0-5.6 AAAAA  Central Mid-Atlantic Ridg  

 

MODERATE QUAKE IN LEYTE, PHILIPPINES; TYPHOON SURIGAE AND SOLAR FLARE RELATED

 

EARTHQUAKE SUMMARY FOR  APRIL 22, 2021

 

The strongest widely felt earthquake in the world today was an M 4.6 in the region of Leyte, Philippines. PHIVOLCS reported it was felt with intensity IV in Sogod Hinunangan, Hinundayan and Libagon, Southern Leyte; III in Saint Bernard and Bontoc, Southern Leyte and II in Mahapiag, Southern Leyte. This event was likely promoted by stresses associated with Super Typhoon Surigae which passed near this epicenter two days ago as reported in this summary at the time:

 

"Typhoon Surigae continued today in the region east of Luzon, Philippines with strong winds up to 140 kts. It is expected to track to the west possibly making landfall in the central Philippines. This storm is likely to promote elevated seismicity including the potential for a moderate to strong regional event in the region of the Philippines and Taiwan in the coming week." (April 20, 2021)

 

One of the strongest solar flares (#9080) of the year maximized minutes before this earthquake and may also have affected the magnitude of this event which lies on the geomagnetic equator - a location where SFE are at maximum. This is the second strongest flare reported by SWPC since the M4.4 on November 29, 2020 and the third largest since June 2020. An M1.1 flare was observed on April 19 and was followed by an M 6.0 earthquake in Sumatra. The parameters of this flare follow:

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

9080       2002   2011      2020   C8.5      (April 22, 2021)   4.8E-03  

 

Today's event is the strongest in Leyte, Philippines since an M 4.9 on January 20, 2021 and an M 5.1 on November 15, 2020. Forecast 133153 had expected today's event within about 50 km was likely around April 22.

 

O: 22APR2021 20:31:24  10.5N  125.1E mb=4.6  EMSC   LEYTE, PHILIPPINES           

P: 22APR2021 133153    11.0N  125.0E 3.5-5.0 AAAAA  Luzon, Philippines         

 

The strongest earthquake in the world today was reported by GEONET in South Island, New Zealand with M 4.9.  GEONET reported this earthquake was felt with light intensity in the area southwest of Haast, South Island. 389 reports of felt intensity came from the area east and north of the epicenter. More than 389 people reported feeling this earthquake with 274 reporting weak shaking and 112 light intensity; 3 with moderate intensity and none with strong, severe or extreme shaking. NEIC reported this earthquake at M 4.1 in South Island, New Zealand was felt with intensity II-III in the area(s) of South Island, New Zealand in Otago at Wanaka and Arrowtown. The last earthquakes with M>=4.9 reported by EMSC within about 200 km of this epicenter in South Island, New Zealand were an M 4.9 on April 26, 2020 and an M 5.5 on June 24, 2020. Forecast 133389 had expected today's activity within about 100 km was likely around April 22, 2021.

 

O: 22APR2021 08:07:31  44.1S  168.6E Mw=4.1  EMSC   SOUTH ISLAND OF NEW ZEALAND  

O: 22APR2021 08:07:31  44.1S  168.6E MS=4.9  GEONET Felt with light intensity

P: 22APR2021 133389    45.0S  168.0E 3.0-4.9 AAAAA  So. Island, N.Z.           

 

A moderate earthquake of M 4.4 in southern Iceland today broke the quiet seismicity in that region which has followed the volcanic eruption of March 20, 2021 and following and still continues. The largest earthquake in the volcanic zone since the eruption began was an M 4.0 on April 20. Regional earthquakes have since occurred - on April 18 and April 1 and 15 with M 4.4 and 4.4. Today's event occurred near local solar noon and may have been promoted by high tidal stresses which maximize near this hour. Forecast 133328 had expected today's activity was likely within about 100 km around April 22. This area is located at  144 degrees from the M 8.1 in the Kermadec Islands of March 4 and may have been promoted by energy from that source.

 

O: 22APR2021 12:07:48  62.7N   24.8W mb=4.4  EMSC   ICELAND REGION               

P: 22APR2021 133328    62.0N   26.0W 3.0-4.5 AAAAA  Iceland area               

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in the Unimak Island area of Alaska. It was not reported felt in this remote area. Two earthquake series with M>=3.9 have occurred in the Unimak Island area in the past five months - an M 4.5 on March 28 and events of M 4.2 and 5.1 on January 10, 2021. Forecast 133319 had expected today's activity was likely around April 26. This 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: 22APR2021 23:25:04  53.4N  163.3W mb=3.9  EMSC   UNIMAK ISLAND REGION, ALASKA 

P: 26APR2021 133319    54.1N  162.8W 3.5-5.1 BAAAA  Unimak Islands, Aleutians  

 

MODERATELY STRONG QUAKE SHAKES CENTRAL CHILE

 

EARTHQUAKE SUMMARY FOR  APRIL 21, 2021

 

The strongest earthquake in the world today was an M 5.5 off the coast of O'Higgins, Chile. NEIC reported it was felt with intensity II-III in San Antonio, Vina del Mar, Valparaiso; Rancagua, O'Higgins; Santiago, Linares, Maule and in Mendoza, Argentina. GUC reported this earthquake was felt with intensity  IV in  O'Higgins at Chepic, Lolol, Navidad, Paredones, Pichilemu and Santa Cruz; III in La Estrella, Mostazal, Rancagua and San Vicente de Tagua; in Maule with IV in Constitucion, III in Curico, Molina and II in Romeral, Sagrada Familia and Teno; in Nuble with III in Trehuaco; in Santiago with III in Colina, El Monte, Macul, San Bernardo and in Valparaiso with III in Casablanca, Valparaiso and Villa Alemana and II in Cartegena and Santo Domingo, Chile. This is the strongest earthquake to date in the swarm of events of M 4.9-5.3 at this episenter of April 19, 2021. This summary noted this swarm at the time as:

 

"Moderate earthquakes continued to shake the region of Central Chile near Valparaiso and Santiago today. These followed similar events reported in the previous issue of this summary as:

 

NEIC reported these earthquakes of M 5.2 and M 5.2 in O'Higgins, Chile was felt with intensity V in the area(s) of Valparaiso, Chile in Valparaiso and Vina del Mar and II-III in Melipilla, San Vicente, El Monte, Penaflor, San Antonio, Limache, Curico, Rancagua, Machal and Santiago." (April 19-20, 2021)

 

The M 5.5 in O'Higgins, Chile is the strongest within about 200 km of this epicenter since an M 6.1 about 100 km to the southwest on November 22, 2020. An M 6.8 hit within about 50 km of today's epicenter on August 1, 2019. This may be a regional aftershock of that event. Forecast 133374 had expected today's activity in this region was likely around April 22.

 

 

O: 21APR2021 08:08:23  34.0S   72.2W ML=4.2  EMSC   OFFSHORE O'HIGGINS, CHILE

O: 22APR2021 00:17     34.0S   72.4W mb=5.3  GUC    O'Higgins at Chepic, Lolol, Na

O: 22APR2021 00:17:15  34.0S   72.3W Mw=5.5  EMSC   OFFSHORE O'HIGGINS, CHILE    

P: 22APR2021 133374    35.0S   72.0W 4.0-6.0 AAAAA  Central Chile              

 

 

A moderate earthquake of M 4.5 in St. Kitts and Nevis was felt with intensity II-III in that area at Gingerland and Basseterre, Saint George today. This earthquake and an M 2.1 on the Virginia-North Carolina border occurred during an arcjet in the GOES geomagnetic field determination. Incidentally, the GRB that accompanied the M1.1 solar flare and the M 6.0 in Sumatra has been given a GRB magnitude of >19.2. The last GRB with significantly larger magnitude in the GRB Swift catalog occurred with V 21.2 on April 10, 2020 more than a year ago. Today's event may be related to the eruption of La Soufriere last week which is located to the south of today's epicenter. While an M 4.9 hit northeast of Barbuda more than 200 km from today's event on December 28, 2020, the last of larger magnitude in the area of Antigua and Barbuda within less than 200 km of this epicenter was an M 5.2 on December 24, 2017. Forecast 133152 had expected enhanced regional seismicity was likely around April 24. This epicenter is at the third node (120 degrees) from the M 8.1 in the Kermadec Islands of March 4 and was probably enhanced by energy from that source.

 

O: 21APR2021 19:43:49  17.5N   62.2W mb=4.5  EMSC   ANTIGUA AND BARBUDA REGION   

P: 24APR2021 133152    16.0N   62.0W 3.0-5.2 BBAAA  Leeward Islands            

 

The strongest earthquake in the U.S. or Canada today was an M 3.7 in Hawaii. NEIC reported this earthquake of M 3.0-3.7 in Hawaii was felt with intensity II-III in the area(s) of Hawaii at Naalehu, Captain Cook, Holualoa, Kailua Kona, Laupahoehoe, Kameula, Honokaa.  The last earthquake of M>=3.7 in Hawaii was an M 3.7 on April 11, 2021. The last of larger magnitude was an M 4.3 on April 3, 2021. Forecast 133151 had expected today's event was likely around April 25. 

 

O: 21APR2021 12:09:03  19.2N  155.5W ML=3.7  EMSC   ISLAND OF HAWAII, HAWAII     

P: 25APR2021 133151    18.8N  155.2W 3.0-4.7 BAAAA  Hawaii                     

 

GAMMA RAY BURST COINCIDES WITH M 6.0 IN SUMATRA; STRONGEST FLARE IN FIVE MONTHS

 

EARTHQUAKE SUMMARY FOR  APRIL 20, 2021

 

A Gamma Ray Burst of strong intensity hit the earth on April 19. This was  identified by the Swift Catalog of GRB's as occurring at 23:27 (GRB # 210419C) but other details are not yet available.  The preliminary parameters of this GRB from the Swift Catalog are:

 

"The last major Gamma Ray Burst (GRB) according to the online NASA Swift GRB Catalog was observed on April 19, 2021 at 23:28 UT with BAT Fluence n/a 10-7 erg/cm2 (MAGNITUDE: n/a), Associated earthquakes: M 6.0 in Sumatra at 23:57 UT)" (April 20, 2021)

 

This GRB coincides with the strongest solar flare observed in nearly 5 months - an M1.1 with the following parameters which was discussed in the previous issue of this summary.

 

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

8290       2319   2342      2359   M1.1      (April 19, 2021)   1.3E-02  

 

The Gamma Ray Burst and Solar flare were followed minutes later by the M 6.0 earthquake in Sumatra at 23:57 UT. This is a similar situation to that discussed with the previous such earthquake in Sumatra as discussed in the previous issue of this summary:

 

 

"The largest earthquake in the world today was an M 5.9-6.1 in Northern Sumatra.

BMG reported it was felt with intensity IV in Nias; II-III in Samosir and II in Medan and Sipirck, Sumatra. BMG reported there was no threat of a tsunami and no immediate reports of damage or casualties from this quake. It is likely that this earthquake was triggered by effects from a strong Gamma Ray Burst (GRB) which was first registered on the Swift Mission Satellite about 6 minutes before this quake initiated. This summary has pointed out the temporal correlation of GRB and strong earthquakes in this region on several occasions in the past including in the instance of the great tsunamigenic earthquake of December 26, 2004 (M 9+) which began the current series of aftershocks in the area. Effects from GRBs may include associated gravity waves which could temporarily disrupt fault parameters leading to an earthquake. Such gravity waves have been hypothesized but never observed without ambiguity. Forecast 81386 had expected this earthquake to occur within 100 km of the epicenter around July 4 with possibly large size. It is the strongest event within 200 km of this epicenter since earthquakes of M 6.0 on December 1, 2013 and M 6.4 on July 25, 2012." (July 5-6, 2014)

 

and

 

"Unusual earthquakes in the Los Angeles area of Southern California of M 4.6 and in Sumatra of M 6.0-6.1 occurred today. These followed a strong Gamma Ray Burst with the earthquake in Sumatra occurring about 7 minutes after the GRB was first identified. There are several methods in which a GRB and associated phenomena could trigger earthquakes including those classified as electromagnetic and gravitational. Under the right circumstances these can be unusual events. Some of the strongest GRB events in the past several years occurred in association with the Virginia earthquake of August 23, 2011 (M 5.8) and an equally unusual Colorado earthquake (M 5.3-5.5). and shortly before the great (M 9+) earthquake in Sumatra which, along with the accompanying tsunami killed nearly a quarter million people on December 26, 2004. This summary lists GRBs as they occur and many are not associated with unusual earthquakes so the data is still ambiguous on a direct cause but the timing of today's Sumatra quake and the GRB is intriguing." (July 5-6, 2014)

 

The timing of today's GRB and Solar Flare 8290 is interesting. The GRB lagged the start of the Solar Flare by 8-9 minutes.  This is time for a particle traveling (or a gravity wave) near the speed of light to traverse the distance from the sun to the earth. One possible scenario is that the GRB first affected the sun, triggering the Flare, then continued on to the earth eight minutes later, triggering the GRB here and subsequently the earthquake of M 6.0 in Sumatra. Another seeming possibility is that the flare triggered the Gamma Ray Burst 8 minutes later. This is highly unlikely as flares do not provide anywhere near the energy required for a GRB.

 

An unusual earthquake of M 2.5 was felt widely in northern Missouri today. NEIC reported intensity II-III in the epicentral area in Missouri at Eureka, High Ridge, Ballwing, House Springs, Valley Park, Fenton, Glencoe, Pacofoc. amd Cesar Mill. The last similar earthquakes within about 100 km of this epicenter occurred with M 2.5-2.7 on September 11, 2019 and October 27, 2019. The last event in the area with greater magnitude was an M 3.1 on September 9, 2017.

Forecast 132946 had expected today's event was likely to the east in mid-April.

 

O: 20APR2021 08:38:26  38.5N   90.6W Md=2.5  EMSC   MISSOURI                     

P: 15APR2021 132946    38.0N   87.0W 2.0-4.3 BABAA  New Madrid area            

 

The strongest earthquake in the U.S. or Canada today was an M 3.9-4.0 in Northern California. NEIC reported this earthquake of M 4.0 in Northern California was felt with intensity II-III in the area(s) of Northern California at Garberville, Myers Flat, Piercy, Redcrest, Scotia, Fontana. This is the strongest earthquake within about 50 km of this epicenter since an M 4.5 on August 28, 2016 and prior to that an M 4.1 on January 4, 2010. Forecast 133278 had expected today's activity was likely around April 20.

 

O: 20APR2021 07:59:29  39.6N  123.3W Md=2.1  EMSC   NORTHERN CALIFORNIA          

O: 20APR2021 17:15:59  40.1N  122.9W Md=2.1  EMSC   NORTHERN CALIFORNIA          

O: 20APR2021 09:48:33  40.2N  123.6W Mw=3.9  EMSC   NORTHERN CALIFORNIA          

O: 20APR2021 09:48:33  40.2N  123.6W Mw=4.0  ANSS   NORTHERN CALIFORNIA          

P: 22APR2021 133278    40.6N  122.4W 2.5-4.4 AAAAA  Northern California        

 

STRONG M1.1 SOLAR FLARE TRIGGERS M 6.0 IN SUMATRA, INDONESIA

 

EARTHQUAKE SUMMARY FOR  APRIL 19, 2021

 

The strongest earthquake in the world today was an M 6.0 (EMSC) to M 6.4 (BMG)  off western Sumatra, Indonesia. NEIC reported this event was felt with intensity VIII in Gunung Stoli, Sumatra. BMG reported light to moderate shaking throughout much of western Sumatra. This earthquake was most likely triggered by solar-geomagnetic effects from an M1.1 class solar flare that maximized minutes before this earthquake at  23:42 UT and was still occurring when the M 6.0-6.4 hit near the geomagnetic  equator at 23:58 UT in Sumatra. This flare followed a significant increase in solar activity throughout the day and the continuing geomagnetic storm noted in this summary as:

 

"The geomagnetic field saw minor storm conditions today. The AP level was 18.  High latitude geomagnetic field  saw minor storm conditions with AP 47. This is the strongest geomagnetic storm since AP reached 29 on March 20 and the strongest at high latitudes since AP reached 62 in polar areas on October 26, 2019. Enhanced seismicity is expected in the next several days near the geomagnetic equator and at high latitudes due to effects from this geomagnetic storm.." (April 19, 2021)

 

The M1.1 solar flare today is the first M-class flare observed in nearly five months. The last such flare was an M4.4 on November 29, 2020. The strongest flare prior to that occurred as an X9.3 on September 10, 2017. Earthquakes of M 5.1 accompanied the November 29, 2020 flare in Southern Sumatra, the western Aleutian Andreanof Islands and Taiwan, with an M 5.8 in Argentina several hours later,  not dissimilar to the current seismic pattern. Today's M1.1 class solar flare occurred with the following parameters from SWPC.

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

8290       2319   2342      2359   M1.1      (April 19, 2021)   1.3E-02  

 

The last earthquake within about 200 km of today's epicenter with M>=6.0 was an M 6.0 on July 5, 2014 about 200 km north of this. The last such event of larger magnitude was an M 6.8 on May 16, 2006. Forecast 132839 had expected today's event in this region was likely around April 19.

 

The event of July 5, 2014 may have been triggered by a Gamma Ray Burst (GRB) which coincided with it as noted at the time in this summary:

 

"The largest earthquake in the world today was an M 5.9-6.1 in Northern Sumatra. BMG reported it was felt with intensity IV in Nias; II-III in Samosir and II in Medan and Sipirck, Sumatra. BMG reported there was no threat of a tsunami and no immediate reports of damage or casualties from this quake. It is likely that this earthquake was triggered by effects from a strong Gamma Ray Burst (GRB) which was first registered on the Swift Mission Satellite about 6 minutes before this quake initiated. This summary has pointed out the temporal correlation of GRB and strong earthquakes in this region on several occasions in the past including in the instance of the great tsunamigenic earthquake of December 26, 2004 (M 9+) which began the current series of aftershocks in the area. Effects from GRBs may include associated gravity waves which could temporarily disrupt fault parameters leading to an earthquake. Such gravity waves have been hypothesized but never observed without ambiguity. Forecast 81386 had expected this earthquake to occur within 100 km of the epicenter around July 4 with possibly large size. It is the strongest event within 200 km of this epicenter since earthquakes of M 6.0 on December 1, 2013 and M 6.4 on July 25, 2012." (July 5-6, 2014)

 

and

 

"Unusual earthquakes in the Los Angeles area of Southern California of M 4.6 and in Sumatra of M 6.0-6.1 occurred today. These followed a strong Gamma Ray Burst with the earthquake in Sumatra occurring about 7 minutes after the GRB was first identified. There are several methods in which a GRB and associated phenomena could trigger earthquakes including those classified as electromagnetic and gravitational. Under the right circumstances these can be unusual events. Some of the strongest GRB events in the past several years occurred in association with the Virginia earthquake of August 23, 2011 (M 5.8) and an equally unusual Colorado earthquake (M 5.3-5.5). and shortly before the great (M 9+) earthquake in Sumatra which, along with the accompanying tsunami killed nearly a quarter million people on December 26, 2004. This summary lists GRBs as they occur and many are not associated with unusual earthquakes so the data is still ambiguous on a direct cause but the timing of today's Sumatra quake and the GRB is intriguing." (July 5-6, 2014)

 

 

O: 19APR2021 23:58:22   0.2N   96.5E Mw=6.0  EMSC   NIAS REGION, INDONESIA       

O: 20APR2021 02:23:05   0.1N   96.5E ML=4.0  EMSC   NIAS REGION, INDONESIA

P: 19APR2021 132849     1.0N   97.0E 4.0-5.6 AAAAA  Nicobar Islands            

 

A moderate earthquake of M 3.9-4.3 was widely felt in eastern Austria and western Hungary today. NEIC reported maximum intensity IV in Austria at Neunkirchen, Ternitz and II-III in Wiener, Mattersburg, Berndorf, Bad Voslau, Pottendorf, Ebeichsdorf and Baden, Niederosterrich and in Sopron, Hungary. This is probably an aftershock of a similar event in Austria that occurred on March 30, 2021 with M 4.2. At the time this summary noted in regard to Austrian earthquakes:

 

"An unusual earthquake of M 4.2 shook regions of Austria today. NEIC reported this event with maximum intensity in Rust, Burgenland, Austria and IV in Neudorfi, Gloggnitz and III in Wiener, Berndorf, Bad Voslau, Traiskirchen, Sopron, Weiner and Modilng. This is the strongest earthquake in Austria within about 150 km of this epicenter since an M 4.2 on May 7, 2009. The last of larger magnitude in the region was an M 4.4 on October 1, 2004." (March 30, 2021)

 

Forecast 132979 had expected today's event was likely within about 150 km in mid-April. Today's event occurred within minutes of exact solar midnight and may have been promoted by strong tidal stresses which maximize near this hour. The event on March 30 was also associated with strong tides accompanying the last full moon a day prior. Earthquakes today in Austria, Iran, Oaxaca, Mexico, Timor, Nias, Indonesia occurred near 103 degrees from the M 6.6 in the south Atlantic of April 3 and may have been promoted by energy from that source.

 

O: 20APR2021 05:16:11  47.8N   16.1E ML=3.0  EMSC   AUSTRIA

O: 19APR2021 22:57:11  47.8N   16.1E ML=4.3  EMSC   AUSTRIA                      

P: 16APR2021 132979    48.0N   18.0E 3.0-5.2 BABAA  Adriatic Sea               

 

Moderate earthquakes continued to shake the region of Central Chile near Valparaiso and Santiago today. These followed similar events reported in the previous issue of this summary as:

 

GUC reported these earthquakes were felt with intensity  IV in  O'Higgins at La Estrella, Litueche, Lolol, Navidad, Paredones, Pichilemu, Santa Crus; III in San Vicente de Tagua, Rancagua, Rengo, Las Cabres, Chimbarongo; in Maule with IV in Curepto, San Rafael; III in Constitucion, Empedrado, Pelarco, San Clemente, Teno, Llico; II in Talca, Sagrada Familia, Romeral, Curico, in Santiago with III in El Monte, Las Condes, Pedro Aguirre Cerda, Quilcura, Tiltil and II in Curacavi; and in Valparaiso with IV in Cartagena, San Antonio and III in Olmue, Quillota, Quilpue, Valparaiso and Villa Alemana, Chile. NEIC reported these earthquakes of M 5.2 and M 5.2 in O'Higgins, Chile was felt with intensity V in the area(s) of Valparaiso, Chile in Valparaiso and Vina del Mar and II-III in Melipilla, San Vicente, El Monte, Penaflor, San Antonio, Limache, Curico, Rancagua, Machal and Santiago.

 

Forecast 133077 had expected this activity within about 100 km was likely to be enhanced in mid-April.

 

NEIC reported today's earthquakes of M 5.3 and M 5.1 in Valparaiso, Chile were felt with intensity IV-VI  in the area(s) of Valparaiso, Chile at San Antonio and Vina del Mar and in Quilpue and Machali, O'Higgins with lesser shaking in O'Higgins in Rancagua and in Santiago at Puente Alto and Santiago, Chile.  NEIC reported the aftershock of M 4.4 in Valparaiso, Chile was felt with intensity II-III in the area(s) of Valparaiso, Chile at San Antonio and Vina del Mar.  GUC reported these events were felt sith intensity  IV-VI in O'Higgins at La Estrella, Litueche, Lolol, Navidad, Paredones, Pichilemu, Santa Crus; III in San Vicente de Tagua, Rancagua, Rengo, Las Cabres, Chimbarongo; in Maule with IV in Curepto, San Rafael; III in Constitucion, Empedrado, Pelarco, San Clemente, Teno, Llico; II in Talca, Sagrada Familia, Romeral, Curico, in Santiago with III in El Monte, Las Condes, Pedro Aguirre Cerda, Quilcura, Tiltil and II in Curacavi; and in Valparaiso with IV in Cartagena, San Antonio and III in Olmue, Quillota, Quilpue, Valparaiso and Villa Alemana, Chile.

 

O: 19APR2021 04:11:27  34.0S   72.3W Mw=5.2  EMSC   OFFSHORE O'HIGGINS, CHILE

O: 19APR2021 04:11     34.0S   72.4W mb=5.0  GUC    O'Higgins at La Estrella, Litu

O: 19APR2021 03:18:57  34.0S   72.3W Mw=5.2  EMSC   OFFSHORE O'HIGGINS, CHILE

O: 19APR2021 11:13:28  34.0S   72.2W mb=5.3  EMSC   OFFSHORE O'HIGGINS, CHILE

O: 19APR2021 13:47:22  34.0S   72.3W mb=4.1  EMSC   OFFSHORE O'HIGGINS, CHILE

O: 19APR2021 15:02:08  34.0S   72.3W mb=4.4  EMSC   OFFSHORE O'HIGGINS, CHILE

O: 19APR2021 13:05:27  33.9S   72.3W Mw=5.1  EMSC   OFFSHORE O'HIGGINS, CHILE    

P: 13APR2021 133077    35.0S   73.0W 4.0-6.0 CAAAA  Central Chile              

 

 

An earthquake of M 4.0 in the Geysers, California today was widely felt in the region today. NEIC reported maximum intensity V in Kelseyville; IV in California at Middletown, and II-III in Geyserville, Hidden Valley Lake, Healdsburg, Calistoga, Lower Lake, Windsor, Pope Valley and Cloverdale.  This is the strongest earthquake in the U.S. or Canada today. The last earthquake of M>=4.0 in the Geysers area of California occurred as an M 4.0 on July 5, 2020. The last such event of significantly larger magnitude was an M 5.0 on December 14, 2016. Forecast 132934 had expected today's activity was likely around April 18. Today's earthquake occurred near local solar noon and may have been promoted by high tidal stresses which maximize near this hour.

 

O: 19APR2021 09:33:47  38.8N  122.8W Md=2.1  EMSC   NORTHERN CALIFORNIA          

O: 19APR2021 18:50:58  38.8N  122.7W Mw=4.0  EMSC   NORTHERN CALIFORNIA

P: 18APR2021 132934    38.5N  122.7W 2.5-4.4 AAAAA  Central California         

 

A light earthquake of M 3.8 in northern California north of the Geysers event of M 4.0 was widely felt later today. NEIC reported this event was felt with intensity II-III in Glenn, Durham, Biggs, Willows, Chico, Colusa, Chico, Gridley, Orland and Live Oak, California. A similar M 3.8 hit this epicenter on December 27, 2020 but the last earthquake within about 100 km of this epicenter with larger magnitude was an M 5.1 on August 10, 2016. Forecast 133002 had expected activity in this area would be enhanced in mid-April.

 

O: 20APR2021 02:39:03  39.5N  122.0W ML=3.5  EMSC   NORTHERN CALIFORNIA

O: 20APR2021 02:39:04  39.5N  122.0W ML=3.8  ANSS   NORTHERN CALIFORNIA

O: 20APR2021 04:25:20  39.5N  122.0W Ml=2.8  EMSC   NORTHERN CALIFORNIA          

P: 13APR2021 133002    40.4N  122.2W 2.5-4.6 CAAAA  Northern California        

 

An M 3.9 also occurred in the southern Idaho aftershock zone near Stanley, Idaho today. This event occurred within about an hour of local solar noon and may have been promoted by strong tidal stresses. A similar M 3.9 occurred last on February 27, 2021, an event closely associated with the full moon of that date, but the last earthquakes in the aftershock zone of larger magnitude were of M 5.0 on January 1 and 3, 2021.  NEIC reported this earthquake of M 3.9 in Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho at Nampa.  Forecast 132992 had expected today's event was likely around April 17 in this aftershock zone.

 

O: 19APR2021 14:31:52  44.3N  115.2W ML=2.5  EMSC   SOUTHERN IDAHO               

O: 19APR2021 20:42:38  44.5N  115.3W Ml=3.9  EMSC   SOUTHERN IDAHO

O: 19APR2021 21:16:48  44.5N  115.2W Ml=2.2  EMSC   SOUTHERN IDAHO

P: 17APR2021 132992    44.6N  115.0W 2.0-4.1 AAAAA  Montana/Idaho              

 

 

 

 

 

 

 

 

STRONG QUAKE ROCKS TAIWAN

 

EARTHQUAKE SUMMARY FOR  APRIL 18, 2021

 

The strongest earthquake in the world today was an M 5.8-6.3 in Taiwan. NEIC reported it was felt with maximum intensity VI in Taiwan at Hualien, V in Hsinchu, IV in Taichung, Changhua and Chiayi, and III in Maoli and Taichung Counties. CWB reported these earthquakes were felt with intensity V-VI in Hualien, IV in Chiayi, Miaoli, Yilan, Nantou, Taichung, Changhua, Taitung, Yunlin; III in Taoyuan, Tainan, Hsinchu, Kaohsiung, Taipei, and II in Keelung City, Pingtung and Penghu Counties, Taiwan. The mainshock followed several minutes after an M 5.4, part of a double mainshock which was felt with lesser intensity in the same area. This activity occurred near local solar midnight and was probably promoted by geomagnetic effects from the strong geomagnetic storm of the past two days. This activity occurred as Tropical Storm Surigae made landfall in central Philippines. Stresses from this storm probably helped magnify the magnitude of the events in Taiwan. This summary had noted this storm in previous issues as:

 

"TS Surigae continued today in the region east of Mindanao, Philippines with strong winds up to 150 kts. It is expected to track to the west possibly making landfall in the central Philippines. This storm is likely to promote elevated seismicity including the potential for a moderate to strong regional event in the region of the Philippines and Taiwan in the coming week." (April 18, 2021)

 

A warning was sent out to phones but no major damage or casualties were immediately reported with today's activity. The only similar earthquake of M>=5.8  in Taiwan in the past year was an M 6.2 about 100 km north of this on December 10, 2020. The last event of M>=6.2 within about 150 km of this epicenter was an M 6.4 on February 6, 2018. Forecast 132920 had expected today's event was possible around April 18. Flare 8080 occurred about the same time as the activity in Taiwan.

 

O: 18APR2021 14:11:38  23.8N  121.6E Mw=5.4  EMSC   TAIWAN

O: 18APR2021 14:14:36  23.8N  121.6E Mw=5.8  EMSC   TAIWAN

O: 18APR2021 14:11:39  23.9N  121.5E ML=5.8  TAI    Hualien, Taiwan              

O: 18APR2021 14:14:37  23.9N  121.5E ML=6.2  TAI    Hualien, Taiwan              

P: 18APR2021 132920    23.0N  122.0E 4.0-5.4 AAAAA  Taiwan                     

 

An M 5.2 began the sequence about half an hour before the earthquakes in Taiwan. This event occurred in Myanmar where it was felt with intensity VI in Fala, China. This epicenter is located at the same latitude and about 30 degrees west of Taiwan and may be related. The last earthquake within about 200 km of this epicenter of equal or larger magnitude was an M 6.3 on August 27, 2020, an aftershock of the M 5.6 on June 21, 2020 which was probably triggered by a solar eclipse of the same date and which was detailed in this summary at the time as:

 

"Some enhanced activity in northern India and Myanmar is anticipated with the new moon today but the strongest of this may be delayed as noted in the tidal seismic forecast with today's solar eclipse:

 

and

 

The earthquake in India/Myanmar today occurred near the sub-solar point at the time of the total eclipse. The sub-solar point is the point on the earth's surface where the sun is directly overhead at local solar noon. On the first day of summer in the northern hemisphere, the sun reaches its zenith at about 23 degree North latitude due to the tilt of the earth's axis." (June 20-21, 2020)

 

Forecast 132913 had expected today's event within about 100 km in Myanmar  was likely around April 17.

 

O: 18APR2021 13:24:33  22.5N   94.3E Mw=5.2  EMSC   MYANMAR                      

P: 17APR2021 132913    23.0N   95.0E 4.0-5.4 AAAAA  Myanmar                    

 

An earthquake of M 4.9 occurred today in the North Atlantic Ocean south of Iceland. This event is not part of the volcanic episode in Iceland as it lies several hundred km to the southwest of that activity. The last earthquakes within about 150 km of this epicenter with equal or larger magnitude occurred in 2017 on June 18 and March 2 with M 5.0-5.1. The last event in the area of significantly larger magnitude was an M 5.2 on May 10, 2005. The largest such event in the past 30 years was an M 5.4 on August 8, 2000. Enhanced seismicity in the North Atlantic had been expected in forecast 133028 to occur around April 17. This activity appears to be related to high tidal stresses with the new moon of April 12 and to the geomagnetic storm  which was near maximum when this event occurred. This summary had expected this in previous issues as:

 

 

"The geomagnetic field saw minor storm conditions today. The AP level was 29.  High latitude geomagnetic field  saw major storm conditions with AP 59. This is the strongest geomagnetic storm since AP reached 29 on March 20 and the strongest at high latitudes since AP reached 62 in polar areas on October 26, 2019. Enhanced seismicity is expected in the next several days near the geomagnetic equator and at high latitudes due to effects from this geomagnetic storm." (April 17-18, 2021)

 

and

 

"The new moon will arrive on April 12 at 02:31 UT. Longitudes which are near local solar midnight at this time are near 37 West and those at local solar noon are near 143 East longitude. In the west these include area of the Atlantic Ocean and in the east much of the western Pacific subduction zone maximizing in Honshu, Japan and the Kuril Islands and in New Guinea, Indonesia. These are the most likely areas to see tidal triggering of seismicity with this new moon. A strong to major quake is possible in the next week to 10 days with this new moon, possibly near these longitudes." (April 9-15, 2021)

 

O: 18APR2021 15:17:18  61.9N   26.7W mb=4.9  EMSC   ICELAND REGION               

P: 17APR2021 133028    58.0N   32.0W 4.0-5.7 ACCAA  North Mid-Atlantic Ridge   

 

MODERATELY STRONG QUAKES IN IRAN, JAPAN ACCOMPANY MAJOR GEOMAGNETIC STORM

 

EARTHQUAKE SUMMARY FOR  APRIL 17, 2021

 

Moderately strong earthquakes of M 5.8 each occurred today in southern Iran and off the east coast of Honshu, Japan. These accompanied the strongest geomagnetic storm in more than a year and were probably promoted by effects from that storm. This summary noted this geomagnetic storm as:

 

"The geomagnetic field saw minor storm conditions today. The AP level was 29.  High latitude geomagnetic field  saw major storm conditions with AP 59. This is the strongest geomagnetic storm since AP reached 29 on March 20 and the strongest at high latitudes since AP reached 62 in polar areas on October 26, 2019. Enhanced seismicity is expected in the next several days near the geomagnetic equator and at high latitudes due to effects from this geomagnetic storm." (April 17-18, 2021)

 

The M 5.8 in Iran was reported with damage and intensity VIIII in Bandar-e Genaveh, Bushehr, Iran with lesser shaking in Boyerahmad, Khuzestan, Fars, Iran and in Kuwait. There were no immediate reports of damage or casualties, but this area often sees damage with earthquakes of this magnitude and further reports will be available later. It is the strongest earthquake recorded in Southern Iran within about 200 km of this epicenter since an M 6.4 on April 9, 2013 and an M 5.8 on September 29, 2010. Forecasts 132697 and 132966 had expected this activity within about 50 km of this epicenter was likely in early to mid-April.  This epicenter is at the fifth node (72 degrees) from the strong Honshu, Japan earthquakes and may have been promoted by energy from those epicenters.

 

O: 18APR2021 06:41:50  29.8N   50.7E Mw=5.8  EMSC   SOUTHERN IRAN                

P:  8APR2021 132697    30.0N   51.0E 3.8-5.3 CAAAA  So. Iran                   

P: 12APR2021 132966    32.0N   49.0E 3.8-5.6 CCBAA  So. Iran                   

 

An earthquake at the same longitude occurred earlier in the day in the Gulf of Aden with M 4.7. The last earthquake of larger size in the Gulf of Aden occurred a year ago with an M 5.0 on April 22, 2020. Forecast 132609 had expected today's event within about 50 km was likely in mid-April. This event is at 102 degrees from the M 6.6 in the South Atlantic of April 3 and may have been promoted by energy from that source.

 

O: 18APR2021 02:02:44  13.1N   50.4E mb=4.7  EMSC   GULF OF ADEN                 

P:  9APR2021 132609    13.0N   51.0E 3.5-4.9 CAAAA  Gulf of Aden               

 

An earthquake of M 5.6-5.8 also occurred off the northeast coast of Honshu, Japan. NEIC reported it was felt with maximum intensity V in Miyagi and IV in Fukushima with lesser shaking in Saitama, Chiba and Tokyo Prefectures, Japan. JMA reported shaking throughout northern Honshu with intensity IV-VI. Today's event follows several weeks of quiet seismicity in this area which followed major quakes of M 7.3 on March 20, 2021 and an  M 7.1 on February 13, 2021. As it is near the maximum stress longitude of the new moon, the area had been expected to see enhanced seismicity with the recent new moon of April 12 as noted in previous issues of this report:

 

"The new moon will arrive on April 12 at 02:31 UT. Longitudes which are near local solar midnight at this time are near 37 West and those at local solar noon are near 143 East longitude. In the west these include area of the Atlantic Ocean and in the east much of the western Pacific subduction zone maximizing in Honshu, Japan and the Kuril Islands and in New Guinea, Indonesia. These are the most likely areas to see tidal triggering of seismicity with this new moon. A strong to major quake is possible in the next week to 10 days with this new moon, possibly near these longitudes." (April 9-15, 2021)

 

The current geomagnetic storm was the strongest since the M 7.3 off the coast of Honshu, Japan on March 20 and probably helped promote today's event in Japan. On March 20, 2021 this summary noted the relation between the strong geomagnetic storm of March 20 and the M 7.3 in Honshu of that day as follows, similar conditions apply to today's events.

 

"A major earthquake of M 7.0-7.2 occurred off the coast of northern Honshu, Japan as the strongest geomagnetic storm since November 22, 2020 occurred. These events were simultaneous. A third major event today, simultaneous with these, was the eruption of  Fagradalsfjall Volcano in Southern Iceland. This is the first eruption of this volcano in at least 6000 years. The geomagnetic storm began slightly before the earthquake but showed a major change in intensity at 09:09 UT (the earthquake in Japan also occurred at 09:09 UT) according to mid-latitude magnetometers (online with NOAA at Boulder, Colorado. This sudden and sharp change in the geomagnetic field was accompanied by KP index of 8 in College, Alaska and 7 in most other mid- and high-latitude geomagnetic stations. This is the strongest geomagnetic storm since September 28, 2020, nearly half a year ago when AP reached 33 and high latitude AP was 47. The AP index today was 29 and the high latitude AP was 42. Both maximized around 09:00 UT.  SWPC expects this storm to strengthen as a CME makes a close encounter around March 23. A strong aurora is expected. These are the conditions under which strong increases in global seismicity can occur." (March 20, 2021)

 

Today's M 5.7 is the strongest aftershock to date of the M 7.0 on March 20, 2021 and was probably triggered by a strong solar flare which occurred minutes before. Forecast 132953 had expected today's event was likely within about 50 km of this epicenter around April 16.

 

O: 18APR2021 00:29:13  38.4N  141.8E Mw=5.7  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 16APR2021 132953    39.0N  142.0E 4.0-5.4 AAAAA  Off East Coast Honshu      

 

A flare of B9.5 occurred today. This is the strongest solar flare observed by SWPC since a C1.6 flare on March 8, 2021. Four flares of larger size have been observed during the year 2021. The parameters for today's larger flares were:

 

Flare #    START  MAX       END    CLASS     DATE    Flux (Jm-2)

#-------------------------------------------------------------------------------

8000       1621   1717      1825   B9.7      (April 17, 2021)   5.2E-03      

8020       2349   ////      0004   B4.1      (April 17-18, 2021)   1.8E-04  

 

Flare 8000 was accompanied by an M 4.9 in the Dodecanese Islands-Turkey border region while Flare 8020 was followed minutes later by the M 5.7-5.8 off eastern Japan and may have triggered that event which occurred near local solar noon when SFE maximize.

 

Today's event in the Dodecanese Islands, Greece/Turkey is an aftershock of the M 5.4 in the region on April 13 and is the strongest aftershock since that event. This activity had been expected within about 100 km of this epicenter around April 18.

 

NEIC reported this earthquake of M 5.0 in the Dodecanese Islands, Greece was felt with intensity II-III in the area(s) of the Dodecanese Islands, Greece in Kos, and Kremasti and in Datca, Mugla, Turkey.

 

O: 17APR2021 20:57:11  36.4N   27.1E mb=4.1  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 17APR2021 22:35:54  36.4N   27.1E mb=4.2  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 17APR2021 17:08:01  36.4N   27.1E mb=4.9  EMSC   DODECANESE IS.-TURKEY BORDER R

P: 18APR2021 132973    37.0N   28.0E 3.5-5.1 AAAAA  Turkey                     

 

A pair of moderate earthquakes of M 5.0 and 5.1 also occurred in the high latitudes of the South Shetland Islands of Antarctica today. The first of these and the strongest occurred within about 45 minutes of local solar midnight and may have been promoted by the strong geomagnetic storm today. The M 5.1 is the strongest aftershock of the M 7.1 which struck this region about 200 km to the northeast  of today's event on January 23, 2021. The only other event within about 150-200 km of today's epicenter with M>=5.1 was an M 5.5 on April 10, 2021. Forecast 133096 had expected today's event within about 50 km was likely around April 14.

 

GUC reported this earthquake of M  5.1 was felt with intensity III in  Antartida at Antartida, and in Base Fildes, Chile.

GUC reported this earthquake of M  5.0 was felt with intensity III in  Antartida at Antartida, Base Frei and in Base Fildes, Chile.

 

O: 18APR2021 06:46:51  62.4S   58.3W mb=5.0  EMSC   SOUTH SHETLAND ISLANDS

O: 18APR2021 02:15:14  62.4S   58.3W Mw=5.1  EMSC   SOUTH SHETLAND ISLANDS       

 

O: 18APR2021 06:46     62.3S   58.4W mb=4.1  GUC    Antartida at Antartida, and in

O: 18APR2021 02:15     62.4S   58.5W mb=5.0  GUC    Antartida at Antartida, Base F

P: 14APR2021 133096    62.0S   58.0W 4.0-5.4 BAAAA  Southern  Ocean            

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in the central Andreanof Islands. It was not felt in this remote area. This is the largest earthquake within about 100 km of this epicenter in the past month - since an  M 4.7 on March 17, 2021. Forecast 133019 had expected today's event within about 30 km was likely around April 17.

 

O: 17APR2021 08:54:10  52.7N  174.3W mb=3.8  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 17APR2021 133019    52.4N  174.3W 3.5-5.0 AAAAA  Andreanoff Isls, Aleutians 

 

MODERATE QUAKES IN NEW ZEALAND ACCOMPANY NEW GEOMAGNETIC STORM

 

EARTHQUAKE SUMMARY FOR  APRIL 16, 2021

 

A moderate geomagnetic storm occurred today and may affect enhanced seismicity

in the next couple of days as reported in this summary:

 

"The geomagnetic field saw active conditions today. The AP level was 19.  High latitude geomagnetic field  saw minor storm conditions with AP 31. This is the strongest geomagnetic storm since AP reached 24 on March 21. Enhanced seismicity is expected in the next several days near the geomagnetic equator and at high latitudes due to effects from this geomagnetic storm." (April 16, 2021)

 

The geomagnetic storm occurred in conjunction with an increase in seismicity throughout New Zealand. The strongest earthquake of the day was an unfelt M 5.5 aftershock in the Kermadec Islands of the M 8.1 of March 4, 2021. The most widely felt event of the day was an M 5.1 in South Island, New Zealand near Te Anau.  GEONET reported this earthquake was felt with weak to light intensity in the area of Southern South Island, New Zealand. 78 felt reports were published including 56 of weak and 20 of light shaking and 1 of moderate intensity, 1 of severe and 1 of extreme intensity. NEIC reported this 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 in Te Anau, Southland and Queenstown, Otago. This is the strongest earthquake within about 150 km of this epicenter since an M 5.5 on June 24, 2020 and an M 5.4 on August 12, 2019. Forecast 133090 had expected today's event was likely within about 50 km around April 14.

 

O: 16APR2021 22:57:04  44.7S  167.1E ML=4.7  EMSC   SOUTH ISLAND OF NEW ZEALAND  

O: 16APR2021 22:57:07  44.6S  167.3E MS=5.1  GEONET Felt with weak to light intensity

P: 14APR2021 133090    45.0S  167.0E 3.0-5.0 AAAAA  So. Island, N.Z.           

 

The M 5.5 in the northern Kermadec Islands was the strongest event in the world today. Like the event half an hour later in South Island, New Zealand it occurred near local solar noon when the geomagnetic storm was nearing its maximum intensity today and was most likely to trigger seismicity. This follows ten days of reduced seismicity in the area, the last such aftershock having occurred on April 7 with M 5.6. Forecast 133067  had expected today's event in this area was likely around April 16.

 

O: 16APR2021 22:13:07  28.9S  176.1W Mw=5.5  EMSC   KERMADEC ISLANDS REGION      

P: 16APR2021 133067    29.0S  177.0W 4.0-5.7 AAAAA  No. Kermadec Islands       

 

An M 5.4 also occurred in the Fiji Islands today. It was not reported felt. Forecast 133074 had expected this earthquake within about 50 km was likely around April 15.

 

O: 16APR2021 16:40:32  21.7S  179.4W Mw=5.4  EMSC   FIJI REGION                  

P: 15APR2021 133074    22.0S  179.0W 4.0-5.8 AAAAA  Tonga Islands              

 

Shishaldin Volcano erupted in the Aleutian Islands of Alaska today. It sent ash as high as 25,000 feet and caused an air traffic alert to be issued. Shishaldin is located about 1000 km southwest of Anchorage near Unimak Island, but is not expected to impact that area due to wind directions at the time of the eruption. This eruption joined a number of others including those in La Soufriere and Iceland which maximized with the new moon of April 12 and was probably promoted by high tidal stresses associated with that alignment.

 

MODERATELY STRONG QUAKES IN SUMBAWA, INDONESIA; NEAR ISLANDS, ALEUTIANS

 

EARTHQUAKE SUMMARY FOR  APRIL 15, 2021

 

The strongest earthquake in the world today was a pair of events of M 5.4-5.5 in the area of Sumbawa, Indonesia. Tropical Cyclone Seroja passed over this epicenter a week ago and probably helped promote today's regional seismicity. This summary noted this possibility at the time as:

 

"TC    SEROJA   2021-04-07  00:00 UT  13.3S  118.0E   55 kts  Sumbawa, Indonesia

 

TC Seroja continued near Sumbawa, Indonesia today with winds up to 55 kts. It is expected to track to the southwest over the next several days and may help enhance seismicity in the area of Timor." (April 6-7, 2021)

 

The last earthquake of M>=5.4 within about 200 km of this epicenter occurred in January (21-23), 2019 with a series of M 6.0, 6.4 and 6.5 and prior to that in 2016. Forecast 133057 had expected today's event within about 100 km was likely around April 17.

 

 

O: 16APR2021 03:42:06  10.3S  117.0E Mw=5.4  EMSC   SOUTH OF LOMBOK, INDONESIA

O: 15APR2021 10:36:20  10.4S  117.1E Mw=5.4  EMSC   SOUTH OF SUMBAWA, INDONESIA

O: 16APR2021 03:20:41  11.4S  117.8E ML=4.7  EMSC   SOUTH OF SUMBAWA, INDONESIA

O: 16APR2021 03:30:40  10.2S  117.1E ML=4.4  EMSC   SOUTH OF SUMBAWA, INDONESIA  

P: 17APR2021 133057    10.0S  116.0E 4.0-5.4 AAAAA  Sumbawa Island area        

 

 

The strongest earthquake in the U.S. or Canada today was an M 5.3 in the Near Islands, Aleutians. It was not reported felt in this remote area. The last earthquake in the Near Islands with M>=5.3 was an M 5.3 on December 9, 2020 wile the last of larger magnitude was an M 5.4 on October 26, 2019. A strong M 6.8 hit the area on June 2, 2017.  This epicenter is at the antipode to the M 6.6 in the South Atlantic Ocean of April 3, 2021. At the time this summary noted this antipodal relation and possible triggering as:

 

"Kamchatka lies in the antipodal region of today's M 6.6 in the South Atlantic but other seismic areas which are antipodal are the Rat and Near Islands and the Komandorsky Island. These are likely to see enhanced seismicity" (April 3-4, 2021)

 

Forecast 132757 had expected today's event was likely within about 100 km the

Near Islands around April 8.

 

O: 15APR2021 08:33:40  53.6N  171.6E Mw=5.3  EMSC   NEAR ISLANDS, ALEUTIAN ISLANDS

P:  8APR2021 132757    53.0N  170.0E 4.0-5.7 CAAAA  Near Islands               

 

An earthquake of M 3.1 was widely felt on the Louisiana and Texas border today. NEIC reported maximum intensity IV in Louisiana at Mooringsport, and II-III in Shreveport, Belcher, Bossier City, and in Texas at Karnack. This follows a series of regional events in this area over the past two days. This was detailed in the previous two summaries as:

 

 

"The second unusual earthquake in Northern Texas today was an M 2.5 near the border with Louisiana. This area has been relatively active in recent weeks but this is the strongest earthquake within about 200 km of this epicenter since an M 3.0 on April 1, 2021 and prior to that an M 2.5 on March 23, 2021 and on May 31, 2019. Forecast 132968 had expected today's event was likely around April 15.

NEIC reported this earthquake of M 2.5 in northern Texas was felt with intensity IV in Shreveport, Louisiana and II-III in the area(s) of Mooringsport." (April 14, 2021)

 

and

 

"An unusual earthquake of M 3.0 occurred today on the border between northern Louisiana and Texas. NEIC reported it was felt with maximum intensity V in Plain Dealing, Louisiana and II-III in Louisiana at Mooringsport, Shreveport, Bossier City, Stonewall, Haughton, and in Texas at Daingerfield and Kilgore. An area about 100 km south of this in Louisiana was active from May, 2012 to January, 2019, but the last event within about 100 km of this epicenter with M>=4 appears to have been an M 3.0 20 years ago on March 3, 2001. Forecast 132698 had expected regional seismic enhancement in early April, 2021." (April 2, 2021)

 

Forecast 132968 had expected today's event in Louisiana was likely around April 15.

 

O: 16APR2021 00:43:51  32.6N   94.0W mb=3.1  EMSC   NORTHERN TEXAS               

P: 15APR2021 132968    33.0N   92.0W 2.0-4.0 AABAA  Southeast U.S.             

 

MODERATE QUAKE SHAKES SUMATRA; UNUSUAL QUAKES IN TEXAS

 

EARTHQUAKE SUMMARY FOR  APRIL 14, 2021

 

The strongest earthquake in the world today was an M 5.5 in Sumatra, Indonesia. NEIC reported it was felt with intensity VII in Gunung Stoli, Sumatra.

BMG reported intensity up to IV in Taluk Dalam and Lahoriti, off western Sumatra. This is the largest earthquake within about 200 km of this epicenter in the area of Nias west of Sumatra in more than a year. An M 6.2 occurred about 200 km to the north on January 7, 2020 and events of M 5.5 and 5.8 hit about  100 km to the east on June 3, 2019. Forecast 132849 had expected today's event was likely within about 100 km around April 19.

 

O: 14APR2021 10:55:15   0.2N   96.6E Mw=5.5  EMSC   NIAS REGION, INDONESIA       

P: 19APR2021 132849     1.0N   97.0E 4.0-5.6 BAAAA  Nicobar Islands            

 

Two moderate earthquakes of M 4.7 and M 5.0 occurred in northern Mindanao, Philippines today. PHIVOLCS reported this earthquake of M 4.9-5.0 in Mindanao, Philippines was felt with intensity II-III in the area(s) of Mindanao, Philippines in Burgos, and San Isidro, Surigao del Norte, Philippines. Forecast 132840 had expected this event within about 100 km was likely around April 18. This may have been promoted by stresses from Tropical Storm Surigae which is currently to the east of this epicenter. Enhanced seismicity was expected in northern Mindanao at this time as:

 

"TS Surigae formed today in the region east of Mindanao, Philippines with winds up to 65 kts. It is expected to track to the west possibly making landfall in the central Philippines. This storm is likely to promote elevated seismicity in the region of the Philippines in the coming week." (April 14-15, 2021)

 

O: 14APR2021 11:09:34  10.1N  126.5E mb=5.0  EMSC   PHILIPPINE ISLANDS REGION    

O: 14APR2021 16:39:23  10.1N  126.5E ML=4.7  EMSC   PHILIPPINE ISLANDS REGION

P: 18APR2021 132840     9.0N  126.0E 4.0-5.4 BBAAA  Central Philippines        

 

Two unusual earthquakes occurred today in the region of northern Texas. This activity is at 100-104 degrees from the major and great eartquakes in the Loyalty Islands, Kermadec Islands and North Island, New Zealand of February and March , 2021 and was likely promoted by energy from that source. The largest of these, and the strongest in the U.S. or Canada was an M 4.3 which hit the Texas Panhandle today. NEIC reported it was felt with intensity IV in Miami, Texas and II-III in Borger, Skellytown, Pampa, Perryton, Groom, Amarillo, and possibly as far as Axtell, Nebraska. This is the strongest earthquake within about 200 km of this epicenter in at least 30 years. The only earthquake in this area of larger magnitude in the past 50 years was an M 4.5-4.6 on February 15, 1974. The strongest quake in this area on record is an M 5.0 on July 30, 1925. Forecast 132955 had expected today's event was likely in this area around April 11.

 

O: 14APR2021 23:54:03  35.9N  101.0W mb=3.7  EMSC   TEXAS PANHANDLE REGION       

O: 14APR2021 23:54:03  35.9N  101.0W mb=4.3  EMSC   TEXAS PANHANDLE REGION       

P: 11APR2021 132955    35.4N  101.8W 2.0-4.0 BAAAA  SW U.S.A                   

 

The second unusual earthquake in Northern Texas today was an M 2.5 near the border with Louisiana. This area has been relatively active in recent weeks but this is the strongest earthquake within about 200 km of this epicenter since an M 3.0 on April 1, 2021 and prior to that an M 2.5 on March 23, 2021 and on May 31, 2019. Forecast 132968 had expected today's event was likely around April 15.

NEIC reported this earthquake of M 2.5 in northern Texas was felt with intensity IV in Shreveport, Louisiana and II-III in the area(s) of Morningsport.

 

 

O: 15APR2021 05:13:57  32.6N   94.1W mb=2.5  EMSC   NORTHERN TEXAS               

P: 15APR2021 132968    33.0N   92.0W 2.0-4.0 AABAA  Southeast U.S.             

 

MODERATE QUAKES RETURN TO DODECANESE ISLANDS, GREECE

 

EARTHQUAKE SUMMARY FOR  APRIL 13, 2021

 

An earthquake of M 5.4 occurred today in the Dodecanese Islands, Greece. NEIC reported it was felt with intensity VI in Drosia, Greece and V in Dardamaina, Dodecanese Islands and Datca, Mugla, Turkey and II in Emborion, Greece. This may be a regional aftershock of the M 7.0 in northern Greece of October 30, 2020 which was about 150 km north of today's epicenter. The last such event within  about 100 km of today's epicenter was an M 6.2 on October 12, 2020. A series of events of M>=5 hit the area in the period between June and October, 2020. Forecast 132648 had expected today's event within about 50 km was likely around April 8. This activity is at 146 degrees from the Loyalty Islands M 7.7 of February 10 and was probably promoted by energy from those sources. It may also have been promoted by high tidal stresses associated with the new moon as it occurred within about an hour of local solar midnight when such stresses maximize.

 

O: 13APR2021 20:30:22  36.5N   27.1E Mw=5.1  EMSC   DODECANESE IS.-TURKEY BORDER REG

O: 13APR2021 20:28:04  36.5N   27.2E ML=5.1  EMSC   DODECANESE IS.-TURKEY BORDER R

O: 13APR2021 20:28:02  36.5N   27.0E ML=5.4  ANSS   DODECANESE IS.-TURKEY BORDER R

P:  8APR2021 132648    37.0N   27.0E 3.0-4.6 BAAAA  Aegean Sea                 

 

The strongest earthquake in the world today occurred in the Galapagos Triple Junction south of Guerrero, Mexico with M 5.7. It was not reported felt in this remote area. The only event in the region within about 200 km of this epicenter in the past 30 years was an M 5.7 on November 24, 1992. The larger area including the Galapagos Triple Junction saw an M 6.0 about 350 km to the northwest on October 16, 2009 and an M 5.7 about 250 km to the northeast on May 1, 2006. Forecast 132845 had expected enhanced seismicity in the Galapagos south of Guatemala was possible around April 19 or to the northwest around April 17 in  forecast 132890. Today's activity is likely part of the increased global volcanism of the past several days.

 

 

O: 14APR2021 04:33:29   1.8N  101.0W Mw=5.7  EMSC   GALAPAGOS TRIPLE JUNCTION REGI

P: 19APR2021 132845     2.0N   91.0W 3.5-5.2 BADAA  Galapagos Islands          

P: 17APR2021 132890    10.0N  104.0W 3.5-5.4 BDCAA  Michoacan, Mexico          

 

The largest earthquake in the U.S. or Canada today was an M 3.9-4.5 in northern Wyoming. NEIC reported it was felt in Wyoming at Ten Sleep, Kaycee, Thermopolis, Casper, Riverton, Evansville, Green River. The last earthquake of M>=3.9 within about 200 km of this epicenter occurred on November 3, 2017 (M 4.0). The last such event of M>=4.5 occurred more than 30 years ago. Forecast 132714 had expected today's event in this area was likely in early to mid-April. This event is near 103 degrees from the recent earthquakes in the Kermadec Island, North Island, New Zealand and the Loyalty Islands and was probably promoted by strong energy from those sources.

 

O: 13APR2021 12:22:37  43.6N  107.3W Ml=4.5  EMSC   WYOMING                      

O: 13APR2021 12:22:37  43.6N  107.3W Ml=3.9  EMSC   WYOMING                      

P:  5APR2021 132714    41.9N  108.7W 2.0-3.9 CBBAA  Colorado area              

 

 

QUIET SEISMICITY CONTINUES

 

EARTHQUAKE SUMMARY FOR  APRIL 12, 2021

 

Global seismicity remained at quiet levels today. The strongest earthquake  in the world was an M 5.2 in the region of the Loyalty Islands. This area has been relatively quiet in the past several weeks after strong and major quakes in the region in early February, 2021. This earthquake may have been promoted by Tropical Cyclone 28S which passed over the southern Loyalty Islands over the past two days as noted in previous issues of this summary:

 

 

"Tropical Cyclone 28S formed today in the area south of Loyalty Islands with winds up to 50 kts. It is expected to track to the east and south over the next several days. Some seismic enhancement in the Loyalty Islands may accompany this storm." (April 11, 2021)

 

Today's event is the strongest in the Loyalty Islands in the past three weeks - since an M 5.4 on March 20. An M 5.2 also occurred about 200 km northwest of this on April 5, 2021. Forecast 133066 had expected today's event was likely around April 12.

 

O: 12APR2021 22:44:32  22.7S  172.1E Mw=5.2  EMSC   SOUTHEAST OF LOYALTY ISLANDS 

P: 12APR2021 133066    23.0S  170.0E 4.0-5.4 AABAA  Loyalty Islands            

 

Other earthquakes of M>=5 in the world today occurred in Ocean Ridge areas with an M 5.1 north of Ascension Island and an M 5.1 in the Mauritius-Reunion area of the South Indian Ocean. These events were not felt in these remote areas. Forecasts 132581 and 132790 had expected these events within about 200 km of these epicenter were likely in early April. The earthquake of M 5.1 in the area north of Ascension Island is at 144 degrees from the M 8.1 in the Kermadec Islands of March 4 and was probably promoted by energy from that source.

 

O: 13APR2021 06:06:00   0.1N   17.4W mb=5.1  EMSC   NORTH OF ASCENSION ISLAND    

P: 10APR2021 132581     1.0S   16.0W 4.0-5.6 BBBAA  Central Mid-Atlantic       

 

The earthquake of M 5.1 in the area north of Mauritius and Reunion Island is at 103 degrees from the M 8.1 in the Kermadec Islands of March 4 and was probably promoted by energy from that source.

 

O: 12APR2021 20:43:30  18.7S   65.5E mb=5.1  EMSC   MAURITIUS - REUNION REGION   

P:  5APR2021 132790    17.0S   67.0E 4.0-5.4 CBBAA  So. Indian Ocean           

 

The strongest earthquake in the U.S. or Canada today was an M 3.8 in the Kodiak Island region of Alaska. The last earthquake in the Kodiak Island region within about 200 km of this epicenter with M>=3.8 was an M 4.9 on January 3, 2021 and prior to that an M 4.1 on October 17, 2020, two days before the M 7.6 in the Alaska Peninsula of October 19, 2020 and possibly a regional foreshock to that event. Forecast 133017 had expected enhanced seismicity in this region in mid-April.

 

 

O: 12APR2021 11:37:59  56.9N  155.0W ML=3.8  EMSC   KODIAK ISLAND REGION, ALASKA 

P: 18APR2021 133017    54.7N  156.9W 3.5-4.9 CCBAA  Alaska Peninsula           

 

VOLCANIC EPISODES CONTINUE; REDUCE GLOBAL AND REGIONAL SEISMICITY

 

EARTHQUAKE SUMMARY FOR  APRIL 11, 2021

 

Active volcanic eruptions continued today in La Soufriere, St. Vincent, southern Iceland and Etna in Sicily, Italy. The eruption in La Soufriere has continued for the third day covering the island of St. Vincent with heavy ash and damaging many buildings there due to its weight. Nearly 100,000 have been evacuated as the volcano continues to rumble. This eruption is expected to continue for some time. Power was out intermittently in the area in the area due to the eruption. The eruption of Mt. Etna in Sicily also entered its third week. This eruption has included copious lava flows and ash and volcanic stones falling. The airport was briefly closed. The eruption in Iceland also continued today where a fourth fissure opened up at Fagradalsfjall near Reykjavik. This eruption is now nearly three weeks old. Other volcanic eruptions were occurring in Pacaya in Guatemala, Fuego in Guatemala, Karymsky in Kamchatka, Popocatepetl north of Mexico City and Dukono in Halmahera and in Suwanose-Jima, Ryukyu Islands. The eruptions in the Ryukyu Island, Kamchatka and Java have been accompanied by large earthquakes. Other eruptions on April 11 occurred in Japan at Ebeko in Paramushir Island and in Sakurajima, in Kyushu, Japan and in Ecuador. Volcanic episodes such as this can reduce regional and global seismicity as volcanoes act as a pressure release for the earth's surface and reducing pressure reduces global seismicity.

 

The strongest earthquake in the U.S. or Canada today was an M 4.0 in the region of the Alaska Peninsula. It appears to be an aftershock of the M 7.6 event of October 19, 2020. Forecast 132747 had expected this event was likely around April 8. 

 

O: 11APR2021 07:10:50  54.4N  159.7W ml=4.0  EMSC   SOUTH OF ALASKA              

P:  8APR2021 132747    54.8N  158.7W 3.5-4.9 BAAAA  Alaska Peninsula           

 

An unusual earthquake of M 3.0 was also felt in Tamil Nadu, Southern India today. NCS of India reported this earthquake was felt with intensity II in the epicentral region. The last earthquake within about 300 km of this epicenter in India reported by NEIC was an M 5.1-5.2 on September 25, 2001, the only such earthquake in the area in the past 30 years at least.  Forecast 132602 had expected regional activity to the northwest was likely around April 8. This earthquake is at 105 degrees from the M 7.3 off North Island, New Zealand of March 4 and may have been promoted by energy from that source.

 

O: 11APR2021 15:11:27  12.1N   79.1E ML=3.0  EMSC   TAMIL NADU, INDIA            

P:  8APR2021 132602    17.0N   74.0E 3.5-5.1 BCCAA  Arabian Sea                

STRONG EARTHQUAKE IN NEW GUINEA PROMOTED BY TIDAL STRESSES

 

EARTHQUAKE SUMMARY FOR  APRIL 10, 2021

 

The strongest earthquake in the world today was an M 6.0-6.1 off the north coast of New Guinea. NEIC reported it was felt in Papua New Guinea with intensity II-III at Madang and Mount Hagen. It was probably promoted by high tidal stresses associated with the New Moon of April 12 as noted in previous issues of this report maximize near this longitude:

 

"The new moon will arrive on April 12 at 02:31 UT. Longitudes which are near local solar midnight at this time are near 37 West and those at local solar noon are near 143 East longitude. In the west these include area of the Atlantic Ocean and in the east much of the western Pacific subduction zone maximizing in Honshu, Japan and the Kuril Islands and in New Guinea, Indonesia. These are the most likely areas to see tidal triggering of seismicity with this new moon. A strong to major quake is possible in the next week to 10 days with this new moon, possibly near these longitudes." (April 8-9, 2021)

 

This epicenter is near the geomagnetic equator and like similar events in the  Celebes Sea and in Java today may have been prompted by the now-concluded strong geomagnetic storm previously identified in this summary as:

 

 

"The geomagnetic field saw active today. The AP level was 17.  High latitude geomagnetic field  saw stormy conditions with AP 35. Strong geomagnetic storms such as this can promote enhanced seismicity in the high latitudes and near the geomagnetic equator and this is likely in the next three days." (April 7-8, 2021)

 

The only events within about 200 km of today's epicenter within the past three years occurred as an M 6.3 on February 7, 2021 and an M 6.2 on January 17, 2019.

Forecast 132591 had expected today's event in New Guinea was likely around April 7.

 

O: 10APR2021 11:38:32   3.5S  145.7E Mw=6.0  EMSC   NEAR N COAST OF NEW GUINEA, PN

P:  7APR2021 132591     7.0S  144.0E 4.0-5.4 BCBAA  Papua New Guinea           

 

A similar M 6.1 occurred several hours earlier in the area of the Celebes Sea south of the Philippines. NEIC reported this earthquake was felt with intensity III in Buayan, Southern Mindanao, Philippines. This is the strongest earthquake in the Celebes Sea region in at least a year. The last within about 200 km of this epicenter with M>=6.1 was an M 6.1 on December 15, 2020 but the last with larger magnitude in this area was an M 6.5 to the west on February 10, 2011. An M 7.3 occurred about 200 km northwest of today's epicenter on January 10, 2017.  Forecast 132574 had expected today's activity to the south was likely around April 9.

 

O: 10APR2021 09:30:44   4.2N  124.6E Mw=6.1  EMSC   CELEBES SEA                  

P:  9APR2021 132574     1.0N  124.0E 4.0-5.6 ACAAA  Mindanao, Philippines       

 

These events followed an M 6.0 felt widely in Java and noted in the previous issue of this summary as:

 

"The earthquake south of Java, Indonesia of M 6.0 is the strongest within about 200 km of  that epicenter since an M 6.0 on July 25, 2015. The last such event with greater magnitude was an M 6.6 on September 28, 1998. Forecast 132592 had expected today's event in this region around April 7." (April 10, 2021)

 

NEIC reported today's earthquake of M 5.1 in Java, Indonesia was felt with intensity II-III in the area(s) of Java, Indonesia at Blitar and Malang.

 

O: 10APR2021 12:49:20   8.9S  112.5E ML=4.2  EMSC   JAVA, INDONESIA

O: 10APR2021 07:00:17   8.4S  112.6E mb=6.0  EMSC   JAVA, INDONESIA              

O: 10APR2021 23:54:58   8.4S  112.5E mb=5.1  EMSC   JAVA, INDONESIA              

P:  7APR2021 132592     9.0S  110.0E 4.0-5.4 BACAA  So. of Java                

 

A moderately strong earthquake of M 5.5 also shook the South Shetland Islands today. It was not reported felt. It is located near the line of maximum longitude in the western hemisphere with the new moon and was probably promoted by strong tidal stresses associated with that alignment. An M 7.1 hit this area on January 23, 2021 and the strongest aftershock to date has been an M 5.5 on January 24, 2021. Forecast 132834 had expected today's event within about 150

km was likely around April 5.

 

O: 10APR2021 07:14:02  62.3S   58.3W Mw=5.5  EMSC   SOUTH SHETLAND ISLANDS       

P:  5APR2021 132834    61.0S   58.0W 3.0-5.6 BAAAA  So. So. America             

 

An unusual earthquake of M 5.0 in the South Pacific Ocean today may also have been related to high tidal stresses. This event is the strongest within about 500 km in at least 30 years. The only recorded event with M>=4 in the general region in this time was an M 4.7 on November 14, 1997 about 550 km  northwest of today's epicenter.

 

O: 10APR2021 17:55:40  40.1S  124.5W mb=5.0  EMSC   SOUTH PACIFIC OCEAN