STRONG SEISMICITY CONTINUES NEAR EQUATOR IN ATLANTIC

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 23, 2020

 

The strongest earthquake in the world today was an M 5.7 in the central mid-Atlantic. It was not felt in the area. This epicenter is at the equator, an area which in the past several days has shown strongly enhanced seismicity in Sumatra, the Central mid-Atlantic, the Galapagos Islands, the northern East Pacific Rise, among others, as noted in previous issues as:

 

"The most active zone of seismicity in the world today was the northern equatorial latitude band between about 0 and 20 degrees north. This band is especially active at this time of year because of strong meteorological ocean storms  (hurricanes and typhoons) which occur in these latitudes and are maximum in September. In the western Hemisphere this included continuing enhanced seismicity in eastern and central Mexico and in the Dominican Republic. The strongest earthquake of the day in this area, however was an M 5.4 in the Galapagos Islands area near the equator. Today is the first day of autumn when the sun reaches its zenith over equator. As has been suggested in this summary in prior issues, this can enhance vertical seismicity in latitudes where the sun reaches its zenith (is directly overhead at local solar noon). In this case that is the equator." (September 20-21, 2020)

 

Similar events of M 5.9 and 6.1 occurred near today's epicenter in the central east Pacific on March 22, 2020 - the first such activity in the area since September 11, 2013. Note that the event in March occurred, like today's on the equinox (in this case, the first day of Spring) while today's event is on the first day of Autumn." (September 21-22, 2020)

 

Today's event may also have been promoted by the occurrence of a geomagnetic storm today, the largest since early September as noted in this summary:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 11.  High latitude geomagnetic field also saw active conditions with AP 29. Geomagnetic disturbances of this level can help promote enhanced seismicity at high latitudes and near the geomagnetic equator. Moderate to moderately strong events in these areas are likely in the next several days." (September 23, 2020)

 

The last earthquake within about 200 km of today's epicenter with M>=5.7 was an M 5.9 on July 23, 2018 and prior to that an M 7.1 on August 29,, 2016. Today's event occurred within about half an hour of local solar midnight and was also likely promoted by strong tidal stresses which maximize at this time. Forecast 127068 had expected today's event was likely in the central Mid-Atlantic within about 100 km of today's epicenter around September 19.

 

O: 24SEP2020 00:27:49   0.2S   18.8W Mw=5.7  EMSC   CENTRAL MID-ATLANTIC RIDGE   

O: 24SEP2020 01:01:28   0.3S   19.1W mb=4.8  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 19SEP2020 127068     1.0S   20.0W 4.0-5.7 BAAAA  Central Mid-Atlantic       

 

An M 4.5 in the Greenland Sea followed the geomagnetic storm today. This is the strongest earthquake within about 400 km of this epicenter in the Greenland Sea since an M 4.6 on March 11 and an M 4.9 on October 29, 2019. Forecast 127546  had expected today's activity was likely within about 100 km of this epicenter around September 30. This event is at 103 degrees from the Banda M 7.0 of August 21 and was probably promoted by energy from that source.

 

O: 24SEP2020 04:44:56  79.6N    3.1E mb=4.5  EMSC   GREENLAND SEA                

P: 30SEP2020 127546    79.0N    7.0E 4.0-5.4 CAAAA  Arctic Ocean Region        

 

Unusual earthquakes occurred in eastern Europe today in Greece with M 4.6 and in Albania with M 4.3. The earthquake of M 4.6 in Greece is the strongest within about 150 km of this epicenter on March 21, 2020. A similar M 4.6 hit south of today's event on July 25, 2020 with M 4.7. Forecast 127428 expected today's event was likely around September 26.

 

NEIC reported this earthquake of M 4.6 in Greece  was felt with intensity II-III in the area(s) of Greece at Karia and Nidrion, Levkas and Vasilika, Trikala.  This event, like that in the Greenland Sea today, is at 103 degrees from the Banda M 7.0 of August 21 and was probably promoted by energy from that source.

 

O: 24SEP2020 05:10:19  38.8N   20.5E mb=4.6  EMSC   GREECE                       

P: 25SEP2020 127428    38.0N   21.0E 3.0-4.5 AAAAA  No. Greece                 

 

The earthquake in Albania of M 4.3 is the strongest within about 150 km of this epicenter in Albania since an M 4.2 on September 12. The last of larger magnitude in the area was an M 4.5 on July 26, 2020. Forecast 127497 had expected today's event in this area was likely around September 25.

 

NEIC reported this earthquake of M 4.3 in  Albania was felt with intensity II-III in the area(s) of Albania at Tirana and Vlore.  This event, like that in the Greenland Sea today, is at 103 degrees from the Banda M 7.0 of August 21 and was probably promoted by energy from that source.

 

O: 23SEP2020 23:25:10  41.0N   19.8E mb=4.3  EMSC   ALBANIA                      

P: 25SEP2020 127497    40.0N   20.0E 3.0-5.2 AAAAA  Romania/NW Turkey          

 

An M 5.3 in northern Mindanao, Philippines today was followed by a series of moderate aftershocks. It occurred within about an hour of local solar noon and may have been enhanced by strong tidal stresses which maximize at this hour as well as by effects from the geomagnetic storm today. It was near sub-solar at the time of the event. This appears to be an aftershock of the M 5.8 which occurred about 50 km southwest of today's epicenter on September 20, 2020. A similar M 5.8 hit he area on July 27, 2020. Forecast 127368 had expected today's event within about 50 km was likely around September 25.

 

NEIC reported this earthquake of M 5.3 in northern Mindanao  was felt with intensity II-III in the area(s) of northern Mindanao, Philippines at Gamut iTago and Alubijid, Caraga, Philippines. Today's event is located at the fifth node (72 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and may have been promoted by energy from that source.

 

O: 23SEP2020 10:21:48   9.3N  126.8E ML=4.2  EMSC   MINDANAO, PHILIPPINES        

O: 23SEP2020 22:19:43   9.3N  127.0E mb=4.7  EMSC   PHILIPPINE ISLANDS REGION    

O: 24SEP2020 02:26:00   9.5N  126.9E Mw=5.3  EMSC   MINDANAO, PHILIPPINES        

O: 23SEP2020 23:32:56  10.1N  126.4E ML=4.0  EMSC   PHILIPPINE ISLANDS REGION    

P: 25SEP2020 127368    10.0N  127.0E 3.5-4.9 AAAAA  Luzon, Philippines         

 

SOUTH SHETLAND ISLANDS SWARM CONTINUES

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 22, 2020

 

The strongest earthquakes in the world today were two events of M 5.2 in the

South Shetland Islands between South America an Antarctica. These events were not reported felt in this remote area. This continues a series of earthquakes at this epicenter which began with an M 5.0 on August 29 and peaked with an M 5.4 on September 1. The most recent was an M 5.3 on September 19. Forecasts 127596 and 127314 had expected moderate seismicity in the South Shetland Islands was likely between September 17 and 24. This activity is at 141 degrees from the M 7.8 in the Alaska Peninsula of July 22 and may have been promoted by energy from that source.

 

O: 22SEP2020 23:44:13  62.3S   58.3W Mw=5.2  EMSC   SOUTH SHETLAND ISLANDS

O: 22SEP2020 23:53:48  62.3S   58.4W Mw=5.2  EMSC   SOUTH SHETLAND ISLANDS

O: 22SEP2020 08:25:21  62.3S   58.0W mb=4.9  EMSC   SOUTH SHETLAND ISLANDS       

P: 17SEP2020 127314    56.0S   55.0W 4.0-5.8 BCBAA  Southern  Ocean            

P: 24SEP2020 127596    56.0S   54.0W 3.0-6.0 ACCAA  South Shetland Is.         

 

The strongest earthquake in the U.S. or Canada today was an M 3.7 near Newfoundland. It was not reported felt in this remote area. The last earthquake within about 300 km of this epicenter with M>=3.7 occurred on February 3, 2020 with M 4.3, the only such event listed by NEIC in the past 30 years.  Forecast 127250 had expected this region would see light to moderate seismicity in

mid-September. Today's earthquake occurred as Tropical Storm Teddy was passing near this epicenter off Labrador. This summary had previously noted the likely effects of Teddy on this region as:

 

"Hurricane Teddy continued today in the Atlantic east of Virginia with winds up to 85 kts. It is expected to track to the north and west over the next week. Some enhanced seismicity may occur in the eastern U.S. and Canada when this storm makes landfall near Nova Scotia around  September 23-24 where some seismicity may be promoted." (September 21-22, 2020)

 

O: 22SEP2020 05:52:09  57.5N   59.6W MB=3.7  ECAN Nutak, NL                      

P: 14SEP2020 127250    67.0N   54.0W 2.5-4.1 CCCAA  Baffin/Davis Strait, Canada

 

An M 4.1 also occurred west of Washington State today. It was not reported felt along the coast line. The last earthquake within about 150 km of this epicenter with M>=4.1 occurred on December 1, 2019 with M 4.1 and prior to that as an M 4.5 on October 11, 2017.  Forecast 127225 had expected today's event about 100 km to the north was likely around September 19.

 

O: 22SEP2020 23:25:49  47.4N  129.0W mb=4.1  EMSC   OFF COAST OF WASHINGTON      

P: 19SEP2020 127225    48.3N  128.5W 2.8-5.0 BAAAA  Vancouver Island area      

 

A swarm of earthquake occurred today at the southeastern most point in Puerto Rico. NEIC reported these earthquakes of M 3.0-4.0 in  Puerto Rico were felt with intensity II-III in the area(s) of Puerto Rico at Lajas, San German, Mayaguez, Cabo Rojo. These epicenters are west of the aftershock group in southern Puerto Rico following the M 6.5 in January, 2020 and do not appear to be aftershocks of that event. The last earthquake this far to the west in southern Puerto Rico of M>=3.4 occurred in February 22, 2016. Forecast 127380 had expected today's activity was likely within about 20 km of these epicenters around September 23.

 

O: 22SEP2020 10:41:58  17.9N   66.6W Md=3.1  EMSC   PUERTO RICO REGION

O: 22SEP2020 10:41:58  17.9N   66.6W Md=3.1  EMSC   PUERTO RICO REGION

O: 22SEP2020 16:27:32  17.9N   66.8W Md=3.0  EMSC   PUERTO RICO REGION

O: 22SEP2020 23:44:23  17.9N   67.1W ML=3.4  EMSC   PUERTO RICO REGION

O: 23SEP2020 01:08:27  17.9N   67.1W ML=3.4  EMSC   PUERTO RICO REGION

O: 23SEP2020 02:05:27  17.9N   67.1W ML=3.1  EMSC   PUERTO RICO REGION

O: 23SEP2020 05:30:44  17.9N   67.1W Md=3.4  EMSC   PUERTO RICO REGION

O: 22SEP2020 09:08:48  17.9N   66.8W Md=3.1  EMSC   PUERTO RICO REGION           

O: 22SEP2020 23:26:50  18.0N   67.1W MD=3.0  EMSC   PUERTO RICO REGION           

P: 23SEP2020 127380    18.0N   67.0W 3.4-5.0 AAAAA  Puerto Rico                

 

 

 

 

STRONG SEISMICITY CONTINUES NEAR THE EQUATOR

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 21, 2020

 

The strongest earthquake in the world today was an M 5.9 in the central East Pacific Rise. It was not reported felt in this remote area. This is part of a pattern of seismicity emphasizing strong activity near the equator.  In the previous issue of this report it was noted that areas near the equator were at particular risk for enhanced seismicity at this time as:

 

"The most active zone of seismicity in the world today was the northern equatorial latitude band between about 0 and 20 degrees north. This band is especially active at this time of year because of strong meteorlogical ocean storms  (hurricanes and typhoons) which occur in these latitudes and are maximum in September. In the western Hemisphere this included continuing enhanced seismicity in eastern and central Mexico and in the Dominican Republic. The strongest earthquake of the day in this area, however was an M 5.4 in the Galapagos Islands area near the equator. Today is the first day of autumn when the sun reaches its zenith over equator. As has been suggested in this summary in prior issues, this can enhance vertical seismicity in latitudes where the sun reaches its zenith (is directly overhead at local solar noon). In this case that is the equator." (September 20-21, 2020)

 

A similar event of M 6.1 occurred near today's epicenter in the central east Pacific on March 22, 2020 - the first such activity in the area since September 11, 2013. Note that the event in March occurred, like today's on the equinox (in this case, the first day of Spring) while today's event is on the first day of Autumn. Forecast 127077 had expected today's activity within about 50 km was likely around September 18.

 

O: 21SEP2020 13:37:14   4.0S  104.4W Mw=5.9  EMSC   CENTRAL EAST PACIFIC RISE

O: 21SEP2020 12:27:56   4.1S  104.3W mb=4.7  EMSC   CENTRAL EAST PACIFIC RISE

O: 21SEP2020 12:06:23   4.0S  104.3W mb=4.7  EMSC   CENTRAL EAST PACIFIC RISE    

P: 18SEP2020 127077     4.0S  104.0W 4.0-5.8 BAAAA  No. East Pacific Rise      

 

A moderately large earthquake of M 5.5 shook the region near Lake Baykal today. It was reported by NEIC to have been felt with maximum intensity VII in Irkutsk, Russia at Shelekhov; IV in Baykalsk, Irkutsk, Angarsk, Kyren, Ulan-Ude, Burjatija; Selenginsk, Naushki and in Zuunharaa Selenge, Mongolia. NEIC reported an aftershock of M 4.6 in Irkutsk, Russia  was felt with intensity II-III in the area(s) of Irkutsk, Russia at Angarsk (V) and Irkutsk. The M 5.5 may have been promoted by high tidal stresses as it occurred within  about 30 minutes of local solar midnight when these stresses are maximized. The last earthquake in the Lake Baykal region within about 300 km of today's epicenter was an M 6.3 on August 27, 2008, the strongest earthquake in the past 30 years in this region. Forecast 127246 had expected today's event in  this region was likely around September 17. These events are at the seventh node (52 degrees) from the Alaska Peninsula M 7.8 of July 22 and were probably promoted by energy from that source.

 

O: 21SEP2020 18:19:55  51.8N  103.5E mb=4.6  EMSC   LAKE BAYKAL REGION, RUSSIA

O: 21SEP2020 18:04:57  51.8N  103.6E Mw=5.5  EMSC   LAKE BAYKAL REGION, RUSSIA   

P: 17SEP2020 127246    56.0N  110.0E 3.0-4.7 BCCAA  So. Siberia                

 

The strongest earthquakes in the U.S. or Canada today were M 4.2 events in southern Alaska. One of these was an M 4.2 aftershock in the Gulf of Alaska, the other occurred in the Kodiak Island area. The last event of M>=4.2 in the Gulf of Alaska was an M 5.1 on March 20, 2020. Forecast 127260 had expected this activity was likely around September 17.

 

O: 21SEP2020 10:30:02  57.0N  149.4W mb=4.2  EMSC   GULF OF ALASKA               

P: 17SEP2020 127260    55.0N  149.0W 3.0-4.8 BBAAA  Northern Alaska            

 

The event in the Kodiak area of Alaska is the strongest in the Kodiak area since an M 5.1 on July 8, 2020. Forecast 127253 had been expected in mid-September. NEIC reported this earthquake of M 4.0-4.2 in Kodiak, Alaska  was felt with intensity II-III in the area(s) of Kodiak, Alaska. This epicenter is near 103 degrees from the M 6.8 in the Central Atlantic of September 18 and was probably enhanced by energy from that source.

 

O: 21SEP2020 18:55:29  57.8N  153.6W ML=4.2  EMSC   KODIAK ISLAND REGION, ALASKA 

P: 15SEP2020 127253    60.2N  153.2W 3.2-5.1 CCAAA  Central Alaska             

 

A swarm of earthquakes occurred in the Mammoth Lakes area of California today. The strongest of these occurred with M 3.0. The last event in the Mammoth Lakes area of M>=3.0 was an M 3.2 on  August 1, 2020. Forecast 127142 had expected today's activity around September 17.

 

NEIC reported this earthquake of M 3.0 in Mammoth Lakes, California  was felt with intensity II-III in the area(s) of Mammoth Lakes, California. This activity is at the fourth node (90 degrees) from the earthquake of M 6.7 in the Mid-Atlantic of September 18 and at 90 degrees from the M 7.4 in the Kermadec  Islands of June 18, 2020 and was probably promoted by energy from these sources.

 

O: 21SEP2020 21:06:32  37.6N  118.9W Md=2.1  EMSC   LONG VALLEY AREA, CALIFORNIA

O: 22SEP2020 01:13:40  37.6N  118.9W Md=2.7  EMSC   LONG VALLEY AREA, CALIFORNIA

O: 22SEP2020 01:14:55  37.7N  119.0W ML=2.5  EMSC   LONG VALLEY AREA, CALIFORNIA

O: 22SEP2020 01:14:55  37.6N  118.9W ML=3.0  ANSS   LONG VALLEY AREA, CALIFORNIA

O: 21SEP2020 15:51:35  37.9N  119.1W ml=2.4  EMSC   CENTRAL CALIFORNIA

O: 21SEP2020 18:31:58  37.5N  118.6W Md=2.8  EMSC   CENTRAL CALIFORNIA           

P: 17SEP2020 127142    37.9N  118.2W 2.5-4.4 BAAAA  California/Nevada area     

 

MODERATE SEISMICITY IN NORTHERN TROPICAL LATITIDES

  

EARTHQUAKE SUMMARY FOR SEPTEMBER 20, 2020

 

The most active zone of seismicity in the world today was the northern equatorial latitude band between about 0 and 20 degrees north. This band is especially active at this time of year because of strong meteorological ocean storms  (hurricanes and typhoons) which occur in these latitudes and are maximum in September. In the western Hemisphere this included continuing enhanced seismicity in eastern and central Mexico and in the Dominican Republic. The strongest earthquake of the day in this area, however was an M 5.4 in the Galapagos Islands area near the equator. Today is the first day of autumn when the sun reaches its zenith over equator. As has been suggested in this summary in prior issues, this can enhance vertical seismicity in latitudes where the sun reaches its zenith (is directly overhead at local solar noon). In this case that is the equator. The earthquake in the Galapagos occurred near local solar midnight, a time when such tidal triggering may be maximized. It was not reported felt but is the strongest event in the Galapagos within about 200 km of this epicenter since an M 5.6 exactly two years ago on September 21, 2018, also the autumn equinox. That event occurred near the epicenter of today's quake. The largest event in the region in the past 30 years was an M 5.8 on March 15, 2009. Forecast 127058 had expected today's event in the Galapagos area was likely in mid-September. This event and the M 5.8 in northern Mindanao, today are located at the fifth node (72-73 degrees) from the M 7.8 in the Alaska Peninsula of July 22, 2020, the last major global earthquake, and may have been promoted by energy from that source. Another active area at the fifth node from Alaska that was active today was the Dominican Republic.

 

O: 20SEP2020 09:50:22   2.4N   95.5W mb=4.7  EMSC   GALAPAGOS ISLANDS REGION

O: 20SEP2020 09:42:15   2.6N   95.3W Mw=5.4  EMSC   GALAPAGOS ISLANDS REGION     

P: 14SEP2020 127058     2.0N   91.0W 3.5-5.0 CACAA  Galapagos Islands          

 

In the eastern hemisphere, seismicity in the band 0-20 north latitude included a series of moderate to moderately strong earthquake in the Philippines. The strongest of these, and the strongest earthquake in the world today was an M 5.8-5.9 in the region of northern Mindanao. It was followed by events of M 5.0-5.4 in southern Mindanao and northern Luzon. The M 5.8 in Northern Mindanao was the strongest within about 200 km of that epicenter since an M 5.8 on July 27, 2020 and an M 5.8 on July 12, 2019. The last of larger magnitude in this area was an M 6.0 on March 8, 2019. Forecast 127055 had expected this event in this area was likely around September 19. 

 

PHIVOLCS reported this earthquake of M 5.7 in northern Mindanao, Philippines  was felt with intensity IV at Bayabas, Surigao Del Sur; III inj Tago, Surigao Del Sur, Claver, Surigao Del Norte; II in Tandag City, Carmen and Cagwait,Surigao del Sur and I in Hinatuan, Surigao Del Sur. PHIVOLCS reported the aftershock of M 5.3 in Mindanao, Philippines  was felt with intensity III in General Santos City; Alabel, Sarangani; II in Mati City; Glan and Malapatan, Sarangani; Don Marcelino, Davao Occidental, Kiblawan and Sta. Cruz, Davao del Sur.

 

 

O: 20SEP2020 23:14:03   9.3N  127.1E ML=4.1  EMSC   PHILIPPINE ISLANDS REGION

O: 21SEP2020 06:35:29   9.3N  127.1E ML=4.0  EMSC   PHILIPPINE ISLANDS REGION

O: 20SEP2020 22:21:48   9.4N  126.9E Mw=5.3  EMSC   MINDANAO, PHILIPPINES

O: 21SEP2020 04:28:58   9.4N  127.2E ML=4.0  EMSC   PHILIPPINE ISLANDS REGION

O: 20SEP2020 22:13:14   9.2N  126.7E Mw=5.8  EMSC   MINDANAO, PHILIPPINES        

P: 19SEP2020 127055     8.0N  125.0E 4.0-5.4 ABBAA  Central Philippines        

 

NEIC reported the earthquake of M 5.0 in Mindanao, Philippines  was felt with intensity II-III in the area(s) of Mindanao, Philippines at Buayan. Forecast 127059 had expected this event was likely around September 20.

 

O: 20SEP2020 13:28:27   6.7N  125.6E Mw=5.0  EMSC   MINDANAO, PHILIPPINES        

P: 20SEP2020 127059     6.0N  127.0E 4.0-5.5 AABAA  Halmahera                  

 

NEIC reported the earthquake of M 4.7 in Northern Philippines  was felt with intensity II-III in the area(s) of Northern Philippines at Claveria, Cagayan Valley. PHIVOLCS reported this earthquake of M 4.9 in Northern Philippines  was felt with intensity IV at Claveria and Sanchez-Mira, Cagayan; Calanasan, Apayao, Pagudpud, Bangui and Adams, Ilocos Norte; III in Pasuquin, Bacarra and Burgos, Ilocos Norte and II in Pamplona, Cagayan, Vintar , Ilocos, Norte. Forecasts 127107 and 127135 had expected this acdtivity was likely in mid-September. This epicenter is at 143 degrees from the Atlantic M 6.7 of September 18 and may have been enhanced by energy from that source.

 

O: 20SEP2020 17:47:19  18.6N  121.0E mb=4.7  EMSC   LUZON, PHILIPPINES           

P: 15SEP2020 127107    19.0N  122.0E 3.5-4.9 BAAAA  Luzon, Philippines         

P: 19SEP2020 127135    20.0N  121.0E 4.0-5.5 ABAAA  Taiwan                     

 

An unusually large M 5.3 also shook regions of central Turkey today. NEIC reported this earthquake of M 5.3 in  Central Turkey was felt with intensity II-III in the area(s) of Central Turkey at Aksaray (IV), Adana and Ankara. This is the strongest earthquake within about 300 km of this epicenter since an M 5.6 northwest of this on December 26, 2007. No such quakes have been recorded within 200 km of today's epicenter in the past 30 years. Forecast 127186 had expected today's epicenter to be active in this area of Turkey within about 100 km of today's event  was likely around September 18.

 

 

O: 20SEP2020 19:08:06  38.0N   34.0E Mw=5.3  EMSC   CENTRAL TURKEY               

O: 21SEP2020 03:37:31  38.1N   34.0E ML=4.0  EMSC   CENTRAL TURKEY               

P: 18SEP2020 127186    37.0N   34.0E 3.5-5.1 AAAAA  Turkey                     

 

 

 

STRONG QUAKE IN MID-INDIAN RIDGE TRIGGERED FROM MID-ATLANTIC

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 19, 2020

 

The strongest earthquake in the world today was an M 5.9 in the Mid-Indian Ridge. It was not felt in this remote area. The last earthquake in the mid-Indian Ridge area within about 300 km of this epicenter with M>=5.9 occurred as an M 6.1 on April 12, 2020 and prior to that an M 6.4 on October 4, 2013 and

an M 6.1 on May 7, 2006.  Forecast 127302 had expected today's event within about 100 km of this epicenter was likely around September 20. This epicenter is antipodal to the area of western  Oklahoma/Texas and Colorado where active seismicity occurs. Some enhanced seismicity in this area is possible in the next several days. This epicenter is located at 102-103 degrees from the M 6.7 in the central-mid Atlantic of September 18. Energy from large events concentrates on the surface after internal reflections at this distance from large earthquakes and can help promote seismicity at this distance, as it apparently did in this case.

 

O: 19SEP2020 21:09:32  37.6S   77.9E Mw=5.9  EMSC   MID-INDIAN RIDGE             

P: 20SEP2020 127302    37.0S   79.0E 4.0-5.4 AAAAA  So. Indian Ocean           

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in the Unimak Island region of Alaska. This is probably a regional aftershock of the M 7.7 in the Alaska Peninsula of July 22, 2020. An earthquake of M 5.6 hit this epicenter on August 13, 2020 but the last of M>=3.9 in the Unimak region was an M 4.5 a month ago on August 23, 2020. Forecast 127248 had expected today's event was likely in the Unimak area around September 17.

 

O: 20SEP2020 02:07:39  53.1N  163.4W mb=3.9  EMSC   UNIMAK ISLAND REGION, ALASKA 

P: 17SEP2020 127248    54.6N  163.6W 3.5-5.3 BAAAA  Unimak Islands, Aleutians  

 

 

STRONG EARTHQUAKE CONTINUES ACTIVE PERIOD IN MID-ATLANTIC

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 18, 2020

 

The strongest earthquake in the world today was an M 6.7 in the Central Mid-Atlantic, continuing strong seismic enhancement in this region. It was probably promoted by stresses associated with a series of tropical storms which have passed near this epicenter in the past several days. The most recent of these was TS Winfred which is discussed in this summary as:

 

"TS Winfred formed today over the western Atlantic with winds up to 40 kts. It is expected to track to the west over the several days. Some seismic enhancement is possible at this time in the central mid-Atlantic Ridge as Winfred passes over. An earthquake of M 6.7 in the central mid-Atlantic today may have been promoted by stresses from this storm." (September 18, 2020)

 

This earthquake was also probably promoted by strong tidal stresses associated with the new moon as it occurred in the longitude band where stresses from this alignment were expected to maximize as follows:

 

"The new moon arrived September 17, 2020 at 11:00 UT. Longitudes which were at sub-solar locations (local solar noon) are near 15 East longitude and include western Europe while those anti-solar regions are near 165 West longitude including areas near the International Date Line (IDL) at 180 East longitude such as the Aleutian Islands, Kamchatka and areas of Tonga, Fiji and regions of the southwest Pacific. These areas will probably see enhanced seismicity in the next week. Other areas may also see tidally-promoted seismicity during this time when a set of strong earthquakes is likely especially in the southwestern and northern Pacific rim." (September 15-18, 2020)

 

Strong earthquakes in the mid-Atlantic in the past month have included an M 6.5 about 300 km west of today's event on August 30 and an M 6.6 more than 1000 km to the northwest on September 6, 2020. The last earthquake within about 250 km  of today's event in the central mid-Atlantic with M>=6.7 occurred more than  30 years ago, this being the strongest quake in the area since an M 6.7 on October 7, 1975 - the largest historical event recorded in this region and the only other such event of M>=6.7.

 

Forecast 127053 had expected today's event within about 100 km of the epicenter was likely around September 14. Today's epicenter is located at 51.4 degrees (node 7) from the Atacama, Chile M 7.0 of September 1 and may have been promoted by energy from that source.

 

O: 18SEP2020 21:43:58   0.8N   26.7W Mw=6.7  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 14SEP2020 127053     1.0N   28.0W 4.0-5.6 BABAA  Central Mid-Atlantic Ridg  

 

The M 6.7 in the Central Mid-Atlantic followed an M 5.2 near the antipode in Papua, New Guinea. It was reported felt with intensity II-III in New Guinea at Lae, Morobe, Finshhafen and Port Moresby. Forecast 127076 had expected this event was likely within about 100 km in mid-September.

 

O: 18SEP2020 20:59:47   5.6S  147.0E Mw=5.2  EMSC   EASTERN NEW GUINEA REG., P.N.G

P: 13SEP2020 127076     5.0S  148.0E 4.0-5.6 BAAAA  New Ireland                

 

An earthquake of M 5.9 also occurred in the region of Crete, Greece today. NEIC reported it was felt with intensity IV in Greece at Ierapetra, Nea Alikarnassoa and Iraklion and in Iraklion with II-III in Pirgos, Stalis, Gournai, Kato Gouvari, Limin Khersonisou, Khanico tou Kokkini and Aghios. This earthquake may also have been promoted by strong tidal stresses associated with the new moon as it lies near the longitude of maximum stress with that event (see above). This is the strongest earthquake in Crete within about 200 km of this epicenter since an M 6.6 on May 2, 2020 and although it occurred about 100 km northwest of that event, may be a regional aftershock of it. The last such activity within about 100 km of today's epicenter was an M 6.1 and 6.0 on June 15 and 16, 2013. Forecast 127150 had expected this event was likely in Crete between September 18 and 20.

 

O: 18SEP2020 16:28:17  34.8N   25.3E Mw=5.9  EMSC   CRETE, GREECE                

P: 18SEP2020 127150    34.0N   24.0E 3.0-4.6 AAAAA  Crete                      

P: 20SEP2020 127150    34.0N   26.0E 3.0-4.4 AAAAA  Crete                      

 

A moderate earthquake of M 4.5 rocked the Los Angeles, California area today. NEIC reported it was felt with maximum intensity V in the epicentral area including at Rico Rivera, Monterey Park, Rosemead, San Gabriel and IV in Montebello, El Monte, South El Monte, Los Angeles, Whittier. This earthquake occurred within about an hour of local solar midnight and was probably promoted by strong tidal stresses associated with the new moon, as these maximize near this hour. The mainshock was preceded by a group to earthquakes of smaller magnitude in the Los Angeles area to the west. Seismicity in the region had been expected in this summary to be enhanced at this time as noted in the September 9, 2020 summary following a moderate earthquake in New Jersey:

 

"This correlation (between earthquakes in the New Jersey area and southern California) is strongest with moderate starting quakes in the region of Delaware. The area of southern California near Northridge is currently at the 23-year cycles of large quakes in the area. A moderate earthquake in the region west of Los Angeles and north to San Francisco is considered possible in the next four days. At the least, residents should check their earthquake preparedness kits to see if they are ready for a moderate quake at this time." (December 1, 2017, September 9, 2020)

 

Today’s event may also have been affected by slopefall of Hurricane Teddy yesterday as described in previouos issues of this summary:

 

“Hurricane Teddy continued today in the mid-Atlantic with winds up to 90 kts. It is expected to track to the west over the next week. Some enhanced seismicity may occur in the northern Mid-Atlantic ridge area in the next several days. It is expected to reach category 4 hurricane winds by September 20 but will probably remain over the Atlantic and not to threaten landfall. If it tracks further to the west it will make slopefall in about a week. This could promote a moderate to strong earthquake in the western rim of North America” (September 15-17, 2020)

 

 

Today's M 4.5 is at the fourth node (90 degrees) from the earlier event of M 6.7 in the mid-Atlantic and may have been promoted by energy from that source. The M 4.5 is the strongest earthquake in Los Angeles within about 50 km of this epicenter since an M 5.1 on March 29, 2014 and prior tot that an M 4.5 on August 8, 2012. The only other such event in the area in the past 12 years was and M 4.7 on May 18, 2009. Forecast 127174 had expected today's event was likely within about 25 km today's epicenter around September 15.

 

O: 18SEP2020 15:42:47  34.0N  118.8W Ml=2.1  EMSC   CHANNEL ISLANDS REG., CALIFORNIA

O: 19SEP2020 06:45:03  34.1N  118.1W Ml=2.1  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 19SEP2020 06:38:45  34.0N  118.1W Mw=4.5  EMSC   GREATER LOS ANGELES AREA, CALI

P: 15SEP2020 127174    33.9N  118.3W 2.5-4.4 BAAAA  So. California             

 

O: 19SEP2020 04:22:49  34.4N  119.3W ML=2.0  EMSC   SOUTHERN CALIFORNIA

O: 19SEP2020 04:05:06  34.4N  119.3W Ml=2.2  EMSC   SOUTHERN CALIFORNIA

O: 19SEP2020 05:06:03  34.5N  119.3W Ml=2.1  EMSC   SOUTHERN CALIFORNIA          

P: 17SEP2020 127177    35.0N  119.2W 2.5-4.5 AAAAA  So. California             

 

TIDAL STRESSES HELP PROMOTE FIJI ISLANDS M 5.6

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 17, 2020

 

An M 5.4-5.6 also continued the current activation of seismicity in the Fiji/Tonga area. It was not reported felt in this area. This is the strongest earthquake within about 150 km of this epicenter since an M 6.4 on August 19, 2018. Forecast 127279 had expected today's event in this region was likely around September 19. As it occurred near the IDL, it was probably enhanced by high tidal stresses associated with today's new moon as described in previous issues of this summary:

 

"The new moon arrived September 17, 2020 at 11:00 UT. Longitudes which were at sub-solar locations (local solar noon) are near 15 East longitude and include western Europe while those anti-solar regions are near 165 West longitude including areas near the International Date Line (IDL) at 180 East longitude such as the Aleutian Islands, Kamchatka and areas of Tonga, Fiji and regions of the southwest Pacific. These areas will probably see enhanced seismicity in the next week. Other areas may also see tidally-promoted seismicity during this time when a set of strong earthquakes is likely especially in the southwestern and northern Pacific rim." (September 15-17, 2020)

 

O: 17SEP2020 17:01:33  16.7S  177.1W Mw=5.4  EMSC   FIJI REGION                  

O: 17SEP2020 17:01:32  16.6S  177.3W Mw=5.6  ANSS   FIJI REGION                  

P: 19SEP2020 127279    16.0S  176.0W 4.0-5.6 AAAAA  Tonga Islands              

 

The second strongest earthquake in the world today was an M 5.5 in the Banda Sea, Indonesia. NEIC reported it was felt with intensity II-III in Northern Territory, Australia at Palmerston and Darwin. This earthquake occurred within half an hour of the new moon and may also have been promoted by strong tidal stresses associated with that alignment. This is the strongest aftershock to date of the M 6.8 Banda Sea quake of May 6, 2020. Forecast 127089 had expected today's event within about 100 km was likely around September 14.

 

O: 17SEP2020 10:32:26   6.8S  129.3E Mw=5.5  EMSC   BANDA SEA                    

P: 14SEP2020 127089     6.0S  130.0E 4.0-5.6 BAAAA  West Irian, PNG            

 

The largest earthquakes in the U.S. or Canada today were an M 4.1 and 3.9 in the

region of the Alaska Peninsula. These are regional aftershocks of the M 7.8 of July 22 in the Alaska Peninsula. The M 3.9 south of the aftershock zone  was somewhat unusual. The last event within about 50-100 km of this epicenter with M>=3.9 was an M 4.2 on July 16, 2010. Forecast 127230 expected today's activity between September 16 and 18.

 

O: 17SEP2020 19:44:42  53.9N  158.1W mb=3.9  EMSC   SOUTH OF ALASKA              

P: 18SEP2020 127230    54.8N  157.7W 3.5-5.3 AAAAA  Alaska Peninsula           

 

O: 17SEP2020 07:51:39  54.8N  160.7W ml=4.1  EMSC   ALASKA PENINSULA             

P: 16SEP2020 127230    54.8N  159.7W 3.5-5.3 AAAAA  Alaska Peninsula           

 

The swarm in the Dominican Republic continued today with an event of M 4.2 and a number of aftershocks with M>=3. This swarm had been noted in the previous issue of this summary as:

 

 

"An earthquake of M 4.5 in the Dominican Republic today continued the activation of that region. NEIC reported it was felt with maximum intensity IV in Nagua Maria and II-III in the Dominican Republic at Las Terrenas, Cenove Duarte, Villa Altagracia, Moca, Santo Domingo, Santiago. This continues active conditions in the Dominican Republic but was to the  east of much of the recent activity. For example, an M 4.0 occurred about 200  km southwest of today's event on September 15 and recent swarms hit northwest of this over the past several days. The last earthquake of M>=4.5 in the Dominican Republic was an M 4.7 about 200 km east of today's event on May 6, 2020. The only other such event in the Dominican Republic in the past year was an M 4.9 on March 6, 2020 which occurred about 200 km southeast of today's epicenter. Forecast 127123 had expected today's activity was likely around September 17."  (September 17, 2020)

 

Forecast 127118 had expected today's activity within about 50 km was likely around September 17.

 

O: 18SEP2020 01:14:51  18.5N   71.0W ML=4.2  EMSC   DOMINICAN REPUBLIC

O: 17SEP2020 22:47:47  18.7N   70.8W ML=3.3  EMSC   DOMINICAN REPUBLIC

O: 17SEP2020 22:50:05  18.7N   70.8W ML=3.6  EMSC   DOMINICAN REPUBLIC

O: 18SEP2020 01:44:35  18.7N   70.8W ML=3.0  EMSC   DOMINICAN REPUBLIC

O: 18SEP2020 03:23:12  18.7N   68.8W ML=3.2  EMSC   DOMINICAN REPUBLIC

O: 17SEP2020 23:22:23  18.8N   70.8W ML=3.1  EMSC   DOMINICAN REPUBLIC

O: 17SEP2020 23:28:14  18.8N   70.8W ML=3.2  EMSC   DOMINICAN REPUBLIC

O: 17SEP2020 16:17:54  18.9N   70.4W ML=3.0  EMSC   DOMINICAN REPUBLIC

O: 17SEP2020 19:51:17  18.0N   70.7W ML=3.0  EMSC   DOMINICAN REPUBLIC REGION    

P: 17SEP2020 127118    19.0N   71.0W 3.4-4.9 AAAAA  Puerto Rico                

 

MODERATE QUAKES IN NORTH ATLANTIC; LOYALTY ISLANDS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 16, 2020

 

A moderately strong M 5.7 aftershock occurred today in the central mid-Atlantic Ocean. It was not reported felt in this area. It follows an M 6.6 on September 6 and is probably an aftershock of that event. Tropical Storm Teddy (now a hurricane) formed over this epicenter on September 13-14 and probably helped trigger today's earthquake. This summary noted at the time:

 

"TS Teddy continued today in the mid-Atlantic with winds up to 50 kts. It is expected to track to the west over the next week. Some enhanced seismicity may occur in the northern Mid-Atlantic ridge area in the next several days …" (September 14, 2020)

 

When the M 6.6 mainshock in this area occurred on September 6, this summary noted:

 

"The strongest earthquake in the world today was an  M 6.6 in the Central Mid-Atlantic Ridge. It was not reported felt in this remote area. This is the strongest earthquake within about 250 km of this epicenter since an M 6.6 on September 10, 2008, the only such event in the area in the past 30 years. Forecast 126789 had expected a moderately large regional event in this area was likely around September 7. This epicenter is at 101 degrees from the M 7.8 in the Alaska Peninsula of July 22 and was probably promoted by energy from that source." (September 6, 2020)

 

Forecast 127053 had expected today's event within the central mid-Atlantic was likely within about 100 km of this epicenter around September 16. This epicenter is located at 101-102 degrees from the M 7.8 in the Alaska Peninsula of July 22, 2020 and was probably promoted by concentrated energy from that source. This event occurred near local solar midnight and was probably enhanced by energy from the new moon as noted in this and previous issues of this summary:

 

“The new moon will arrive September 17, 2020 at 11:00 UT. Longitudes which are at sub-solar locations (local solar noon) are near 15 East longitude and include western Europe while those anti-solar regions are near 165 West longitude including areas near the International Date Line (IDL) at 180 East longitude such as the Aleutian Islands, Kamchatka and areas of Tonga, Fiji and regions of the southwest Pacific. These areas will probably see enhanced seismicity in the next week. Other areas may also see tidally-promoted seismicity during this time when a set of strong earthquakes is likely especially in the southwestern and northern Pacific rim.” (September 15-17, 2020)

 

O: 17SEP2020 03:00:20   7.6N   37.0W Mw=5.7  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 16SEP2020 127053     8.0N   38.0W 4.0-5.6 AAAAA  Central Mid-Atlantic Ridg  

 

A moderately large M 5.6 also occurred today in the area southeast of the Loyalty Islands south of Vanuatu. It was not reported felt in this remote epicentral area. The last earthquake within about 200 km of this epicenter in the area southeast of the Loyalty Islands with M>=5.6 occurred on December 2, 2018 with M 5.7 two days before an M 7.5 about 250 km to the west of today's epicenter. Forecast 127285 had expected today's event within about 150 km was likely around September 19.  This epicenter is located at 101-102 degrees from the M 7.0 in the Atacama Chile event of September 1, 2020 and was probably promoted by concentrated energy from that source. A swarm in northern Canada today including an M 3.5 was also located at this distance from Atacama, Chile.

 

O: 16SEP2020 08:44:30  22.3S  171.6E Mw=5.6  EMSC   SOUTHEAST OF LOYALTY ISLANDS 

P: 19SEP2020 127285    23.0S  170.0E 4.0-5.4 BABAA  Loyalty Islands            

 

An earthquake of M 4.5 in the Dominican Republic today continued the activation of that region. NEIC reported it was felt with maximum intensity IV in Nagua Maria and II-III in the Dominican Republic at Las Terrenas, Cenove Duarte, Villa Altagracia, Moca, Santo Domingo, Santiago. This continues active conditions in the Dominican Republic but was to the east of much of the recent activity. For example, an M 4.0 occurred about 200 km southwest of today's event on September 15 and recent swarms hit northwest of this over the past several days. The last earthquake of M>=4.5 in the Dominican Republic was an M 4.7 about 200 km east of today's event on May 6, 2020. The only other such event in the Dominican Republic in the past year was an M 4.9 on March 6, 2020 whihc occurred about 200 km southeast of today's epicenter. Forecast 127123 had expected today's activity was likely around September 17.

 

O: 16SEP2020 12:06:26  19.3N   69.9W mb=4.5  EMSC   DOMINICAN REPUBLIC           

P: 17SEP2020 127123    20.0N   71.0W 3.0-4.6 AAAAA  Bahamas/No. Caribbean      

 

The strongest earthquake in the U.S. or Canada today was an M 4.2 in the Rat Islands, Aleutians. It was not reported felt in this remote area. The last earthquake in the Rat Islands with M>=4.2 was an M 4.7 on August 27, 2020. Forecast 127245 had expected today's event was likely around September 17.

 

O: 17SEP2020 03:29:26  52.3N  177.8E mb=4.2  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 17SEP2020 127245    51.0N  177.0E 4.0-5.8 ABAAA  Rat Islands                

 

An unusual M 3.4 shook the border between eastern Utah and Colorado today. NEIC reported this earthquake of M 3.4 in Colorado  was felt with intensity II-III in the area(s) of Utah at Provo, and Lehi. The last earthquake of M>=3.4 within about 150 km of this epicenter in Colorado or Utah was an M 4.5 on March 4, 2019 and prior to that an M 3.9 on January 24, 2013. Forecast 127149 had expected today's event was likely within about 10 km around September 18.

 

O: 16SEP2020 15:26:40  38.3N  108.9W ML=3.4  EMSC   COLORADO                     

P: 18SEP2020 127149    38.3N  108.9W 2.0-4.4 AAAAA  Colorado area              

 

MODERATE EARTHQUAKE SHAKES NEPAL

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 15, 2020

 

An unusual earthquake of M 5.3 occurred today in Nepal. NEIC reported it was felt with intensity IV in Nebal at Bhimeshwar, Dhulikhet, Banepa, Panauti, Bhaktapur,Tribuvannagar, Kathmando, Lalitpur, Kirtipur and Kamalama, Nepal.

This was the largest earthquake located in the world today. This is the largest earthquake in Nepal located within about 200 km of this epicenter since an  M 5.4 on November 27, 2016. These are probably aftershocks of the great M 7.8 quake of April 25, 2015 which did much damage to built structures in the area and which occurred about 100 km northwest of today's epicenter. The event was followed by an M 7.3 about 25 km from today's epicenter on May 12, 2015. Forecast 127190 had expected moderate seismicity to the northwest of this was likely in mid-September.

 

O: 15SEP2020 23:34:03  27.9N   85.9E mb=5.3  EMSC   NEPAL                        

P: 17SEP2020 127190    30.0N   82.0E 3.8-5.3 ACCAA  Xizang                      

 

The strongest earthquake in the U.S. or Canada today was an M 4.2 in western Nevada. NEIC reported it was felt with intensity II in the epicentral area.

This is the strongest aftershock in western Nevada of the M 6.5 of May 15, 2020 since an M 4.2 shook the region on July 23, 2020 and was followed by an M 4.4 about 30 km to the east on July 26, 2020.  Forecast 127142 had expected today's event within about 25 km of this epicenter was likely around September 17.

 

O: 15SEP2020 16:52:41  38.2N  118.0W ml=2.4  EMSC   NEVADA

O: 15SEP2020 17:37:43  38.2N  118.0W ml=2.3  EMSC   NEVADA

O: 15SEP2020 17:59:55  38.2N  117.9W ml=2.4  EMSC   NEVADA

O: 15SEP2020 17:59:55  38.2N  117.9W ml=2.4  EMSC   NEVADA

O: 16SEP2020 03:49:26  38.2N  118.0W ml=2.7  EMSC   NEVADA

O: 16SEP2020 04:08:34  38.2N  118.0W ml=2.0  EMSC   NEVADA

O: 15SEP2020 16:33:35  38.2N  117.9W ML=4.0  EMSC   NEVADA                       

O: 15SEP2020 16:33:35  38.2N  117.9W ML=4.2  ANSS   NEVADA                       

P: 17SEP2020 127142    37.9N  118.2W 2.5-4.4 AAAAA  California/Nevada area     

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 14, 2020

 

The strongest earthquake in the world today was an M 6.4 in the region of Kamchatka. Today's event in Kamchatka was accompanied by smaller regional earthquakes. It occurred at the height of the strongest geomagnetic storm since September 1. The last earthquake of M>=5.5 in Kamchatka was an M 5.5 which occurred on September 1, 2020 at the height of the previous large geomagnetic storm and was noted in this summary at the time:

 

" M 5.6 in Kamchatka, Russia. These event are not uncommon but illustrate the impact that geomagnetic storms can have on antipodal seismicity. The Kamchatka event occurred within about 30 minutes of local solar noon while the South Sandwich event occurred near local solar midnight. Both may also have been affected by strong tidal stresses associated with the full moon which maximize at these hours." (September 1, 2020)

 

and

 

"Antipodal activity at moderate levels continued today in the South Sandwich Islands (M 4.7) and as a swarm in the region of Kamchatka. This antipodal activity began several days ago and may involve some volcanic activity in Kamchatka." (September 5, 2020)

 

Today's earthquake at high latitude in Kamchatka was located at a deep focus and was not reported felt in the epicentral area and occurred near local solar noon.

The last earthquake in Kamchatka of M>=6.4 occurred as an M 6.9 on June 10, 2004. The only other such event in this area in the past 30 years was an M 6.9 on June 16, 2003. Today's event is the strongest intermediate to deep focus earthquake in this area of Kamchatka in the past 30 years. Forecast 127238 had expected today's event was likely in this area around September 14.

 

O: 15SEP2020 03:41:25  56.0N  158.4E Mw=6.4  EMSC   KAMCHATKA PENINSULA, RUSSIA  

P: 14SEP2020 127238    56.0N  160.0E 4.0-5.4 AAAAA  E. of Kamchatka            

 

The event in Kamchatka was followed 30 minutes later by an M 6.1 in the area of Fiji west of Samoa. It was reported by NEIC to have been felt in Lombasa, Fiji with intensity V. The Fiji  event occurred at a distance of 72 degrees from Kamchatka (node 5). Surface waves from Kamchatka were in the epicentral area of the Fiji quake at the time it occurred and probably triggered it.

 

This activity may also have been promoted by geomagnetic effects. A geomagnetic storm reached maximum intensity at high latitudes at the time of the Kamchatka earthquake and probably promoted it. Fiji is on the geomagnetic equator. This summary noted this geomagnetic storm as:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 11.  High latitude geomagnetic field also saw active conditions with AP 25. This is the most active geomagnetic storm since the strong storm at the end of August and early September. Such storms can enhance seismicity near the geomagnetic equator and at high latitudes" (September 14, 2020)

 

The area to the east of this has recently seen moderate to large scale activity in Samoa. These included an M 5.2 on September 9 and an M 5.4 on September 8, 2020. These events were more than 500 km to the east of today's epicenter. The last event within about 250 km of today's Fiji quake with M>=6.1 and west of 180 degrees longitude was an M 6.2 twenty years ago today on September 14, 2000, the only such event in this area in the past 30 years. Earthquakes about 250 km to the southwest of this occurred on April 7, 2006 (M 6.4) and November 22, 2001 (M 6.2), but today's earthquake is a highly unusual regional event.  Forecast 127270 had expected today's event in this area was likely around September 18.

This earthquake is at 100 degrees from the M 7.0 Atacama, Chile event of September 1 and may have been promoted by concentrated energy from that source.

It is also at the fifth node (72 degrees) from the earlier Kamchatka M 6.4 and from the M 7.8 in the Alaska Peninsula of July 22 and may have also been promoted by energy from those sources.

 

O: 15SEP2020 04:12:17  15.0S  179.8E Mw=6.1  EMSC   FIJI                         

P: 18SEP2020 127270    16.0S  178.0E 4.0-5.6 BABAA  Fiji Islands               

 

The activity in Kamchatka and Fiji today may also have been promoted by tidal stresses associated with the upcoming new moon of September 17 as described in this summary as:

 

"The new moon will arrive September 17, 2020 at 11:00 UT. Longitudes which are at sub-solar locations (local solar noon) are near 15 East longitude and include western Europe while those anti-solar regions are near 165 West longitude including areas near the International Date Line (IDL) at 180 East longitude such as the Aleutian Islands, Kamchatka and areas of Tonga, Fiji and regions of the southwest Pacific. These areas will probably see enhanced seismicity in the next week. Other areas may also see tidally-promoted seismicity during this time when a set of strong earthquakes is likely especially in the southwestern and northern Pacific rim." (September 14, 2020)

 

The strongest earthquakes in the U.S. or Canada today were a pair of M 3.4 events in Northern California. NEIC reported these earthquakes of M 3.4 in Northern California were felt with intensity II-III in the area(s) of Northern California at Laytonville, Percy, Covelo and Leggett. This activity is the largest within about 50 km of these epicenters since an M 4.3 on December 14, 2017. Forecast 127145 had expected these events in this area were likely around September 16.

 

O: 14SEP2020 14:15:16  39.9N  123.4W ML=3.0  EMSC   NORTHERN CALIFORNIA          

O: 14SEP2020 14:15:16  39.9N  123.4W ML=3.4  ANSS   NORTHERN CALIFORNIA          

O: 14SEP2020 15:36:58  39.9N  123.3W ML=2.9  EMSC   NORTHERN CALIFORNIA

O: 14SEP2020 15:36:58  39.9N  123.3W ML=3.4  ANSS   NORTHERN CALIFORNIA

P: 16SEP2020 127145    39.3N  123.2W 2.5-4.8 AAAAA  Central California         

 

 

L

 

UNUSUAL M 5.0 IN SAKHALIN, RUSSIA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 13, 2020

 

An unusual series of moderate earthquakes occurred today in the region of Sakhalin, Russia. This included an M 4.9-5.0 and several aftershocks of M 4.6 and 3.9. These were not reported felt in the epicentral area. It may have been promoted by stresses associated with Super Typhoon Haishen which passed over the area on September 8 as noted in this summary at the time:

 

"Super-Typhoon Haishen (TD 11W) continued today over Korea with winds up to 45 kts. It is expected to dissipate in the next day." (September 8, 2020)

 

The only moderate earthquake located in Sakhalin, Russia in the past year was an

M 4.2 on January 23, 2020. But the last shallow focus event in Sakhalin within about 200 km of today's event with M>=4.9 was an M 5.2 on April 23, 2017. An earthquake of M 5.6 also occurred at deep focus on July 1, 2018. Strong earthquakes and tsunamis can occur in the area but are uncommon. The last major event in the region of Sakhalin was an M 6.8 on August 8, 2000 and generated a major damaging and deadly tsunami. Forecast 127222 had expected today's event was likely in this area around September 15. This activity is located at 147 degrees from the M 7.0 in Atacama, Chile of September 1 and may have been promoted by energy from that source.

 

O: 13SEP2020 13:42:26  48.9N  142.1E mb=5.0  ANSS   SAKHALIN, RUSSIA

O: 13SEP2020 13:42:26  49.0N  142.1E mb=4.9  EMSC   SAKHALIN, RUSSIA

O: 13SEP2020 16:12:43  49.0N  142.1E mb=3.9  EMSC   SAKHALIN, RUSSIA

O: 13SEP2020 14:09:01  48.9N  142.2E mb=4.6  EMSC   SAKHALIN, RUSSIA             

P: 15SEP2020 127222    47.0N  142.0E 3.5-5.7 ABAAA  So. Kurils                 

 

The strongest earthquake in the world today was an M 5.5 in eastern New Guinea.

NEIC reported this earthquake of M 5.5 in Papua New Guinea  was felt with intensity II-III in the area(s) of Papua New Guinea at Kainantu, Bulolo and Goroka. The last earthquake within about 200 km of this epicenter with M>=5.5 was an M  7.0 about 200 km southeast of today's epicenter on July 17, 2020. The last such event within the 200 km radius was an M 72. on May 6, 2019. Forecast 127076 had expected an event up to M 5.6 was likely in this area  around September 13.

 

O: 13SEP2020 10:28:19   6.0S  147.0E mb=5.5  EMSC   EASTERN NEW GUINEA REG., P.N.G

P: 13SEP2020 127076     5.0S  148.0E 4.0-5.6 AAAAA  New Ireland                

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 in Southern Alaska. NEIC reported this earthquake of M 4.1 in southern Alaska  was felt with intensity II-III in the area(s) of southern Alaska at Valdez, Glennallen, Palmer, Copper Center, Chugiak, Girdwood, Eagle River, Wasilla, and Anchorage.

The last earthquake of M>=4.1 within about 150 km of this epicenter in southern Alaska occurred as an M 4.3 nearly two years ago on October 16, 2018. Forecast 127252 had expected today's event within about 50 km of this epicenter was likely around September 16. This event is located at 104 degrees from the M 7.0 in Sumatra of August 18 and 107 degrees from the Atacama quake of September 1, 2020 and was probably promoted by concentrated seismic energy from those sources.

 

O: 13SEP2020 15:10:09  61.5N  146.4W ML=4.1  EMSC   SOUTHERN ALASKA              

P: 16SEP2020 127252    61.3N  147.2W 3.2-4.9 BAAAA  Central Alaska             

 

 

The northern Caribbean continued at active seismic conditions today. The strongest earthquake in the area was an M 4.4 in the U.S. Virgin Islands. This was joined by a continuing swarm in the Dominican Republic and aftershocks in Haiti and southern Puerto Rico.  A similar earthquake of M 4.4-4.5 occurred in the Virgin Islands on August 26, 2020. The only other earthquake of M>=4.4 in the Virgin Islands in the past year was an M 5.0 on October 6, 2019. Forecast 127105 had expected today's event in the Virgin Islands within about 50 km of the epicenter of the M 4.4 This activity may have been enhanced by the passage of several tropical storms and hurricanes to the north as detailed in previous issues of this summary:

 

"TS Paulette continued today over the northern Mid-Atlantic ridge with winds up to 55 kts. It is expected to track to the west over the several days. Some seismic enhancement is possible at this time in the central mid-Atlantic Ridge as Paulette passes over. It will pass near Bermuda as a hurricane, but this area has little seismicity." (September 11, 2020)

 

NEIC reported this earthquake of M 4.4 in the Virgin Islands  was felt with intensity II-III in the area(s) of the Virgin Islands at San Juan, Puerto Rico.

 

O: 13SEP2020 07:12:57  19.2N   64.5W mb=4.4  EMSC   VIRGIN ISLANDS REGION        

P: 13SEP2020 127105    19.0N   64.0W 3.0-5.1 AAAAA  Leeward Islands            

 

VANUATU ISLANDS CONTINUES ACTIVE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 12, 2020

 

The largest earthquake in the world today was an M 5.9-6.0 in central Vanuatu. NEIC reported it was felt with intensity II in Vila Shefa, Vanuatu. An earthquake of M 6.2 hit the area on September  7 following a similar event on September 6. Today's event is probably an aftershock of that. At the time this summary noted in this regard:

 

 

"The M 6.2 in Vanuatu was reported by NEIC to have been felt with intensity IV in Vila Shefa, Vanuatu. It was accompanied by aftershocks of M 4.9, 5.1 and 5.2. It occurred in an area of active volcanism and may have been related to that. The last shallow focus earthquake within about 250 km of this epicenter in the Vanuatu Islands with M>=6.2 was an M 6.5 on August 21, 2018 and prior to that an M 7.0 on April 28, 2016. Forecast 127011 had expected today's event within about 25 km was likely around September 7. This epicenter is at 103-105 degrees from the earthquake of M 7.0 in Atacama, Chile of September 1 and from the M 6.3 in Coquimbo, Chile today  and from the M 7.4 in Oaxaca, Mexico of June 23 and was probably promoted by energy from those sources." (September 5-6, 2020)

 

Forecast 127280 had expected this activity was likely around September 15.

Note that the earthquake of M 6.1 in Honshu, Japan, like this event in Vanuatu, was also located at 103 degrees from Oaxaca, Mexico.

 

O: 12SEP2020 08:34:27  17.1S  167.6E Mw=5.9  EMSC   VANUATU                      

P: 15SEP2020 127280    18.0S  168.0E 4.0-5.4 BAAAA  Vanuatu Islands            

 

 

The northern Caribbean was at active seismic conditions today. The strongest earthquake in the area was an M 4.4 in the U.S. Virgin Islands.  A similar earthquake of M 4.4-4.5 occurred in the Virgin Islands on August 26, 2020. The only other earthquake of M>=4.4 in the Virgin Islands in the past year was an M 5.0 on October 6, 2019. Forecast 127105 had expected today's event in the Virgin Islands within about 50 km of the epicenter of the M 4.4 This activity may have been enhanced by the passage of several tropical storms and hurricanes to the north as detailed in previous issues of this summary:

 

"TS Paulette continued today over the northern Mid-Atlantic ridge with winds up to 55 kts. It is expected to track to the west over the several days. Some seismic enhancement is possible at this time in the central mid-Atlantic Ridge as Paulette passes over. It will pass near Bermuda as a hurricane, but this area has little seismicity." (September 11, 2020)

 

NEIC reported this earthquake of M 4.4 in the Virgin Islands  was felt with intensity II-III in the area(s) of the Virgin Islands at San Juan, Puerto Rico.

 

O: 12SEP2020 23:22:04  19.1N   64.4W mb=4.4  EMSC   VIRGIN ISLANDS REGION

O: 12SEP2020 08:10:26  19.2N   64.8W ML=3.0  EMSC   VIRGIN ISLANDS REGION

O: 12SEP2020 08:03:46  19.0N   64.9W ML=3.3  EMSC   VIRGIN ISLANDS REGION        

P: 13SEP2020 127105    19.0N   64.0W 3.0-5.1 AAAAA  Leeward Islands            

 

Enhanced seismicity also occurred today in the region of Haiti with events of M 3.4 and 3.5 and as a series of light earthquakes of M 3.0-3.5 in the Dominican Republic, continuing active seismicity in that region. An M 3.7 occurred on September 11 in Haiti but only one earthquake of M>=4 has occurred in this region in the past year - an M 4.7 on May 31, 2020.

 

O: 13SEP2020 00:50:37  19.5N   73.9W ML=3.4  EMSC   HAITI REGION

O: 13SEP2020 00:49:17  19.5N   73.9W ML=3.5  EMSC   HAITI REGION                 

P: 17SEP2020 127118    19.0N   71.0W 3.4-4.9 BACAA  Puerto Rico                

 

The activity in the Dominican Republic follows a similar swarm in the area that occurred yesterday, September 11. Two earthquakes of M 3.6 were recorded today, the largest in the area since an M 4.4 on August 25. Forecast 127123 had expected today's activity in the Dominican Republic was likely in mid-September.

 

O: 12SEP2020 07:10:11  18.7N   69.3W ML=3.5  EMSC   DOMINICAN REPUBLIC

O: 12SEP2020 07:14:14  19.2N   70.8W ML=3.2  EMSC   DOMINICAN REPUBLIC

O: 12SEP2020 07:32:30  19.2N   68.6W ML=3.2  EMSC   DOMINICAN REPUBLIC REGION

O: 12SEP2020 11:23:39  19.6N   69.9W ML=3.4  EMSC   DOMINICAN REPUBLIC

O: 12SEP2020 18:49:17  19.8N   70.7W ML=3.2  EMSC   DOMINICAN REPUBLIC

O: 12SEP2020 08:23:21  20.1N   70.8W ML=3.6  EMSC   DOMINICAN REPUBLIC REGION

O: 12SEP2020 08:38:23  20.1N   70.8W ML=3.4  EMSC   DOMINICAN REPUBLIC REGION

O: 12SEP2020 10:02:24  20.2N   70.7W ML=3.5  EMSC   DOMINICAN REPUBLIC REGION

O: 12SEP2020 11:39:12  20.2N   70.7W ML=3.4  EMSC   DOMINICAN REPUBLIC REGION

O: 12SEP2020 15:18:42  20.5N   70.4W ML=3.3  EMSC   DOMINICAN REPUBLIC REGION    

P: 17SEP2020 127123    20.0N   71.0W 3.0-4.6 BAAAA  Bahamas/No. Caribbean      

 

TYPHOONS PROMOTE STRONG EARTHQUAKE OFF NORTHERN HONSHU, JAPAN

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 11, 2020

 

The strongest earthquake of the day was an M 6.1 off the east coast of northern Honshu, Japan. NEIC reported it was felt with intensity IV in Japan at Miyagi and Fukushima and II-III in Aomori, Chiba, Tokyo, and Shizuoka. JMA reported intensity III-IV in Aomori, Iwate and Miyagi, Akita, Yamagata, Fukushima, Ibaraki. This event may have been enhanced by energy from Super-Typhoon Haishen and a storm currently located south of Honshu, Japan as reported in the previous issue of this summary:

 

"A tropical cyclone may be forming south of Honshu, Japan. It is currently located at 25N 141E in the Volcano Islands of Japan and expected to track to the north over the next several days. Some seismic enhancement may occur in the Volcano and Bonin Islands with this storm and later in eastern Honshu, Japan." (September 10, 2020)

 

and

 

"TD 12W continued today off Honshu, Japan with winds up to 35 kts. It is expected to track to the northeast and to enhance seismicity off the coast of Honshu, Japan in the next several days." (September 11, 2020)

 

and

 

"Super-Typhoon Haishen (TD 11W) continued today north of the Ryukyu Islands, Japan with winds up to 115 kts. It is expected to track to the north reaching southern Honshu and Kyushu September 6-7. It could promote a moderate to strong earthquake in western Honshu or the Ryukyu Islands with or after landfall." (September 7, 2020)

 

Today's event of M 6.1 off the coast of Honshu, Japan was the strongest within  about 150 km of this epicenter since can M 6.3 on April 19, 2020. The only other such  earthquake in the past three years in this region was an M 6.3 on August 4, 2019. Forecasts 127164, 127181 and 126895 had expected today's activity between September 7 and 18. This epicenter is also at 147 degrees from the M 6.3 in Tarapaca, Chile earlier in the day. This is a distance at which energy is concentrated on the surface after internal earth reflections and often sees elevated seismicity after major earthquakes. Likewise it is at 103 degrees from the M 7.5 in Oaxaca, Mexico of June 23, 2020, a distance where similar concentration of energy occurs following major earthquakes. The activity in Honshu had been expected in this summary at that time as:

 

"Far-field triggering is likely with this earthquake. ...  Areas at 103 degrees from the Oaxaca epicenter include the east coast of Honshu, Japan" (June 24, 2020)

 

Recent strong activity, including an M 5.1 today, in Vanuatu is also occurring at 103 degrees from Oaxaca.

 

O: 12SEP2020 02:50:42  38.7N  142.1E mb=4.9  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 12SEP2020 03:00:30  38.7N  142.3E ML=4.2  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 12SEP2020 03:03:30  38.7N  142.2E ML=4.1  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 12SEP2020 03:49:05  38.7N  142.3E Mw=4.5  EMSC   NEAR EAST COAST OF HONSHU, JAPAN

O: 12SEP2020 02:44:12  38.8N  142.1E Mw=6.1  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 18SEP2020 127164    38.0N  141.0E 4.0-5.5 CAAAA  Off East Coast Honshu      

P: 18SEP2020 127181    38.0N  143.0E 4.0-5.4 CAAAA  So. of Honshu              

P:  7SEP2020 126895    39.0N  142.0E 4.0-5.5 BAAAA  Off East Coast Honshu      

 

The strongest earthquake in the U.S. or Canada today was an M 4.3-4.6 in Southern Alaska. NEIC reported it was felt with intensity II-III in Southern Alaska at Willow, Anchorage, Wasilla, Kenai.  NEIC reported an aftershocks of M 3.4 in  southern Alaska was felt with intensity II-III in the area(s) of southern Alaska at Elmendorf AFB, Anchorage, Fort Richardson, Wasilla.  The last earthquake within about 150 km of this epicenter with M>=4.6  occurred October 4, 2019 and prior to that on September 17, 2019. Forecast 127255 had expected today's event was likely within about 50 km around September 14.

 

O: 11SEP2020 13:58:31  61.6N  152.2W mb=4.6  EMSC   SOUTHERN ALASKA              

P: 14SEP2020 127255    61.3N  152.3W 3.2-5.1 BAAAA  Central Alaska             

 

An M 4.0-4.2 was also felt widely in the aftershock zone in Central California near the Nevada border. It was followed by several aftershocks of M 3.3 and 3.6. NEIC reported the M 4.2 was felt with intensity II-III in California at Three Rivers, Lone Pine, Kings Canyon National Park, Ridgecrest, Visalia, Delano, Sanger and Fresno. It is likely this activity was triggered by seismic waves from the M 6.2 in Tarapaca, Chile which occurred 20 minutes earlier at 72 degrees distance. The S-phase from Chile arrived in central California at the same time the activity in Central California began and is the likely trigger for this activity. Today's event is an aftershock of the M 5.8 of June 24 and M 4.6 of June 23, 2020 and is the largest such aftershock since June 24. An M 4.8 occurred about 50 km to the east of today's epicenter on August 19, 2020. Forecast 127140 had expected today's event was likely around September 15.

 

O: 11SEP2020 08:11:04  36.4N  118.0W ML=3.1  EMSC   CENTRAL CALIFORNIA

O: 11SEP2020 08:12:22  36.4N  118.0W Ml=2.0  EMSC   CENTRAL CALIFORNIA

O: 12SEP2020 04:44:50  36.4N  118.0W Ml=2.3  EMSC   CENTRAL CALIFORNIA

O: 11SEP2020 08:14:09  36.5N  118.0W ML=3.4  EMSC   CENTRAL CALIFORNIA

O: 11SEP2020 07:55:44  36.4N  118.0W ML=4.0  EMSC   CENTRAL CALIFORNIA           

O: 11SEP2020 07:55:44  36.4N  118.0W ML=4.2  ANSS   CENTRAL CALIFORNIA           

P: 15SEP2020 127140    36.1N  118.1W 2.5-4.4 BAAAA  California/Nevada area     

 

Moderate earthquakes in the Tarapaca area of northern Chile continued to be felt in the Iquique, Tarapaca area today. This summary noted this activity in the previous issue as:

 

 

"A strong M 6.3 hit the northern Chile region of Tarapaca today. Minor damage was felt in the epicentral region near Tocopilla, Antofagasta, Chile (VII) with NEIC reporting VI in Iquique, Tarapaca and V in Calama and Arica, Antofagasta.

GUC reported this earthquake was felt with intensity  VI in  Tarapaca at Iquique and in Arica at Arica with IV, Chile. This is part of a series of strong earthquakes along the coast of Chile in the past week which has included an M 6.9 in Atacama and an M 6.2 in Coquimbo, Chile to the south of today's epicenter. The last earthquake within about 200 km of today's epicenter with M>=6.3 occurred as an M 8.2 and aftershocks in early April, 2014 about 150-200 km to the north of today's epicenters. Forecast 127016 had expected today's event within about 100 km was likely around September 9. This epicenter is near 106 degrees from the M 7.8 in the Alaska Peninsula of July 22. Seismic energy from large events can concentrate at this distance and help trigger larger regional events." (September 11, 2020)

 

O: 11SEP2020 07:35:56  21.4S   69.8W Mw=6.3  EMSC   TARAPACA, CHILE

O: 11SEP2020 10:13:43  21.4S   70.0W mb=4.5  EMSC   TARAPACA, CHILE

O: 12SEP2020 06:45:04  21.4S   69.9W mb=4.5  EMSC   TARAPACA, CHILE

O: 11SEP2020 08:25:07  21.5S   69.9W mb=4.6  EMSC   ANTOFAGASTA, CHILE

O: 11SEP2020 09:48:07  21.3S   69.9W ML=4.0  EMSC   TARAPACA, CHILE              

P:  9SEP2020 127016    22.0S   69.0W 4.0-5.6 AAAAA  Coast No. Chile            

 

STRONG EARTHQUAKE SHAKES TARAPACA, CHILE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 10, 2020

 

A strong M 6.3 hit the northern Chile region of Tarapaca today. Minor damage was felt in the epicentral region near Tocopilla, Antofagasta, Chile (VII) with NEIC reporting VI in Iquique, Tarapaca and V in Calama and Arica, Antofagasta. GUC reported this earthquake was felt with intensity  VI in  Tarapaca at Iquique and in Arica at Arica with IV, Chile. This is part of a series of strong earthquakes along the coast of Chile in the past week which has included an M 6.9 in Atacama and an M 6.2 in Coquimbo, Chile to the south of today's epicenter. The last earthquake within about 200 km  of today's epicenter with M>=6.3 occurred as an M 8.2 and aftershocks in early April, 2014 about 150-200 km to the north of today's epicenters. Forecast 127016 had expected today's event within about 100 km was likely around September 9. This epicenter is near 106 degrees from the M 7.8 in the Alaska Peninsula of July 22. Seismic energy from large events can concentrate at this distance and help trigger larger regional events. This summary has noted the relation between southern Peru and northern Chile and the Alaska Peninsula in many previous issues such as when an M 5.5 hit Tarapaca on August 3:

 

"Other recent activity in southern Peru and northern Chile commented on in this summary may have been precursory to today's event. This event is at 104-105 degrees from the M 7.8 of July 22 n the Alaska Peninsula and was probably promoted by energy from that source." (August 4, 2020)

 

O: 11SEP2020 00:57:20  20.9S   69.1W mb=4.6  EMSC   TARAPACA, CHILE              

O: 11SEP2020 07:35:56  21.4S   69.8W Mw=6.3  EMSC   TARAPACA, CHILE              

O: 11SEP2020 07:35     21.4S   69.9W mb=6.3  GUC    Tarapaca at Iquique and in Ari

P:  9SEP2020 127016    22.0S   69.0W 4.0-5.6 AAAAA  Coast No. Chile            

 

A series of light earthquakes occurred in the Yellowstone National Park area of Wyoming today. These were reported with intensity II-III in the epicentral area of Yellowstone. The largest of these was an M 2.8. A less energetic swarm hit the Yellowstone region about 50 km to the northwest of today's epicenters on May 29 but the last event in the area with M>=2.8 occurred on March 31, 2020 with M 2.9 and followed the M 6.5 in southern Idaho. One of the strongest aftershocks of that event occurred with M 4.4 yesterday. The only earthquake of M>2.9 in Yellowstone in the past year was an M 3.2 on December 15, 2019. Forecast 126958 had expected today's activity in Yellowstone was likely around September 7. This activity is at the third node (120 degrees) from the Banda Sea and may have been promoted by energy from that source.

 

O: 10SEP2020 11:03:02  44.3N  110.5W Ml=2.1  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 11:40:22  44.3N  110.5W Ml=2.6  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 11:42:54  44.3N  110.5W ML=2.5  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 11:44:41  44.3N  110.5W Ml=2.1  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 11:48:47  44.3N  110.5W Ml=2.2  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 12:09:31  44.3N  110.5W Md=2.8  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 12:19:33  44.3N  110.5W Ml=2.4  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 12:21:58  44.3N  110.5W ML=2.5  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 12:23:14  44.3N  110.5W MD=2.2  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 12:50:06  44.3N  110.5W Ml=2.7  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 13:01:51  44.3N  110.5W Ml=2.3  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 13:07:01  44.3N  110.5W Ml=2.4  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 13:19:34  44.3N  110.5W Ml=2.2  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 13:26:40  44.3N  110.5W ML=2.5  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 13:40:46  44.3N  110.5W Ml=2.0  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 18:33:53  44.3N  110.5W ML=2.4  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 18:36:46  44.3N  110.5W ML=2.3  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 18:56:01  44.3N  110.5W Ml=2.0  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 19:57:39  44.3N  110.5W Ml=2.0  EMSC   YELLOWSTONE NAT. PARK, WYOMING

O: 10SEP2020 10:54:34  44.3N  110.5W ML=2.0  EMSC   YELLOWSTONE NAT. PARK, WYOMING

P:  7SEP2020 126958    44.6N  110.8W 2.0-4.1 BAAAA  Yellowstone/Wyoming        

 

The largest earthquake in the U.S. or Canada today occurred south of the Rat Islands, Aleutians, Alaska. It was not reported felt in this remote area. It may be an outer-rise earthquake indicating pent-up stress to the north near 174 East longitude in the Rat Islands. The last earthquake of M>=4.7 south of the Rat Islands within about 150 km of today's event was an M 4.9 on February 8, 2012. Forecast 126971 had expected today's earthquake in the Rat Islands was likely around September 10. It was also unusual today that no other earthquakes of M>=3 occurred in the area of Alaska east of the IDL. Seismicity in California was also at very low levels today with only four events of M>=2 and none of M>=2.3. It appears the aftershock sequences in that State may have been temporarily suspended.

 

O: 11SEP2020 04:44:33  50.6N  174.0E mb=4.7  EMSC   SOUTH OF ALEUTIAN ISLANDS     

P: 10SEP2020 126971    52.0N  176.0E 4.0-5.7 ABBAA  Rat Islands                

 

MODERATE QUAKES CONTINUE IN SOUTHWEST PACIFIC

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  9, 2020

 

Global seismicity returned to relatively quiet levels today after a week of active seismicity. The largest of today's events was an M 5.6 in the Talaud

Islands of Indonesia and was followed by a series of moderate aftershocks.

The second strongest was an  5.4 in the New Britain area, PNG. An M 5.2 also occurred near Samoa. These may be belatedly related to the strong geomagnetic storm at the beginning of September as they occurred near the geomagnetic equator. The event in Samoa is not an aftershock of the M 5.6 there yesterday as it occurred about 400 km to the west of that epicenter. It is the strongest within about 150 km of this epicenter since an M 5.7 on December 6, 2019. Forecast 127001 had expected this event within about 10 km of this epicenter was likely around September 7. The earthquakes in Samoa and New Britain are both at the fifth node (72 degrees) from the M 7.8 in Alaska of July 22 and were probably promoted by energy from that source.

 

O:  9SEP2020 22:55:55  14.9S  176.0W Mw=5.2  EMSC   SAMOA ISLANDS REGION         

P:  7SEP2020 127001    15.0S  176.0W 4.0-5.4 AAAAA  Samoa Islands              

 

The second largest earthquake in the world today was an M 5.4 in the Bougainville region, PNG near New Britain and the Solomon Islands. It continues an active period in the area which in recent days has included earthquakes of M 6.1 in New Britain on August 25; an M 6.0 in New Guinea on August 1 and an M 7.0 in New Guinea on July 17, 2020. The last event within about 200 km of today's epicenter with M>=5.4 was an M 5.4 on July 11, 2020 and prior to that an M 6.1 on May 7, 2020. Forecast 126809 had expected today's event to the north around September 9.

 

O:  9SEP2020 10:57:10   6.2S  154.4E Mw=5.4  EMSC   BOUGAINVILLE REGION, P.N.G.  

P:  9SEP2020 126809     4.0S  154.0E 4.0-5.7 ACAAA  New Britain                

 

The strongest earthquake today was an M 5.6 in the Talaud Islands, Indonesia.

It was followed by a number of moderate sized aftershocks. This is about 200 km east of the M 6.3 in the Mindanao, Philippines quake two days ago and was preceded by events to the south of M 5.9 on September 6 and to the east of M 6.4 on June 4, 2020. The last within about 150 km of today's epicenter with M>=5.6 occurred one year ago on September 10, 2019 with M 5.6. Forecast 126797 had expected today's activity was likely around September 8 within about 100 km of today's epicenter. This activity is near 144 degrees from the Atacama Chile quake of M 7.0 on September 1 and may have been promoted by energy from that source.

 

O: 09SEP2020 18:46:54   3.7N  127.2E ML=4.3  EMSC   KEPULAUAN TALAUD, INDONESIA

O: 09SEP2020 07:41:19   4.0N  126.6E ML=4.4  EMSC   KEPULAUAN TALAUD, INDONESIA

O: 09SEP2020 07:48:31   4.1N  126.8E ML=4.5  EMSC   KEPULAUAN TALAUD, INDONESIA

O: 09SEP2020 07:18:43   4.2N  126.7E Mw=5.6  EMSC   KEPULAUAN TALAUD, INDONESIA

O: 09SEP2020 08:51:51   4.2N  126.8E mb=4.5  EMSC   KEPULAUAN TALAUD, INDONESIA

O: 09SEP2020 10:26:07   4.2N  126.9E ML=4.4  EMSC   KEPULAUAN TALAUD, INDONESIA

O: 09SEP2020 08:04:01   4.5N  126.7E ML=4.6  EMSC   KEPULAUAN TALAUD, INDONESIA

O:  9SEP2020 14:17:16   3.7N  126.1E ML=4.2  EMSC   KEPULAUAN TALAUD, INDONESIA  

P:  8SEP2020 126797     4.0N  126.0E 4.0-5.4 AAAAA  Mindanao, Philippines      

 

The strongest earthquake in the U.S. or Canada today was an M 4.3 in Southern Alaska. NEIC reported this earthquake of M 4.0-4.3 in Southern Alaska  was felt with intensity II-III in the area(s) of Southern Alaska in Wasilla, Elmendorf, Willow, Anchorage, and Chugiak. The last earthquake with M>=4.3 within about 100 km of this epicenter was an M 5.2 nearly a year ago on September 17, 2019 and prior to that an M 4.4 on February 18, 2019. Forecast 126979 had expected today's event was likely around September 10.

 

O: 10SEP2020 02:17:59  61.5N  149.9W mb=4.3  EMSC   SOUTHERN ALASKA              

P: 10SEP2020 126979    61.0N  151.4W 3.2-4.9 AAAAA  Central Alaska             

 

Two light earthquakes of M 3.5-3.6 struck Hawaii today - in the area of the island of Hawaii and in Maui. This continues regional seismic enhancement which has been occurring in Hawaii in the past several days and has included an M 3.6-3.8 in Maui on September 5 and an M 4.3 in the island of Hawaii on September 6. Forecast 126857 had expected the Maui quake and 126833 the event south of the island of Hawaii in early September.

 

NEIC reported this earthquake of M 3.0 in Hawaii  was felt with intensity II-III in the area(s) of Hawaii at Naalehu, Captain Cook and Kamuela. The earthquakes in Hawaii and in Southern Alaska today are both at 103-104 degrees from the M 7.0 in Sumatra of August 18 and were probably promoted by  concentrated seismic energy from those sources.

 

O:  9SEP2020 10:18:41  19.2N  155.4W ML=3.5  EMSC   ISLAND OF HAWAII, HAWAII     

P:  9SEP2020 126833    18.8N  155.2W 3.0-4.4 AAAAA  Hawaii                     

 

O: 10SEP2020 03:47:13  20.3N  155.6W ML=3.6  EMSC   HAWAII REGION, HAWAII        

P:  5SEP2020 126857    20.1N  156.1W 4.0-5.5 BAAAA  Hawaii area                

 

IGHT, UNUSUAL QUAKES WIDELY FELT IN ENGLAND AND NEW JERSEY

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  8, 2020

 

An unusual earthquake of M 3.9 south of London, England today was widely felt. It was reported with intensity IV in England at Cheddington and Eaton Bray and II-III in Aston, Clinton, Ivinghoe-Pitstone, Tring, Wendover, Weston, Aylesbury, Chesham and Dunstable and as far to the north as Salford (V), Christchurch and London and Leven, in the west in Ireland and to the south in France. This is the strongest earthquake in southeastern England within about 200 of this epicenter since an M 3.9 on October 26, 2008 and an M 5.0 on April 28, 2007. However no earthquakes have occurred within 100 km of today's epicenter in the past 30 years. The closest was an M 4.4 on February 15, 1994.  Forecast 126975 had expected today's earthquake was likely in this area around September 9.

This epicenter is at 101 degrees from the M 7.0 in Atacama, Chile of September 1, 2020 and the M 7.0 in Sumatra of August 18, 2020. Seismic energy from large earthquakes returns to the surface at this distance from the mainshock after reflections and refractions off internal earth boundaries and can help trigger seismicity at this distance.

 

O:  8SEP2020 08:45:27  51.9N    0.7W ML=3.9  EMSC   ENGLAND, UNITED KINGDOM      

P:  9SEP2020 126975    51.0N    3.0W 3.0-4.5 AABAA  United Kingdom             

 

An M 3.1 earthquake was widely felt in New Jersey today. NEIC reported maximum intensity IV in New Jersey at Freehold, Marlbobo, Colts Neck, Englishtown, Farmingdale, Morganville, Howell, Lincroft, Eatontown and Holmdel among other communities. It was also reported felt lightly as far as New York, Maryland, Washington, D.C., Massachusetts, Virginia, New Hampshire, Pennyslvania, Ohio.

Earthquakes in New Jersey are not common but there are faults in the area such as the Rampino Fault on which these can occur. Another possibility for quakes in this area, which often are not well explained, include destabilizing clathrate deposits on the seabed offshore. The last earthquake in the region of New Jersey within about 150 km of this epicenter with M>=3.1 was an M 4.1 about 150 km to the southwest on November 30, 2017. The only earthquakes within this distance from today's epicenter in the past 30 years with M>=3.1 occurred August 5, 2003 (M 3.8) and January 9, 2992 (M 3.1). The strongest earthquakes in the area within about 200 km of today's event occurred on January 16, 1994 with M 4.2 and 4.6. These occurred hours before the Northridge earthquake in California and were probably precursory to that earthquake. Forecast 126939 had expected today's event to the northeast was likely in New England in early September. When the event occurred on November 30, 2017 this summary noted in this regard:

 

"The earthquake in Delaware is one of the strongest recorded in that State.

Earthquake in this area are often followed within days by a strong quake in  southern or central California, such as occurred in the Northridge quake of M 6.7 on January 17, 1994 (preceded by an M 4.6 in southern Pennsylvania on January 16, 1994) and the Morgan Hill quake of April 24, 1984 preceded by an M 4.4 in Pennsylvania on April 23, 1984.  The events in August 2011 were later found to occur at the time of one of the strongest cosmic ray events known, possibly associated with a gravity wave and other effects which may have triggered this series. A similar relation may be found with today's events, but these area usually not announced until extensive data anaylsis. As this list includes the largest events in the Delaware area in the past 50 years and some of the strongest earthquakes in Central and southern California in the same period, it may be significant. This correlation is strongest with moderate starting quakes in the region of Delaware. The area of southern California near Northridge is currently at the 23-year cycles of large quakes in the area. A moderate earthquake in the region west of Los Angeles and north to San Francisco is considered possible in the next four days. At the least, residents should check their earthquake preparedness kits to see if they are ready for a moderate quake at this time." (December 1, 2017)

 

Today's event in New Jersey was located at 144 degrees from the M 7.0 in Sumatra of August 18, 2020 and from the Banda Sea quake of August 21 (M 6.8). Other activity at this distance from Sumatra today included a series of moderate quakes in the Gulf of California and aftershocks in Coquimbo and Atacama, Chile.

 

O:  9SEP2020 06:00:13  40.3N   74.3W mb=3.1  EMSC   NEW JERSEY                   

P:  5SEP2020 126939    43.0N   71.0W 2.0-4.1 BCBAA  New England                

 

The strongest earthquake in the world today was an M 5.4 in the region of Samoa. NEIC reported it was felt with intensity III in the Apia Urban area of Samoa. This is not unusual seismicity for the area. An event of M 5.5 hit this same epicenter on May 5, 2020 and an M 6.0 was located in the area on March 17, 2020. Today's event is probably the strongest aftershock to date of the May 5 event. Forecast 127007 had expected today's activity around September 5. This epicenter is located at the fifth node (72 degrees) from the Alaska Peninsula M 7.8 of July 22. It was probably promoted from that source. Other earthquakes today at the fifth node from the Alaska Peninsula included the M 3.9 in England, quakes in Puerto Rico and Dominican Republic and an M 4.2 in Luzon, Philippines.

 

O:  8SEP2020 08:28:51  15.2S  172.9W Mw=5.4  EMSC   SAMOA ISLANDS REGION         

P:  5SEP2020 127007    17.0S  172.0W 4.0-5.6 BBAAA  Tonga Islands              

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the southern Idaho aftershock zone. It and an M 3.9 foreshock were reported by NEIC to have been felt with intensity up to V in Idaho at Cascade and III-IV in Stanley, Lowman, McCall, Garden Valley, Ketchum, Challis, Ellis, New Meadows and Garden City. This is the strongest aftershock of the M 6.5 in southern Idaho of March 31, 2020 since an M 4.6 on June 25, 2020. Other aftershocks of M>=4.4 have hit the area on May 14 and May 21, 2020. Today's event followed an M 3.9 half an hour earlier. No major damage was reported. Forecast 126935 had expected today's earthquake was likely around September 5.

 

O: 08SEP2020 16:32:46  44.3N  115.2W ML=2.9  EMSC   SOUTHERN IDAHO

O: 08SEP2020 20:38:02  44.4N  115.2W ML=3.2  EMSC   SOUTHERN IDAHO

O: 08SEP2020 12:24:14  44.4N  115.2W Ml=3.5  EMSC   SOUTHERN IDAHO

O: 08SEP2020 20:42:39  44.5N  115.2W ML=3.0  EMSC   SOUTHERN IDAHO

O: 08SEP2020 07:26:53  44.5N  115.2W Ml=2.7  EMSC   SOUTHERN IDAHO

O: 08SEP2020 20:24:29  44.5N  115.2W Mw=4.4  EMSC   SOUTHERN IDAHO

O: 08SEP2020 20:23:49  44.5N  115.2W mb=3.9  EMSC   SOUTHERN IDAHO

O: 08SEP2020 21:50:27  44.5N  115.3W ML=2.6  EMSC   SOUTHERN IDAHO

O:  8SEP2020 09:10:40  44.1N  115.1W Ml=2.0  EMSC   SOUTHERN IDAHO               

P:  5SEP2020 126935    44.5N  115.2W 2.0-4.2 BAAAA  Montana/Idaho              

 

 

 

 

 

 

STRONG QUAKE SHAKES BANDA SEA, INDONESIA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  7, 2020

 

An earthquake of M 6.0-6.1 occurred today in the Banda Sea of Indonesia today. NEIC reported it was felt with intensity II-III in Sorong, Papua, Indonesia and in Darwin, Northern Territory, Australia. This continues activation of central Indonesia and southern Philippines which has included an M 6.4 in Mindanao and an M 6.3 in the Molucca Sea over the past two days. This is the strongest earthquake in the Banda Sea within about 200 km of this epicenter since an M 7.3 on June 24, 2019 about 150 km to the south. The last within about 150 km was an M 7.1 on December 10, 2012. Forecast 126821 had expected today's event within about 200 km was likely around September 8.

 

O:  8SEP2020 00:45:21   4.9S  129.8E Mw=6.1  EMSC   BANDA SEA                    

P:  8SEP2020 126821     3.0S  130.0E 4.0-5.6 ABAAA  West Irian, PNG            

 

An M 5.2 occurred today in the northern Ryukyu Islands, Japan. NEIC reported it was felt with intensity II-III in Okinawa at Nago, Ishikawa, Yomitan, Gushikawa, Okinawa, Chatan, Giniowan and Urasoe. This area has been in the path of several typhoons in the past week and had been expected in this summary to see enhanced seismicity at this time. For example when Super Typhoon passed over this epicenter on September 6, it was noted:

 

"Super-Typhoon Haishen (TD 11W) continued today north of the Ryukyu Islands, Japan with winds up to 115 kts. It is expected to track to the north reaching southern Honshu and Kyushu September 6-7. It could promote a moderate to strong earthquake in western Honshu or the Ryukyu Islands with or after landfall." (September 5-7, 2020)

 

This earthquake occurred within about an hour of local solar noon and may have been promoted by high tidal stresses which maximize near this hour. The last  event of M>=5.2 in the northern Ryukyu Islands was an M 6.7 on June 13, 2020 and prior to that  M 5.9 north of this on May 3, 2020. The last within about 200 km was an M 5.9 on May 3, 2020.  Forecast 126865 had expected today's event within about 100 km of this epicenter in the Ryukyu Islands around September 5.

 

O:  8SEP2020 02:58:14  27.0N  127.8E mb=5.2  EMSC   RYUKYU ISLANDS, JAPAN        

P:  5SEP2020 126865    28.0N  127.0E 4.0-5.4 BAAAA  Ryukyu Islands             

 

The strongest earthquake in the U.S. or Canada today occurred in the Northwest Territory of Canada near Banks Island where it was not reported felt. Forecast 126991 had expected activity within about 200 km of this epicenter was likely  around September 6.  This is the largest earthquake within about 200 km of this epicenter since an M 4.2 west of this on July 15, 2017 and an M 4.3 on April 24, 2012. The strongest earthquake in the area in the past 30 years was an M 4.8 on August 13, 1992.  This epicenter is near 103 degrees from the Banda Sea quake of August 21 (M 6.9) and Sumatra of August 18 (M 6.8) and was probably promoted by energy from that source.

 

O:  8SEP2020 03:56:43  71.8N  127.0W mb=4.1  EMSC   BANKS ISLAND, NW TERR., CANADA

P:  6SEP2020 126991    70.0N  131.0W 2.5-4.0 ABAAA  Yukon Territory, Canada    

 

A series of moderate earthquakes including an M 5.4 in Guam occurred in the Mariana Islands today. These were not reported felt but the M 5.4 was probably felt in Guam. Forecasts 126843 and 126850 had expected this activity was likely

in early September. This activity is near 144 degrees from the M 7.0 in Atacama,

Chile of September 1 and was probably promoted by energy from that source. Other earthquakes today at this distance from Atacama, Chile occurred in Java (M 4.6); south of Sumatra (M 4.6, 4.8); Gujarat, India (M 3.1, 3.8); and Uzbekistan (M 4.8).

 

O:  7SEP2020 18:44:31  17.1N  147.5E mb=4.6  EMSC   MARIANA ISLANDS REGION       

P:  4SEP2020 126843    19.0N  147.0E 4.0-5.5 BBAAA  No. Marianas               

 

O:  8SEP2020 00:54:06  13.2N  144.4E mb=5.4  EMSC   GUAM REGION                  

P:  7SEP2020 126850    13.0N  145.0E 4.0-5.6 AAAAA  So. Marianas/Guam          

 

O:  7SEP2020 07:32:32  14.1N  146.6E mb=4.8  EMSC   ROTA REGION, N. MARIANA ISLAND

P:  7SEP2020 126850    13.0N  145.0E 4.0-5.6 ABBAA  So. Marianas/Guam          

 

STRONG EARTHQUAKES CONTINUE IN VANUATU AND MINDANAO, PHILIPPINES

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  6, 2020

 

The group of strong earthquakes detailed in this summary in the previous issue continued today with additional strong events of M 6.2 and 5.9 in Vanuatu and M 6.4 in Mindanao, Philippines today. Most seismic areas of the world today also saw enhanced seismicity with moderate earthquake abundant. These included the northern and southern area of the Atlantic region.

 

The earthquake of M 6.2 in Vanuatu is east of  the location as an M 6.3 yesterday and was also felt, like that event, with intensity III in Vila Shefa, Vanuatu according to data from NEIC. This series was discussed in the previous issue of this report as:

 

 

"The M 6.2 in Vanuatu was reported by NEIC to have been felt with intensity IV in Vila Shefa, Vanuatu. It was accompanied by aftershocks of M 4.9, 5.1 and 5.2. It occurred in an area of active volcanism and may have been related to that. The last shallow focus earthquake within about 250 km of this epicenter in the Vanuatu Islands with M>=6.2 was an M 6.5 on August 21, 2018 and prior to that an M 7.0 on April 28, 2016. Forecast 127011 had expected today's event within about 25 km was likely around September 7. This epicenter is at 103-105 degrees from the earthquake of M 7.0 in Atacama, Chile of September 1 and from the M 6.3 in Coquimbo, Chile today  and from the M 7.4 in Oaxaca, Mexico of June 23 and was probably promoted by energy from those sources." (September 5-6, 2020)

 

The epicenter of today's M 6.2 is more than 50 km to the northeast of the M 6.2 yesterday in the Vanuatu Islands. It is the strongest earthquake in this area of the Vanuatu Islands east of 168 East longitude since an M 6.8 on January 23, 2015. Forecast 127011 had expected today's activity was likely around September 7.

 

O: 07SEP2020 06:12:41  17.1S  168.4E Mw=6.2  EMSC   VANUATU

O: 07SEP2020 06:29:15  17.2S  168.5E Mw=5.7  EMSC   VANUATU

O:  7SEP2020 04:41:27  17.0S  167.8E mb=5.0  EMSC   VANUATU                       

P:  7SEP2020 127011    17.0S  168.0E 4.0-5.5 AAAAA  Vanuatu Islands            

 

The earthquake of M 6.3 in southern Mindanao, Philippines was also widely felt today. Damage was reported with intensity VII in Southern Mindanao at Kapuan and Buayan, with V in Ilangay and Sarangani and IV shaking at Polomolok, Bato and Davao. Lesser intensities were reported from Silway, Camudmud and Ula, Southern Mindanao, Philippines. An M 6.4 hit Mindanao about 200 km northwest of this epicenter on August 1, 2020 but the last such event within 200 km was an M 6.6 on October 29, 2019 and an M 6.8 on December 15, 2019. Today's event is probably a regional aftershock of the December 15, 2019 event. Forecast 126797 had expected today's event within about 100 km of this epicenter was likely around September 6.

 

O:  6SEP2020 15:23:42   6.4N  125.7E Mw=6.4  EMSC   MINDANAO, PHILIPPINES        

P:  6SEP2020 126797     6.0N  125.0E 4.0-5.5 AAAAA  Mindanao, Philippines      

 

Two light earthquakes of M 2.8 and 3.2 were widely felt in the area of San Francisco, California today. NEIC reported maximum intensity III in San Leandro, San Lorenzo, Hayward, Castro Valley, Oakland, among others. The last earthquake in the San Francisco Bay area with M>=3.2 within about 50 km of today's epicenter on the Hayward Fault was an M 4.5 on October 15, 2019. Forecast 126877 had expected today's activity in this area was likely around September 9.

 

O:  6SEP2020 18:36:03  37.7N  122.1W Md=2.6  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O:  6SEP2020 18:43:57  37.7N  122.1W Mw=3.2  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P:  9SEP2020 126877    37.8N  122.6W 2.5-4.4 BAAAA  Central California         

 

The strongest earthquakes in the U.S. or Canada today were a pair of M 4.4 events in the Andreanof Islands, Alaska. This area has been active with events up to M 4.7 over the past week. Several of the events in this swarm have been felt at Adak, Alaska. Forecast 126961 had expected today's activity in the Andreanof Islands was likely around September 5.

 

O: 06SEP2020 18:19:26  51.2N  179.7W mb=4.4  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS.

O: 06SEP2020 17:30:52  51.3N  178.9W mb=4.4  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS.

O:  6SEP2020 18:39:10  51.1N  179.7W mb=4.1  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P:  5SEP2020 126961    50.8N  175.8W 3.5-4.9 AACAA  Andreanoff Isls, Aleutians 

 

An earthquake of M 4.3 was also recorded on the island of Hawaii today.

NEIC reported this earthquake of M 3.4-4.3 in Hawaii  was felt with intensity II-III in the area(s) of Hawaii at Pahala (IV), Naalehu, Captain Cook, Volcano, Holualoa, Hilo, Panoa, Kealakekua, Paauilo and Hakalau. An M 4.2 occurred near this epicenter on August 16, but the last event in Hawaii of larger or equal magnitude was an M 4.4 on August 1, 2020. Forecast 126833 had expected today's event was likely around September 5.

 

O:  6SEP2020 12:19:45  19.2N  155.5W ML=4.3  EMSC   ISLAND OF HAWAII, HAWAII     

P:  5SEP2020 126833    19.3N  155.1W 3.0-4.5 AAAAA  Hawaii                     

 

High latitude ocean ridges continued at active conditions today. Moderate

earthquakes were located in the South Atlantic in the Scotia Sea (M 4.7); Falkland Islands (M 5.0) and the South Shetland Islands (M 4.7) and in the north Atlantic in Iceland and the Reykjanes Ridge (M 4.4, 4.4). This activity follows several days of enhanced seismicity in these regions and had been expected in forecasts 127050 and 126968 in early September.

 

O:  7SEP2020 00:01:17  57.1S   54.9W mb=4.7  EMSC   SCOTIA SEA                   

O:  7SEP2020 00:01:58  52.3S   55.3W mb=5.0  EMSC   FALKLAND ISLANDS REGION      

P:  5SEP2020 127050    62.0S   54.0W 3.0-5.9 ACAAA  So. So. America            

 

O:  6SEP2020 07:36:18  60.7N   28.7W mb=4.4  EMSC   REYKJANES RIDGE              

O:  6SEP2020 15:17:09  60.8N   28.5W mb=4.4  EMSC   REYKJANES RIDGE              

P:  8SEP2020 126968    59.0N   31.0W 4.0-5.4 ABBAA  North Mid-Atlantic Ridge   

 

O:  7SEP2020 00:00:42  62.4S   58.5W mb=4.7  EMSC   SOUTH SHETLAND ISLANDS       

P:  5SEP2020 127050    62.0S   54.0W 3.0-5.9 AABAA  So. So. America            

 

O:  7SEP2020 06:21:09  63.9N   22.1W ML=3.3  EMSC   ICELAND REGION               

P:  5SEP2020 126984    65.0N   22.0W 3.0-4.8 ABAAA  Iceland area               

 

 

STRONG EARTHQUAKES HIT MANY AREAS

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  5, 2020

 

A series of strong earthquakes hit around the world today. These included events in the Mid-Atlantic of M 5.3 and 6.6; in Vanuatu of M 6.2; in Coquimbo, Chile of M 6.3 and in Molucca, Indonesia of M 6.0. Much of today's activity followed on the full moon of September 1 and the geomagnetic storm which occurred in early September and had been anticipated as a continuation of the enhanced activity in mid-ocean ridges and near 80 West longitude in previous issues of this summary as:

 

 

"The earthquakes in Panama suggest the effect of the full moon is not yet complete. The area to watch for the next several days continues to be the western coast of South America in the region of Chile. The area at 103-108 degrees from the Atacama event in Chile of M 7.0 on September 1 is in the region of Vanuatu where a moderate to large earthquake is also possible in the near term." (September 4-5, 2020)

 

and

 

"Ocean Ridges remained active today with moderate quake southwest of Africa (M 5.0); in the South Shetland Islands (M 5.0; the South Sandwich Islands (M 4.9) and the Owen's Fracture Zone (M 4.5, 4.5). The activation of ocean ridges began with the strong geomagnetic storm of the past several day, an event which is now in decline." (September 4, 2020)

 

The strongest earthquake in the world today was an  M 6.6 in the Central Mid-Atlantic Ridge. It was not reported felt in this remote area. This is the strongest earthquake within about 250 km of this epicenter since an M 6.6 on September 10, 2008, the only such event in the area in the past 30 years. Forecast 126789 had expected a moderately large regional event in this area was likely around September 7. This epicenter is at 101 degrees from the M 7.8 in the Alaska Peninsula of July 22 and was probably promoted by energy from that source.

 

O:  6SEP2020 06:51:21   7.7N   37.2W Mw=6.6  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P:  7SEP2020 126789     7.0N   35.0W 4.0-5.8 AABAA  Central Mid-Atlantic Ridg  

 

The M 6.6 in the Central Mid-Atlantic Ridge followed an M 5.2-5.3 in the Northern Mid-Atlantic Ridge by 13 minutes. It may have been triggered by surface waves and/or S-phase waves from the northern Atlantic event 40 degrees to the north as these were in the area when the M 6.6 occurred. The earthquake in the northern Mid-Atlantic is the strongest within about 250 km of that epicenter since an M 5.4 on September 30, 2013. The strongest in the past 30 years in the area was an M 5.9 on December 19, 2008. Forecast 126941 had expected a moderate earthquake in this area of the northern Mid-Atlantic was likely around September 4.

 

O:  6SEP2020 06:38:35  47.8N   27.5W mb=5.2  EMSC   NORTHERN MID-ATLANTIC RIDGE  

O:  6SEP2020 06:38:35  47.7N   27.5W mb=5.3  ANSS   NORTHERN MID-ATLANTIC RIDGE  

P:  4SEP2020 126941    45.0N   28.0W 4.0-5.6 ACAAA  No. Mid-Atlantic Ridge     

 

The M 6.2 in Vanuatu was reported by NEIC to have been felt with intensity IV in Vila Shefa, Vanuatu. It was accompanied by aftershocks of M 4.9, 5.1 and 5.2. It occurred in an area of active volcanism and may have been related to that. The last shallow focus earthquake within about 250 km of this epicenter in the Vanuatu Islands with M>=6.2 was an M 6.5 on August 21, 2018 and prior to that an M 7.0 on April 28, 2016. Forecast 127011 had expected today's event within about 25 km was likely around September 7. This epicenter is at 103-105 degrees from the earthquake of M 7.0 in Atacama, Chile of September 1 and from the M 6.3 in Coquimbo, Chile today  and from the M 7.4 in Oaxaca, Mexico of June 23 and was probably promoted by energy from those sources.

 

O: 06SEP2020 04:20:50  17.1S  167.8E mb=5.1  EMSC   VANUATU

O: 06SEP2020 04:39:23  17.1S  167.7E mb=5.2  EMSC   VANUATU

O: 06SEP2020 03:44:25  17.2S  167.7E mb=4.9  EMSC   VANUATU

O:  6SEP2020 02:59:15  17.1S  167.8E Mw=6.2  EMSC   VANUATU                      

P:  7SEP2020 127011    17.0S  168.0E 4.0-5.5 AAAAA  Vanuatu Islands            

 

The M 6.3 in Coquimbo, Chile was not an aftershock of the Atacama event of September 1, 2020 but may have been affected by stress redistribution from that event which occurred about 200 km to the north of today's event. Today's event was reported with intensity V in Coquimbo at Ovalle, Andacollo, Coquimbo, La Serena, and in Valparaiso, Chile. Intensity IV was reported in La Ligua with II-III in Illapel, Vina del Mar, Villa Alemana, Valparaiso and in San Juan, Argentina. GUC reported this earthquake was felt with intensity   VI in  Coquimbo at Coquimbo and La Serena; V in Andacollo, Canela, Paiguano, Punitaqui, Vicuna; IV in Rio Hurtado, Ovalle, Monte Patria, La Higuera, Illapel, and Combarbala; in Atacama with V in Vallenar and IV in Alto del Carmen, Copiapo, Freirina, Huasco and Tierra Amarilla; in Valparaiso with V at Valparaiso; IV in Llaillay, Papudo, Vina del Mar ; III in San Felipe and II in Villa Alemana and Limache; in Valparaiso with IV in Colina, Puente Alto Penalolen, III in Lampa, Santiago, La Reina, Los Condes, Lo Barnechea, San Miguel, Pudahuel, Macul, Pedro Aguirre Cerda; in O'Higgins with III in Codegua and Mostazal, Chile.\ Today's M 6.3 is the strongest earthquake in the Coquimbo, Chile area within about 150 km of this epicenter since an M 6.4 on June 14. 2019. Both are probably aftershocks of an M 6.7 on January 29, 2019.  Forecast 127027 had expected today's earthquake was likely within this area around September 4. This epicenter is at 144 degrees from the M 7.0 in Sumatra of August 18 and was probably promoted by energy from that source as well as by redistributed stress from the Atacama M 7.0 of September 1. Other earthquakes of 144 degrees from Sumatra today included an M 2.2 in Oklahoma and a series of M 3.4, 3.8 and 3.4 in the Gulf of California.

 

O:  6SEP2020 01:16     30.4S   71.4W mb=6.3  GUC    Coquimbo at Coquimbo and La Se

O: 06SEP2020 01:16:57  30.4S   71.5W Mw=6.3  EMSC   COQUIMBO, CHILE

O: 06SEP2020 01:20:19  30.4S   71.5W ML=4.4  EMSC   COQUIMBO, CHILE

P:  4SEP2020 127027    31.0S   72.0W 4.0-5.9 AAAAA  Central Chile              

 

An M 5.9-6.0 in the Molucca Sea of Indonesia was reported by NEIC to have been felt with intensity II in Manado, Sulawesi. The area has been active in the past several weeks, but the last earthquake within about 200 km of today's epicenter in the Molucca Sea occurred on November 14, 2019 with M 7.1 and 6.0. Today's event appears to be the largest aftershock of that M 7.1 to date.  Forecast 126517 had expected today's event was likely within this area at the end of August or in early September.

 

O:  6SEP2020 00:21:11   1.7N  126.6E Mw=6.0  EMSC   MOLUCCA SEA                  

P: 31AUG2020 126517     3.0N  127.0E 4.0-5.5 ACBAA  Halmahera                  

 

An earthquake of M 3.8 followed the event in Coquimbo, Chile west of Los Angeles, California. NEIC reported this unusual event was felt with intensity II-III in southern California at Solvang, Goleta, Santa Ynez, Los Olivos, Buellton, Santa Barbara and Lompoc. This epicenter is at 79 degrees from and 33 minutes after Coquimbo. Seismic waves from that source such as SSS and surface phases may have helped trigger the event in southern California. This is the strongest earthquake in the region within about 100 km and west of Santa Barbara since an M 3.8 on January 7, 2018. Forecast 126905 had expected today's event near Santa Barbara around September 4. Aftershocks of M 2.4 and 2.1 followed the mainshock.

 

O: 06SEP2020 03:39:51  34.6N  120.1W Ml=2.4  EMSC   SOUTHERN CALIFORNIA

O: 06SEP2020 04:01:40  34.6N  120.1W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

O:  6SEP2020 01:48:31  34.4N  120.3W ML=3.6  EMSC   SANTA BARBARA CHANNEL, CALIF.

O:  6SEP2020 01:48:31  34.4N  120.3W ML=3.8  ANSS   SANTA BARBARA CHANNEL, CALIF.

P:  4SEP2020 126905    34.7N  119.0W 2.5-4.4 AAAAA  So. California             

 

An unusual earthquake in Maui, Hawaii also occurred today. NEIC reported it was widely felt in Maui with maximum intensity IV in Hawaii at Hana and II-III in Kaunakakai, Lahaina, Kula, Wailuku, Kihei, Kahului, Haiku, Paia, Makawao. This event of M 3.6-3.8 is the strongest in the region of Maui since an M 3.7 two years ago on September 15, 2018 and an M 4.0 on September 28, 2018. Forecast 126857 had expected today's event near Maui, Hawaii was likely around September 5. This epicenter is at 103 degrees from the M 7.0 in Sumatra of August 18 and was probably promoted by energy from that source.

 

O:  5SEP2020 07:43:16  20.9N  156.3W ML=3.6  EMSC   MAUI REGION, HAWAII          

O:  5SEP2020 07:43:16  20.9N  156.3W ML=3.8  ANSS   MAUI REGION, HAWAII          

P:  5SEP2020 126857    20.1N  156.1W 4.0-5.5 AAAAA  Hawaii area                

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 in the Alaska Peninsula. NEIC reported this earthquake of M 3.6-4.1 in the Alaska Peninsula  was felt with intensity II-III in the area(s) of the Alaska Peninsula at Chignik. This is about 200 km northeast of the M 7.8 mainshock of July 22 and is not part of the classical aftershock sequence in the area. Most moderate aftershocks have been occurring west of the mainshock epicenter. The last earthquake within about 100 km of today's event with M>4.1 was an M 4.7 on February 17, 2020 and prior to that an M 4.4 on February 1, 2020. Forecast 126960 had expected today's event was likely in this area around September 4.

 

O:  5SEP2020 12:43:38  55.0N  158.3W ML=3.0  EMSC   ALASKA PENINSULA             

O:  5SEP2020 08:20:27  56.8N  156.9W mb=4.1  EMSC   ALASKA PENINSULA             

P:  4SEP2020 126960    54.8N  159.6W 3.5-5.4 AABAA  Alaska Peninsula           

 

 

 

 

 

MODERATELY STRONG QUAKES IN PANAMA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  4, 2020

 

The strongest earthquake in the world today was an M 5.6 in Panama. NEIC reported it was felt with intensity VI in Panama at Puerto Armuelles, Rio Sereno, and VII in Los Algarrbos, Chirqui; IV in Volcan, Quiteno, and II-III in Golfito, David, Palmira, Bouquete, and Almirante Bocas del Toro. An aftershock of M 5.3 was reported felt with intensity III in Panama at Guarumal, Potrerillos Abajo, Puerto Nuevo and Volcan, Chiriqui. Like much of the stronger activity in the world in the past three days, this event occurred near 80 degrees west longitude and was apparently  promoted by strong tidal stresses associated with the full moon of September 2 as noted in previous issues of this summary:

 

"The full moon arrived at 05:22 UT on September 2, 2020. Longitudes which were at local solar midnight at this time are near 80 West while those at solar noon are near 100 East. These include in the west, Central America and western South America and in the east Sumatra and western Indonesia and southeast Asia. These regions are likely to see moderate seismic with this full moon. Tidal triggering is not usually major at full moon but can occur  - normally near local solar midnight and noon in areas where seismicity is controlled by vertical tectonics and/or fluid motions." (September 1-3, 2020)

 

The earthquakes in Panama suggest the effect of the full moon is not yet complete. The area to watch for the next several days continues to be the western coast of South America in the region of Chile. The area at 103-108 degrees from the Atacama event in Chile of M 7.0 on September 1 is in the region of Vanuatu where a moderate to large earthquake is also possible in the near term.

 

The last earthquake within about 150 km of today's M 5.6 in Panama was an M 6.2 on June 26, 2019. Forecasts 126515 and 126793 had expected today's activity was likely within about 50 km of this epicenter in late August or early September. Today's activity is near the antipode of the M 7.0 in Sumatra of August 18, 2020 and may have been promoted by antipodal focusing of energy from that event.

 

O: 04SEP2020 17:58:30   8.3N   83.0W ML=4.1  EMSC   COSTA RICA

O: 04SEP2020 20:03:30   8.3N   83.0W ML=4.4  EMSC   COSTA RICA

O: 04SEP2020 23:29:30   8.3N   83.0W ML=4.0  EMSC   COSTA RICA

O: 04SEP2020 23:56:30   8.3N   83.0W ML=4.6  EMSC   PANAMA-COSTA RICA BORDER REGION

O: 05SEP2020 05:21:30   8.3N   83.0W ML=4.1  EMSC   COSTA RICA

O: 05SEP2020 05:38:14   8.3N   82.9W mb=4.5  EMSC   PANAMA-COSTA RICA BORDER REGION

O: 04SEP2020 17:45:21   8.4N   83.0W Mw=5.5  EMSC   PANAMA-COSTA RICA BORDER REGION

O: 04SEP2020 17:45:21   8.4N   83.0W Mw=5.6  ANSS   PANAMA-COSTA RICA BORDER REGION

O: 04SEP2020 17:46:43   8.4N   82.8W mb=5.3  EMSC   PANAMA-COSTA RICA BORDER REGION

O:  4SEP2020 17:48:53   8.4N   83.0W mb=4.9  EMSC   PANAMA-COSTA RICA BORDER REGIO

P:  7SEP2020 126793     9.0N   85.0W 3.5-5.3 BABAA  Costa Rica                 

P: 28AUG2020 126515     8.0N   83.0W 3.5-4.9 CAAAA  Costa Rica                  

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 in the western Andreanof Islands, Aleutians, Alaska. It was reported with intensity III felt in Adak, Alaska. This is the third such event in the Andreanof Islands region in the past three days. Previous events were reported in the last issue of this summary as:

 

"The strongest earthquake in the U.S. or Canada today was an M 4.4 in the western Andreanof Islands, Aleutians, Alaska. This is the second such event in the area in the past two days. This summary noted the previous in yesterday's summary. The last earthquake with M>=4.4 in the Andreanof Islands occurred on July 22, 2020 with M 4.9. Forecast 126691 had expected today's activity was likely at the end of August or early September.

 

NEIC reported this earthquake of M 4.4 in the Andreanof Islands, Alaska  was felt with intensity II-III in the area(s) of the Andreanof Islands, Alaska at Adak." (September 3-4, 2020)

 

Forecast 126961 had expected this event of M 4.7 was likely around September 5.

This activity is located at the third node (120 degrees) from the M 7.0 in

Atacama, Chile of September 1 and may have been promoted by energy from that source.

 

O:  5SEP2020 05:14:51  51.7N  178.5W mb=4.7  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P:  5SEP2020 126961    50.8N  175.8W 3.5-4.9 AABAA  Andreanoff Isls, Aleutians 

 

Antipodal activity at moderate levels continued today in the South Sandwich Islands (M 4.7) and as a swarm in the region of Kamchatka. This antipodal activity began several days ago and may involve some volcanic activity in Kamchatka. This was first reported in this summary on September 1 as:

 

 

"An antipodal pair of earthquakes occurred today - first in the South Sandwich Islands with M 4.8 and about an hour-and-a-half later as an M 5.6 in Kamchatka, Russia. These events are not uncommon but illustrate the impact that geomagnetic storms can have on antipodal seismicity. The Kamchatka event occurred within about 30 minutes of local solar noon while the South Sandwich event occurred near local solar midnight. Both may also have been affected by strong tidal stresses associated with the full moon which maximize at these hours. The event in the South Sandwich Islands had been expected in forecast 126786 to occur around August 27. (September 1, 2020)

 

Today's event in the South Sandwich Islands occurred near local solar noon and may have been promoted by tidal stresses which maximize at this hour. Forecast 127049 had expected this activity within about 50 km of the epicenter was likely around September 8.

 

O:  4SEP2020 11:49:35  55.4S   27.4W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P:  8SEP2020 127049    55.0S   28.0W 4.0-5.7 BAAAA  So. Sandwich Islands       

 

The activity in the region of Kamchatka also occurred near local solar noon

and may have been tempered by tidal stresses. Forecast 126965 had expected

this activity in Kamchatka around September 5.

 

O: 04SEP2020 23:01:51  52.2N  160.3E mb=4.3  EMSC   OFF EAST COAST OF KAMCHATKA

O: 05SEP2020 00:21:26  52.3N  160.0E mb=4.6  EMSC   OFF EAST COAST OF KAMCHATKA

O: 04SEP2020 21:14:26  52.4N  159.9E mb=4.7  EMSC   OFF EAST COAST OF KAMCHATKA

O: 04SEP2020 21:50:21  52.5N  160.1E mb=4.4  EMSC   OFF EAST COAST OF KAMCHATKA

O:  4SEP2020 21:10:13  52.2N  160.2E mb=4.8  EMSC   OFF EAST COAST OF KAMCHATKA  

P:  5SEP2020 126965    52.0N  158.0E 4.0-5.9 AABAA  Kamchatka                  

 

A moderate earthquake of M 5.0 shook the northern Ryukyu Islands of Japan today.

This is the strongest earthquake in the Ryukyu Islands within about 250 km of  this epicenter since an M 6.6 on June 13, 2020 and an M 5.2 on January 6, 2020.

Forecasts 126591 and 126859 had expected this activity in early September. Typhoon Maysak passed over this epicenter two days ago and stresses associated with this typhoon probably helped trigger today's activity as noted in previous issues of this report:

 

"Typhoon Maysak (TD 10W) continued today over the Ryukyu Islands with winds up to 150 kts. It is expected to track to the north and west and could enhance seismicity in the  Ryukyu Islands in the next several days." (September 1-2, 2020)

 

O:  4SEP2020 19:36:21  29.3N  130.6E Mw=5.0  EMSC   RYUKYU ISLANDS, JAPAN        

P:  1SEP2020 126591    29.0N  129.0E 4.0-5.4 BAAAA  Ryukyu Islands             

P:  8SEP2020 126859    29.0N  131.0E 4.0-5.4 BAAAA  Kyushu Japan               

 

LIGHT EARTHQUAKE SHAKES ALABAMA AND FLORIDA

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  3, 2020

 

An unusual M 3.8 shook areas of Alabama and Florida today. NEIC gave maximum intensity IV in Jay, Florida and II-III in Florida at Century, Milton, Contonment, Holt, and in Alabama at Flomaton, Brewton, Almore. This epicenter is near where Hurricane Laura made landfall this week and many have been promoted by energy from that event. This event at 87W longitude also confirms the likely role of tidal effects from the full moon in the occurrence of this earthquake at this time. The tidal seismicity forecast in this summary had read:

 

"The full moon arrived at 05:22 UT on September 2, 2020. Longitudes which were at local solar midnight at this time are near 80 West while those at solar noon are near 100 East. These include in the west, Central America and western South America and in the east Sumatra and western Indonesia and southeast Asia. These regions are likely to see moderate seismic with this full moon. Tidal triggering is not usually major at full moon but can occur  - normally near local solar midnight and noon in areas where seismicity is controlled by vertical tectonics and/or fluid motions." (September 1-3, 2020)

 

The last earthquake in Alabama within about 200 km of this epicenter with M>=3.8 occurred on June 30, 2015 and November 20, 2014 (both with M 3.8). Two other such events have occurred in this area in the past 30 years - an M 4.3 on November 7, 2004 and an M 4.9 on October 24, 1997. Forecast 126644 had expected regional activity enhancement at the end of August or in early September. This epicenter is at the sixth node (60 degrees) from  the M 7.0 in Atacama, Chile of September 1 and was probably promoted by energy from that source.

 

O:  3SEP2020 15:07:53  31.0N   87.2W Mw=3.8  EMSC   ALABAMA                      

P: 31AUG2020 126644    34.0N   85.0W 2.0-4.1 BCBAA  Southeast U.S.             

 

The strongest earthquake in the world today was an M 5.0-5.7 in northern South Island, New Zealand. GEONET reported this earthquake was felt with moderate intensity in northern South Island. 25279 people reported feeling this event; 12184 with weak intensity; 10960 with light shaking; 1954 moderate; 145 strong; 12 with severe and 24 with extreme shaking. NEIC reported this earthquake of M 4.7 in South Island, New Zealand was felt with intensity II-III in the area(s) of South Island, New Zealand at Culverden, Canterbury.  A light foreshock about 50 km northeast of this of M 4.0 occurred on August 30, 2020. The last earthquake within about 200 km of this epicenter with M>=5.2 was an M 5.4 on January 5, 2107. The last of larger magnitude was an M 6.5 on November 13-14, 2016. Forecast 127044 had expected today's activity was likely within about 100 km of the epicenter around September 5. This earthquake is at the fourth node (90 degrees) from the Atacama quake of September 1, 2020 and at 100-102 degrees from the M 7.5 in Oaxaca, Mexico of June 23, 2020 and the Alaska Peninsula quake of M 7.8 on July 22, 2020. Seismic energy is concentrated at this distance on the surface following large event and can help promote enhanced seismicity at this distance. Other moderate earthquakes at this distance from Oaxaca today occurred in Honshu, Japan (M 5.0, 5.0, 5.3) and in Greece (M 4.3).

 

O: 03SEP2020 10:13:00  41.8S  172.7E ML=5.7  GEONET Felt with moderate intensity

O:  3SEP2020 10:12:59  41.8S  172.7E Mw=5.2  EMSC   SOUTH ISLAND OF NEW ZEALAND  

P:  5SEP2020 127044    42.0S  174.0E 3.0-5.2 AAAAA  So. Island, N.Z.           

 

Ocean Ridges remained active today with moderate quake southwest of Africa (M 5.0); in the South Shetland Islands (M 5.0; the South Sandwich Islands (M 4.9) and the Owen's Fracture Zone (M 4.5, 4.5). The activation of ocean ridges began with the strong geomagnetic storm of the past several day, an event which is now in decline. The M 5.0 southwest of Africa is near the antipode of the  M 7.8 and aftershocks in the Alaska Peninsula of July 22 and was probably promoted by focused energy from that source.

 

O:  4SEP2020 03:23:37  52.5S   13.6E mb=5.0  EMSC   SOUTHWEST OF AFRICA          

 

The M 4.9 in the South Sandwich Islands is at 103 degrees from the M 7.0 in

Sumatra of August 18 and was probably promoted by energy from that source.

 

O:  3SEP2020 22:52:19  60.4S   25.4W mb=4.9  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 31AUG2020 126787    61.0S   26.0W 4.0-5.6 BAAAA  Southern  Ocean            

 

O:  3SEP2020 23:29:39  62.4S   58.2W Mw=5.0  EMSC   SOUTH SHETLAND ISLANDS       

P:  5SEP2020 127050    62.0S   54.0W 3.0-5.9 ABAAA  So. So. America            

 

The activity in the Owen Fracture zone is at 104 degrees from the M 7.8 in

the Alaska Peninsula of July 22 and was probably promoted by concentrated

energy from that source.

 

O: 03SEP2020 20:40:43  14.4N   56.4E mb=4.5  EMSC   OWEN FRACTURE ZONE REGION

O: 03SEP2020 20:25:25  14.5N   56.3E mb=4.5  EMSC   OWEN FRACTURE ZONE REGION

O:  3SEP2020 20:36:55  14.4N   56.3E mb=4.3  EMSC   OWEN FRACTURE ZONE REGION    

P: 31AUG2020 126549    15.0N   56.0E 3.5-4.9 BAAAA  Arabian Sea                

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the western

Andreanof Islands, Aleutians, Alaska. This is the second such event in the area in the past two days. This summary noted the previous in yesterday's summary.

The last earthquake with M>=4.4 in the Andreanof Islands occurred on July 22, 2020 with M 4.9.  Forecast 126691 had expected today's activity was likely at the end of August or early September.

 

NEIC reported this earthquake of M 4.4 in the Andreanof Islands, Alaska  was felt with intensity II-III in the area(s) of the Andreanof Islands, Alaska at Adak.

 

O:  3SEP2020 23:35:57  51.3N  178.6W mb=4.4  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 28AUG2020 126691    51.7N  176.4W 3.5-4.9 BABAA  Andreanoff Isls, Aleutians 

 

SEISMIC ENHANCEMENT NEAR 80 WEST LONGITUDE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  2, 2020

 

Seismic enhancement was observed near 80 degrees West longitude today in Colombia, Panama and Costa Rica. This was expected in the tidal seismicity forecast of this summary in previous issues as:

 

"The full moon will arrive at 05:22 UT on September 2, 2020. Longitudes which are at local solar midnight at this time are near 80 West while those at solar noon are near 100 East. These include in the west, Central America and western South America and in the east Sumatra and western Indonesia and southeast Asia. These regions are likely to see moderate seismic with this full moon. Tidal triggering is not usually major at full moon but can occur  - normally near local solar midnight and noon in areas where seismicity is controlled by vertical tectonics and/or fluid motions." (September 1, 2020)

 

The enhancement was joined by the low pressure unloading associated with

Tropical Storm Nana as reported in previous issues of this report:

 

"TS Nana formed today in the area north of Guatemala and Honduras with winds up to 50 kts. It is expected to track to the west over the next several days and will probably promoted seismicity in Guatemala and eastern Mexico in the next several days, including the possibility of a moderately large regional earthquake at this time." (September 1-2, 2020)

 

The largest of today's event occurred as an M 5.3 south of Panama at 79.9 West longitude. This was the second strongest earthquake in the world today following an M 5.4 in Papua New Guinea.  Forecasts 126515 and  126514 had expected this event was likely to the southeast of today's epicenter. The last earthquake of equal or greater magnitude in the area occurred with an M 5.3 on June 13, 2019 and an M 5.7 on January 31, 2018. Other moderate events in the region today occurred about 250 km north of this event with M 4.6 and about 300 km southeast in Colombia with M 4.5.  This activity is located at the antipode of the M 7.0 in Sumatra of August 18 and was probably also promoted by focused energy from that source.

 

NEIC reported this earthquake of M 5.3 in Panama  was felt with intensity IV in the area(s) of Panama at Panama City and I in Ancon.

 

O:  2SEP2020 21:09:24   6.2N   79.9W Mw=5.3  EMSC   SOUTH OF PANAMA              

P: 23AUG2020 126514     5.0N   78.0W 4.0-5.5 CBBAA  Colombia                   

 

 

NEIC reported the earthquake of M 4.5 in Costa Rica  was felt with intensity II-III in the area(s) of Puerto Armuelles, Panama.

 

O: 03SEP2020 05:39:30   8.3N   83.0W ML=4.1  EMSC   COSTA RICA

O: 03SEP2020 05:40:30   8.3N   83.0W ML=4.3  EMSC   PANAMA-COSTA RICA BORDER REGION

O: 03SEP2020 05:29:55   8.4N   83.0W mb=4.5  EMSC   PANAMA-COSTA RICA BORDER REGION

O:  2SEP2020 18:49:39   7.7N   82.3W mb=4.6  EMSC   SOUTH OF PANAMA              

P: 28AUG2020 126515     8.0N   83.0W 3.5-4.9 BAAAA  Costa Rica                 

 

NEIC reported the earthquake of M 4.5 in  Colombia was felt with intensity II-III in the area(s) of Colombia at Turbo Antioquia.

 

O:  3SEP2020 03:23:37   8.2N   76.9W mb=4.5  EMSC   NEAR NORTH COAST OF COLOMBIA 

P: 31AUG2020 126514     7.0N   73.0W 4.0-5.4 BBCAA  Colombia                   

 

O:  2SEP2020 07:06:10  11.1N   86.9W mb=4.2  EMSC   NEAR COAST OF NICARAGUA      

P: 27AUG2020 126566    11.0N   86.0W 3.5-5.4 BAAAA  Nicaragua                  

 

 

A series of light earthquakes also occurred in the area of southern Baja California, Mexico and in the Gulf of California. These had been forecast in 126582 within about 100 km of these epicenters. This summary expected this activity with passage of Tropical Storms Iselle and Hernan through the region in late August as:

 

"TS Iselle continued today in the area south of the Gulf of California with winds up to 50 kts. It is expected to track to the north but not make landfall. Some moderate seismicity in the Gulf of California and Baja could be enhanced while Iselle is in the region." (August 29-30, 2020)

 

and

 

"TS Hernan continued today in the area south of the Gulf of California with winds up to 45 kts. It is expected to track to the north into the Gulf of California. Some moderate seismicity in the Gulf of California and Baja could be enhanced while Iselle is in the region." (August 29-30, 2020):45  24.1N  110.3W ML=2.9  EMSC   BAJA CALIFORNIA SUR, MEXICO

 

O: 02SEP2020 09:15:32  24.2N  110.3W ML=3.4  EMSC   BAJA CALIFORNIA SUR, MEXICO

O: 03SEP2020 02:45:22  24.2N  110.1W ML=3.3  EMSC   BAJA CALIFORNIA SUR, MEXICO

O:  2SEP2020 07:51:11  24.1N  110.3W ML=2.9  EMSC   BAJA CALIFORNIA SUR, MEXICO  

P: 31AUG2020 126582    24.0N  109.0W 3.5-5.0 AAAAA  Gulf of California         

 

NEIC reported the earthquake of M 3.3 in  the Gulf of California was felt with intensity II-III in the area(s) of the Gulf of California at La Paz, Baja California.

 

O:  2SEP2020 18:52:41  27.5N  111.3W ML=3.4  EMSC   GULF OF CALIFORNIA           

P: 27AUG2020 126582    28.0N  112.0W 3.5-4.9 BAAAA  Gulf of California         

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in the Northwest Territories of Canada. The last earthquake within about 100 km of this epicenter with M>=3.9 was and M 4.7 on July 25, 2020 with an aftershock of M 3.9 on August 13, 2020. Today's event is an aftershock in that series. Forecast 126724 had expected today's event within about 100 km of this epicenter was likely around August 31. This event is located at 101 degrees from the epicenter of M 7.0 in Atacama, Chile of September 1 and was probably triggered by strong concentrated  energy from that event.

 

O:  2SEP2020 07:43:42  61.9N  126.2W MB=3.9  ECAN Tungsten, NT                   

O:  2SEP2020 07:43:42  61.9N  126.2W ML=3.9  EMSC   NORTHWEST TERRITORIES, CANADA

P: 31AUG2020 126724    62.1N  124.2W 2.5-4.1 AAAAA  Northwest Terr., Canada    

 

The swarm of earthquake north of North Island, New Zealand continued at active levels today. The strongest events in this swarm today were M 4.4, 4.3 and 4.1. This was probably triggered by the strong geomagnetic storm of the past several days as this area has seen similar behavior with strong changes in the geomagnetic field in the past. This summary had noted when this swarm began:

 

 

"The series of earthquake off North Island, New Zealand continued today. The largest of today's events was an M 4.9 which occurred within about 15 minutes of local solar midnight and was probably promoted by tidal stresses which maximize at this hour and by geomagnetic effects from the current geomagnetic disturbance. In the prior issue of this summary it had been noted in regard to this series:

 

 

"The strongest earthquake in the world today was an M 5.5 north of North Island, New Zealand. NEIC reported it was felt with intensity V in New Zealand at Waihi and II-III in Pauanui Beach, Katikati, Bay of Plenty, Whitianga, Paeroa, Thames, Auckland and North Shore. ... It was accompanied by a series of lighter foreshocks and aftershocks beginning about 33 minutes before the mainshock. This may indicate volcanism was involved in this swarm. An M 5.8 hit near this same epicenter on November 23, 2019." (August 29, 2020)

 

and

 

"The geomagnetic field saw active conditions today. The AP level was 26.  High latitude geomagnetic field saw storm conditions with AP 42. This is the most disturbed the field has been in nearly a year since October 25-26, 2019 when the AP level reached 29 and 25 and high latitude AP reached 62. Strong seismic enhancement is likely with this storm especially near the geomagnetic equator and at high latitudes during the next four days." (August 31, 2020)

 

This activity is at the fourth node (90 degrees) from the Atacama quake of September 1, 2020 and may have been enhanced by energy from that source.

 

O: 02SEP2020 21:18:21  36.8S  177.2E ML=3.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 02SEP2020 22:09:51  36.8S  177.1E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 02SEP2020 22:13:07  36.8S  177.0E ML=3.4  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 03SEP2020 01:04:53  36.8S  177.1E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 03SEP2020 02:22:37  36.8S  177.1E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 03SEP2020 02:26:08  36.8S  177.1E ML=3.5  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 03SEP2020 05:19:39  36.8S  177.1E ML=3.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 02SEP2020 07:28:15  36.9S  177.1E ML=4.1  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 02SEP2020 09:45:59  36.9S  177.1E ML=3.9  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 02SEP2020 19:46:23  37.0S  176.8E ML=4.3  EMSC   NORTH ISLAND OF NEW ZEALAND

O:  2SEP2020 19:45:00  36.8S  177.1E ML=4.4  EMSC   OFF E. COAST OF N. ISLAND, N.Z

P:  4SEP2020 127035    37.0S  178.0E 3.0-4.7 AAAAA  North Island, N.Z.         

P: 30AUG2020 126770    37.0S  178.0E 3.0-4.5 AAAAA  North Island, N.Z.         

 

An unusual earthquake of M 4.8 occurred north of New Zealand today as well. No similar events have occurred within about 300 km of this epicenter in the past 30 years. The last earthquake near 300 km of this epicenter with M>=4 was an M 4.8 on September 13, 1993.

 

O:  2SEP2020 18:42:44  31.2S  174.0E ML=4.8  EMSC   NORTH OF NEW ZEALAND         

 

The strongest earthquake in the world today was an M 5.4 in Papua New Guinea, Indonesia. NEIC reported this earthquake of M 5.4 in Papua, Indonesia  was felt with intensity II-III in the area(s) of Papua, Indonesia at Kiunga Fly River, PNG. The last earthquake of larger magnitude within about 200 km of this epicenter was an M 5.7 on April 26, 2016 with M 5.7. Forecast 126538 had expected today's activity in late August.

 

O:  2SEP2020 23:25:37   5.4S  140.4E mb=5.4  EMSC   PAPUA, INDONESIA             

P: 23AUG2020 126538     4.0S  140.0E 4.0-5.4 CBAAA  Papua New Guinea           

 

 

 

 

 

 

 

 

 

STRONG AFTERSHOCKS CONTINUE IN ATACAMA, CHILE

 

EARTHQUAKE SUMMARY FOR SEPTEMBER  1, 2020

 

The strongest earthquake in the world today was an M 6.5 aftershock in the Atacama region of Chile. This follows an M 6.8 and 6.3 yesterday. NEIC reported today's event was felt with maximum intensity V in Atacama at Vallenar, Copiapo and in Valparaiso and II-III in Coquimbo at La Serena, Coquimbo, Vicuna, Andacollo as well as in Villa Alemana, Valparaiso and Santiago and in San Juan, Argentina. GUC reported the aftershock of M 6.3 was felt with intensity   VI in  Atacama at Copiapo, Freirina, Huasco, Tierra Amarilla, Vallenar; V in Alto del Carmen; IV in Caldera and III in Chanaral, Diego de Almagro and in Coquimbo with V in La Serena, IV in La Higuera, Rio Hurdado, Vicuna; III in Combarbala, Monte Patria, Ovalle, Punitaqui, Chile. GUC reported the aftershock of M 4.9 was felt with intensity  III in  Atacama at Caldera, Freirina, Huasco, Vallenar and II in Alto del Carmen, Copiapo and Tierra Amarilla, Chile. Other moderate earthquakes of M 5.7, 5.7 and 5.0 occurred also were lightly felt in Atacama today. These are probably related to the full moon which arrived early on September 2 and the ongoing geomagnetic storm as discussed in the previous issue of this summary:

 

"The geomagnetic field saw active conditions today. The AP level was 26.  High latitude geomagnetic field saw storm conditions with AP 42. This is the most disturbed the field has been in nearly a year since October 25-26, 2019 when the AP level reached 29 and 25 and high latitude AP reached 62. Strong seismic enhancement is likely with this storm especially near the geomagnetic equator and at high latitudes during the next four days." (August 31, 2020)

 

and

 

"The full moon will arrive at 05:22 UT on September 2, 2020. Longitudes which are at local solar midnight at this time are near 80 West while those at solar noon are near 100 East. These include in the west, Central America and western South America and in the east Sumatra and western Indonesia and southeast Asia. These regions are likely to see moderate seismic with this full moon. Tidal triggering is not usually major at full moon but can occur  - normally near local solar midnight and noon in areas where seismicity is controlled by vertical tectonics and/or fluid motions." (September 1, 2020)

 

and

 

 

"Today's M 6.8-7.0 in Atacama, Chile is the strongest recorded within about 200 km of these epicenters since an M 6.9 on November 11, 2015. The only event with M>=6.8 in this area closer that 150 km in the past 30 years was an M 5.8 on January 30, 2013.  Forecast 126753 had expected today's activity was likely within about 150 km of the epicenters around August 28. This earthquake is located at 146 degrees from the M 6.8 in Sumatra of August 18 and at 143 degrees from the Banda Sea quake of August 21, 2020 and at the seventh node (51 degrees) from the M 7.5 in Oaxaca, Mexico of June 23, 2020 and may have been promoted by concentrated energy from those sources." (September 1, 2020)

 

O:  2SEP2020 03:04     27.9S   71.4W mb=4.9  GUC    Atacama at Caldera, Freirina,

O:  1SEP2020 21:09     28.0S   71.6W mb=6.3  GUC    Atacama at Copiapo, Freirina,

O: 01SEP2020 14:01:31  27.7S   71.5W mb=4.4  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 09:55:26  27.8S   71.5W mb=4.7  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 13:51:25  27.8S   71.6W mb=4.6  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 14:23:13  27.8S   71.6W ML=4.2  EMSC   OFFSHORE ATACAMA, CHILE

O: 02SEP2020 03:04:26  27.8S   71.5W Mw=4.7  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 10:31:51  27.9S   71.5W Mw=5.7  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 17:13:21  27.9S   71.4W Mw=5.0  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 21:09:17  27.9S   71.3W Mw=6.5  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 07:01:26  28.0S   71.2W Mw=5.7  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 20:11:59  28.0S   71.2W ML=4.0  EMSC   OFFSHORE ATACAMA, CHILE

P: 28AUG2020 126753    29.0S   70.0W 4.0-5.6 BAAAA  Coast Central Chile        

 

Moderate earthquakes continued in the high latitude ocean ridges today with  events of M 4.5 and 5.4 in the South Shetland Islands; an M 5.3 in the Pacific-Antarctic Ridge and an M 5.1 in the South Sandwich Islands. This extends the ocean ridge activity to the highest latitudes. This summary had addressed the relation between this and the current strong geomagnetic storm on August 31 as:

 

"The earthquakes in Chile followed a strong series of earthquakes, mostly near the geomagnetic equator on mid-ocean ridges." (August 31, 2020)

 

The earthquake in the South Sandwich Islands occurred near local solar midnight and was likely also promoted by tidal stresses. Forecasts 126786  had expected this event around August 31 while 126787 had expected activity in the South Shetland area was also likely around August 31.

 

O:  2SEP2020 00:21:12  56.1S   27.7W mb=5.1  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 31AUG2020 126786    55.0S   29.0W 4.0-5.7 ABAAA  So. Sandwich Islands       

 

O:  1SEP2020 23:17:12  56.2S  143.8W Mw=5.3  EMSC   PACIFIC-ANTARCTIC RIDGE      

 

The earthquake of M 5.4 in the South Shetland Islands is the strongest in the region in the past year, surpassing the beginning of the current series when an M 5.3 occurred on August 30 and an M 5.0 on August 29, 2020.

 

O: 01SEP2020 10:53:14  62.2S   58.0W mb=4.5  EMSC   SOUTH SHETLAND ISLANDS

O:  1SEP2020 10:56:20  62.3S   58.4W mb=5.4  EMSC   SOUTH SHETLAND ISLANDS       

P: 31AUG2020 126787    60.0S   44.0W 3.0-5.7 ACCAA  So. So. America            

 

The strongest earthquake in the U.S. or Canada today was an M 3.9 in the Andreanof Islands, Alaska. It was not reported felt in this remote area.

The last event in the Andreanof Islands of M>=3.9 was an M 4.2 on August 30, 2020 but the last within about 100 km of today's epicenter was an M 5.3 on July 15, 2020. Forecast 126691 had expected the Andreanof Islands would be active at the end of August or in early September.

 

O:  2SEP2020 03:00:23  51.1N  180.0W mb=3.9  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 28AUG2020 126691    51.7N  176.4W 3.5-4.9 BABAA  Andreanoff Isls, Aleutians 

 

An unusual series of light earthquakes (up to M 3.3) in the Cornwallis Island area of Nunavut, Canada occurred today. This activity is the strongest within about 150 km of this epicenter  and the only such event in the area in the past 30 years was an M 4.0 on November 26, 2012. Today's swarm is at 103-104 degrees from the M 7.0 in Atacama, Chile yesterday and was probably promoted by concentrated energy from that source. Energy from large earthquakes  reflects and refracts off internal earth boundaries and returns to around 103 degrees on the surface of the earth, often triggering unusual seismicity at that distance from the mainshock.

 

 

O:  1SEP2020 09:51:00  74.8N   96.6W ML=3.3  EMSC   CORNWALLIS ISLAND, NUNAVUT, CA

O: 01SEP2020 10:14:25  74.8N   96.6W ML=2.8  EMSC   CORNWALLIS ISLAND, NUNAVUT, CAN.

O: 01SEP2020 11:19:52  74.9N   95.5W ML=2.5  EMSC   CORNWALLIS ISLAND, NUNAVUT, CAN.

O: 01SEP2020 21:18:30  74.8N   96.6W MB=1.6  ECAN Resolute, NU    

O: 01SEP2020 20:15:03  74.8N   96.6W MB=2.2  ECAN Resolute, NU    

O: 01SEP2020 17:51:44  74.8N   96.6W MB=1.0  ECAN Resolute, NU    

O: 01SEP2020 17:50:59  74.8N   96.6W MB=1.5  ECAN Resolute, NU    

O: 01SEP2020 11:19:52  74.9N   95.5W MB=2.5  ECAN Resolute, NU    

O: 01SEP2020 10:14:25  74.8N   96.6W MB=2.8  ECAN Resolute, NU    

O: 01SEP2020 09:51:00  74.8N   96.6W MB=3.3  ECAN Resolute, NU    

 

An M 4.8 in Nicaragua today may have been triggered by tidal effects from the full moon and by atmospheric unloading associated with Tropical Storm Omar as noted in this summary:

 

"TD Omar (15E) continued today in the area off the east coast of North Carolina with winds up to 35 kts. It is expected to track to the east into the north Atlantic but not make landfall and to dissipate in the next three days. There should be little effect on local or regional seismicity with this storm." (September 1, 2020)

 

Forecast 126566 had expected today's event within about 100 km was likely at the end of August.

 

O:  2SEP2020 05:04:24  11.2N   86.8W mb=4.8  EMSC   NEAR COAST OF NICARAGUA      

P: 27AUG2020 126566    11.0N   86.0W 3.5-5.4 BAAAA  Nicaragua                  

 

STRONG SEISMICITY ACCOMPANIES STRONGEST GEOMAGNETIC STORM SINCE OCTOBER, 2019

 

EARTHQUAKE SUMMARY FOR AUGUST 31, 2020

 

Seismicity around the world today exploded following the strongest geomagnetic storm since late October, 2019. Today's activity appeared to be confined to a series of large events in Ocean Ridges during the first half of the day, but was followed early on September 1 by strong earthquakes in Atacama Chile of M 6.8 and 6.3. The Ocean Ridge events occurred on nearly all the world's ocean ridges including in the Central Atlantic, South Pacific, Indian Ocean and an M 6.5 in the Central Mid-Atlantic yesterday. A slightly smaller geomagnetic storm on February 18, 2020 had a similar effect on oceanic seismicity as noted at time in this summary:

 

"A series of earthquakes  occurred at high latitudes today. These included an M 4.5 in the Arctic Ocean near Svalbard; an M 5.1 in the South Sandwich Islands of the South Atlantic and an M 5.0 in the Bouvet Island region of the South Atlantic. The occurrence of these events at this time may be related to the strong geomagnetic storm at high latitudes which continued today and was reported on in this summary" (February 19, 2020) in the

 

A series of strong earthquakes occurred today in the region of Atacama, Chile. The largest of these was an M 6.8-7.0 followed by an aftershock of M 6.3.

GUC reported the M 7.0 event was felt with intensity VII in   Atacama at Copiapo and Tierra Amarilla; VI in Caldera, Chanaral, Vallenary, V in Alto del Carmen, Diego de Almagro, Freirina and Huasco; in Coquimbo with V in Andacollo, Coquimbot, La Higuera, La Serena, Ovalle, Paiguano, Rio Hurtado, Vicuna; IV in Combarbala, Monte Patria, Salamanca and II in Punitaqui; in Valparaiso with V; II-III in Santiago and Lampa, and IV in Taltal, Antofagasta, Chile.

The M 6.1 was felt in the same area with slightly less intensity. NEIC reported the mainshock of M 6.8 was felt with light damage in Atacama Chile at Vallenar and Copiapo with intensity VI; in Coquimbo with V at Coquimbo, Ovalle; IV in La Serena, Chile and La Rioja, Argentina and San Juian as well as in Antofagasta, Vina del Mar and Villa Alemana, Chile. The M 6.3 aftershock was felt with slightly less intensity in a similar area. This activity which maximized within about 30 minutes of  local solar midnight was probably promoted by the upcoming full moon alignment as noted in previous issues of this summary:

 

 

"The full moon will arrive at 05:22 UT on September 2, 2020. Longitudes which are at local solar midnight at this time are near 80 West while those at solar noon are near 100 East. These include in the west, Central America and western South America and in the east Sumatra and western Indonesia and southeast Asia. These regions are likely to see moderate seismic with this full moon. Tidal triggering is not usually major at full moon but can occur  - normally near local solar midnight and noon in areas where seismicity is controlled by vertical tectonics and/or fluid motions." (August 30-31, 2020)

 

The earthquakes in Chile area near the geomagnetic equator which runs through northern Chile and southern Peru in this region. They occurred during the strongest geomagnetic storm in the past 10 months and were also probably promoted by geomagnetic effects which also maximize near local solar midnight and noon as noted in previous issues of this summary:

 

"The geomagnetic field saw active conditions today. The AP level was 26.  High latitude geomagnetic field saw storm conditions with AP 42. This is the most disturbed the field has been in nearly a year since October 25-26, 2019 when the AP level reached 29 and 25 and high latitude AP reached 62. Strong seismic enhancement is likely with this storm especially near the geomagnetic equator and at high latitudes during the next four days." (August 31, 2020)

 

Another factor which may have promoted today's events in Chile was its near-antipodal location with Typhoon Maysak which is currently ravaging the Ryukyu Islands of Japan with winds up to 150 kts. Surface energy from large disturbances such as this focuses on the antipodal region (in this case central Chile) and can lead to earthquake triggering.

 

Today's M 6.8-7.0 in Atacama, Chile is the strongest recorded within about 200 km of these epicenters since an M 6.9 on November 11, 2015. The only event with M>=6.8 in this area closer that 150 km in the past 30 years was an M 5.8 on January 30, 2013.  Forecast 126753 had expected today's activity was likely within about 150 km of the epicenters around August 28. This earthquake is located at 146 degrees from the M 6.8 in Sumatra of August 18 and at 143 degrees from the Banda Sea quake of August 21, 2020 and at the seventh node (51 degrees) from the M 7.5 in Oaxaca, Mexico of June 23, 2020 and may have been promoted by concentrated energy from those sources.

 

O: 01SEP2020 04:36:35  27.9S   71.1W mb=5.4  EMSC   ATACAMA, CHILE

O: 01SEP2020 05:14:41  27.9S   71.6W mb=4.6  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 05:19:39  27.9S   71.3W mb=4.7  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 05:26:21  27.9S   71.2W mb=4.8  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 06:25:10  27.9S   71.2W mb=4.5  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 06:28:23  27.9S   71.2W mb=4.8  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 04:09:30  28.0S   71.0W Mw=6.8  EMSC   ATACAMA, CHILE

O: 01SEP2020 04:30:01  28.0S   71.2W Mw=6.3  EMSC   OFFSHORE ATACAMA, CHILE

O: 01SEP2020 05:29:37  28.0S   71.3W Mw=5.5  EMSC   OFFSHORE ATACAMA, CHILE

O:  1SEP2020 04:44:09  27.8S   71.1W mb=5.1  EMSC   OFFSHORE ATACAMA, CHILE      

O:  1SEP2020 04:09     28.0S   71.2W mb=7.0  GUC    Atacama at Copiapo and Tierra

O:  1SEP2020 04:30     28.1S   71.2W mb=6.1  GUC    Atacama at Copiapo and Tierra

P: 28AUG2020 126753    28.0S   67.0W 4.0-5.7 BACAA  Argentina                  

P: 28AUG2020 126753    29.0S   70.0W 4.0-5.6 BAAAA  Coast Central Chile        

 

The earthquakes in Chile followed a strong series of earthquakes, mostly near the geomagnetic equator on mid-ocean ridges. These began yesterday with an M 6.5 on the mid-Atlantic Ridge. This summary had noted this in the previous issue as:

 

"At M 6.5 this is the strongest earthquake within about 400 km of this epicenter in the Central Mid-Atlantic since an M 6.7 on December 10, 1996, the only other such event in the area in the past 30 years. Forecast 126511 had expected today's earthquake within about 50 km of the epicenter was likely around August 31." (August 31, 2020)

 

O: 30AUG2020 21:20:30   0.9N   29.7W Mw=6.5  EMSC   CENTRAL MID-ATLANTIC RIDGE   

O: 31AUG2020 09:56:03   0.8N   29.9W mb=4.8  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 31AUG2020 126511     1.0N   29.0W 4.0-5.6 AAAAA  Central Mid-Atlantic Ridg  

 

A strong M 6.2 also occurred in the Indian Ocean today in the Chagos Archipelago area. NEIC reported this earthquake of M 6.2 in  the Chagos Archipelago was felt with intensity II-III in the area(s) of the Malives in Hithadhoo, Fuvammulah, Mundhoo and Male. This lies near the geomagnetic equator in the area and occurred near local solar midnight, suggesting tidal and geomagnetic triggering effects. The only event within about 300 km of this epicenter with M>=6.2 in the past 30 years was an M 7.6 on July 15, 2003. Forecast 126530 had expected today's event in this area was likely around August 28.

 

O: 31AUG2020 17:24:05   4.0S   70.1E Mw=6.2  EMSC   CHAGOS ARCHIPELAGO REGION    

P: 28AUG2020 126530     1.0S   70.0E 4.0-5.9 BCAAA  Indian Ocean               

 

An earthquake of M 5.8 also occurred today in the Pacific-Antarctic Ridge. It was not reported felt in this remote area. It was likely triggered by tidal and geomagnetic effects as it occurred within about 10 minutes of local solar noon, a prime time for these effects. It is the strongest earthquake within about 300 km of this epicenter since an M 6.3 on December 12, 2018 and prior to that an M 6.0 on February 16, 2016.

 

O: 31AUG2020 20:28:13  55.6S  129.6W Mw=5.8  EMSC   PACIFIC-ANTARCTIC RIDGE      

 

An earthquake in the South Atlantic in the Tristan da Cunha region of M 5.9 was also recorded today. The last event within about 300 km of this epicenter with M>=5.9 was an M 7.0 on June 17, 2015 and an M 6.6 on February 16, 2005. An M 5.9 about 300 km north of today's epicenter was also recorded on March 22, 2011. Both the events in Tristan da Cunha and the Pacific-Antarctic Ridge area at 107 degrees from the M 6.9 in Sumatra of August 18 and may have been promoted by concentrated energy from that source.

 

O: 31AUG2020 21:18:02  35.6S   15.7W Mw=5.9  EMSC   TRISTAN DA CUNHA REGION      

 

An antipodal pair of earthquakes occurred today - first in the South Sandwich Islands with M 4.8 and about an hour-and-a-half later as an M 5.6 in Kamchatka, Russia. These event are not uncommon but illustrate the impact that geomagnetic storms can have on antipodal seismicity. The Kamchatka event occurred within about 30 minutes of local solar noon while the South Sandwich event occurred near local solar midnight. Both may also have been affected by strong tidal stresses associated with the full moon which maximize at these hours. The event in the South Sandwich Islands had been expected in forecast 126786 to occur around August 27.

 

O: 31AUG2020 23:16:12  58.6S   24.9W mb=4.8  EMSC   SOUTH SANDWICH ISLANDS REGION

P: 27AUG2020 126786    57.0S   26.0W 4.0-6.0 BBAAA  So. Sandwich Islands       

 

The earthquake in Kamchatka of M 5.6 is the strongest within about 150 km of that epicenter since an M 6.4 on July 7, 1996, the only other such event in the region of M>=5.6 in the past 30 years. Forecast 126693 had expected this earthquake in Kamchatka around August 31.

 

O:  1SEP2020 00:51:16  58.8N  159.0E Mw=5.6  EMSC   KAMCHATKA PENINSULA, RUSSIA  

P: 31AUG2020 126693    56.0N  162.0E 4.0-5.5 ACBAA  E. of Kamchatka            

 

UNPRECEDENTED M 4.6 IN BAHIA, BRAZIL FOLLOWED BY STRONG M 6.5 IN ATLANTIC

 

EARTHQUAKE SUMMARY FOR AUGUST 30, 2020

 

The strongest earthquake in the world today was an M 6.5 on the Central Mid-Atlantic Ridge. NEIC reported it might have been felt in northern Brazil at Parnamirim Rio Grande do Norte. This epicenter is near the antipode of the M 6.1 and M 5.9 in New Britain of August 25, 2020 and may have been promoted by focusing of energy at the antipode of those earthquakes. At the time of those quakes this summary noted:

 

"The last earthquake in the New Britain area within about 200 km of these epicenters with M>=6.1 occurred on February 9, 2020 with M 6.2 - the only such earthquake in the past year. An M 7.5 hit the area on May 14, 2019." (August 26, 2020) 

 

The Atlantic quake was also near the location of a new Tropical storm located to the north and may have been enhanced by energy associated with that weather system.

 

At M 6.5 this is the strongest earthquake within about 400 km of this epicenter in the Central Mid-Atlantic since an M 6.7 on December 10, 1996, the only other such event in the area in the past 30 years. Forecast 126511 had expected today's earthquake within about 50 km of the epicenter was likely around August 31. As well as being near the antipode to New Britain, this epicenter is near 103 degrees from the M 7.8 in the Alaska Peninsula of July 22 and may have been promoted by energy from that source.

 

O: 30AUG2020 21:20:30   0.9N   29.7W Mw=6.5  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P: 31AUG2020 126511     1.0N   29.0W 4.0-5.6 AAAAA  Central Mid-Atlantic Ridg  

 

The earthquake in the Atlantic was preceded earlier in the day by a highly unusual M 4.6 in Bahia, Brazil. That event was reported by NEIC to have been felt with maximum intensity VI in Castro Alves, Bahia and IV in Bahia at Mutuipe, Santo Antonia de Jesus, Salvador and II-III in Valenca, Jaguaquara, and Lauro de Freitas, Brazil. This is the largest earthquake within about 400 km of this epicenter in Brazil in at least 30 years. No earthquakes of M>=3.5 have been recorded in this area in the last 30 years as well. Energy from this event may have helped trigger the larger M 6.5 in the Central Mid-Atlantic later in the day.

 

O: 30AUG2020 10:44:31  13.3S   39.5W mb=4.6  EMSC   BAHIA, BRAZIL                

 

The swarm of moderate earthquakes north of North Island, New Zealand continued today. The largest of these today was an M 5.1. NEIC reported it was felt with maximum intensity V at Waihi Waikato and II-III in Whangamata, Whitianga and Auckland. This earthquake occurred within about an hour of local solar midnight and may have been enhanced by tidal energy. In the previous issue this summary had noted this activity as:

 

"The series of earthquake off North Island, New Zealand continued today. The largest of today's events was an M 4.9 which occurred within about 15 minutes of local solar midnight and was probably promoted by tidal stresses which maximize at this hour and by geomagnetic effects from the current geomagnetic disturbance. In the prior issue of this summary it had been noted in regard to this series:

 

 

"The strongest earthquake in the world today was an M 5.5 north of North Island, New Zealand. NEIC reported it was felt with intensity V in New Zealand at Waihi and II-III in Pauanui Beach, Katikati, Bay of Plenty, Whitianga, Paeroa, Thames, Auckland and North Shore. ... It was accompanied by a series of lighter foreshocks and aftershocks beginning about 33 minutes before the mainshock. This may indicate volcanism was involved in this swarm. An M 5.8 hit near this same epicenter on November 23, 2019." (August 29, 2020)

 

"The geomagnetic field saw quiet conditions today. The AP level was 8.  High latitude geomagnetic field saw disturbed conditions  with AP at 15. This is the most disturbed the field has been at high latitudes since August 3, 2020 when high latitude AP reached 26. Some enhanced seismicity at high latitudes may occur with this disturbance." (August 28, 2020)

 

This storm may have helped promoted this seismicity off North Island at this time. Forecast 126770 had expected today's event within about 100 km was likely around August 30." (August 30, 2020)

 

 

O: 31AUG2020 03:56:58  36.6S  177.2E ML=3.5  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 11:49:55  36.7S  177.2E ML=3.7  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 21:02:08  36.7S  177.1E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 31AUG2020 04:50:44  36.7S  177.2E ML=4.0  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 09:59:09  36.8S  177.1E ML=3.7  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 10:46:39  36.8S  177.1E ML=4.0  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 10:46:39  36.8S  177.1E ML=4.0  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 13:37:19  36.8S  177.1E ML=3.7  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 14:58:14  36.8S  177.2E ML=3.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 15:38:16  36.8S  177.1E ML=4.2  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 15:44:05  36.8S  177.1E ML=4.0  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 13:25:21  36.9S  177.1E ML=3.9  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 13:26:47  36.9S  177.3E Mw=5.1  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 15:34:25  36.9S  177.2E ML=3.5  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 15:36:47  36.9S  177.3E ML=3.5  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 17:04:01  36.9S  177.1E ML=3.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 13:29:03  37.2S  177.1E ML=4.1  EMSC   OFF E. COAST OF N. ISLAND, N.Z

P: 30AUG2020 126770    37.0S  178.0E 3.0-4.5 AAAAA  North Island, N.Z.         

 

The strongest earthquake in the U.S. or Canada today was an M 4.2 in the western Andreanof Islands, Aleutians, Alaska. It was not reported felt in this remote area. The last earthquake in this area with M>=4.2 was an M 4.9 and 4.3 on July 22 and 23, 2020, events associated with the M 7.8 in the Alaska Peninsula of the same date. Forecast 126691 had expected today's activity at the end of August.

 

O: 30AUG2020 11:20:02  51.4N  178.3W ml=4.2  EMSC   ANDREANOF ISLANDS, ALEUTIAN IS

P: 28AUG2020 126691    51.7N  176.4W 3.5-4.9 AAAAA  Andreanoff Isls, Aleutians 

 

An M 4.6 in the Ryukyu Islands, Japan today occurred as Typhoon Maysak passed near the epicenter. The earthquake was felt lightly in Okinawa according to data from JMA. Forecast 126591 had expected this event was likely around  August 27. In previous issues this summary had noted the potential for enhanced seismicity in the Ryukyu Islands as Typhoon Maysak passed over as:

 

"Typhoon Maysak (TD 10W) continued today east of Taiwan with winds up to 115 kts. It is expected to track to the north and west and could enhance seismicity in the Philippines and in the Ryukyu Islands in the next several days." (August 29-30, 2020)

 

O: 30AUG2020 21:00:44  27.3N  128.8E mb=4.6  EMSC   RYUKYU ISLANDS, JAPAN        

P: 27AUG2020 126591    26.0N  129.0E 4.0-5.4 BBAAA  Ryukyu Islands             

 

LIGHT EARTHQUAKE FELT WIDELY IN NORTHEASTERN ARKANSAS

 

EARTHQUAKE SUMMARY FOR AUGUST 29, 2020

 

An unusually large M 3.6-3.7 was widely felt in northeastern Arkansas today. NEIC reported it was felt with intensity V in Arkansas at Tyronza and Lepanto; IV in Marked Tree, Turrell and II-III in Trumann, Bay, Caraway, Black Oak, Etowan and Lake City. The last earthquakes of M>=3.7 within about 75 km of this epicenter in Arkansas occurred as an M 3.7 on October 15, 2017 and February 23, 2013. The last of larger magnitude was an M 3.7 on February 23, 2013. The largest earthquake in the area in  the past 30 years was an M 4.2 near today's epicenter on February 10, 2005. Hurricane Laura passed over this epicenter two days ago and probably promoted today's event. This summary had noted this possibility in previous issues as:

 

"Hurricane Laura is currently located over Arkansas after making landfall near the Texas-Louisiana border today with high storm surge and winds. Considerable damage (but less than expected) occurred with this storm when landfall was made (for further details see the weather-related seismicity section of this report). It is expected to track  to the east from Arkansas. Seismicity in this area is possible and some enhanced seismicity, especially in the Appalachian Mountains is likely in the next several days as the remnants of Laura pass over the area." (August 27, 2020)

 

Forecasts 126621 had expected today's event was likely within Arkansas within this area around August 31.

 

O: 30AUG2020 02:34:43  35.5N   90.5W mb=3.7  EMSC   ARKANSAS                     

P: 31AUG2020 126621    35.0N   89.0W 2.0-4.1 AAAAA  New Madrid area            

P: 31AUG2020 126621    35.0N   92.0W 2.0-4.2 AAAAA  New Madrid area            

 

The largest earthquake in the U.S. or Canada today was an M 3.8 in Central Alaska. NEIC reported this earthquake of M 3.6-3.8 in Central Alaska  was felt with intensity II-III in the area(s) of Central Alaska in Healy, Fairbanks and Willow. The last earthquake in this area within about 100 km of this epicenter with M>=3.8 was an M 4.0 more than a year ago on September 25, 2019. Forecast 126717 had expected this event in this area was likely around August 29.

 

O: 30AUG2020 02:07:32  64.0N  148.8W ML=3.8  EMSC   CENTRAL ALASKA                

P: 29AUG2020 126717    63.3N  151.0W 3.2-5.0 AAAAA  Central Alaska             

 

The series of earthquake off North Island, New Zealand continued today. The largest of today's events was an M 4.9 which occurred within about 15 minutes of local solar midnight and was probably promoted by tidal stresses which maximize at this hour and by geomagnetic effects from the current geomagnetic disturbance. In the prior issue of this summary it had been noted in regard to this series:

 

 

"The strongest earthquake in the world today was an M 5.5 north of North Island, New Zealand. NEIC reported it was felt with intensity V in New Zealand at Waihi and II-III in Pauanui Beach, Katikati, Bay of Plenty, Whitianga, Paeroa, Thames, Auckland and North Shore. ... It was accompanied by a series of lighter foreshocks and aftershocks beginning about 33 minutes before the mainshock. This may indicate volcanism was involved in this swarm. An M 5.8 hit near this same epicenter on November 23, 2019." (August 29, 2020)

 

"The geomagnetic field saw quiet conditions today. The AP level was 8.  High latitude geomagnetic field saw disturbed conditions  with AP at 15. This is the most disturbed the field has been at high latitudes since August 3, 2020 when high latitude AP reached 26. Some enhanced seismicity at high latitudes may occur with this disturbance." (August 28, 2020)

 

This storm may have helped promoted this seismicity off North Island at this time. Forecast 126770 had expected today's event within about 100 km was likely around August 30.

 

NEIC reported the earthquake of M 4.9 in  North Island, New Zealand was felt with intensity IV in the area(s) of North Island, New Zealand in Whangamata Waikato. An M 4.7 was also felt with intensity II-III in Waihi, Whitianga, Katikati, Bay of Plenty and Auckland.

 

 

O: 30AUG2020 03:31:01  36.7S  177.2E ML=4.0  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 05:04:48  36.7S  177.2E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 05:04:48  36.7S  177.2E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 29AUG2020 08:29:50  36.8S  177.1E mb=4.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 29AUG2020 12:45:18  36.8S  177.1E mb=4.9  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 29AUG2020 20:18:16  36.8S  177.1E ML=3.6  EMSC    OFF E. COAST OF N. ISLAND, N.Z.

O: 29AUG2020 20:18:16  36.8S  177.1E ML=3.6  EMSC    OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 03:32:44  36.8S  177.1E ML=4.0  EMSC    OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 05:09:46  36.8S  177.4E ML=3.9  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 05:10:48  36.8S  177.2E ML=3.9  EMSC    OFF E. COAST OF N. ISLAND, N.Z.

O: 30AUG2020 06:10:23  36.8S  177.1E ML=4.2  EMSC    OFF E. COAST OF N. ISLAND, N.Z.

O: 29AUG2020 10:43:17  36.9S  177.1E ML=4.1  EMSC    OFF E. COAST OF N. ISLAND, N.Z.

O: 29AUG2020 21:28:46  36.5S  177.2E ML=3.8  EMSC   OFF E. COAST OF N. ISLAND, N.Z

 

A moderate M 4.3 occurred in the southern aftershock zone of Puerto Rico today. This was accompanied by a moderate swarm in the Dominican Republic. The last earthquake of M>=4.3 in the Puerto Rico aftershock zone was an M 5.1 on August 7, 2020. Forecasts 126572 and 126573 had expected today' event at the end of August.

 

O: 29AUG2020 16:33:45  18.0N   67.0W mb=4.3  EMSC   PUERTO RICO REGION            

P: 27AUG2020 126572    18.0N   66.0W 3.4-5.0 AAAAA  Puerto Rico                

P: 30AUG2020 126573    19.0N   67.0W 3.4-5.0 AAAAA  Puerto Rico                

 

O: 29AUG2020 11:28:59  19.0N   71.0W ML=3.1  EMSC   DOMINICAN REPUBLIC

O: 30AUG2020 03:57:50  19.8N   71.2W ML=3.3  EMSC   DOMINICAN REPUBLIC

O: 29AUG2020 08:30:02  19.9N   71.0W ML=3.1  EMSC   DOMINICAN REPUBLIC

O: 29AUG2020 20:36:13  20.0N   71.0W ML=3.4  EMSC   DOMINICAN REPUBLIC REGION

O: 29AUG2020 09:18:32  20.2N   70.2W ML=3.5  EMSC   DOMINICAN REPUBLIC REGION

O: 29AUG2020 15:12:58  20.3N   70.8W ML=3.2  EMSC   DOMINICAN REPUBLIC REGION

P: 26AUG2020 126573    20.0N   71.0W 3.4-5.1 BAAAA  Puerto Rico                

 

The activation of southeastern Africa continued today with an M 4.5 in Mozambique. This does not appear to be an aftershock of either the M 4.9 on August 11 nor the M 4.8 on July 26, 2020 as it occurred midway between these two epicenters. The only event within about 250 km of today's epicenter in the past year was an M 4.4 on January 27, 2020. The last quake with M>=4.4 in this area was an M 4.9 on March 17, 2018 about 150 km north of today's epicenter. Forecast 126759 had expected activity in this area at the end of August.

 

O: 30AUG2020 04:06:23  17.8S   35.0E mb=4.5  EMSC   MOZAMBIQUE                   

P: 27AUG2020 126759    22.0S   33.0E 4.0-5.6 BABAA  So. Indian Ocean           

 

The largest earthquake in the world today was an M 5.3 in the Fiji Islands of the southwest Pacific. It was not reported felt in this remote area. Forecast 126742 had expected today's event within about 100 km was likely around August 30.

 

O: 29AUG2020 07:46:07  14.7S  177.6W mb=5.3  EMSC   FIJI REGION                  

P: 30AUG2020 126742    14.0S  177.0W 4.0-5.7 AAAAA  Samoa Islands               

 

MODERATE QUAKE SHAKES NORTH ISLAND, NEW ZEALAND

 

EARTHQUAKE SUMMARY FOR AUGUST 28, 2020

 

The strongest earthquake in the world today was an M 5.5 north of North Island, New Zealand. NEIC reported it was felt with intensity V in New Zealand at Waihi and II-III in Pauanui Beach, Katikati, Bay of Plenty, Whitianga, Paeroa, Thames, Auckland and North Shore. GEONET reported this earthquake of M 5.2 felt by 2577 people with weak intensity by 1255 and light intensity by 1067 persons and moderate intensity by 236; with strong shaking by 16; with severe intensity by 2 and with extreme motion by 1. It was accompanied by a series of lighter foreshocks and aftershocks beginning about 33 minutes before the mainshock. This may indicate volcanism was involved in this swarm. An M 5.8 hit near this same epicenter on November 23, 2019. At the time this summary noted:

 

 

"An event of M 5.9-6.1 also occurred north of North Island, New Zealand today. NEIC reported maximum intensity IV in Waharoa with II-III shaking in Opotiki, Bay of Plenty, Taneatua, Huhaka, Hawke's Bay, Auckland, Te Kauwhata, Hastings and Ashburton, New Zealand. GEONET reported this earthquake was felt with light intensity in the area of northern North Island,  New Zealand. 5051 persons reported feeling this earthquake with 2006 of weak intensity; and 2325 with light shaking; 678 with moderate intensity 39 with strong shaking; 1 with severe and 2 with extreme shaking in North Island, New Zealand. The last earthquake within about 200 km of this epicenter with M>=5.8 was an M 5.8 on September 5, 2016. The last of M>=6.3 occurred September 1, 2016 following an M 5.8 foreshock of August 31, 2016." (November 24, 2019)

 

The M 7.1 on September 1, 2016 occurred east of today's epicenter and was coincident with a solar eclipse and a strong geomagnetic storm (like the November 23, 2019 event) as noted in this summary at the time:

 

"While the solar eclipse was not visible in New Zealand, the path of the eclipse maximum stress did pass directly over New Zealand, suggesting this was the prime trigger for today's earthquake. ...

 

 

Another factor which probably promoted this earthquake at this time was a major geomagnetic storm which reached maximum levels near the time of the New Zealand earthquake." (September 2, 2016)

 

A moderate geomagnetic disturbance today, the strongest in nearly a month also preceded today's event as noted in the previous issue of this summary:

 

 

"The geomagnetic field saw quiet conditions today. The AP level was 8.  High latitude geomagnetic field saw disturbed conditions  with AP at 15. This is the most disturbed the field has been at high latitudes since August 3, 2020 when high latitude AP reached 26. Some enhanced seismicity at high latitudes may occur with this disturbance." (August 28, 2020)

 

This storm may have helped promoted this seismicity off North Island at this time. Forecast 126770 had expected today's event within about 100 km was likely around August 30. This epicenter is near 100 degrees from the M 7.5 in Oaxaca, Mexico of June 23, 2020 and may have been promoted by energy from that source.

 

O: 28AUG2020 15:47:03  36.8S  177.1E ML=5.2  GEONET reported felt by 2577 people

O: 28AUG2020 15:24:15  36.7S  177.1E ML=3.7  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 16:16:16  36.7S  177.2E ML=3.9  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 15:37:24  36.8S  177.1E ML=3.9  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 15:47:04  36.8S  177.1E Mw=5.5  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 22:32:13  36.8S  177.1E ML=3.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 22:32:13  36.8S  177.1E ML=3.6  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 12:38:02  37.0S  177.0E ML=3.7  EMSC   OFF E. COAST OF N. ISLAND, N.Z.

O: 28AUG2020 15:24:15  36.7S  177.1E ML=3.7  EMSC   OFF E. COAST OF N. ISLAND, N.Z

P: 30AUG2020 126770    37.0S  178.0E 3.0-4.5 AAAAA  North Island, N.Z.         

 

The series of events in Baja California continued today with an M 3.5-3.7 but the strongest earthquake in the U.S. or Canada today was a light M 3.4 in Northern Alaska. It was not reported felt in this remote area. This is the largest earthquake within about 150 km of this epicenter since an M 3.7 about 150 km to the southwest on May 7, 2020. The last within about 100 km of this epicenter with M>=3.4 was an M 4.1 on May 1, 2019. Forecast 126720 had expected a moderate regional quake around August 29.

 

O: 29AUG2020 01:12:13  67.3N  156.3W ML=3.4  EMSC   NORTHERN ALASKA              

P: 29AUG2020 126720    64.0N  155.0W 3.0-4.6 ACAAA  Northern Alaska            

 

MODERATE QUAKE ALONG INDIA-MYANMAR BORDER

 

EARTHQUAKE SUMMARY FOR AUGUST 27, 2020

 

An earthquake of M 5.3-5.4 in the India-Myanmar border region was the largest earthquake in the world today. NEIC reported moderately strong shaking of VII in Alzawl, Mizorfam, India and V in Champhai with IIV in North Vanlaiphai and Chattagam, Bangladesh. This is probably the strongest aftgershock to date of the M 5.6 of June 21, 2020, an event associated with the total solar eclipse of the same date which was at its maximum near this epicenter. The only other such earthquake in the area in the past year was an M 5.9 about 100 km southeast of today's epicenter on April 16, 2020. Forecast 126587 had expected today's event within about 100 km was likely around August 27. This epicenter is at 102 degrees from the M 7.4 of June 18, 2020 in the Kermadec Islands and may have been promoted by energy from that source.

 

O: 27AUG2020 12:46:10  23.2N   93.2E ML=3.6  EMSC   MYANMAR-INDIA BORDER REGION

O: 27AUG2020 13:17:21  23.2N   93.2E mb=4.5  EMSC   MYANMAR-INDIA BORDER REGION

O: 27AUG2020 12:07:15  23.2N   93.4E mb=5.4  EMSC   MYANMAR-INDIA BORDER REGION  

P: 27AUG2020 126587    24.0N   94.0E 4.0-5.7 AAAAA  Myanmar                    

 

An unusual earthquake occurred northeast of Taiwan today with M 4.6-5.5. It was not reported felt. This epicenter was passed over by Tropical Storm (Typhoon) Bavi two days ago - a storm expected to enhance regional seismicity as reported in this summary at the time:

 

"TS Bavi continued today north of  Taiwan with winds up to 70 kts.  It could have a minor effect of regional seismicity in the Philippines and Taiwan as it passes through the area." (August 23, 2020)

 

The last earthquake in this area northeast of Taiwan with M>=4.6 within about

north of 25 North latitude and within 100 km of this epicenter was an M 4.7 on January 14, 2018. Many events of M 4.5-5.0 have since occurred south of 25 North latitude including a swarm on June 14, 2020. Forecast 126595 had expected today's event in this area was likely around August 26. CWB reported this earthquake was felt with intensity II in Hualien and Taitung and I in Yilan, Nantou and Chiayi Counties, Taiwan.

 

O: 26AUG2020 22:15:07  25.1N  123.2E mb=4.6  EMSC   NORTHEAST OF TAIWAN          

O: 26AUG2020 22:15:06  25.0N  123.2E ML=5.5  TAI    Hualien, Taiwan              

P: 31AUG2020 126590    25.0N  123.0E 4.0-5.6 BAAAA  Ryukyu Islands             

P: 26AUG2020 126595    24.0N  123.0E 4.0-5.4 ABAAA  Taiwan                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 in the eastern Rat Islands. This is the second such event in the area in the past two day. When an M 4.7 occurred yesterday this summary noted:

 

"The strongest earthquake in the U.S. or Canada today was an M 4.7 in the Rat Islands, Alaska. It was not reported felt in this remote area.  The last earthquake in the Rat Islands with M>=4.7 was an M on 4.7-4.8 on April 17, 2020. The last of larger magnitude was an M 5.3 on February 4, 2020. Forecast 126702 had expected today's event was likely within about 50 km of this epicenter around August 28-30." (August 27, 2020)

 

 

O: 27AUG2020 07:14:45  51.3N  179.2E mb=4.6  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 30AUG2020 126702    51.0N  178.0E 4.0-5.8 BAAAA  Rat Islands                 

 

An earthquake of M 5.3 also occurred at the antipode to the Rat Islands in the Bouvet Island area of the South Atlantic. The last earthquake within about 250 km of this epicenter with M>=5.3 occurred on January 12, 2020 and prior to that an M 5.4 on November 17, 2019. Forecast 126783 had expected today's event was likely around August 31. This epicenter is at 102 degrees from the M 6.9 in the Banda Sea of August 21 and may have been promoted by energy from that event. An M 4.5 in Svalbard today was also at 102 degrees from the Banda Sea. These and an M 4.8 in the Macquarie Islands region of Australia suggest that the geomagnetic disturbance today at high latitudes may have helped promote this activity as noted in this summary:

 

 

"The geomagnetic field saw quiet conditions today. The AP level was 8.  High latitude geomagnetic field saw disturbed conditions  with AP at 15. This is the most disturbed the field has been at high latitudes since August 3, 2020 when high latitude AP reached 26. Some enhanced seismicity at high latitudes may occur with this disturbance." (August 27, 2020)

 

O: 28AUG2020 02:24:17  54.8S    1.5E mb=5.3  EMSC   BOUVET ISLAND REGION         

P: 31AUG2020 126783    55.0S    2.0E 4.0-5.6 BAAAA  Atlantic-Indian Ridge      

 

O: 27AUG2020 16:32:50  52.8S  140.4E mb=4.8  EMSC   WEST OF MACQUARIE ISLAND     

 

O: 27AUG2020 12:56:50  78.5N    7.0E mb=4.5  EMSC   SVALBARD REGION              

P: 27AUG2020 126728    79.0N    7.0E 4.0-5.4 AAAAA  Arctic Ocean Region        

 

MODERATE EARTHQUAKES CONTINUE IN NORTHERN CARIBBEAN

 

EARTHQUAKE SUMMARY FOR AUGUST 26, 2020

 

A moderate earthquake of M 4.5 was widely felt in Jamaica today. NEIC reported maximum intensity V in Jamaica at Discovery Bay; IV in Spaldings, Bamboo, Saint Ann, Runaway Bay, Saint Anns Bay, Mandeville and Clarendon and II-III in Ocho Rios and Duncan. An M 4.5 also occurred in the Virgin Islandsi along with a swarm of moderate events in the Oaxaca, Mexico aftershock zone (see AMERICA section below). These were the strongest earthquakes felt in the world today and were probably triggered by stresses associated with the recent passage over these epicenters of Tropical Storms/Hurricanes Marco and Laura as noted in previous issues of this report:

 

"TS Laura (TD 13) continued today over western Cuba, Caribbean with winds up to 55 kts. It is expected to track to the west over the next four days towards Louisiana. These areas are likely to see enhanced seismicity with this storm. It is expected to track  into Louisiana over the next four days reaching category 1 Hurricane status over the Gulf of Mexico in the next several days. An M 6.0 in Costa Rica today may have been enhanced by stresses related to TS Laura." (August 25, 2020)

 

"TD 13 (Laura)  formed today east of the Windward Islands, Caribbean with winds up to 35 kts. It is expected to track to the west over the next four days passing over the Virgin Islands August 22 amd Puerto Rico August 23. These areas are likely to see enhanced seismicity with this storm." (August 20, 2020)

 

This summary has noted that these cyclones have been quite active in promoting regional seismicity as in the report from August 25:

 

 

"Two strong Tropical Storms are currently active in the Gulf of Mexico. Both are expected to make landfall in Louisiana in the next several days. These are Hurricane Laura and TS Marco. In previous issues of this summary it had been hypothesized that these low pressure systems could affect regional seismicity." (August 25, 2020)

 

The earthquake in Jamaica of M 4.5 today was the strongest in the region of Jamaica since an M 4.7 on May 16, 2011 and prior to that an M 5.2 on June 13, 2005. Only two other events of M>=4.5 have hit near Jamaica in the past 30 years - an M 5.5 on January 13, 1993, and an M 4.6 on August 10, 2002. More recent activity has been occurring to the northwest in the Cayman Islands area about 200 km from today's epicenter near the M 7.7 that struck the area on January 28, 2020. In the past year earthquakes have occurred near Jamaica with M 4.0 on June 14; M 2.9 on July 13 and 3.0 on May 14, 2020. Forecast 126551 had expected a regional event in this area was likely in late August or early September. Several foreshocks have occurred in the past week. Hurricane Laura passed over Jamaica two days ago.

 

Hurricane Laura is currently located over Arkansas after making landfall near the Texas-Louisiana border today with high storm surge and winds. Considerable damage (but less than expected) occurred with this storm when landfall was made (for further details see the weather-related seismicity section of this report). It is expected to track  to the east from Arkansas. Seismicity in this area is possible and some enhanced seismicity, especially in the Appalachian Mountains is likely in the next several days as the remnants of Laura pass over the area.

 

O: 26AUG2020 12:28:09  18.3N   77.4W mb=4.5  EMSC   JAMAICA REGION               

P:  1SEP2020 126551    19.0N   81.0W 3.5-5.1 BACAA  Caribbean Sea              

 

The last earthquake in the Virgin Islands with M>=4.5 was an M 4.7 on December 7, 2019 and prior to that an M 5.0 on October 6, 2019. No such event have shook the Virgin Islands in the current year. Forecast 126560 had expected today's event within about 50 km was likely around August 26.

 

NEIC reported this earthquake of M 4.2-4.5 in the Virgin Islands  was felt with intensity II-III in the area(s) of the Virgin Islands at Saint Thomas.

 

O: 26AUG2020 17:57:32  19.3N   64.5W mb=4.5  EMSC   VIRGIN ISLANDS REGION        

P: 26AUG2020 126560    19.0N   65.0W 3.0-5.1 AAAAA  Leeward Islands            

 

An unusual earthquake occurred northeast of Taiwan today with M 4.6. It was not reported felt. This epicenter was overpassed by Tropical Storm (Typhoon) Bavi two days ago - a storm expected to enhance regional seismicity as reported in this summary at the time:

 

"TS Bavi continued today north of  Taiwan with winds up to 70 kts.  It could have a minor effect of regional seismicity in the Philippines and Taiwan as it passes through the area." (August 23, 2020)

 

The last earthquake in this area northeast of Taiwan with M>=4.6 within about

north of 25 North latitude and within 100 km of this epicenter was an M 4.7 on January 14, 2018. Many events of M 4.5-5.0 have since occurred south of 25 North latitude including a swarm on June 14, 2020. Forecast 126595 had expected today's event in this area was likely around August 26.

 

O: 26AUG2020 22:15:07  25.1N  123.2E mb=4.6  EMSC   NORTHEAST OF TAIWAN          

P: 26AUG2020 126595    24.0N  123.0E 4.0-5.4 ABAAA  Taiwan                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 in the Rat Islands, Alaska. It was not reported felt in this remote area.  The last earthquake in the Rat Islands with M>=4.7 was an M on 4.7-4.8 on April 17, 2020. The last of larger magnitude was an M 5.3 on February 4, 2020. Forecast 126702 had expected today's event was likely within about 50 km of this epicenter around August 28-30.

 

O: 27AUG2020 02:00:43  51.3N  177.6E mb=4.7  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P: 28AUG2020 126702    52.0N  176.0E 4.0-5.7 AAAAA  Rat Islands                

P: 30AUG2020 126702    51.0N  178.0E 4.0-5.8 BAAAA  Rat Islands                

 

The strongest earthquake in the world today was a moderate M 5.0 in the New Britain aftershock zone. This is an aftershock of the M 6.0 in New Britain of August 25. Forecast 126532 had expected this activity at the end of August.

 

O: 27AUG2020 05:00:24   5.6S  151.7E mb=5.0  EMSC   NEW BRITAIN REGION, P.N.G.   

P: 29AUG2020 126532     5.0S  154.0E 4.0-5.6 AACAA  New Britain                

 

STRONG EARTHQUAKES SHAKE NEW BRITAIN

 

EARTHQUAKE SUMMARY FOR AUGUST 25, 2020

 

The strongest seismicity in the world today occurred in the New Britain/New

Ireland area of Papua New Guinea where an M 5.9 and 6.1 occurred. When a foreshock of M 5.5 hit near today's epicenter on August 23, this summary noted in thie regard:

 

"The event in New Britain was the largest in that area within about 200 km of that epicenter since an M 6.2 on February 9, 2020, the only such event in the area in the past year. Forecast 126532 had expected today's event was likely at the end of August in this area." (August 23, 2020)

 

The last earthquake in the New Britain area within about 200 km of these epicenters with M>=6.1 occurred on February 9, 2020 with M 6.2 - the only such earthquake in the past year. An M 7.5 hit the area on May 14, 2019.  Forecasts 126534 and 126532 expected this activity in New Britain within this area was likely around August 28-29. Like a swarm in the region of the Dominican Republic today, this epicenter is located at the fifth node (72 degrees) from the epicenter of the Alaska Peninsula quake of July 22, 2020  and at the seventh node (51 degrees) from the M 6.9 in Sumatra of August 18 and was probably promoted by energy from those sources.

 

O: 25AUG2020 19:08:55   5.5S  151.9E Mw=6.1  EMSC   NEW BRITAIN REGION, P.N.G.

O: 25AUG2020 20:02:55   5.5S  151.9E mb=5.1  EMSC   NEW BRITAIN REGION, P.N.G.

O: 25AUG2020 19:03:00   5.5S  151.8E Mw=5.9  EMSC   NEW BRITAIN REGION, P.N.G.   

P: 28AUG2020 126534     6.0S  149.0E 4.0-5.6 AACAA  New Ireland                

P: 29AUG2020 126532     5.0S  154.0E 4.0-5.6 BABAA  New Britain                

 

An earthquake of M 4.6-4.7 occurred today in the region of Martinique, Caribbean. NEIC reported this earthquake was felt with intensity II-III in Martinique at Ducos Le Marin, Riviere-Pilote Le Marin, Saint-Esprit, Fort-d-France, Saint-Joseph, Sainte-Marie, Saint-Pierre and in Anse-la Raye, Saint Lucia. This earthquake occurred where Hurricane Laura made landfall on August 21-22 as reported in this summary at the time:

 

"TD 13 continued today east of the Windward Islands, Caribbean with winds up to 35 kts. It is expected to track to the west over the next four days passing over the Virgin Islands August 22 and Puerto Rico August 23. These areas are likely to see enhanced seismicity with this storm." (August 21, 2020)

 

The earthquake was probably promoted by stresses from the landfall of TD13 (Laura). The last earthquake within about 200 km of this epicenter of M>=4.6 was an M 4.8 on January 15, 2020, several days after the M 6.5 in Puerto Rico. Forecast 126559 had expected this earthquake was likely to the north around August 24.

 

O: 26AUG2020 05:03:42  14.5N   61.0W mb=4.7  EMSC   MARTINIQUE, WINDWARD ISLANDS 

P: 24AUG2020 126559    16.0N   60.0W 3.0-5.3 ABAAA  Leeward Islands            

 

The M 4.6 in Martinique was joined by a pair of moderate earthquakes of M 4.2 and 4.4 in the Dominican Republic. No major damage was reported with these earthquakes which continue regional activity in the area. This activity in the Dominican Republic was probably triggered by the passage of Tropical Storm Laura over the area two days ago as noted in this summary at the time:

 

"TS Laura (TD 13) continued today of Haiti and the Dominican Republic, Caribbean with winds up to 55 kts. It is expected to track to the west over the next four days passing Puerto Rico August 22-23. These areas are likely to see enhanced seismicity with this storm. It is expected to track over Cuba and into Louisiana over the next four days reaching category 1 Hurricane status over the Gulf of Mexico next week." (August 24, 2020)

 

Forecast 126573 had expected today's earthquake within about 50 km of these epicenter was likely around August 26. This activity is at 144 degrees from the M 6.9 in Samar, Philippines of August 18 and from the M 7.3 in New Guinea of July 17, 2020 and at the fifth node (72 degrees) from the Alaska Peninsula quake of July 22 and was probably enhanced by energy from those sources.

 

 

O: 25AUG2020 11:41:05  19.8N   71.2W mb=4.4  EMSC   DOMINICAN REPUBLIC

O: 25AUG2020 12:50:58  19.8N   71.2W ML=3.6  EMSC   DOMINICAN REPUBLIC

O: 25AUG2020 19:55:34  19.8N   71.1W ML=3.1  EMSC   DOMINICAN REPUBLIC

O: 25AUG2020 23:36:16  19.8N   71.2W ML=3.1  EMSC   DOMINICAN REPUBLIC

O: 26AUG2020 01:06:05  19.8N   71.2W ML=3.0  EMSC   DOMINICAN REPUBLIC

O: 26AUG2020 03:10:51  19.8N   71.1W ML=3.0  EMSC   DOMINICAN REPUBLIC

O: 25AUG2020 10:26:21  19.8N   71.3W mb=4.2  EMSC   DOMINICAN REPUBLIC           

P: 26AUG2020 126573    20.0N   71.0W 3.4-5.1 AAAAA  Puerto Rico                

 

 

HURRICANES LAURA AND MARCO PROMOTE REGIONAL SEISMICITY

 

EARTHQUAKE SUMMARY FOR AUGUST 24, 2020

 

Two strong Tropical Storms are currently active in the Gulf of Mexico. Both are expected to make landfall in Louisiana in the next several days. These are Hurricane Laura and TS Marco. In previous issues of this summary it had been hypothesized that these low pressure systems could affect regional seismicity as:

 

"TS Marco (TD 14) continued today south of Louisiana with winds up to 60 kts. It is expected to track to the northwest over the next several days reaching hurricane strength in the Gulf of Mexico around August 25 and making landfall in the area of Louisiana and Texas on August 26. Low pressure from this system could encourage seismicity in Chiapas, Mexico to Costa Rica in the next several days." (August 23-24, 2020)

 

and

 

 

"TS Laura (TD 13) continued today of Haiti and the Dominican Republic, Caribbean with winds up to 55 kts. It is expected to track to the west over the next four days passing Puerto Rico August 22-23. These areas are likely to see enhanced seismicity with this storm. It is expected to track over Cuba and into Louisiana over the next four days reaching category 1 Hurricane status over the Gulf of Mexico next week. An M 4.7 near the antipode of this storm in Queensland, Australia today may have been promoted by antipodal effects of this storm." (August 22-24, 2020)

 

Regional seismicity today included a strong M 6.0 in Costa Rica; an M 2.6 in  northern Arkansas and an M 5.5 on the Peru-Ecuador border and active conditions in Puerto Rico and the Dominican Republic. Each of these was probably affected by Laura and Marco.

 

The strongest earthquake in the world today was an M 6.0 in Costa Rica. NEIC reported it was felt with maximum intensity V in Costa Rica at Jaco and Parrita, Puntarenas; IV in Paquera, Quepos and Colon, San Jose and III in Santiago, Atenas, Puntarenas, Esquipulas and San Ramon, Alajuela. The epicenter in Costa Rica is directly south of the eye of Hurricane Laura and slightly east of the eye of TS Marco at the time of the earthquake and was probably promoted by energy from these storms.

 

TS    LAURA    2020-08-25  00:00 UT  22.5N   85.0W   55 kts  Cuba                             

TS    MARCO    2020-08-25  00:00 UT  29.0N   89.8W   30 kts  South of Louisiana        

 

The last earthquake in Costa Rica with M>=6.0 within about 200 km of today's epicenter occurred as an M 6.5 on November 13, 2017. Events of M 6.0-6.2 occurred about 250 km to the southeast of today's epicenter on June 26 and May 12, 2019 and on August 17, 2018. Forecast 126515 had expected today's event within about 100 km was likely at the end of August in Costa Rica. This epicenter is in the antipodal  area of the M 6.9 in Sumatra of August 18 and at the fifth node (72 degrees) from the Alaska Peninsula M 7.8 of July 22 and may also have been enhanced by energy from those sources.

 

O: 24AUG2020 21:51:10   9.7N   84.6W Mw=6.0  EMSC   COSTA RICA                   

P: 31AUG2020 126515     9.0N   85.0W 3.5-5.2 CAAAA  Costa Rica                 

 

An M 5.5 also shook regions south of Costa Rica on the Peru-Ecuador border today. NEIC reported this earthquake of M 5.5 in the Peru-Ecuador border  was felt with intensity II-III in the area(s) of the Peru-Ecuador border at Zorritos (V) and Talara (IV), Peru and in Marcavelica, Santa Rosa and San Luis, Peru and in Ecuador at Pasaje, Cariamanga, Cuenca Azuay.  While this earthquake occurred within minutes of local solar midnight and may have been promoted by high tidal stresses which maximize at this hour, it is also likely to have been affected by the same atmospheric effects associated with Laura and Marco as the M 6.0 in Costa Rica. This is the strongest earthquake within about 200 km of this epicenter in more than three years - since an M 5.6 on June 5, 2017. Forecast 126528 had expected today's event within about 100 km was likely at the end of August.

 

O: 25AUG2020 05:18:12   4.1S   80.8W Mw=5.5  EMSC   PERU-ECUADOR BORDER REGION   

P: 31AUG2020 126528     4.0S   80.0W 4.0-5.4 CAAAA  Ecuador                    

 

Active conditions also continued in East Africa today where event of M 5.0 occurred in Malawi and Burundi. The area has seen seismic activation in the past two weeks This included an M 6.0 in Tanzania on August 12, the largest in that area in the past 25 years as well as moderate events in Mozambique and Mayotte.

 

"The strongest earthquake in the world today was an M 6.0 that occurred off the east coast of Tanzania. NEIC reported it was felt with maximum intensity in Tanzania at Mkuranga, Dar es Salaam, Magomeni, Koani, Zanzibar and Pemba, and Morogoro and II-III at Vikindu, Pwani, Kisarawe, Zanzibar, Chake and Wete.

The last earthquake of M>=4.5 in Tanzania was an M 4.6 about 150 km northwest of today's epicenter on April 15, 2020. The last within about 250 km of today's epicenter with M>=6.0 occurred as events of  M 6.0 and 6.2 on May 14, 1985. These are the only previously reported earthquakes in the area of M>=6.0, making today's event remarkable. The earthquakes in Mayotte, Mozambique and Tanzania over the past several days may be related to their approximate antipodal location with respect to TD 10E, a tropical cyclone currently located in  the area south east of Hawaii. Energy from such storms can focus near the antipode and may enhance regional seismicity in that area." (August 13, 2020)

 

The earthquake in Malawi is the strongest in the area within about 250 km of that epicenter since an M 5.1 on December 31, 2014 and prior to that an M 6.0 on December 19, 2009 more than ten years ago. Forecast 126464 had expected today's activity was likely to the east in mid-August.

 

NEIC reported this earthquake of M 5.0 in Malawi  was felt with intensity II-III in the area(s) of Malawi at Blantyre City.

 

O: 24AUG2020 07:03:48  11.3S   34.6E mb=5.0  EMSC   MALAWI                       

P: 15AUG2020 126464    10.0S   41.0E 3.0-5.1 CBCAA  Madagascar area            

 

Forecast 126265 had expected today's event near Burundi about 200 km to the south was likely around August 21. It appears to be the strongest earthquake in

Burundi within about 150 km of this epicenter in at least 30 years. Earthquakes of M 5.0 hit about 150 km to the southwest of this on September 18, 1990 and July 31, 1993. This epicenter is at the fifth node (72 degrees) from the Sumatra quake of M 6.9 of August 18 and may have enhanced by energy from that source.

NEIC reported this earthquake of M 5.0 in Burundi  was felt with intensity II-III in the area(s) of Burundi at Bujumbura.

 

O: 24AUG2020 14:13:13   3.8S   29.3E mb=5.0  EMSC   BURUNDI                      

P: 21AUG2020 126265     6.0S   30.0E 3.0-4.6 BCAAA  Lake Victoria area         

 

A light earthquake of M 2.6 was felt widely in northern Arkansas today. NEIC reported maximum intensity IV in Arkansas at Pocahontas and II-III in Walnut Ridge, Bono, Delaplaine, Paragould, Jonesboro, Greenway, Tyronza and Wynne and in Missouri at Steele. This occurred as TS Laura made landfall in Louisiana to the south of this epicenter and was probably promoted by effects from that storm. It is the strongest earthquake in Arkansas within about 100 km of this epicenter since an M 2.8 on May 6, 2018 more than two years ago and prior to that an M 2.6 on January 28, 2014. Forecast 126621 had expected activity to the southwest of today's epicenter in Arkansas was likely at the end of August.

 

O: 25AUG2020 03:22:11  36.1N   90.8W Md=2.6  EMSC   ARKANSAS                     

P: 31AUG2020 126621    35.0N   92.0W 2.0-4.2 CBAAA  New Madrid area            

 

An M 5.6 also occurred today in Tonga south of Samoa. Forecast 126742 had expected this event was likely within about 50 km  of this epicenter around August 27. The area has seen several moderate to large earthquakes this summer including an M 6.1 about 200 km to the east of today's epicenter on July 18, 2020.

 

O: 24AUG2020 17:14:56  15.4S  174.3W Mw=5.6  EMSC   TONGA                        

P: 27AUG2020 126742    15.0S  174.0W 4.0-5.4 BAAAA  Samoa Islands              

 

MODERATE QUAKES RECORDED IN SOUTHWEST PACIFIC

 

EARTHQUAKE SUMMARY FOR AUGUST 23, 2020

 

The largest earthquakes in the world today occurred in the southwest Pacific as an M 5.5 in the New Britain area and an M 5.4 in the northern Kermadec Islands of New Zealand. Neither was reported felt. The event in New Britain was the largest in that area within about 200 km of that epicenter since an M 6.2 on February 9, 2020, the only such event in the area in the past year. Forecast 126532 had expected today's event was likely at the end of August in this area.

 

O: 23AUG2020 16:46:49   4.8S  152.6E Mw=5.5  EMSC   NEW BRITAIN REGION, P.N.G.   

O: 23AUG2020 08:12:50   5.9S  153.8E mb=4.8  EMSC   NEW IRELAND REGION, P.N.G.   

P: 29AUG2020 126532     5.0S  154.0E 4.0-5.6 CAAAA  New Britain                

 

The second strongest earthquake in the world today was an M 5.4 in the northern Kermadec Islands of New Zealand. It was not reported felt in this remote area.

While the southern Kermadec Islands have been active this summer, this is the strongest earthquake in the northern Kermadecs since an M 5.8 about 250 km northwest of this epicenter on May 28 and the largest within about 100 km of this epicenter since an M 5.6 on March 5, 2020. Forecast 126756 had expected today's event within about 50 km was likely around August 25.

 

O: 24AUG2020 00:45:09  28.9S  176.4W Mw=5.4  EMSC   KERMADEC ISLANDS REGION      

P: 25AUG2020 126756    29.0S  177.0W 4.0-5.7 AAAAA  No. Kermadec Islands       

 

The largest earthquake in the U.S. or Canada today was an M 4.5 in the Unimak Island area of Alaska west of the Alaska Peninsula. It appears to be part of the westward migration of aftershocks from the M 7.8 of July 22 in the Alaska Peninsula. It is the strongest aftershock to date of the M 5.6 near this epicenter which occurred on August 13. Forecast 126706 had expected this activity was likely within the Unimak Island area around August 25.

 

O: 23AUG2020 22:40:41  53.5N  163.7W mb=4.5  EMSC   UNIMAK ISLAND REGION, ALASKA 

P: 25AUG2020 126706    54.3N  162.7W 3.5-4.9 AAAAA  Unimak Islands, Aleutians  

 

Aftershocks continued in the area of Baja California south of the California border today. At least eight of these reached M>=3. This is the most active the area has been since the M 5.2 mainshock on August 17. Forecast 126635 had expected today's activity around August 25. This activity is at the third node (120 degrees) from the M 6.9 in the Banda Sea of August 21 and may have been enhanced by energy from that source.

 

O: 23AUG2020 21:24:49  31.4N  115.7W ML=3.3  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 07:53:46  31.5N  115.5W ML=3.6  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 08:29:34  31.5N  115.6W ML=3.7  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 08:59:18  31.5N  115.6W ML=3.4  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 09:26:23  31.5N  115.6W ML=3.5  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 17:58:00  31.5N  115.5W ML=3.5  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 17:59:33  31.5N  115.5W ML=3.4  EMSC   BAJA CALIFORNIA, MEXICO

O: 23AUG2020 23:05:38  31.5N  115.6W ML=3.3  EMSC   BAJA CALIFORNIA, MEXICO      

P: 25AUG2020 126635    31.9N  116.0W 2.5-4.6 AAAAA  So. California             

UNUSUAL QUAKES IN QUEENSLAND, AUSTRALIA; ASCENSION ISLAND

 

EARTHQUAKE SUMMARY FOR AUGUST 22, 2020

 

The strongest seismicity in the world today was an M 5.9-6.0 followed by an aftershock of M 5.4 in the area of Ascension Island, Central Atlantic. It was not reported felt in this remote area. Only two earthquake of M>=6 have occurred within about 300 km of this epicenter in the Atlantic in the past 30 years - both of M 6.0 on August 10, 2011 and March 7, 2001 with about a recurrence time of 10 years. Forecast 126272 had expected today's event in this area was likely around August 18.

 

O: 22AUG2020 08:38:04   7.1S   12.6W Mw=5.9  EMSC   ASCENSION ISLAND REGION      

O: 22AUG2020 08:38:04   7.1S   12.7W Mw=6.0  ANSS   ASCENSION ISLAND REGION      

O: 22AUG2020 10:21:30   7.2S   12.9W Mw=5.4  EMSC   ASCENSION ISLAND REGION      

P: 18AUG2020 126272     5.0S   12.0W 4.0-5.5 BCAAA  No. of Ascension Isl       

 

An unusual earthquake of M 4.7 was felt in Queensland, Australia today. NEIC reported maximum intensity IV in Ingham, Queensland and II-III in Charters Towers and Townsville. This may have been promoted by energy from several sources. It is near the longitude of maximum stress with the new moon as described in previous issues of this report:

 

"The new moon  arrived on August 19 at 02:41 UT. Longitudes which were antisolar (near local solar midnight) at this hour are near 40 West and 140 East. These include in the west, areas of the central Atlantic and in the east much of the western subduction zone of the Pacific plate including Japan, and Indonesia. These areas may see enhanced seismicity during the period August 16-23 with the potential for a strong earthquake. Other areas can also be triggered by tides and global seismicity is expected to be at moderately high levels during this period. Tidal triggering is most prominent near local solar noon and midnight." (August 17-22, 2020)

 

The Australian epicenter is also near the antipode of Tropical Storm Laura which passed near the antipode on August 19-20. Antipodal effects of this storm may have helped promote the earthquake in Queensland. This had been noted in previous issues of this report as:

 

"TD    13       2020-08-20  00:00 UT  15.2N   49.8W   35 kts  East of Windward Islands         

 

TD 13 formed today east of the Windward Islands, Caribbean with winds up to 35 kts. It is expected to track to the west over the next four days passing over the Virgin Islands August 22 and Puerto Rico August 23. These areas are likely to see enhanced seismicity with this storm." (August 19-22, 2020)

 

The earthquake in Queensland is the strongest within about 300 km of that epicenter since an M 4.9 on April 15, 2020 and prior to that an M 5.7 on August 18, 2016 and an M 5.0 on April 16, 2011.

 

O: 23AUG2020 03:00:52  21.0S  146.3E mb=4.7  EMSC   QUEENSLAND, AUSTRALIA        

 

TS Laura continued today in the Caribbean region as noted in this report:

 

"TS Laura (TD 13) continued today south of Puerto Rico, Caribbean with winds up to 45 kts. It is expected to track to the west over the next four days passing Puerto Rico August 22-23. These areas are likely to see enhanced seismicity with this storm. It is expected to track over Cuba and into Louisiana over the next four days reaching category 1 Hurricane status over the Gulf of Mexico next week. An M 4.7 near the antipode of this storm in Queensland, Australia today may have been promoted by antipodal effects of this storm." (August 22, 2020)

 

An earthquake of M 3.9-4.0 also occurred today in the aftershock zone in southern  Puerto Rico as Tropical Storm Laura made landfall on that island.  The only event of equal or larger magnitude in the area in the past 1.5 months was an M 4.8 on August 7, 2020. A moderate M 5.3 occurred on July 3, 2020. Forecast 126572 had expected today's event was likely around August 25.

 

NEIC reported this earthquake of M 3.4-3.9 in Puerto Rico  was felt with intensity IV in the area(s) of Puerto Rico at Guayanilla, Yauco, Lajas and II-III in Guanica, Sabana Grande, Ponce, Adjuntas, Coto Laurel and Cabo Rojo. 

 

O: 22AUG2020 13:21:36  18.1N   66.8W ML=3.9  EMSC   PUERTO RICO                  

P: 25AUG2020 126572    18.0N   67.0W 3.4-5.1 BAAAA  Puerto Rico                

 

The most unusual earthquake in the U.S. or Canada today was an M 4.7 in southeastern Alaska near Juneau. It was followed about a half minute later by an M 3.6-4.0 aftershock. The last earthquake within about 150 km of this epicenter with M>=4.7 recorded by NEIC was an M 5.2 about 150 km to the southwest of this on December 18, 2019. The only such event within about 100 km of today's epicenter in the past two years was an M 5.0 on September 1, 2019. Strong events of M 6.2 and 6.3 hit this epicenter on May 1, 2017. Today's events appear to be aftershocks of those in 2017. Forecasts 126427, 126692 and 126705 had expected this area to be active towards the end of August.

 

At the time of the event on May 1, 2017, this summary placed this in historical context as:

 

"An M 6.2 hit the area 17 years ago on January 6, 2000. The M 6.3 in this region today is the strongest within about 200 km of this epicenter since an M 6.7 on July 1, 1973. Other events of M>=6.3 were recorded on July 10, 1958 (M 7.9); February 3, 1944 (M 6.4); October 24, 1927 (M 7.1); January 18, 1901 (M 7.1) and in September, 1899 (M 8.6). A strong aftershock is considered likely since it has been 44 years since the last such event in the region." (May 1, 2017)

 

NEIC reported today's earthquakes in Southeast Alaska were felt with intensity II-III in the area(s) of Southeast Alaska in Haines, and Whitehorse Yukon, Canada. This activity is located at 101 degrees from the M 6.9 in the Banda Sea of August 21 and was probably enhanced by energy from that source.

 

O: 23AUG2020 05:19:28  59.8N  136.7W Mw=3.6  EMSC   SOUTHEASTERN ALASKA           

O: 23AUG2020 05:19:28  59.8N  136.7W MB=4.0  ECAN of Skagway, AK                 

O: 23AUG2020 05:19:03  57.9N  135.3W MB=4.7  ECAN OF JUNEAU, AK                  

P: 18AUG2020 126427    58.3N  133.5W 3.0-4.9 BAAAA  British Colombia           

P: 23AUG2020 126692    55.0N  135.0W 3.0-5.3 ACAAA  British Colombia           

P: 31AUG2020 126705    59.0N  136.0W 3.0-4.4 CAAAA  Southeast Alaska           

 

The strongest earthquake in the U.S. or Canada today was an M 4.9 in the Fox Islands, Aleutians where it was not reported felt. This appears to be a continuation of the westward migration of moderate to strong seismicity following the M 7.8 in the Alaska Peninsula of July 22, 2020. Forecast 126695 had expected activity in this area of the Fox Islands around August 24.

 

O: 23AUG2020 01:49:01  52.2N  169.6W Mw=4.9  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 24AUG2020 126695    53.7N  167.0W 3.5-5.1 ABBAA  Fox Islands, Aleutians     

 

Nine years ago today an M 5.7 occurred in the area of Virginia west of Washington, D.C. and did considerable damage in the area. This summary notes this in the History section below as:

 

(NEIC) Moderately heavy damage (VIII) occurred in a rural region of Louisa County southwest of Mineral. Widespread light to moderate damage occurred from central Virginia to southern Maryland including the District of Columbia area. Minor damage reported in parts of Delaware, southeastern Pennsylvania and southern New Jersey. Very strongly felt (VII) at Boston, Bumpass, Kents Store, Louisa, Mineral, Rhoadesville and Sumerduck. Felt strongly in much of central Virginia and southern Maryland. Felt throughout the eastern US from central Georgia to central Maine and west to Detroit, Michigan and Chicago, Illinois. Felt in many parts of southeastern Canada from Montreal to Windsor.

 

LIGHT EARTHQUAKE SHAKES MICHIGAN

 

EARTHQUAKE SUMMARY FOR AUGUST 21, 2020

 

An unusual earthquake of M 3.2 was widely felt in the area south of Detroit, Michigan today. NEIC reported maximum intensity IV in Michigan at Monroe, Luna Pier, South Rockwood and II-III in Newport, La Salle, Carleton, Rockwood, Erie, Flat Rock. The earthquake was felt with light intensity as far as Ohio, Pennsylvania, Wisconsin, Illinois, New Jersey, New York, Tennessee, North Carolina, Massachusetts, Georgia, Connecticut and Missouri among other states in the eastern U.S. No major damage was reported. The last earthquake in the Detroit area occurred as an M 3.4 on April 20, 2018. The largest regional earthquake in the past 30 years was an M 4.2 on May 2, 2015. An M 2.0 also occurred when a meteor hit the earth near Detroit on January 16, 2018. Other recent quakes occurred as an M 4.0 near Kalamazoo on May 2, 2015. Today's earthquake did not affect operations at the area's two nuclear power plant.

 

When the M 4.2 occurred in May, 2015 this summary noted:

 

"The last earthquake within about 200 km of this epicenter with M>=4.2 occurred on August 10, 1947 with M 4.7. Other recent earthquakes in the area occurred on February 4, 1883 and February 4, 1833 (may be an error in the year).

 

The earthquake in 1883 was felt in northern Indiana and southern Michigan in Kalamazoo, Michigan. Windows were cracked and chimneys damaged in Kalamazoo. It was felt as far as St. Louis, Missouri and in Bloomington, Illinois. The earthquake in 1947 was also located near the epicenter of today's event. It was felt through southern Michigan where damage was reported. It was also felt with intensity up to VI in Illinois, Michigan, Indiana and Wisconsin. Damage included cracked plaster, with windows and items thrown down from store shelves." (May 3, 2015)

 

Today's epicenter is at 143 degrees from the M 6.8 and 6.9 in Sumatra of August 18 and may have been promoted by concentrated energy from that source.    Other earthquakes today at this distance from Sumatra occurred in Oklahoma and Texas.

 

O: 21AUG2020 22:55:09  41.9N   83.3W Mw=3.2  EMSC   MICHIGAN                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Alaska Peninsula aftershock sequence following the M 7.8 there on July 22, 2020. Today's event was not reported felt in the area. Forecast 126424 had expected this event was likely around August 21.

 

O: 21AUG2020 19:10:18  55.5N  158.3W mb=4.4  EMSC   ALASKA PENINSULA             

P: 21AUG2020 126424    54.8N  158.7W 3.5-5.3 AAAAA  Alaska Peninsula           

 

The strongest earthquake in the world today was an M 5.5-5.7 in southern Sumatra, Indonesia. This is an aftershock of the events of M 6.8 and 6.9 of August 18, 2020 – the strongest to date. BMG reported it was felt with intensity II-III in Bengkulu and II in Kepahiang, Sumatra. Forecast 126276 had expected this activity in Sumatra in mid-August.

 

O: 22AUG2020 03:17:45   4.3S  101.0E mb=4.6  EMSC   SOUTHERN SUMATRA, INDONESIA

O: 21AUG2020 19:01:00   4.4S  101.0E ML=4.2  EMSC   SOUTHWEST OF SUMATRA, INDONESIA

O: 22AUG2020 00:39:36   4.0S  101.1E Mw=5.5  EMSC   SOUTHERN SUMATRA, INDONESIA  

O: 22AUG2020 00:39:36   4.0S  101.0E Mw=5.7  BMG    SOUTHERN SUMATRA, INDONESIA  

P: 14AUG2020 126276     2.0S  101.0E 4.0-5.4 CBAAA  So. of Sumatera            

P: 18AUG2020 126276     6.0S  103.0E 4.0-5.6 BBBAA  So. of Sumatera            

 

LIGHT EARTHQUAKE SHAKES MICHIGAN

 

EARTHQUAKE SUMMARY FOR AUGUST 21, 2020

 

An unusual earthquake of M 3.2 was widely felt in the area south of Detroit, Michigan today. NEIC reported maximum intensity IV in Michigan at Monroe, Luna Pier, South Rockwood and II-III in Newport, La Salle, Carleton, Rockwood, Erie, Flat Rock. The earthquake was felt with light intensity as far as Ohio, Pennsylvania, Wisconsin, Illinois, New Jersey, New York, Tennessee, North Carolina, Massachusetts, Georgia, Connecticut and Missouri among other states in the eastern U.S. No major damage was reported. The last earthquake in the Detroit area occurred as an M 3.4 on April 20, 2018. The largest regional earthquake in the past 30 years was an M 4.2 on May 2, 2015. An M 2.0 also occurred when a meteor hit the earth near Detroit on January 16, 2018. Other recent quakes occurred as an M 4.0 near Kalamazoo on May 2, 2015. Today's earthquake did not affect operations at the area's two nuclear power plant.

 

When the M 4.2 occurred in May, 2015 this summary noted:

 

"The last earthquake within about 200 km of this epicenter with M>=4.2 occurred on August 10, 1947 with M 4.7. Other recent earthquakes in the area occurred on February 4, 1883 and February 4, 1833 (may be an error in the year).

 

The earthquake in 1883 was felt in northern Indiana and southern Michigan in Kalamazoo, Michigan. Windows were cracked and chimneys damaged in Kalamazoo. It was felt as far as St. Louis, Missouri and in Bloomington, Illinois. The earthquake in 1947 was also located near the epicenter of today's event. It was felt through southern Michigan where damage was reported. It was also felt with intensity up to VI in Illinois, Michigan, Indiana and Wisconsin. Damage included cracked plaster, with windows and items thrown down from store shelves." (May 3, 2015)

 

Today's epicenter is at 143 degrees from the M 6.8 and 6.9 in Sumatra of August 18 and may have been promoted by concentrated energy from that source.    Other earthquakes today at this distance from Sumatra occurred in Oklahoma and Texas.

 

O: 21AUG2020 22:55:09  41.9N   83.3W Mw=3.2  EMSC   MICHIGAN                     

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Alaska Peninsula aftershock sequence following the M 7.8 there on July 22, 2020. Today's event was not reported felt in the area. Forecast 126424 had expected this event was likely around August 21.

 

O: 21AUG2020 19:10:18  55.5N  158.3W mb=4.4  EMSC   ALASKA PENINSULA             

P: 21AUG2020 126424    54.8N  158.7W 3.5-5.3 AAAAA  Alaska Peninsula           

 

The strongest earthquake in the world today was an M 5.5-5.7 in southern Sumatra, Indonesia. This is an aftershock of the events of M 6.8 and 6.9 of August 18, 2020 – the strongest to date. BMG reported it was felt with intensity II-III in Bengkulu and II in Kepahiang, Sumatra. Forecast 126276 had expected this activity in Sumatra in mid-August.

 

O: 22AUG2020 03:17:45   4.3S  101.0E mb=4.6  EMSC   SOUTHERN SUMATRA, INDONESIA

O: 21AUG2020 19:01:00   4.4S  101.0E ML=4.2  EMSC   SOUTHWEST OF SUMATRA, INDONESIA

O: 22AUG2020 00:39:36   4.0S  101.1E Mw=5.5  EMSC   SOUTHERN SUMATRA, INDONESIA  

O: 22AUG2020 00:39:36   4.0S  101.0E Mw=5.7  BMG    SOUTHERN SUMATRA, INDONESIA  

P: 14AUG2020 126276     2.0S  101.0E 4.0-5.4 CBAAA  So. of Sumatera            

P: 18AUG2020 126276     6.0S  103.0E 4.0-5.6 BBBAA  So. of Sumatera            

 

STRONG EARTHQUAKE BENEATH BANDA SEA, INDONESIA FITS EXPECTED PATTERN

 

EARTHQUAKE SUMMARY FOR AUGUST 20, 2020

 

A strong M 6.9 earthquake hit at a deep focus beneath the Banda Sea, Indonesia today. BMG reported intensity III-IV in Waingapu; III in Mataram; II-III i Kota Bima; Sumbawa, Ende, Ruteng, Kairatu, Banda, Wakotobi and II n Tambolaka, Kota Kupang, Alor, Ternate, Tarakan, NEIC reported moderate shaking in Indonesia with II-III in Dili Dili East Timor, Poso Sulawesi, Ubud and Denpasar, Bali and in Kalimantan and Brunei. As is typical for large deep earthquakes in the Banda Sea this event was also felt with intensity III-IV in Northern Territory, Australia at Coonawarra, Darwin and Palmerston. This earthquake occurred within minutes of local solar noon at a longitude where tidal stresses with the last new moon of August 19 were near maximum and was probably promoted by tidal stresses as noted in previous issues of this summary.

 

"The new moon  arrived on August 19 at 02:41 UT. Longitudes which were antisolar (near local solar midnight) at this hour are near 40 West and 140 East. These include in the west, areas of the central Atlantic and in the east much of the western subduction zone of the Pacific plate including Japan, and Indonesia. These areas may see enhanced seismicity during the period August 16-23 with the potential for a strong earthquake. Other areas can also be triggered by tides and global seismicity is expected to be at moderately high levels during this period. Tidal triggering is most prominent near local solar noon and midnight." (August 16-20, 2020)

 

This epicenter is also at the fourth node (90 degrees) from the M 7.8 in the Alaska Peninsula of July 22, 2020 and was probably promoted by surface energy from that source. This summary had expected this at the time of the Alaska events as:

 

"Far field triggering is likely with the earthquake in Alaska. ... Recent unusual quakes at the fourth node (90 degrees) may continue in northern Peru, Tunisia, Andaman Islands, Spain and Peninsular India, the southern Kermadec Island among others." (July 22, 2020)

 

In the past four days strong earthquakes have hit in Samar, Philippines at the  fifth node (72 degrees) from the Alaska Peninsula epicenter; the 101-103 distance in Southern Sumatra (6.8, 6.9) and today in the Banda Sea at the fourth node (90 degrees). This illustrates the continuing importance of the M 7.8 in the Alaska Peninsula on the location of stronger global earthquakes at this time which continue at nodal distances from Alaska.

 

A further promotional stress for this Banda Sea event could be TD 13 which was located near the antipode of this epicenter east of the Windward Islands at the time of the Banda Sea Earthquake. This system was described in the previous issue of this summary as:

 

"TD    13       2020-08-20  10:00 UT  15.2N   49.8W   35 kts  East of Windward Islands         

 

TD 13 formed today east of the Windward Islands, Caribbean with winds up to 35 kts. It is expected to track to the west over the next four days passing over the Virgin Islands August 22 amd Puerto Rico August 23. These areas are likely to see enhanced seismicity with this storm." (August 19-20, 2020)

 

When an M 6.9 hit the same area on February 27, 2015 this summary noted in terms of far-field activity:

 

"While the daily earthquake map shows the normal nodal distance, the great depth of this earthquake will displace these nodes somewhat and readers should expect a more diffuse pattern of far-field aftershocks from the Flores Sea event." (February 28, 2015)

 

This comment is equally applicable to today's event as it was five years ago.

 

This event of M 6.9 is the strongest within the Banda Sea within about 250 km

of today's epicenter since an M 7.0 on February 27, 2015 and an M 6.9 on August 28, 2009. A major M 7.9 hit the region on June 17, 1996 at a deep focus. Forecast 126257 had expected today's event within this area was likely around

August 19.

 

O: 21AUG2020 04:09:52   6.7S  123.5E Mw=6.9  EMSC   BANDA SEA                    

O: 21AUG2020 04:42:37   6.9S  123.5E mb=4.8  EMSC   BANDA SEA                    

P: 19AUG2020 126257     6.0S  125.0E 4.0-5.5 AABAA  Banda Sea                  

 

The strongest earthquake in the U.S. or Canada today was an M 5.0 in the region of the western Alaska Peninsula and is an aftershock of the M 7.8 in the area of

July 22. Today's event was reported felt with intensity III in King Cove, Alaska. Forecast 126441 had expected today's event was likely around August 17.

 

O: 20AUG2020 16:35:09  54.3N  162.8W Mw=5.0  EMSC   ALASKA PENINSULA             

P: 17AUG2020 126441    54.5N  161.8W 3.5-5.1 BAAAA  Unimak Islands, Aleutians  

 

PANAMA EARTHQUAKE AT ANTIPODE TO SUMATRA

 

EARTHQUAKE SUMMARY FOR AUGUST 19, 2020

 

The strongest earthquake in the world today occurred near the exact antipode of the two M 6.8 events in Sumatra yesterday. This event of M 5.4 was located in the area south of Panama. Compare the epicenter of this event at 5N 78.3W with the epicenters of the Sumatra events yesterday at 4.2S 101.2E. Readers will recall that two epicenters are exactly antipodal when the latitudes are the same and in different hemispheres and the longitudes in different hemispheres add numerically to 180. In this case the latitudes are 5N and 4.2S  - within 100 km  - and the longitudes add to 179.5 - within 50 km. The sites are about 100 km from exactly antipodal. This is remarkable and there can be little doubt that energy focusing from Sumatra in the vicinity of Panama triggered the subsequent M 5.4 there. This summary has long argued the case for antipodal triggering from large earthquakes and this is an excellent example of antipodal triggering.

 

Today's earthquake of M 5.4 is the strongest within about 200 km of this epicenter since an M 6.7 on August 13, 2013. Forecast 126247 had expected today's event was likely within about 25 km around August 21. When the M 6.7 occurred in 2013 this summary noted:

 

"This epicenter (south of Panama) is at the exact antipode of an M 5.3 which hit south of Sumatra two days ago and may have been promoted or triggered by that event. Frequent readers of this summary know that two epicenters are antipodal if their latitudes are the same and in opposite hemispheres (6N and 6S in the current pair) and their longitudes add to 180 and are in opposite hemispheres (78W and 102E in the current pair). Further activity in Sumatra near this epicenter is likely in the next several days. After this was written an M 4.6 did occur in this region of Sumatra." (August 13-14, 2013)

 

How is that for consistency?

 

 

O: 20AUG2020 01:16:27   5.2N   78.3W Mw=5.4  EMSC   SOUTH OF PANAMA              

P: 21AUG2020 126247     5.0N   78.0W 4.0-5.5 AAAAA  Colombia                   

 

 

O: 18AUG2020 22:23:58   4.3S  101.2E Mw=6.8  EMSC   SOUTHERN SUMATRA, INDONESIA

O: 18AUG2020 22:29:26   4.1S  101.4E Mw=6.9  EMSC   SOUTHERN SUMATRA, INDONESIA  

P: 14AUG2020 126276     2.0S  101.0E 4.0-5.4 BBAAA  So. of Sumatera            

P: 18AUG2020 126276     6.0S  103.0E 4.0-5.6 ABBAA  So. of Sumatera            

 

The strongest earthquake in the U.S. or Alaska today was an M 5.1 aftershock in the region of the Alaska Peninsula. NEIC reported it was felt with intensity IV in Sand Point and III in King Cove, Alaska. This epicenter is near 100 degrees from the Sumatra events of M 6.8 yesterday and may have been enhanced by energy from those. A similar event (M 4.7) at this distance from Sumatra today occurred in the South Pacific. Forecast 126425 had expected today's event was likely within about 25 km around August 18.

 

O: 19AUG2020 17:44:37  54.9N  159.8W ML=3.4  EMSC   SOUTH OF ALASKA

O: 19AUG2020 19:45:58  55.0N  160.4W Mw=5.1  EMSC   ALASKA PENINSULA              

P: 18AUG2020 126425    54.8N  160.7W 3.5-5.4 AAAAA  Alaska Peninsula           

 

O: 19AUG2020 09:03:31  56.1S  144.1W mb=4.7  EMSC   PACIFIC-ANTARCTIC RIDGE      

 

A moderate aftershock of M 4.8 also was widely felt in the Ridgecrest, California aftershock zone today. NEIC reported intensity II-III in California at Death Valley, Lone Pine, Ridgecrest, Trona, Inyokern, Shoshone, Three Rivers, Kings Canyon, Porterville, and Miramonte. This earthquake is located at 104 degrees from the M 6.9 in Samar, Philippines which occurred August 18. This is a distance at which surface energy from large earthquakes concentrates due to internal reflections and refractions in the earth and can help trigger or enhance seismicity at this distance from large sources of energy on the earth's surface. This is probably the case in this instance. This had been anticipated in this summary when the event in Samar occurred as:

 

"Today's event (in Samar, Philippines) is unlikely to trigger much far-field seismicity as it is on the lower end of being able to do so. However Central California is located at 103 degrees from this epicenter and has shown some enhanced seismicity in recent days which may be further promoted in coming days." (August 18, 2020)

 

Today's M 4.7-4.8 is the strongest aftershock to date of the M 5.8 on June 24, 2020 but occurred about 50 km east of that epicenter and may represent a new epicenter in this seismic active area. Forecast 126332 had expected enhanced regional seismicity at this aftershock zone around August 16.

 

O: 19AUG2020 17:37:36  36.5N  117.5W ML=2.1  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 17:40:30  36.5N  117.5W ML=2.4  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 17:50:52  36.5N  117.5W ML=2.7  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 17:50:52  36.5N  117.5W ML=2.7  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 19:31:36  36.5N  117.5W ML=2.4  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 19:46:18  36.5N  117.5W ML=2.4  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 23:22:36  36.5N  117.5W ML=2.9  EMSC   CENTRAL CALIFORNIA

O: 20AUG2020 03:09:31  36.5N  117.5W ML=2.4  EMSC   CENTRAL CALIFORNIA

O: 19AUG2020 17:32:10  36.5N  117.5W Mw=4.7  EMSC   CENTRAL CALIFORNIA           

O: 19AUG2020 17:32:11  36.5N  117.5W Mw=4.8  ANSS   CENTRAL CALIFORNIA           

P: 16AUG2020 126332    36.5N  118.0W 2.5-4.5 BAAAA  California/Nevada area     

 

The aftershock series in Idaho also re-energized today with a number of light earthquakes. This area is also at 103 degrees from Samar, Philippines and was probably promoted by energy from that source. Forecast 126400 had expected this enhancement in the Idaho aftershock zone in mid-August.

 

O: 19AUG2020 20:10:26  44.2N  115.1W ML=2.9  EMSC   SOUTHERN IDAHO

O: 19AUG2020 08:37:14  44.3N  115.6W ML=2.3  EMSC   SOUTHERN IDAHO

O: 19AUG2020 10:26:22  44.3N  115.2W Ml=2.3  EMSC   SOUTHERN IDAHO

O: 19AUG2020 10:52:57  44.3N  115.1W Ml=2.3  EMSC   SOUTHERN IDAHO

O: 19AUG2020 13:58:11  44.3N  115.1W Ml=2.3  EMSC   SOUTHERN IDAHO

O: 19AUG2020 16:55:42  44.3N  115.0W Ml=2.0  EMSC   SOUTHERN IDAHO

O: 19AUG2020 10:44:19  44.4N  115.2W Ml=2.1  EMSC   SOUTHERN IDAHO

O: 19AUG2020 12:04:45  44.4N  115.2W Ml=2.6  EMSC   SOUTHERN IDAHO

O: 19AUG2020 18:48:19  44.5N  115.2W Ml=2.1  EMSC   SOUTHERN IDAHO

O: 19AUG2020 15:40:05  44.1N  115.1W Ml=2.1  EMSC   SOUTHERN IDAHO               

P: 16AUG2020 126400    44.4N  115.1W 2.0-3.9 BAAAA  Montana/Idaho              

 

A moderate earthquake also occurred in the Madeira Islands, Portugal southwest of Portugal in the Atlantic Ocean with M 4.5. It was not reported felt in this area. The last earthquake within about 250 km of this epicenter in the Madeira Island with M>=4.5 occurred on March 7, 2020 with M 5.2, the only such quake in  the area in at least 30 years.

 

O: 19AUG2020 11:27:01  32.1N   16.3W mb=4.5  EMSC   MADEIRA ISLANDS, PORTUGAL REGI

 

DOUBLE STRONG QUAKE IN SOUTHERN SUMATRA

 

EARTHQUAKE SUMMARY FOR AUGUST 18, 2020

 

A pair of earthquakes of M 6.8 each hit south of Sumatra, Indonesia today. BMG reported the M 6.9 was felt with intensity IV in Bengkulu, Bengkulu Utara, Mukomuko, Seluma, Depahiang; III in Bengkulu Selatan, Kaur, Curup, Lebong and II-III in Lubuk Linggau, Sumatra, Indonesia. NEIC reported intensity IV-V in Bengkulu and II-III in Curup, Padang, Jakarta and Singapore for both of these events. BMG reported the second  was felt with intensity IV in Kepahiang and II in Liwa. These epicenters are at 100 degrees from the M 7.8 in the Alaska Peninsula of July 22, 2020 and had been expected in this summary as a far-field area for triggering from that event as:

 

"Far field triggering is likely with the earthquake in Alaska.  ... those near 103 degrees include northern Chile and southern Peru; South Island, New Zealand; Sumatra and southwestern Indonesia." (July 22, 2020)

 

It is interesting that strong earthquakes have occurred in the month since the Alaska Peninsula quake in each of the areas outlined in the far-field forecast near 103 degrees from that epicenter with the inclusion of the earthquakes south of Sumatra today.

 

The new moon arrived near the time of today's Sumatra earthquakes. This summary had expected strong triggering from this tidal alignment in Indonesia in previous issues as:

 

"The new moon will arrive on August 19 at 02:41 UT. Longitudes which are antisolar (near local solar midnight) at this hour are near 40 West and 140 East. These include in the west, areas of the central Atlantic and in the east much of the western subduction zone of the Pacific plate including Japan, and Indonesia. These areas may see enhanced seismicity during the period August 16-23 with the potential for a strong earthquake. Other areas can also be triggered by tides and global seismicity is expected to be at moderately high levels during this period. Tidal triggering is most prominent near local solar noon and midnight." (August 16-18, 2020)

 

The M 6.9 is the strongest earthquake in southern Sumatra within about 250 km  of this epicenter since an M 7.8 ten years ago on October 25, 2010. An M 8.5 hit within about 50 km of today's epicenter on September 12, 2007. Forecast 126276 had expected today's event between August 14 and 18.

 

O: 18AUG2020 22:23:58   4.3S  101.2E Mw=6.8  EMSC   SOUTHERN SUMATRA, INDONESIA

O: 18AUG2020 22:57:10   4.3S  101.1E ML=4.5  EMSC   SOUTHERN SUMATRA, INDONESIA

O: 19AUG2020 01:37:58   4.3S  101.2E mb=4.6  EMSC   SOUTHERN SUMATRA, INDONESIA

O: 18AUG2020 22:29:26   4.1S  101.4E Mw=6.9  EMSC   SOUTHERN SUMATRA, INDONESIA  

P: 14AUG2020 126276     2.0S  101.0E 4.0-5.4 BBAAA  So. of Sumatera            

P: 18AUG2020 126276     6.0S  103.0E 4.0-5.6 ABBAA  So. of Sumatera             

 

A moderate earthquake of M 4.0-4.6 in northern California today was followed by a series of lightly felt aftershocks. The mainshock was reported by NEIC to have been felt with intensity IV in northern California at Redwood Valley, Potter Valley and Willits and II-III in Ukiah, Comptche, Upper Lake, Fort Bragg, Lakeport, Mendocino and Littleriver, California. The largest aftershock of M 3.8 was felt with intensity III in Redwood Valley, Willits, Potter Valley, Ukiah, Comptche, Phio, Fort Bragg, Mendocino and Littleriver. A foreshock of M 3.1 was also felt lightly with intensity II-III in Redwood Valley and Willits, California. This is the strongest earthquake within about 75 km of this epicenter since an M 4.3 on April 29, 2019 and prior to that an M 4.3 on December 14, 2017 to the northwest of today's epicenter. Forecast 126339 had expected today's mainshock within about 10 km was likely with magnitude up to M 4.6 around August 18. Today's activity in northern California is at 100 degrees from Sumatra and may have been triggered by concentrated surface energy from that source.

 

O: 19AUG2020 00:55:23  39.4N  123.3W ML=3.8  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 00:59:33  39.4N  123.3W ML=4.0  ANSS   NORTHERN CALIFORNIA

O: 19AUG2020 01:43:41  39.4N  123.2W ML=3.2  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 01:54:35  39.4N  123.3W MD=2.2  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 01:54:35  39.4N  123.3W MD=2.2  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 01:59:32  39.4N  123.2W ML=3.5  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 01:59:32  39.4N  123.2W ML=3.5  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 02:00:39  39.4N  123.3W ML=2.9  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 02:00:39  39.4N  123.3W ML=2.9  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 02:15:33  39.4N  123.3W Md=2.7  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 02:53:41  39.4N  123.3W Md=2.4  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 02:55:03  39.4N  123.1W Md=2.8  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 03:15:53  39.4N  123.3W Md=2.2  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 05:25:57  39.4N  123.3W Md=2.1  EMSC   NORTHERN CALIFORNIA

O: 19AUG2020 00:46:16  39.4N  123.2W ML=2.7  EMSC   NORTHERN CALIFORNIA          

P: 18AUG2020 126339    39.3N  123.2W 2.5-4.6 AAAAA  Central California         

 

A series of moderate earthquakes occurred south of Taiwan today. NEIC reported these earthquake were felt with intensity IV in Tainan, Taiwan.  CWB reported the M 4.5 was felt with intensity III in Tainan and Chiayi Counties and II in Yunlin, Kaohsiung, and I in Nantou, Taitung and Changhua Counties, Taiwan.

The M 4.7 was felt with maximum intensity IV in Chiayi County but was otherwise felt in a similar pattern as the M 4.5. This activity may have been promoted by stresses from Tropical Storm Higos which passed over these epicenters yesterday. This summary had noted the possibility of triggering in Taiwan from this storm in previous issues as:

 

"Tropical Storm Higos formed north of the Philippines with winds up to 50 kts.  It may help generate enhanced seismicity in the northern Philippines and Taiwan over the next three days. An M 6.6 in Samar, Philippines today was probably triggered by landfall of this storm about the same time." (August 17-18, 2020)

 

Forecast 126327 had expected today's activity was likely in Taiwan around August 20. The last event in this region of Taiwan with M>=4.7 was an M 4.7 on June 26, 2020.

 

O: 19AUG2020 00:33:01  23.2N  120.4E ML=4.5  TAI    Hualien, Taiwan              

O: 19AUG2020 00:41:51  23.2N  120.4E ML=4.2  TAI    Hualien, Taiwan               

O: 19AUG2020 03:13:31  23.2N  120.4E ML=4.7  TAI    Hualien, Taiwan              

P: 20AUG2020 126327    22.0N  121.0E 4.0-5.6 ABAAA  Taiwan                     

 

An M 4.7 earthquake occurred today in the Revilla Gigedo Islands area of western Mexico. This epicenter was directly beneath the eye of Hurricane Genevieve at the time of the earthquake and was probably triggered by stresses from this storm as  noted in previous issues of this summary:

 

"HURR GENEVIEVE 2020-08-19  00:00 UT  19.1N  108.8W  135 kts  South of Baja Mexico

 

Hurricane Genevieve  continued south of Baja California, Mexico today with winds up to 135 kts.  This system is is expected to track to the northwest possibly impacting western Mexico. The area of Jalisco and the Gulf of California and Baja California may see enhanced seismicity with Hurricane Genevieve through August 25." (August 17-19, 2020)

 

The only other event in the Revilla Gigedo Islands of M>=4.7 within about 200 km of this epicenter in the past year was an M 5.1 on February 5, 2020 and prior to that in August 14, 2019. Forecast 126290 had expected today's event within about 50 km of this epicenter was likely around August 18.

 

O: 18AUG2020 20:51:24  19.4N  108.4W mb=4.7  EMSC   REVILLA GIGEDO ISLANDS REGION

P: 18AUG2020 126290    19.0N  109.0W 3.5-5.1 AAAAA  Coast of Jalisco, Mexico   

 

The strongest earthquake in the U.S. or Canada today was an M 5.1 aftershock in the Alaska Peninsula. This is some what unusual. To date, significant seismicity in the region has been occurring west of the M 7.8 mainshock of July 22.  The only event in the region within about 100 km east of the mainshock in the past four years was an M 5.2 at today's epicenter on August 9, 2020. The last in this area previously of M>=5.1 was an M 5.5 on December 7, 2013. Forecast 126424 had expected today's activity around August 21.

 

O: 18AUG2020 18:28:34  55.1N  158.0W Mw=5.1  EMSC   ALASKA PENINSULA             

P: 21AUG2020 126424    54.8N  158.7W 3.5-5.3 BAAAA  Alaska Peninsula           

 

STRONG EARTHQUAKE DAMAGING IN SAMAR, PHILIPPINES

 

EARTHQUAKE SUMMARY FOR AUGUST 17, 2020

 

A strong earthquake of M 6.6 was damaging in Samar, Central Philippines today. NEIC reported major damage with intensity IV at Placer, and Mayngaran, Bicol, Philippines. Intensity VIII was felt in the Eastern Visayas at Polangi with VII in San Pedro. Intensity VI was reported from Cataingan, Usab, with V in Bacciod and Baleno and lesser shaking in Napuro and Calace, Philippines. PHIVOLCS reported intensity VII in Cataingan, Masbate; V in the City of Masbate, Masbate; Almagro and Tagapul-an, Samar; IV in Palanas and San Jacinto, Masbate;City of Sorsogon, Sorsogon; City of Legazpi, Albay, San Andres, Quezon; Mapanas and Palapag, Northern Samar, Barugo, Dagami, Dulag, Julita, La Paz, Palo, and Tanauan, Leyte, Sit of Sagay, Nebros Occidental, III in City of Baybay, Isabel, Javier and Kananga, Leyte, Ormos City; Mulanay, Quezon, City of Iloilo, and II ni Guinayangan and Lopez, Quezon; President Roxas, Capiz, Patnongon, Patnongo, San Jose de Buenavista and Tibiao, Antique, Philippines. At least one person was killed in the earthquake according to AP. Among damages were a three-story house which collapsed in the town of Cataingan near the coast. At least 25 people were reported injured in the quake which also damaged dams, roads, bridges and other structures. No tsunami was reported with this land-based earthquake. The earthquake apparently occurred on the Philippine Fault. It is likely that this earthquake was promoted by stresses from Tropical Storm Higos which made landfall in northern Philippines about the time of this earthquake as noted in previous issues of this summary:

 

"A tropical cyclone may be forming north of the Philippines. This system is currently located at 19N 122E with winds up to 20 kts and moving northwestward at 14 kts. It may help generate enhanced seismicity in the northern Philippines and Taiwan over the next three days." (August 16-17, 2020)

 

It was also likely promoted by tidal stresses associated with the upcoming new moon as described in previous issues of this summary as:

 

"The new moon will arrive on August 19 at 02:41 UT. Longitudes which are antisolar (near local solar midnight) at this hour are near 40 West and 140 East. These include in the west, areas of the central Atlantic and in the east much of the western subduction zone of the Pacific plate including Japan, and Indonesia. These areas may see enhanced seismicity during the period August 16-23 with the potential for a strong earthquake. Other areas can also be triggered by tides and global seismicity is expected to be at moderately high levels during this period. Tidal triggering is most prominent near local solar noon and midnight." (August 16-17, 2020)

 

A foreshock of M 4.8 hit the area on August 11, 2020. As reported in previous issues of this summary:

 

"NEIC reported this earthquake of M 4.8 in Leyte, Philippines  was felt with intensity II-III in the area(s) of Leyte, Philippines  at Pawing, Mandaue and Cebu, Visayas." (August 12, 2020)

 

Today's event follows an M 6.4 to the south of of August 3, 2020 which likewise may have been promoted by the full moon lunar alignment and its distance  at the fifth node (72 degrees) from the event of July 22, 2020 in the Alaska Peninsula as noted at the time in this summary:

 

"The full moon will arrive at 15:59 UT on August 3, 2020. Longitudes which are sub-solar (local solar noon) at this time are 60 West and 120 East and include in the west the Caribbean and Puerto Rico and portions of northern and western South America. Those in the east include the Philippines and central Indonesia near Sulawesi. These areas may see moderate seismic enhancement at this time. Many areas can see tidal enhancement with lunar-solar alignments so the seismicity of the earth is expected to be at active conditions through August 7." (August 1-2, 2020)

 

"The strongest earthquake in the world today was an M 6.4 in Mindanao, Philippines. It was reported by NEIC to have been felt with intensity IV in Mindano at Simuay and Taviran and with light intensity in Libertad. This earthquake is located at 124 East longitude, near the maximum tidal stress with this full moon.  This is the strongest earthquake in Mindanao within about 200 km of this epicenter during 2020" (August 3, 2020)

 

"this epicenter is at the fifth node (72 degrees ) from the Alaska Peninsula and probably promoted by energy from that source. Other such events today occurred at or near 72 degrees from Alaska in Mindanao, Philippines (M 6.4)," (August 1 2, 2020

 

Today's event is unlikely to trigger much far-field seismicity as it is on the lower end of being able to do so. However Central California is located at  103 degrees from this epicenter and has shown some enhanced seismicity in recent days which may be further promoted in coming days. The last earthquake within about 250 km of today's epicenter with M>=6.6 was an M 7.1 on October 15, 2013 and prior to that an M 7.6 on August 31, 2012. Forecast 126296 had expected today's event within about 0-25 km was likely in mid-August.

 

O: 18AUG2020 00:03:48  12.0N  124.2E Mw=6.6  EMSC   SAMAR, PHILIPPINES           

O: 18AUG2020 00:03:48  12.1N  124.2E Mw=6.9  BMG    SAMAR, PHILIPPINES           

O: 18AUG2020 00:03:48  12.0N  124.0E Mw=6.6  PHIV   SAMAR, PHILIPPINES           

P: 14AUG2020 126296    12.0N  124.0E 3.5-5.3 BAAAA  Luzon, Philippines         

 

A moderate earthquake of M 5.1 was widely felt in Baja and Southern California today. NEIC reported this event was followed a series of light aftershocks including an M 4.5 and an M 4.4 foreshock, many of which were lightly felt. The mainshocks was felt with intensity II-III in Baja California at Camalu, Maneadero, Vicente Guerrero, San Felipe, Ensenada, Guadalupe Victoria, Puetla, Mexicali and in southern California in Calexico and Jacumba and in general within about 400 km of the epicenter of the mainshock. The M 4.4 foreshock was reported felt with maximum intensity IV in San Quintin, Baja and II-III in Vicente Guerrero, Puebla, Tecate, and in Southern California at Ocotillo, Chula Vista, Julian, Spring Valley and El Cajon among others.  This activity may have been promoted by TS Genevieve (now a hurricane) as noted in the previous issue of this report:

 

"Tropical Storm Genevieve  formed south of Guerrero, Mexico today with winds up to 55 kts.  This system is expected to track to the northwest possibly impacting western Mexico. The area of Jalisco and the Gulf of California and Baja California may see enhanced seismicity with TS Genevieve through August 25." (August 16-18, 2020)

 

It may also be the continuation of a series of events north of this on the California-Baja border several days ago. This summary had noted in this regard at the time:

 

"A swarm of light earthquakes has been occurring in southeastern California near the Mexican border. This swarm began shortly after a C-class solar flare the strongest in more than two months. Swarms in this area of high heat flow are often associated with unusual flares or solar activity. Such swarms occasionally grow over several days and include a moderate sized event. But it also occurs that they grow without a recognizable mainshock and gradually dissipate." (August 12, 2020)

 

Following is a list of events in this series of M>=3.5. A more extensive listing can be found in the "CALIFORNIA" regional seismicity section below in this summary. Forecast 126364 had expected today's activity was likely around August 19  about 100 km to the north. The M 5.2 is the strongest earthquake within about 150 km of this epicenter since an M 5.5 about 150 km southeast of this on March 7, 2020. The only other such event in the region in the past four years was an M 5.2 about 200 km southeast in the northern Gulf of California on April 6, 2019.

 

O: 17AUG2020 15:09:03  31.4N  115.6W Mw=4.4  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 15:32:41  31.4N  115.6W Mw=4.3  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 15:30:32  31.5N  115.7W Mw=5.2  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 18:59:33  31.5N  115.5W ML=3.6  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 19:39:46  31.5N  115.5W ML=3.7  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 19:47:03  31.5N  115.5W ML=3.7  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 21:10:48  31.5N  115.6W ML=3.7  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 21:46:45  31.5N  115.5W ML=3.6  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 15:31:41  31.6N  115.7W ML=4.2  EMSC   BAJA CALIFORNIA, MEXICO

O: 17AUG2020 16:29:49  31.3N  115.7W Mw=3.7  EMSC   BAJA CALIFORNIA, MEXICO      

P: 19AUG2020 126364    32.5N  115.7W 2.5-4.5 ABAAA  So. California             

 

 

An earthquake of M 4.9 occurred today south of Africa within several km of the exact antipode of the M 7.8 in the Alaska Peninsula of July 22, 2020. This continues a series of events in this region which have occurred with moderate to large magnitude since the Alaska Peninsula quake. The area was expected to see enhanced activity at this time due to antipodal energy focusing from Alaska. Today's event is the nearest of these event to the exact antipode (compare 54N 158W and 53S 26E). Today's earthquake is the strongest in the region within about 300 km of this epicenter since an M 5.1 on February 9, 2020. The only other such event in the region in the past two years was an M 5.4 on January 10, 2020. Forecast 126506 had expected today's activity in this area was likely around August 21.

 

O: 17AUG2020 18:30:12  52.5S   26.7E mb=4.9  EMSC   SOUTH OF AFRICA              

P: 21AUG2020 126506    51.0S   29.0E 4.0-5.4 BBAAA  Atlantic-Indian Ridge      

 

A series of light earthquakes including an M 3.3 and 2.9 also occurred today in the region south of San Francisco, California. These may have been promoted by strong tidal stresses associated with the new moon as they occurred within minutes of local solar noon, a time when such stresses are maximized. The last earthquake of M>=3.3  in this area south of San Francisco was an M 3.4 on June 17, 2020. The only other such event in the region this year was an M 3.9 south of today's epicenter on January 2, 2020. This epicenter is located at 101-102 degrees from the earthquake in Samar, Philippines today. This may tend to promote further seismicity with a moderate sized event in the next lunar cycle. Readers may also note that the foreshock to the Loma Prieta earthquake in San Francisco of October, 1989 occurred with M 5.0 on this date - August 18, 1989. Forecast 126337 had expected today's activity within about 25 km of these epicenters in mid-August.

 

NEIC reported these earthquakes of M 2.6, 2.9  and 3.3 south of San  Francisco, California  were felt with intensity II-III in the area(s) south of San  Francisco, California at Saratoga, Boulder Creek, Cupertino, Los Gatos, Ben Lomond, San Jose, Santa Cruz,  Milpitas, Alviso.

 

O: 17AUG2020 20:29:06  37.5N  121.8W MD=2.9  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 17AUG2020 20:35:17  37.5N  121.8W Md=2.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 18AUG2020 05:57:42  37.5N  121.8W Md=2.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 17AUG2020 20:27:49  37.5N  121.8W Mw=3.3  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P: 14AUG2020 126337    37.7N  121.9W 2.5-4.5 BAAAA  Central California         

P: 16AUG2020 126337    37.1N  121.5W 2.5-4.5 AAAAA  Central California         

 

Further enhancement of regional seismicity in Central California may come from active conditions at the antipode in the southwest Indian Ridge. An M 5.2 was recorded in that area today. Forecast 126496 had expected this activity was likely around August 21.

 

O: 18AUG2020 04:40:33  36.4S   52.1E mb=5.2  EMSC   SOUTHWEST INDIAN RIDGE       

P: 21AUG2020 126496    35.0S   55.0E 4.0-5.5 BBBAA  So. Indian Ocean           

 

MODERATELY STRONG QUAKE IN FOX ISLANDS, ALEUTIANS, ALASKA

 

EARTHQUAKE SUMMARY FOR AUGUST 16, 2020

 

The strongest earthquake in the world today was an M 5.8 in the Fox Islands, Alaska. It was not reported felt in this remote area. This continues the westward migration of moderate to strong earthquakes following the M 7.8 in the Alaska Peninsula of July 22, 2020. This has included moderately large to large regional events recently in the area west of the epicenter of M 5.8-6.0; an M 5.8 in the Unimak Islands area of Alaska and today's event of M 5.8 in the Fox Islands and had been anticipated in previous issues of this summary as:

 

"The strongest earthquake in the U.S. or Canada today was an M 5.6 in the Unimak Island area of Alaska. This epicenter continues a westward migration of major aftershocks from the mainshock of M 7.8 on July 22, 2020 in the Alaska Peninsula. Further strong seismicity in this migration is likely." (August 13, 2020)

 

Today's event follows a series at the same epicenter described in the previous issue of this summary as:

 

"The strongest earthquake in the U.S. or Canada today was an M 4.5 in a minor swarm in the Fox Islands, Aleutians, Alaska. It was not reported felt in this remote area. Aftershocks of M 3.4 and 3.6 also were recorded. The last earthquake in the Fox Islands of M>=4.5 was an M 4.6 on July 12, 2020 and prior to that an M 4.5 on June 25. Forecast 126426 had expected today's event within about 100 km was likely around August 15." (August 16, 2020)

 

The last earthquake in the Fox Islands with M>=5.8 within about 250 km of today's epicenter was an M 5.8  on October 26, 2019. The last of M>5.9 was an M 6.2 to the west on November 9, 2015. An M 6.9 hit near today's epicenter on September 2, 2011. Forecast 126426 had expected today's event within about 100 km was likely around August 15.

 

O: 16AUG2020 20:05:50  51.4N  171.0W mb=5.8  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 15AUG2020 126426    52.1N  172.8W 3.5-5.0 AAAAA  Andreanoff Isls, Aleutians 

 

The strongest earthquakes in the U.S. or Canada outside Alaska occurred in Hawaii. An M 3.6 was reported with intensity II-III at Volcano, Mountain View, Pahoa, Kurtistown, Hilo, Keaau, Papaikou, Pepeekeo, Hakalau and Honomu, Hawaii.

The M 3.6-4.2 was the second in the area of the day - an earlier event of M 3.5-4.0 was felt with similar intensity in the same area. The last earthquake in Hawaii of M>=4.2 2as an M 4.4 on August 1. The strongest this year was an M 4.7 on July 3, 2020. Forecast 126293 had expected today's activity within about 25 km was likely around August 15.

 

O: 16AUG2020 15:47:23  19.4N  155.3W ML=3.1  EMSC   ISLAND OF HAWAII, HAWAII

O: 16AUG2020 15:45:41  19.4N  155.3W ML=3.9  EMSC   ISLAND OF HAWAII, HAWAII

O: 16AUG2020 11:25:16  19.1N  155.6W ML=4.2  EMSC   ISLAND OF HAWAII, HAWAII     

P: 15AUG2020 126293    19.2N  155.2W 3.0-4.4 AAAAA  Hawaii                     

 

STRONG SOLAR FLARE TRIGGERS STRONG EASTER ISLAND QUAKE

 

EARTHQUAKE SUMMARY FOR AUGUST 15, 2020

 

The second strongest solar flare (C2.0) of the year was observed early on August 15 with the following parameter per SWFC:

 

 

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

 

6320       0632   0647      0700   C2.0      (August 15, 2020)   1.9E-03  

 

The maximum of this flare occurred while longitudes of 112 West were within minutes of local solar midnight -  a maximum time for solar flare effects to affect seismicity. In the previous issue of this summary an unusual earthquake in the Eastern Island region of the South Pacific had been noted as:

 

O: 15AUG2020 06:40:37  22.7S  112.3W Mw=5.8  EMSC   EASTER ISLAND REGION         

P: 16AUG2020 126483    25.0S  112.0W 4.0-5.4 ACAAA  So. East Pacific Rise      

 

 

"The strongest earthquake in the world today was an M 5.8 in the region of Easter Island, South Pacific. It was not reported felt. This is the strongest earthquake within about 300 km of this epicenter since an M 6.0 on May 2, 2018 and an M 5.8 on November 2, 2013. The last of significantly larger magnitude was an M 6.9 on September 5, 1996." (August 15, 2020)

 

This earthquake occurred several minutes before the solar flare maximized and within several minutes of local solar midnight. It is highly likely it was triggered by Solar Flare Effects (SFE).

 

The antipode of Easter Island is in southern Pakistan where an M 4.2, probably enhanced by tidal effects occurred earlier in the day as noted in the previous summary.

 

O: 14AUG2020 08:57:18  29.0N   69.8E mb=4.2  EMSC   PAKISTAN                     

P:  8AUG2020 126100    30.0N   70.0E 3.8-5.4 CAAAA  Pakistan                   

P: 15AUG2020 126324    29.0N   68.0E 3.5-4.9 AABAA  Pakistan                    

 

The strongest seismicity in the world today occurred as aftershocks of M 5.1, 5.0, 4.9, 4.8 and 4.6 of the M 5.8 in Easter Island. Forecast 126483 had expected today's activity in the Easter Island region was likely around August 16. This epicenter in the Easter Island area is near the fourth node (90 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and may also have been promoted by energy from that source.

 

O: 15AUG2020 09:19:41  22.5S  112.2W mb=4.6  EMSC   EASTER ISLAND REGION

O: 15AUG2020 10:48:40  22.8S  112.5W mb=5.0  EMSC   EASTER ISLAND REGION

O: 15AUG2020 22:29:20  22.8S  112.4W mb=5.1  EMSC   EASTER ISLAND REGION

O: 15AUG2020 22:30:24  22.8S  112.4W mb=4.9  EMSC   EASTER ISLAND REGION

O: 15AUG2020 23:24:44  22.8S  112.2W mb=4.8  EMSC   EASTER ISLAND REGION

P: 16AUG2020 126483    25.0S  112.0W 4.0-5.4 ACAAA  So. East Pacific Rise      

 

The strongest earthquake in the U.S. or Canada today was an M 4.5 in a minor swarm in the Fox Islands, Aleutians, Alaska. It was not reported felt in this remote area. Aftershocks of M 3.4 and 3.6 also were recorded. The last earthquake in the Fox Islands of M>=4.5 was an M 4.6 on July 12, 2020 and prior to that an M 4.5 on June 25. Forecast 126426 had expected today's event within about 100 km was likely around August 15. Alaska, in general, was fairly active today with a variety of epicenters experiencing light to moderate earthquakes.

 

O: 15AUG2020 17:14:52  51.2N  170.9W ML=3.4  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 15AUG2020 16:47:59  51.7N  171.2W mb=4.5  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 15AUG2020 21:03:46  51.8N  171.2W mb=3.6  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 15AUG2020 126426    52.1N  172.8W 3.5-5.0 AAAAA  Andreanoff Isls, Aleutians 

 

MODERATELY STRONG QUAKE NEAR EASTER ISLAND

 

EARTHQUAKE SUMMARY FOR AUGUST 14, 2020

 

The strongest earthquake in the world today was an M 5.8 in the region of Easter Island, South Pacific. It was not reported felt. This is the strongest earthquake within about 300 km of this epicenter since an M 6.0 on May 2, 2018 and an M 5.8 on November 2, 2013. The last of significantly larger magnitude was an M 6.9 on September 5, 1996. Forecast 126483 had expected today's event was likely to the south around August 16. This epicenter is at the fourth node (90 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and may have been promoted by energy from that source.

 

O: 15AUG2020 06:40:37  22.7S  112.3W Mw=5.8  EMSC   EASTER ISLAND REGION         

P: 16AUG2020 126483    25.0S  112.0W 4.0-5.4 ACAAA  So. East Pacific Rise      

 

An earthquake of M 3.9 was widely felt in the U.S. Virgin Islands today. This event may have been triggered by stresses from Tropical Storm Josephine which was passing with the eye near this epicenter when the earthquake occurred. In previous issues of this summary enhanced seismicity in the Virgin Islands associated with Josephine had been expected as:

 

"TS Josephine (TD 11E) continued today in the central Atlantic east of the Windward Islands with winds up to 35 kts. It is expected to track to the northwest over the next several days and to miss the Caribbean. Some increases in seismicity in the Virgin Islands could, however may accompany this storm August 14-15." (August 13, 2020)

 

This is the strongest earthquake in the U.S. Virgin Islands since an M 4.0 on

July 26, 2020. The last earthquake of M>4 in the region was an M 4.4 on December 28, 2019. Forecast 126295 had expected today's event within the Virgin Islands around August 14.

 

O: 15AUG2020 03:37:44  18.6N   64.5W ML=3.7  EMSC   VIRGIN ISLANDS REGION        

O: 15AUG2020 03:37:44  18.7N   64.6W ML=3.9  ANSS   VIRGIN ISLANDS REGION        

P: 14AUG2020 126295    18.0N   65.0W 3.0-5.1 AAAAA  Leeward Islands            

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Rat Islands, Aleutians, Alaska. It was not reported felt in this remote area. Recent similar earthquakes in the Rat Islands occurred on August 8 and 10, 2020 with M 4.4-4.5 after a four month period of quiet in the area. Forecast 126437 had expected today's activity within about 100 km of this epicenter was likely in mid-August.

 

O: 15AUG2020 05:51:50  51.2N  176.2E mb=3.9  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

O: 15AUG2020 03:34:32  51.9N  178.3E mb=4.4  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

O: 15AUG2020 03:34:32  51.9N  178.3E mb=4.5  ANSS   RAT ISLANDS, ALEUTIAN ISLANDS

P: 19AUG2020 126437    51.0N  178.0E 4.0-5.8 BAAAA  Rat Islands                

 

 

 

 

 

 

 

EAST AFRICAN SEISMIC ENHANCEMENT CONTINUES

 

EARTHQUAKE SUMMARY FOR AUGUST 13, 2020

 

The largest earthquake in the world today was an M 5.0 aftershock in Tanzania.

NEIC reported this aftershock of M 5.0  in Tanzania  was felt with intensity II-III in the area(s) of Tanzania at Dar es Salaam and Magomeni. The Tanzania activity was accompanied by a M 4.4 regional shock in Mayotte. This summary had noted the regionally enhanced seismicity in the previous issue as:

 

 

"The strongest earthquake in the world today was an M 6.0 that occurred off the east coast of Tanzania. NEIC reported it was felt with maximum intensity in Tanzania at Mkuranga, Dar es Salaam, Magomeni, Koani, Zanzibar and Pemba, and Morogoro and II-III at Vikindu, Pwani, Kisarawe, Zanzibar, Chake and Wete. The last earthquake of M>=4.5 in Tanzania was an M 4.6 about 150 km northwest of today's epicenter on April 15, 2020. The last within about 250 km of today's epicenter with M>=6.0 occurred as events of  M 6.0 and 6.2 on May 14, 1985. These are the only previously reported earthquakes in the area of M>=6.0, making today's event remarkable. The earthquakes in Mayotte, Mozambique and Tanzania over the past several days may be related to their approximate antipodal location with respect to TD 10E, a tropical cyclone currently located in  the area south east of Hawaii. Energy from such storms can focus near the antipode and may enhance regional seismicity in that area. This summary had noted this storm as:

 

"TD 10E formed today with winds up to 40 kts Southeast of Hawaii. It is expected to track to the west over the next several days but not to impact seismicity. The antipode near the east coast of central Africa has seen enhanced seismicity in the past several days including an M 6.0 in Tanzania today; an M 4.7 in Mozambique two days ago and several moderate events in Mayotte. These may have been affected by antipodal effects from TD 10E but are not exactly antipodal." (August 12, 13, 2020)

 

Forecasts 126003 and 126264 had expected this activity in the Indian Ocean off Tanzania was likely around August 11-15 within about 50 km of today's epicenter.

 

O: 13AUG2020 14:54:54   7.4S   39.9E Mw=5.0  EMSC   TANZANIA                     

P: 15AUG2020 126264     7.0S   40.0E 4.0-5.4 AAAAA  Indian Ocean                

 

The area of Mayotte became active with an M 4.6 on May 13, 2018 but regional seismicity has been on the decline in the past year. Four earthquakes of M>=4.4 have been recorded in this area in the past year, the last of which was an  M 5.0 on March 21 and M 5.1 on January 2, 2020. Forecast 126464 had expected today's event in Mayotte around August 16. This event is at 143 degrees from the  M 7.5 in Oaxaca of June 23 and was probably promoted by energy from that source.

 

O: 13AUG2020 15:35:31  12.8S   45.5E ML=4.4  EMSC   MAYOTTE REGION               

P: 16AUG2020 126464    12.0S   43.0E 3.0-5.1 BAAAA  Mayotte    area            

 

A light earthquake of M 2.9 was felt in the St. Lawrence Valley, Quebec today.

NEIC reported this earthquake of M 2.9 in The St. Lawrence Valley, Quebec  was felt with intensity IV-V   in the area(s) of The St. Lawrence Valley, Quebec at Baie-Saint-Paul, Quebec and in La Malbaie, Quebec, Canada.  It is the strongest earthquake in the St. Lawrence Valley since a similar M 2.9 more than 9 months ago on November 2, 2019.  The last such event of larger magnitude was an M 3.3 on August 29, 2019 and prior to that an M 3.0 on May 22, 2017. Forecast 126397 had expected this event within about 50 km was likely around August 14. This epicenter is located at the seventh node (52 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and was probably promoted by energy from that source.

 

O: 14AUG2020 06:59:09  47.6N   70.2W mb=2.9  EMSC   ST. LAWRENCE VALLEY REG., CANA

P: 14AUG2020 126397    47.0N   70.0W 2.0-4.1 AAAAA  Maine                      

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 in the continuing aftershock series in southern Idaho.  NEIC reported this earthquake of M 3.4 in  Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho in Caldwell. The earlier M 3.7-4.2 was reported with intensity IV in Idaho at Caldwell and II-III in Stanley, Garden Valley, Boise. It was accompanied by a series of lighter aftershocks including an M 3.0 and 3.4. This is the strongest aftershock of the M 6.5 mainshock of March 31, 2020 in Idaho since an M 4.2 on August 8, 2020 and an M 4.6 on June 25, 2020.

 

O: 14AUG2020 06:34:07  44.4N  115.2W ML=3.4  EMSC   SOUTHERN IDAHO

O: 13AUG2020 07:18:32  44.4N  115.2W Ml=2.1  EMSC   SOUTHERN IDAHO

O: 13AUG2020 19:46:25  44.4N  115.2W Ml=2.2  EMSC   SOUTHERN IDAHO

O: 13AUG2020 21:13:19  44.4N  115.2W Ml=2.4  EMSC   SOUTHERN IDAHO

O: 13AUG2020 19:54:22  44.4N  115.2W Ml=4.1  EMSC   SOUTHERN IDAHO

O: 13AUG2020 22:10:24  44.5N  115.3W Ml=2.7  EMSC   SOUTHERN IDAHO

O: 13AUG2020 22:24:51  44.8N  115.8W Ml=3.0  EMSC   SOUTHERN IDAHO

O: 14AUG2020 05:41:23  44.1N  115.1W ML=2.7  EMSC   SOUTHERN IDAHO               

P: 16AUG2020 126400    44.4N  115.1W 2.0-3.9 AAAAA  Montana/Idaho              

 

STRONG, REMARKABLE EARTHQUAKE SHAKES TANZANIA

 

EARTHQUAKE SUMMARY FOR AUGUST 12, 2020

 

The strongest earthquake in the world today was an M 6.0 that occurred off the east coast of Tanzania. NEIC reported it was felt with maximum intensity in Tanzania at Mkuranga, Dar es Salaam, Magomeni, Koani, Zanzibar and Pemba, and Morogoro and II-III at Vikindu, Pwani, Kisarawe, Zanzibar, Chake and Wete. The last earthquake of M>=4.5 in Tanzania was an M 4.6 about 150 km northwest of today's epicenter on April 15, 2020. The last within about 250 km of today's epicenter with M>=6.0 occurred as events of  M 6.0 and 6.2 on May 14, 1985. These are the only previously reported earthquakes in the area of M>=6.0, making today's event remarkable. The earthquakes in Mayotte, Mozambique and Tanzania over the past several days may be related to their approximate antipodal location with respect to TD 10E, a tropical cyclone currently located in  the area south east of Hawaii. Energy from such storms can focus near the antipode and may enhance regional seismicity in that area. This summary had noted this storm as:

 

"TD 10E formed today with winds up to 40 kts Southeast of Hawaii. It is expected to track to the west over the next several days but not to impact seismicity. The antipode near the east coast of central Africa has seen enhanced seismicity in the past several days including an M 6.0 in Tanzania today; an M 4.7 in Mozambique two days ago and several moderate events in Mayotte. These may have been affected by antipodal effects from TD 10E but are not exactly antipodal." (August 12, 2020)

 

At the time of the M 4.9 in northern Mozambique on August 11, this summary noted:

 

"An unusual earthquake of M 4.9 was felt in northern Mozambique today. NEIC reported it was felt with intensity II in Nacala, Nampula, Mozambique.  This is the strongest earthquake in northern Mozambique within about 300 km of this epicenter since an M  4.9 on August 11, 2020 and prior to that an M 5.2 on July 15, 2015." (August 10-11, 2020)

 

Forecasts 126003 and 126264 had expected this activity in the Indian Ocean off Tanzania was likely around August 11-15 within about 50 km of today's epicenter.

 

O: 12AUG2020 17:13:15   7.4S   39.9E Mw=6.0  EMSC   TANZANIA                     

P: 11AUG2020 126003     5.0S   36.0E 4.0-5.4 ACCAA  Indian Ocean               

P: 15AUG2020 126264     7.0S   40.0E 4.0-5.4 BAAAA  Indian Ocean               

 

A moderately large M 4.8-5.7 was also felt in South Island, New Zealand today. NEIC reported maximum intensity IV in Queenstown, Otago and II in Te Anau Southland, New Zealand. GEONET reported 1808 people felt this quake of M 5.7 with 958 with weak intensity; 762 with light intensity and 85 with moderate intensity. 3 reported strong shaking, 0 with severe intensity and 2 extreme intensity. GEONET reported that 2 people felt an aftershock weak intensity; 0 with light intensity and 0 with moderate intensity. 0 reported strong shaking, 0 with severe intensity and 0 extreme intensity. The last earthquake in the Te Anau region of South Island recorded by NEIC with M>=5.7 was an M 6.1 on August 5, 2009, an aftershock of an M 7.8 of July 15, 2009. An M 5.8 last hit within about 350 km of this epicenter on November 24, 2018. This epicenter is at 103 degrees from the M 7.8 in the Alaska Peninsula of July 22, a distance at which far-field triggering had been expected in this summary as:

 

"Far field triggering is likely with the earthquake in Alaska. .. (areas) near 103 degrees include northern Chile and southern Peru; South Island, New Zealand; Sumatra and southwestern Indonesia." (July 22, 2020)

 

This epicenter is also at 105 degrees from the M 7.5 in Oaxaca, Mexico of June 23 and was also probably enhanced by energy from that epicenter.

 

Forecasts 126234 and 126503 had expected today's activity within about 50 km  of the epicenter between August 10 and 14.

 

O: 12AUG2020 10:16:44  44.6S  167.5E ML=5.7  GEONET reported 1808 people felt this

O: 12AUG2020 13:41:14  44.6S  167.5E ML=4.2  GEONET reported 2 people felt this

O: 12AUG2020 10:16:44  44.7S  167.5E Mw=4.8  EMSC   SOUTH ISLAND OF NEW ZEALAND

O: 12AUG2020 13:21:48  44.7S  167.7E ML=3.7  EMSC   SOUTH ISLAND OF NEW ZEALAND

O: 12AUG2020 08:37:11  45.1S  167.4E ML=3.5  EMSC   SOUTH ISLAND OF NEW ZEALAND

O: 12AUG2020 13:41:14  44.7S  167.5E ML=4.2  EMSC   SOUTH ISLAND OF NEW ZEALAND  

P: 10AUG2020 126234    45.0S  168.0E 3.0-5.0 AAAAA  So. Island, N.Z.           

P: 14AUG2020 126503    44.0S  168.0E 3.0-5.9 AAAAA  So. Island, N.Z.           

 

The strongest earthquake in the U.S. or Canada today was an M 5.6 in the Unimak Island area of Alaska. This epicenter continues a westward migration of major aftershocks from the mainshock of M 7.8 on July 22, 2020 in the Alaska Peninsula. Further strong seismicity in this migration is likely. The only event of M>=4.5 in the Unimak Island area in the past year was an M 4.7 on May 9, 2020. The only events of equal or larger magnitude in the Unimak area of Alaska in the past 10 years occurred with M 5.7-5.8 on November 6, 2011 and October 27, 2016. Forecasts 126177, 126425 and 126429 had expected this event in the Unimak Island area was likely between August 9 and 15.

 

O: 13AUG2020 06:40:01  53.6N  163.7W Mw=5.6  EMSC   UNIMAK ISLAND REGION, ALASKA 

P:  9AUG2020 126177    54.1N  162.8W 3.5-5.0 BAAAA  Unimak Islands, Aleutians  

P: 15AUG2020 126425    54.8N  161.7W 3.5-5.5 ABBAA  Alaska Peninsula           

P: 15AUG2020 126429    53.5N  163.2W 3.5-4.9 AAAAA  Fox Islands, Aleutians     

 

An unusual earthquake of M 4.5 also hit southeastern Alaska and the Northwest Territories of Canada today. The event in the Northwest Territories occurred about 15 minutes before that in the area of southeastern Alaska and may have helped trigger that following event. The event in southeastern Alaska is the strongest within about 150 km of that epicenter since an M 4.7 on March 11, 2019 and prior to that an M 4.8 on February 26, 2013 - probably an aftershock of the M 6.2 which shook the region on November 12, 2012. Forecasts 126176 and 126440 had expected this event in this region was likely between August  7 and 14.

 

O: 13AUG2020 02:49:39  58.6N  141.5W mb=4.5  EMSC   OFF COAST OF SOUTHEASTERN ALAS

P:  7AUG2020 126176    59.0N  139.0W 3.0-4.6 CBAAA  Southeast Alaska           

P: 14AUG2020 126440    59.0N  139.0W 3.0-4.6 ABAAA  Southeast Alaska           

 

The earthquake in the Northwest Territories of Canada was the first within

about 200 km of that epicenter with M>=4.5 since an M 4.7 on July 25, 2020 and was probably an aftershock of that event. Prior to that there had been no events

in the area of M>=4.5 since July 12, 2013 when an M 4.5-4.7 occurred aboutg 50 km southeast of today's epicenter. Forecast 126160 had expected the area southeast of this to be active in early August.

 

O: 13AUG2020 02:34:17  62.2N  124.4W mb=4.0  EMSC   NORTHWEST TERRITORIES, CANADA

O: 13AUG2020 02:34:19  62.1N  124.8W MB=4.5  ECAN of Wrigley, NT                 

P:  3AUG2020 126160    56.0N  120.0W 2.0-4.5 CCCAA  Alberta                    

 

An M 3.9 also occurred today in the Geysers area of Northern California. NEIC reported maximum intensity IV at Middletown and Kelseyville, California and II-III in Geyserville, Hidden Valley Lake, Healdsburg, Lower Lake, Calistoga, Cloverdale, Windsor and Pope Valley. This is the strongest earthquake in the California Geysers area since an M 3.9 on July 5, 2020. The only other such event in the Geysers area this year was an M 4.1 on March 25, 2020. Forecast 126079 had expected today's events within about 25 km around August 11.

 

O: 12AUG2020 11:48:51  38.8N  122.8W Md=2.1  EMSC   NORTHERN CALIFORNIA

O: 12AUG2020 11:45:43  38.8N  122.8W Mw=3.9  EMSC   NORTHERN CALIFORNIA          

P: 11AUG2020 126079    39.0N  122.8W 2.5-4.4 AAAAA  Central California         

 

An unusual earthquake of M 4.9-5.0 also occurred in the South Georgia Island area west of the South Sandwich Islands today. While an M 4.9 occurred in the region on March 8, 2020, the last event of larger magnitude was an M 5.2 on November 17, 2002, an aftershock of an M 6.6 on November 15, 2002. Forecasts 126239 and 126507 had expected this activity between August 7 and 14 to the east. This area had been expected to see far-field seismic enhancement following the M 7.8 in the Alaska Peninsula of July 22 as noted in previous issues of this summary:

 

"Far field triggering is likely with the earthquake in Alaska. .. Areas at 144 degrees from Alaska include Mozambique, the South Atlantic and Georgia and the western South Sandwich Islands" (July 22, 2020)

 

Today's event was at 148 degrees from the Alaska Peninsula epicenter.

 

O: 12AUG2020 07:39:42  55.3S   35.9W mb=4.9  EMSC   SOUTH GEORGIA ISLAND REGION  

O: 12AUG2020 07:39:42  55.3S   35.9W mb=5.0  ANSS   SOUTH GEORGIA ISLAND REGION  

P:  7AUG2020 126239    60.0S   29.0W 4.0-5.6 BCCAA  So. Sandwich Islands       

P: 14AUG2020 126507    60.0S   29.0W 4.0-5.6 ACCAA  So. Sandwich Islands       

 

MODERATE QUAKES IN KERMADEC; TONGA ISLANDS, XIZANG, CHINA

 

EARTHQUAKE SUMMARY FOR AUGUST 11, 2020

 

It was a quiet day in global seismicity today. The largest earthquakes of the day were of M 5.0 and were not reported felt. These occurred in Xizang, China and in the Tonga and Kermadec Islands of the southwest Pacific.

 

O: 11AUG2020 21:27:28  30.3N   94.8E mb=4.4  EMSC   EASTERN XIZANG               

O: 11AUG2020 18:14:19  30.4N   95.0E mb=5.0  EMSC   EASTERN XIZANG               

P: 11AUG2020 126108    32.0N   95.0E 3.5-5.0 ABAAA  So. China                  

 

O: 11AUG2020 10:53:40  28.4S  176.8W mb=5.0  EMSC   KERMADEC ISLANDS REGION      

P:  8AUG2020 126212    29.0S  176.0W 4.0-5.6 BAAAA  No. Kermadec Islands       

 

O: 11AUG2020 23:42:41  24.0S  175.6W mb=5.0  EMSC   TONGA REGION                 

P:  8AUG2020 126218    24.0S  175.0W 4.0-5.6 BAAAA  Tonga Islands              

 

The strongest earthquake reported felt today was an M 4.9 in El Salvador.

NEIC reported this earthquake of M 4.9 in El Salvador was felt with intensity IV-V in the area(s) of El Salvador at Nuevo Cuscatlan, Soyapango, San Salvador and III in Antiguo Cuscatlan and Nueva San Salvador. Forecast 126028 had expected seismicity within about 150 km of this epicenter was likely around August 8.

 

O: 12AUG2020 03:25:11  12.7N   88.3W mb=4.9  EMSC   OFFSHORE EL SALVADOR         

P:  8AUG2020 126028    14.0N   89.0W 3.5-5.3 BBAAA  Coast of Central America   

 

The swarm in southern California has largely dissipated. The strongest event at the end of the swarm was an M 3-4-3.6 near Bombay Beach. NEIC reported it was felt with maximum intensity IV in Indio and II-III in Ramona, Costa Mesa and Studio City, California. The strongest earthquakes in the swarm today were of M 3.4 and 2.7. The M 3.4 occurred south of the swarm of the past several days. Forecast 126102 had expected today's activity was likely within about 50 km around August 11.

 

O: 11AUG2020 11:20:30  33.2N  115.7W Ml=2.7  EMSC   SOUTHERN CALIFORNIA

O: 11AUG2020 21:52:39  31.7N  115.9W ML=3.4  EMSC   BAJA CALIFORNIA, MEXICO      

P: 11AUG2020 126102    32.8N  116.0W 2.5-4.5 AAAAA  So. California             

 

The strongest earthquakes in the U.S. or Canada today were a series of M 3.7 events in Alaska - in the Alaska Peninsula, Bering Sea and Northern Alaska. None of these were reported felt in these remote areas. Forecast 126166 had expected activity in the Alaska Peninsula around August 8.

 

O: 12AUG2020 05:02:59  54.6N  160.9W mb=3.7  EMSC   ALASKA PENINSULA             

O: 11AUG2020 07:15:55  54.7N  160.6W ML=3.3  EMSC   ALASKA PENINSULA

P:  8AUG2020 126166    55.0N  161.3W 3.5-4.9 BAAAA  Alaska Peninsula           

 

The earthquake in the Bering Sea is the strongest within about 250 km of that epicenter since an M 5.0 on January 16, 2018. That was followed by a series of aftershocks to the north lasting through an M 3.8 on September 30, 2018. The last event within about 200 km of today's epicenter was an M 4.6 on March 12, 1997.

 

O: 11AUG2020 18:38:01  61.5N  171.5W ml=3.7  EMSC   BERING SEA                   

 

O: 11AUG2020 20:23:18  65.3N  163.0W ML=3.7  EMSC   NORTHERN ALASKA              

 

 

MODERATE QUAKE SHAKES CALIFORNIA-MEXICO BORDER

 

EARTHQUAKE SUMMARY FOR AUGUST 10, 2020

 

The swarm of light earthquakes in southern California near the Mexico border continued today, maximizing with several events of M 4.0. NEIC reported maximum intensity up to IV in Calipatria, Westmorland and II-III in Brawley, El Centro and Trabuco Canyon among others. This summary had reported on this swarm in the previous issues as:

 

"A swarm of light earthquakes has been occurring in southeastern California near the Mexican border. This swarm began shortly after a C-class solar flare the strongest in more than two months. Swarms in this area of high heat flow are often associated with unusual flares or solar activity. Such swarms occasionally grow over several days and include a moderate sized event. But it also occurs that they grow without a recognizable mainshock and gradually dissipate. The C-Class solar flare was noted in the previous issues of this report as:

 

"The first solar flare of C-class or higher since May 29, 2020 (C9.3, M1.0) occurred near local solar midnight in North Carolina on August 8. This is the second largest solar flare in the past year following the May 29 event. Solar flares, especially rare ones such as this, can also help trigger seismicity in earthquake-prone areas.

 

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

 

6190       0342   0349      0355   C1.5      (August 8, 2020)   5.5E-04  

" (August 9, 2020)

 

The last series in this region which included an M 4.0 or greater event occurred on January 12, 2020; November 12, 2019 and November 19, 2018. Forecast 126102 had expected today's activity was likely around August 6-11. This activity is located at the 10th node (36 degrees) from the Alaska Peninsula and was probably promoted by energy from that source." (August 10, 2020)

 

The largest of today's earthquakes in Southern California was an M 4.6. NEIC reported It was felt with maximum intensity IV in Southern California at Niland and II-III in Calipatria, Thermal, Mecca, Brawley, El Centro, Coachella, Desert Center, Indio and La Quinta. Following is a listing of events in this swarm tpday of M>=3. A more extensive list of M>=2 events can be found in the "CALIFORNIA" regional listing below. It is also located at 100 degrees from the epicenter of the M 7.3 in New Guinea of July 17, 2020 and was probably promoted by energy from that event. Forecast 126120 had expected today's activity within about 50 km was likely around August 11. A foreshock to today's activity occurred several hours after the New Guinea quake on July 17.

 

O: 10AUG2020 22:44:51  33.1N  115.7W ML=3.3  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 13:33:56  33.2N  115.7W ML=3.0  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 15:58:16  33.2N  115.7W ML=3.2  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 16:03:39  33.2N  115.7W Mw=4.0  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 17:39:15  33.2N  115.7W Mw=3.5  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 18:29:59  33.2N  115.7W ML=3.2  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 18:53:21  33.2N  115.7W ML=3.1  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 18:58:52  33.2N  115.7W ML=3.1  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 16:00:13  33.3N  115.7W ML=3.0  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 16:13:55  33.3N  115.7W Mw=3.7  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 19:29:29  33.3N  115.7W Mw=4.0  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 15:55:47  33.3N  115.7W ML=4.0  EMSC   SOUTHERN CALIFORNIA

O: 10AUG2020 15:56:14  33.2N  115.7W mw=4.6  ANSS   SSE of Bombay Beach          

P: 11AUG2020 126102    32.8N  116.0W 2.5-4.5 AAAAA  So. California             

 

The largest earthquake in the world today was an M 5.7 near Savannah, Honduras.

NEIC reported maximum intensity V was felt in Honduras at Islas de la Bahia in Jose Santos Guardiola, Roatan, and Tocca Colon with IV in Savannah Bight, Monte Placentero, Sandy Bay, Trujillo Colon and lesser shaking at French Harbor, Rio Estebanand Utila, Honduras. This is the strongest earthquake in the area of Honduras within about 250 km of today's epicenter since an M 6.0 on April 16, 2020. Both may be aftershocks of an M 7.6 quake to the northeast on January 10, 2018.  Forecast 126039 had expected today's event within about 15 km of the epicenter was likely around August 9. This earthquake is at the sixth node (60 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and was probably promoted from that source.

 

O: 10AUG2020 14:13:28  16.9N   85.9W Mw=5.7  EMSC   OFFSHORE HONDURAS            

P:  9AUG2020 126039    17.0N   86.0W 3.5-5.3 AAAAA  Nicaragua                  

 

An unusual earthquake of M 4.9 was felt in northern Mozambique today. NEIC reported it was felt with intensity II in Nacala, Nampula, Mozambique.  This is the strongest earthquake in northern Mozambique within about 300 km of this epicenter since an M  4.9 on August 11, 2020 and prior to that an M 5.2 on July 15, 2015.

 

O: 11AUG2020 05:10:18  14.0S   40.8E mb=4.9  EMSC   MOZAMBIQUE                   

 

Earthquakes of M 4.5 and 4.6 also continued in Alaska today - in the Alaska Peninsula and in the Rat Islands, Aleutians. These were not reported felt. They had been expected in early August in forecasts 126174, 126166 and 126159.

 

O: 10AUG2020 14:30:21  51.3N  178.7E mb=4.5  EMSC   RAT ISLANDS, ALEUTIAN ISLANDS

P:  3AUG2020 126174    52.0N  178.0E 4.0-5.8 CAAAA  Rat Islands                

 

O: 10AUG2020 12:54:39  55.1N  158.0W mb=4.6  EMSC   ALASKA PENINSULA

O: 10AUG2020 18:53:37  55.9N  157.5W ML=2.7  EMSC   ALASKA PENINSULA

O: 11AUG2020 03:06:58  56.0N  156.1W ML=3.1  EMSC   SOUTH OF ALASKA

O: 10AUG2020 15:33:20  54.6N  160.6W mb=3.7  EMSC   ALASKA PENINSULA             

P:  7AUG2020 126159    54.7N  156.9W 3.5-5.1 BAAAA  Alaska Peninsula           

P:  8AUG2020 126166    55.0N  161.3W 3.5-4.9 AAAAA  Alaska Peninsula           

 

 

MODERATE SWARM ON CALIFORNIA-MEXICO BORDER

 

EARTHQUAKE SUMMARY FOR AUGUST 9, 2020

 

A swarm of light earthquakes has been occurring in southeastern California near the Mexican border. This swarm began shortly after a C-class solar flare the strongest in more than two months. Swarms in this area of high heat flow are often associated with unusual flares or solar activity. Such swarms occasionally grow over several days and include a moderate sized event. But it also occurs that they grow without a recognizable mainshock and gradually dissipate. The C-Class solar flare was noted in the previous issues of this report as:

 

"The first solar flare of C-class or higher since May 29, 2020 (C9.3, M1.0) occurred near local solar midnight in North Carolina on August 8. This is the second largest solar flare in the past year following the May 29 event. Solar flares, especially rare ones such as this, can also help trigger seismicity in earthquake-prone areas.

 

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

 

6190       0342   0349      0355   C1.5      (August 8, 2020)   5.5E-04  

" (August 9, 2020)

 

The last series in this region which included an M 4.0 or greater event occurred on January 12, 2020; November 12, 2019 and November 19, 2018. Forecast 126102 had expected today's activity was likely around August 6-11. This activity is located at the 10th node (36 degrees) from the Alaska Peninsula and was probably promoted by energy from that source.

 

O: 08AUG2020 12:49:50  32.9N  115.5W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O: 08AUG2020 12:42:19  32.9N  115.5W Ml=2.4  EMSC   SOUTHERN CALIFORNIA

O: 09AUG2020 02:45:11  33.0N  115.9W ML=2.8  EMSC   SOUTHERN CALIFORNIA

O: 09AUG2020 01:14:48  33.0N  115.9W Ml=2.2  EMSC   SOUTHERN CALIFORNIA

O: 09AUG2020 01:11:06  33.0N  115.9W Ml=2.0  EMSC   SOUTHERN CALIFORNIA

O:  8AUG2020 23:40:31  33.2N  115.6W Ml=2.0  EMSC   SOUTHERN CALIFORNIA          

O: 09AUG2020 21:03:23  33.3N  115.7W Ml=2.1  EMSC   SOUTHERN CALIFORNIA

P:  6AUG2020 126102    32.4N  115.8W 2.5-4.4 AAAAA  So. California             

P: 11AUG2020 126102    32.8N  116.0W 2.5-4.5 BAAAA  So. California             

 

The strongest earthquake in the world today was an M 5.9 in the area south of

Africa. It was accompanied by an M 5.4 aftershock of the M 6.3 in the Prince

Edward Islands in the same general region of the South Indian Ocean. This epicenter is near the antipode of the M 7.8 quake of July 22 in the Alaska Peninsula and had been expected to see antipodal triggering at this times in this summary as:

 

 

"Far field triggering is likely with the earthquake in Alaska. The antipode is located south of South Africa in the Indian Ocean east of Bouvet Island and is a possible site for triggered activity." (July 22, 2020)

 

The last earthquake within about 400 km of this epicenter with M>=5.9 was an M 6.6 on January 28, 2019 and prior to that an M 6.7 on October 10, 2017. Forecast 126237 had expected today's event to the east around August 11.

 

O:  9AUG2020 23:42:36  53.0S   11.7E Mw=5.9  EMSC   SOUTHWEST OF AFRICA           

P: 11AUG2020 126237    53.0S   19.0E 4.0-5.4 AACAA  Atlantic-Indian Ridge      

 

Other areas of the mid-ocean ridges were also active today. These included  an M 5.2 in the Central Mid-Atlantic Ridge and an M 4.7 in the Southern East Pacific Rise. These had been anticipated in early August in forecasts 125971 and 125982 within about 50 km of these epicenters.

 

O:  9AUG2020 16:30:30  41.7S   42.6E Mw=5.4  EMSC   PRINCE EDWARD ISLANDS REGION 

P: 30JUL2020 125971    41.0S   43.0E 4.0-5.4 CAAAA  So. Indian Ocean           

 

O:  9AUG2020 12:42:12   0.9N   27.7W Mw=5.2  EMSC   CENTRAL MID-ATLANTIC RIDGE   

P:  8AUG2020 125982     1.0N   28.0W 4.0-5.9 AAAAA  Central Mid-Atlantic Ridg  

 

O: 10AUG2020 01:39:13  23.5S  115.2W mb=4.7  EMSC   SOUTHERN EAST PACIFIC RISE   

P: 11AUG2020 126214    24.0S  115.0W 4.0-5.7 AAAAA  So. East Pacific Rise      

 

The strongest seismicity in the U.S. or Canada once again occurred in the Alaska Peninsula aftershock zone with M 5.2. It was not reported felt in this remote area. Forecasts 126166 and 126177 had expected this aftershock activity around August 8-9.

 

O: 09AUG2020 20:48:14  54.7N  161.2W ml=3.7  EMSC   ALASKA PENINSULA

O: 09AUG2020 12:39:46  54.9N  158.6W ml=3.4  EMSC   SOUTH OF ALASKA

O: 10AUG2020 06:49:42  54.9N  160.3W ML=4.1  EMSC   ALASKA PENINSULA

O:  9AUG2020 14:57:53  55.2N  158.1W Mw=5.2  EMSC   ALASKA PENINSULA             

P:  5AUG2020 126166    55.1N  159.3W 3.5-4.9 BAAAA  Alaska Peninsula           

P:  8AUG2020 126166    55.0N  161.3W 3.5-4.9 AAAAA  Alaska Peninsula           

P:  9AUG2020 126177    54.1N  162.8W 3.5-5.0 AAAAA  Unimak Islands, Aleutians  

 

MODERATE QUAKE IN VIRGINIA-NORTH CAROLINA WIDELY FELT

 

EARTHQUAKE SUMMARY FOR AUGUST 8, 2020

 

An earthquake of M 5.1 shook large areas of eastern U.S. today. This event was centered on the North Carolina-Virginia border. It was reported by nearly 100,000 persons to NEIC. Maximum intensity V was felt in North Carolina at Sarta, Glade Valle, Ennice, Roaring Gap, Traphill and Hays with IV in Laurel Springs, Thurmond, North Carolina and Independence, Virginia. Light to moderate shaking was reported throughout most of the eastern U.S. including in Tennessee, Virginia, Kentucky, North and South Carolina. It was also reported up to 1500 km from the epicenter in South Dakota, Kansas, Ontario, Nova Scotia, and Arizona among most other states in between.  While lighter foreshocks of M 2.2 and 2.1 occurred about a day earlier, an M 2.6 foreshock near local solar midnight may have been tidally enhanced. It was reported felt with maximum intensity V in North Wilkesboro, North Carolina; IV in North Carolina at Sparta, Hiddenite, Lenoir and Statesville among other localities. Damage was minimal but internet pictures showed store items thrown to the floor in many areas and cleanup will be extensive. Some structural damage was reported including the collapse of a chimney in Sparta, North Carolina. The last earthquake of similar or larger magnitude in the area was an M 5.2 on 1916 in the Great Smoky Mountains.

The earthquake of August, 2011 near Mineral, Virginia of M 5.8 was one of the largest in east coast history and did extensive damage as far as Washington, D.C. A series of foreshocks hit the region in the day prior to the mainshock with M 2.1-2.6.

 

Hurricane Isaias passed near this epicenter 5-6 days ago and stresses associated with that storm, the second in the region this year (following TS Arthur on May 17-18, 2020), probably enhanced the likelihood of today's seismicity. This was reported in this summary as possibly affecting regional seismicity at the time as:

 

TROPICAL STORM ISAIAS  

 

----  -------  ----------  --------  -----  ------  -------  ---------------

TS    ISAIAS   2020-08-03  00:00 UT  35.0N   74.9W   45 kts  U.S. east coast

 

TS Isaias continued today in the area along the U.S. east coast with winds up to 45 kts. It is expected to track to the north and west over the next several days. Enhanced seismicity in Puerto Rico and the Dominican Republic is expected with this storm while it is in the area. It is then expected track along the eastern seaboard of the U.S. at category 1 hurricane levels. Some minor seismicity in the region is possible with this weak storm, but no major earthquakes on the east or west coasts of the U.S. are thought likely with the track of this storm." (August 4-5, 2020)

 

 

Some of this activity may have also been promoted by tidal stresses. The main foreshocks of M 2.6 occurred within minutes of local solar midnight, a prime time for tidal stresses to trigger seismicity. The longitude is also near the longitude of maximum tidal stress with the previous full moon of August 3 as noted in previous issues of this summary:

 

"The full moon  arrived at 15:59 UT on August 3, 2020. Longitudes which were sub-solar (local solar noon) at this time are 60 West and 120 East and include in the west the Caribbean and Puerto Rico and portions of northern and western South America. Those in the east include the Philippines and central Indonesia near Sulawesi. These areas may see moderate seismic enhancement at this time. Many areas can see tidal enhancement with lunar-solar alignments so the seismicity of the earth is expected to be at active conditions through August 7." (August 2-5, 2020)

 

The first solar flare of C-class or higher since May 29, 2020 (C9.3, M1.0) occurred near local solar midnight in North Carolina on August 8. This is the second largest solar flare in the past year following the May 29 event. Solar flares, especially rare ones such as this, can also help trigger seismicity in earthquake-prone areas.

 

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

 

6190       0342   0349      0355   C1.5      (August 8, 2020)   5.5E-04  

 

Today's epicenter in North Carolina is near the seventh node (52 degrees) from the M 7.8 of July 22 in the Alaska Peninsula and was probably enhanced by energy from that source.

 

This is the strongest earthquake within about 250 km of this epicenter in the North Carolina-Virginia border region since an M 5.2 on July 8, 1926 and prior to that an M 5.5 on February 21, 1916 and 5.2 on January 1, and March 28, 1913. The largest quake in the area in recorded history was an M 5.8 on May 31, 1897.

The only event of M>=5.2 in this region  in the past 75 years was an M 5.6 west of this on November 30, 1973. This summary had noted this event in the history section of this report as:

 

 

"Felt over an area of about 150,000 sq. km. in Georgia, Kentucky, South Carolina, Tennessee, North Carolina, Tennessee, Virginia and West Virginia.  Cracks in walls were observed at the University of Tennessee Hospital in Knoxville.  Minor damage to walls and chimneys and cracked windows reported in Alcoa and Maryville, Tennessee. Electrical power was cut. This was the largest shock in eastern Tennessee in more than 60 years - since March 28, 1913." (November 30, 1919)

 

The M 5.2  on July 8, 1926 had been noted:

 

"Houses rattled, chimneys cracked, building foundations cracked, water pipelines broke and small objects moved within 6 miles of the epicenter." (July 8, 2020)

 

and that of M 5.3 on March 28, 2013 as:

 

"Near Knoxville, Tenn. Two shocks were felt over an area 70 by 40 miles, with noticeable rise and fall of ground in some places.  Fire alarms were set off. Knox County Courthouse, a massive structure trembled for two minutes. Movable objects were overthrown and bricks fell from chimneys. Nausea was reported by some." (March 28, 2020)

 

Forecast 126086 had expected enhanced seismicity within about 100 km of this epicenter was likely around August 9.

 

O: 08AUG2020 11:05:39  36.5N   81.1W ML=2.0  EMSC   VIRGINIA-N CAROLINA BORDER REG

O: 08AUG2020 11:12:32  36.5N   81.1W Md=2.3  EMSC   VIRGINIA-N CAROLINA BORDER REG

O: 09AUG2020 05:57:16  36.5N   81.1W mb=2.7  EMSC   VIRGINIA-N CAROLINA BORDER REG

O:  9AUG2020 12:07:37  36.5N   81.1W Mw=5.1  EMSC   VIRGINIA-N CAROLINA BORDER REG

O:  9AUG2020 12:07:37  36.5N   81.1W Mw=5.2  ANSS   VIRGINIA-N CAROLINA BORDER REG

P:  9AUG2020 126086    37.2N   81.9W 2.0-4.2 AAAAA  Kentucky/Tennessee/NC      

 

Earthquakes of M 3.7-3.8 off the coast of Northern California were also felt along the coastline. NEIC reported it was felt with intensity II-III in California at Ferndale, Whitethorn, Eureka, Arcata and Fort Bragg. Forecast 126143 had expected this activity was likely around August 6.

 

O: 09AUG2020 00:00:34  40.3N  124.7W Mw=3.7  EMSC   OFFSHORE NORTHERN CALIFORNIA

O:  9AUG2020 03:23:49  40.3N  124.9W ML=3.1  EMSC   OFFSHORE NORTHERN CALIFORNIA 

P:  6AUG2020 126143    40.2N  124.2W 2.5-4.6 BAAAA  Off Coast of No. Calif     

 

 

An earthquake of M 3.6 also occurred today off the coast of Oregon. NEIC reported it was felt lightly in Florence and Eugene, Oregon. When an M 6.3 earthquake occurred in the Prince Edward Island region yesterday, this summary noted the antipodal relation to areas off western Oregon and northwestern California as:

 

"This epicenter (in Prince Edward Islands) is near the antipode off the coast of Northern California and Oregon and could help enhance seismicity in that area in the next several days." (August 7, 2020)

 

Forecast 126145 had expected the event off Oregon was likely within about 50 km around August 5. The last event in this region of equal or larger magnitude was an M 3.9 on July 6, 2020.

 

O:  8AUG2020 08:51:25  43.9N  129.0W mb=3.6  EMSC   OFF COAST OF OREGON          

P:  5AUG2020 126145    44.4N  129.3W 3.0-4.5 BAAAA  Off Coast of Oregon        

 

The largest earthquake in the U.S. or Canada today was an M 5.5 aftershock in the Alaska Peninsula. NEIC reported it was felt with intensity IV in King Cove ad III in Chignik, Alaska. After an initial lull in aftershocks following the M 7.8 of July 22, 2020, earthquakes of M>=5 have been nearly a daily occurrence in the aftershock zone. Forecasts 126177 and 126166 had expected today's activity was likely around August 5-7.

 

O: 08AUG2020 16:12:02  54.7N  161.1W ML=3.4  EMSC   ALASKA PENINSULA

O: 09AUG2020 01:51:41  54.7N  161.2W mb=4.5  EMSC   ALASKA PENINSULA

O: 09AUG2020 03:30:21  54.7N  161.0W mb=3.9  EMSC   ALASKA PENINSULA

O: 08AUG2020 14:42:54  54.8N  161.2W Mw=5.5  EMSC   ALASKA PENINSULA

O: 08AUG2020 18:13:19  54.8N  161.2W ml=3.5  EMSC   ALASKA PENINSULA

O:  9AUG2020 06:39:49  54.6N  161.1W ML=3.3  EMSC   ALASKA PENINSULA             

P:  7AUG2020 126177    54.7N  161.2W 3.5-5.1 AAAAA  Unimak Islands, Aleutians  

 

O:  8AUG2020 12:53:00  55.0N  158.5W Mw=5.4  EMSC   SOUTH OF ALASKA              

P:  5AUG2020 126166    55.1N  159.3W 3.5-4.9 BAAAA  Alaska Peninsula           

 

An M 4.3 shook areas of South Island, New Zealand today. NEIC reported intensity II-III in Richmond, Nelson, Blenheim, Wellington and Christchurch. GEONET reported it was felt with moderate intensity in northern South Island. 2726 people reported feeling this event; 1765 with weak intensity; 883 with light shaking; 70 moderate; 5 strong; 2 with severe and 1 with extreme shaking. The last event listed by NEIC with M>=4.7 within about 150 km of this epicenter occurred October 22, 2017 with M 4.9. Forecast 126233 had expected today's event within about 10 km of the epicenter was  likely around August 7. This epicenter is at 100 degrees from the  Alaska Peninsula M 7.8 of July 22 and was probably promoted by energy from that event concentrated at the surface at this distance.

 

O: 08AUG2020 07:51:34  41.9S  173.0E ML=4.7  GEONET Felt with moderate intensity

O:  8AUG2020 07:51:32  41.9S  173.0E Mw=4.3  EMSC   SOUTH ISLAND OF NEW ZEALAND  

P:  7AUG2020 126233    42.0S  173.0E 3.0-5.1 AAAAA  So. Island, N.Z.           

 

MODERATE QUAKE RATTLES NORTHERN XINJIANG, CHINA

 

EARTHQUAKE SUMMARY FOR AUGUST 7, 2020

 

A moderate earthquake of M 5.3 shook regions of northern Xinjiang, China today.

NEIC reported this earthquake of M 5.3 in northern Xinjiang, China  was felt with intensity II-III in the area(s) of northern Xinjiang, China at Urumqi.

It was not reported with damage. This is the strongest earthquake in northern

Xinjiang, China within about 250 km of this epicenter since an M 5.5 about 100 km to the west on March 29, 2013.  Forecast 126130 had expected today's activity to the southwest was likely around August 10. Recent flooding in China may have helped promote this activity.

 

O:  8AUG2020 00:35:07  43.3N   87.7E mb=5.3  EMSC   NORTHERN XINJIANG, CHINA     

P: 10AUG2020 126130    42.0N   83.0E 4.0-5.4 ABCAA  Kirgizstan/Xinjiang        

 

An unusual visitor to modern seismicity occurred today in the Gilbert Islands, Kiribati area of the Pacific Ocean with  4.8.     This is the strongest earthquake in the Gilbert Islands regions within about 400 km of this epicenter in at least 30 years. A major swarm hit the region beginning in late 1981 and lasting through March, 1983 with many moderately large earthquakes. The area has been quiet since that time. There are no major tectonic features suggesting the region should be subject to this type of seismicity so this swarm remains largely unexplained. Today's event bears watching as it may be the first in renewed regional activity in this area.

 

O:  7AUG2020 14:12:56   3.6S  177.6E mb=4.8  EMSC   GILBERT ISLANDS, KIRIBATI REGI

 

A moderate aftershock in southern Idaho occurred today with M 4.2. NEIC reported it was felt with maximum intensity V in Idaho at Ketchum and IV in Lowman with II-III shaking in Stanley, Idaho City, Horseshoe Bend, Hailey, Garden City, Boise and Mountain Home and in general within about 100 km of the epicenter. This is the strongest aftershock in this long-lasting aftershock sequence of the M 6.5 of March 31, 2020 since an M 4.6 on June 25, 2020. Forecast 126133 had expected today's event within about 25 km was likely around August 6.

 

O:  8AUG2020 02:11:30  44.2N  115.1W mb=4.2  EMSC   SOUTHERN IDAHO               

P:  6AUG2020 126133    44.5N  115.1W 2.0-4.2 AAAAA  Montana/Idaho              

 

High latitude seismicity in the Arctic Ocean continued today was an M 4.5 in the Svalard region and an M 4.6 in Iceland. The event in Svalbard is the strongest in that region within about 250 km since an M 4.5 on May 10, 2020 although more recent events of M 5.0-5.2 have occurred on June 5 and most recently north ot this on August 5 (M 5.3) in this region. This summary noted the event on August 5 as:

 

"An unusual M 5.3 struck near the North Pole north of Svalbard today. It was not reported felt in this remote area. This is the farthest north of any event of M>=5.3 in at least 30 years. Activity had been expected at high latitudes such as this associated with the geomagnetic  disturbance as noted in previous issues of this report:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 16.  High latitude geomagnetic field active conditions  with AP at 26. This is the most active the geomagnetic field has been in the past month. The last period of more disturbance was on April 20, 2020 when AP was 18. Moderate geomagnetic storms such as this can help promote seismicity at high latitudes and near the geomagnetic equator within several days of the storm.." (August 3-5, 6, 2020)

 

Forecast 125923 had expected today's event within about 50 km was likely at the end of July or in early August.

 

O:  7AUG2020 13:18:57  78.6N    7.1E mb=4.5  EMSC   SVALBARD REGION              

P: 29JUL2020 125923    79.0N    7.0E 4.0-5.6 CAAAA  Arctic Ocean Region        

 

The M 4.6 in Iceland is the strongest in that area since an M 6.0 shook the area on June 21, 2020. Forecast 126186 had expected this activity was likely to the southeast around August 7.

 

O: 08AUG2020 03:52:58  66.3N   18.4W ML=3.7  EMSC   ICELAND REGION

O:  8AUG2020 03:42:33  66.3N   18.4W ML=4.6  EMSC   ICELAND REGION               

P:  7AUG2020 126186    65.0N   16.0W 3.0-4.8 ABAAA  Iceland area               

 

 

M 6.3 NEAR ALASKA ANTIPODE IN PRINCE EDWARD ISLAND REGION, INDIAN OCEAN

 

EARTHQUAKE SUMMARY FOR AUGUST 6, 2020

 

Ocean ridges were active today with moderately large to large events in the region of the Prince Edward Islands (M 6.3) and in the Easter Island area of the south Pacific (M 5.4). The largest earthquake in the world today was an  6.3 in the south Indian Ocean near Prince Edward Islands. While not exact, this is in the antipodal region of the M 7.8 in the Alaska Peninsula of July 22, 2020 and may have been promoted by energy from that event as noted in previous issues of this report:

 

"Far field triggering is likely with the earthquake in Alaska. The antipode is located south of South Africa in the Indian Ocean east of Bouvet Island and is a possible site for triggered activity." (July 22, 2020)

 

This epicenter is near the antipode off the coast of Northern California and Oregon and could help enhance seismicity in that area in the next several days. The only events in this area of M>=6.3 in the past 20 years were an M 6.7 on January 22, 2019 and an M 6.3 on July 4, 2005. Forecast 125971 had expected today's activity within about 100 km was likely in late July or early August, 2020.

 

O:  6AUG2020 23:36:45  41.7S   42.5E Mw=6.3  EMSC   PRINCE EDWARD ISLANDS REGION 

P: 30JUL2020 125971    41.0S   43.0E 4.0-5.4 CAAAA  So. Indian Ocean           

 

The earthquake of M 5.5 in the Easter Island region, South Pacific was not felt in that remote area. The last event within about 300 km of this epicenter with M>=5.5 was an M 5.5 on January 23, 2016. Forecast 126214 had expected today's activity about 200 km to the south around August 5.

 

O:  6AUG2020 13:57:37  22.8S  112.4W mb=5.5  EMSC   EASTER ISLAND REGION         

P:  5AUG2020 126214    25.0S  112.0W 4.0-5.4 ACAAA  So. East Pacific Rise      

 

The strongest earthquake felt in the world today was another of M 5.5 in the series in southern Peru which has been ongoing since the M 7.8 in the Alaska Peninsula of July 22. This area is at about 103 degrees from the Alaskan epicenter and subject to triggering from energy concentration related to that event. NEIC reported today's event was felt with intensity V in Acari, Arequipa and II in Marcona, Ica, Peru. There have been several moderately large quakes felt in southern Peru in the past several days. In a previous summary some of this activity was summarized as:

 

 

"The strongest earthquake in the world today was an M 5.5 in northern Chile. NEIC reported it was felt in Northern Chile with IV in Iquique, Tarapaca and in Arica and Calama, Antofagasta and in southern Peru with II-III in Arequipa and Tacna. This area has been active with moderate earthquakes since the M 7.8 in the Alaska Peninsula of July 22. It is located at 102-104 degrees from that epicenter and is likely being promoted by concentrated energy from that source.

GUC reported this earthquake was felt with intensity V in  Tarapaca at Camina, La Tirana; IV in Alto Hospicio, Huara, Iquique, Mamina, Pica; III in Pisagua and Pozo Almonte; in Arica with IV in Codpa and Cuya and III in Arica, San Miguel de Azapa and Cocon Chile, Chile. An aftershock about 100 km to the south occurred later with M 4.5-4.7. GUC reported the earthquake of M 4.5 was felt with intensity IV in  Tarapaca at Pica; III in Alto Hospicio and Iquique and II in Camina and in Arica at Arica with intensity III, Chile. NEIC reported this earthquake of M 4.7 in northern Chile  was felt with intensity II-III in the area(s) of northern Chile at Iquique, Tarapaca. The only similar event within about 100 km of this epicenter in the past two years was an M 6.3 6.2 on November 1, 2018 near today's epicenter. Forecasts 126217 and 126203 had expected today's activity within this area was likely around August 4-5. Other recent activity in southern Peru and northern Chile commented on in this summary may have been precursory to today's event. This event is at 104-105 degrees from the M 7.8 of July 22 n the Alaska Peninsula and was probably promoted by energy from that source." (August 4, 2020)

 

Forecasts 126196 and 126202 had expected this activity in early August in southern Peru. Today's epicenter is at 101-102 degrees from the western edge of the Alaska Peninsula M 7.8 of July 22, the region current showing the most aftershock activity.

 

O:  6AUG2020 22:18:06  15.9S   74.9W Mw=5.5  EMSC   NEAR COAST OF SOUTHERN PERU  

P:  8AUG2020 126202    16.0S   72.0W 4.0-5.7 AABAA  So. Peru/Bolivia           

P: 11AUG2020 126196    15.0S   76.0W 4.0-5.4 BAAAA  Central Peru               

 

An earthquake of M 4.9 was widely felt with minor damage in Algeria today. NEIC reported maximum intensity IV in Algeria at Qararim, Milah; V in Constantine, IV in Ruwasad, Faji Mazallah, Hamma, Ayn Samara, al-Hurub and III in Tamalus and al-Harus. Two similar events hit northern Algeria in the past year - an M 5.0 on March 24 and an M 4.9 on January 24, 2020. These events occurred northwest of today's epicenter. An earthquake of M 4.6 in Northern Algeria occurred on July 4, 2020 and two of M 4.5 hit south of today's event on July 14 and 17, part of a minor regional swarm. Forecast 126119 had expected today's activity was likely to the west of this epicenter around August 5. This is at the fifth node (72 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and at twice this distance (144 degrees) from the M 6.8 in New Guinea and may have been promoted by energy from these sources. Puerto Rico often sees enhanced seismicity at this time of year due to interactions of strong hurricanes with regional plates. The last great tsunami-genic earthquake in the region of Puerto Rico occurred 74 year ago as an M 8.0+ event on August 4, 1946 in the Puerto Rico trench far to the north of today's epicenter. A repeat of this event is overdue in the area.

 

O:  7AUG2020 06:15:37  36.5N    6.3E Mw=4.9  EMSC   NORTHERN ALGERIA             

O:  6AUG2020 15:09:24  36.9N    5.9E mb=4.1  EMSC   NORTHERN ALGERIA             

P:  5AUG2020 126119    37.0N    3.0E 3.0-4.5 AABAA  Western Mediterranean      

 

An aftershock of M 4.8-5.1 in the southern region of Puerto Rico was felt throughout the island today. NEIC reported maximum intensity IV in Yauco, Adjuntas, Laja, Lares, Hatillo and II-III at Ponce, Ciales, Cabo Rojo, Isabela and Corozal among other communities in Puerto Rico. The last earthquake in the southern aftershock of M>=5.1 was an M 5.3 on July 3, 2020. These are the strongest far-period aftershocks of the M 6.5 in the area of January 7, 2020. An M 5.3-5.4 also hit the area on May 2, 2020, the first such from mid-January through July. Forecast 126045 had expected today's event was likely within  the aftershock zone around August 6.

 

O:  6AUG2020 22:28:49  17.9N   66.7W mb=4.0  EMSC   PUERTO RICO REGION           

O:  7AUG2020 03:26:59  18.0N   66.8W mb=5.1  EMSC   PUERTO RICO REGION            

P:  6AUG2020 126045    18.0N   67.0W 3.4-4.9 AAAAA  Puerto Rico                

 

An unusually large M 5.4 also occurred in the Buru area of Indonesia today.

The last earthquake within about 200 km of this epicenter with M>=5.4 was an

M 5.6 on June 9, 2020, the only such event since a similar M 5.6 on October 11, 2018. Forecast 125999 had expected today's event within about 100 km was likely around

August 5.

 

O:  7AUG2020 03:00:39   3.8S  126.3E Mw=5.4  EMSC   BURU, INDONESIA              

P:  5AUG2020 125999     4.0S  127.0E 4.0-5.4 AAAAA  Ceram area                 

 

An earthquake of M 3.0 was widely felt south of San Francisco, California today. It was reported with intensity II-III in California at Pescadero, Davenport, Santa Cruz, Boulder Creek, Felton, Scotts Valley, Portola Valley, Los Altos and Los Gatos among others. It occurred at a somewhat unusual epicenter off the coast. In the past unusual quake off the coast of central California have occasionally been followed within days by larger events on the San Andreas Fault Zone.  The last such event of M>=3 off the coast of southern San Francisco was an  M 3.4 on June 4, 2016. An M 2.8-2.9 hit near this epicenter on June 23, 2020, the last of M>=2.8 since an M 2.8 on June 22, 2018. Forecast 126078 had expected today's activity was likely around August 7.

 

O:  6AUG2020 16:00:27  37.1N  122.4W ML=2.7  EMSC   OFFSHORE NORTHERN CALIFORNIA 

O:  6AUG2020 16:00:27  37.1N  122.4W ML=3.0  ANSS   OFFSHORE NORTHERN CALIFORNIA 

P:  7AUG2020 126078    37.3N  121.6W 2.5-4.5 AAAAA  Central California         

 

STRONG EARTHQUAKE IN VANUATU TIDALLY PROMOTED

 

EARTHQUAKE SUMMARY FOR AUGUST 5, 2020

 

A strong M 6.5 earthquake shook central Vanuatu today. It occurred less than

an hour from local solar midnight, a time when tidal stresses are maximized

and was probably enhanced by stresses associated with the full moon of

August 3. The last earthquake within about 200 km of today's epicenter in

Vanuatu of M>=6.5 was an M 6.6 on July 31, 2019 and prior to that an M 6.8 on May 9, 2017.  Forecasts 125941 and 126207 had expected this activity was likely within about 100 km in late July or early August. Vanuatu is located near the geomagnetic equator and may have been promoted by the geomagnetic storm yesterday, the strongest in at least three months. This epicenter is also at 144-145 degrees from the M 7.5 in Oaxaca, Mexico of June 23, a distance at which energy is concentrated on the earth's surface following major earthquake and was probably enhanced by energy from that source.

 

O:  5AUG2020 12:05:36  16.1S  168.1E Mw=6.5  EMSC   VANUATU                      

P:  6AUG2020 126207    18.0S  168.0E 4.0-5.5 ABAAA  Vanuatu Islands            

P: 30JUL2020 125941    17.0S  168.0E 4.0-5.6 BAAAA  Vanuatu Islands            

 

An antipodal pair was completed today when an M 5.5 occurred in the Sunda area of Indonesia. The antipode in northern Venezuela saw an M 5.0 on August 2.  NEIC reported the earthquake of M 5.0 in northern Venezuela  was felt with intensity II-III in the area(s) of northern Venezuela at Mucurapo Diego, Port of Spain, Tunapuna, Trinidad and Tobago and at Saint Georges and Saint Davids, Grenada.  Forecast 126049 had expected this event in Venezuela was likely around August 7. Earthquakes of larger magnitude in northern Venezuela in the past year occurred on April 7, 2020 (M 5.2) and September 9, 2019 (M 5.5).

 

O:  2AUG2020 00:03:47  10.8N   62.6W Mw=5.0  EMSC   OFFSHORE SUCRE, VENEZUELA    

P:  7AUG2020 126049    10.0N   63.0W 3.4-5.1 BAAAA  Windward Islands           

 

The M 5.5 in Sunda, Indonesia was reported by BMG to have been felt with intensity III in Kota Bima, Tambolaka, Wainngapu and Waitabula, Sumba, Indonesia. It is the strongest within about 250 km of that epicenter since an M 6.4 on January 22, 2019 and an M 6.0 on January 21, 2019. The last such earthquake within about 200 km of today's epicenter was an M 6.2 on December 29, 2016. It is likely that the earthquake in Indonesia and the Venezuelan quake were promoted by strong tidal stresses as they occur very near the longitudes of maximum tidal stress with the full moon of August 3 as earlier reported in this summary:

 

"The full moon  arrived at 15:59 UT on August 3, 2020. Longitudes which were sub-solar (local solar noon) at this time are 60 West and 120 East and include in the west the Caribbean and Puerto Rico and portions of northern and western South America. Those in the east include the Philippines and central Indonesia near Sulawesi. These areas may see moderate seismic enhancement at this time. Many areas can see tidal enhancement with lunar-solar alignments so the seismicity of the earth is expected to be at active conditions through August 7." (August 2-5, 2020)

 

Forecasts 125937 and 126001 had expected this activity in late July or early August within about 150 km of this epicenter. This is near geomagnetic equator and the fourth node (90 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and may have been promoted by energy from those sources.

 

O: 05AUG2020 09:18:17   9.8S  119.1E ML=4.3  EMSC   SUMBA REGION, INDONESIA

O: 05AUG2020 12:04:51   9.9S  119.2E ML=4.1  EMSC   SUMBA REGION, INDONESIA

O:  5AUG2020 08:27:11   9.7S  119.1E mb=5.5  EMSC   SUMBA REGION, INDONESIA      

P: 11AUG2020 126001     7.0S  120.0E 4.0-5.6 ACAAA  Flores Island area         

P: 27JUL2020 125937    11.0S  119.0E 4.0-5.5 CBAAA  So. of Indonesia           

 

An unusually large earthquake of M 5.4 shook areas of eastern Honshu, Japan today northeast of Tokyo. This epicenter is at 103-104 degrees from the M 7.5 in Oaxaca, Mexico of June 23, 2020 and may have been enhanced by concentrated energy from that source. The last earthquake with M>=5.4 within about 200 km of this epicenter occurred on June 24, 2020 as an M 5.9 south of this epicenter. The last earthquake in this area of M>=6.0 was an M 6.3 a year ago on August 4, 2019 about 200 km north of today's event. Quakes within about 150 km of this epicenter in the past year of M>=5.4 occurred on May 10 (M 5.8) and January 2, 2020 (M 5.6). Forecast 126097 had expected today's event within about 100 km of this epicenter was likely around August 6.

 

NEIC reported this earthquake of M 5.4  off eastern Honshu, Japan  was felt with intensity II-III in the area(s) of eastern Honshu, Japan in Chiba and Ibaraki.

 

O:  5AUG2020 17:53:59  36.1N  141.7E Mw=5.4  EMSC   NEAR EAST COAST OF HONSHU, JAP

P:  6AUG2020 126097    37.0N  142.0E 4.0-5.4 AAAAA  Off East Coast Honshu      

 

The strongest earthquake in the U.S. or Canada today was an M 5.2 aftershock in the Alaska Peninsula zone. It was reported by NEIC to have been felt with intensity III in King Cove, Alaska. This aftershock zone has been active with such events over the past week to 10 days. but this and a similar event of M 5.2 yesterday is the strongest aftershock in the area since an M 5.6 on July 29. Forecast 126177 had expected today's event was likely within about 10 km of this epicenter around August 7. It was preceded by an M 3.7 foreshock about 1.5 minutes earlier.

 

O: 05AUG2020 16:16:13  54.1N  160.3W mb=3.7  EMSC   ALASKA PENINSULA

O: 05AUG2020 20:36:57  54.5N  160.5W mb=4.0  EMSC   ALASKA PENINSULA

O:  5AUG2020 16:17:41  54.6N  161.2W Mw=5.2  EMSC   ALASKA PENINSULA             

P:  7AUG2020 126177    54.7N  161.2W 3.5-5.1 AAAAA  Unimak Islands, Aleutians  

 

An unusual M 5.3 struck near the North Pole north of Svalbard today. It was not reported felt in this remote area. This is the farthest north of any event of M>=5.3 in at least 30 years. Activity had been expected at high latitudes such as this associated with the geomagnetic  disturbance as noted in previous issues of this report:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 16.  High latitude geomagnetic field active conditions  with AP at 26. This is the most active the geomagnetic field has been in the past month. The last period of more disturbance was on April 20, 2020 when AP was 18. Moderate geomagnetic storms such as this can help promote seismicity at high latitudes and near the geomagnetic equator within several days of the storm.." (August 3-5, 2020)

 

Forecast 125923 had expected a moderate event to the south of this was likely in late July or early August.

 

O:  5AUG2020 08:48:05  87.4N    7.6E mb=5.3  EMSC   NORTH OF SVALBARD            

P: 29JUL2020 125923    79.0N    7.0E 4.0-5.6 CDAAA  Arctic Ocean Region        

 

MODERATELY STRONG QUAKES SHAKE TURKEY; GUATEMALA

 

EARTHQUAKE SUMMARY FOR AUGUST 4, 2020

 

Moderately strong earthquakes of M 5.8 and M 5.5  occurred in the regions of

Guatemala and eastern Turkey today.  The earthquake of M 5.8 shook regions of Guatemala today. NEIC reported it was felt with intensity II-III in San Marcos, Guatemala and in Villahermosa, Tabasco, Mexico. An M 4.1 aftershock followed the mainshock half an hour later. The only quake in or near Guatemala of equal or larger magnitude in the past year was an M 5.9 about 100 km northeast of today's epicenter on December 19, 2019. The last of M>=6 in Guatemala was an M 6.8 on June 22, 2017. Forecasts 126030 and 126025 had expected this activity in Guatemala was like around August 6. Today's mainshock in Guatemala occurred within about an hour of local solar noon, a prime time for tidal triggering and may have been enhanced by tidal stresses associated with the full moon of August 3.

 

O:  4AUG2020 19:17:52  13.3N   92.0W Mw=5.8  EMSC   OFFSHORE GUATEMALA           

O:  4AUG2020 19:48:12  13.3N   92.5W ML=4.1  EMSC   OFF THE COAST OF GUATEMALA   

P:  6AUG2020 126030    13.0N   91.0W 3.5-5.3 AAAAA  Guatemala                  

P:  6AUG2020 126025    14.0N   93.0W 3.5-5.3 AAAAA  Chiapas, Mexico             

 

A moderate earthquake of M 5.5 also occurred in eastern Turkey today. NEIC reported it was felt with intensity V in Turkey at Diyarbakir and IV in Malatya and Elazig. An aftershock of M 4.5 was also felt with intensity III in Arapkir, Malatya, Turkey. This appears to be the strongest aftershock to date of an M 6.8 on January 24, 2020. It was followed by moderate aftershocks of its own of M 4.8, 4.4 and 4.0. Today's M 5.5 occurred within minutes of local solar noon when tidal stresses are maximized and was probably enhanced by tidal stresses associated with the full moon of August 3. Forecasts 125835 and 126116 had expected today's activity was likely within about 50 km of this epicenter in late July or early August.

 

O: 04AUG2020 13:10:18  38.2N   38.8E mb=4.0  EMSC   EASTERN TURKEY

O: 04AUG2020 15:30:58  38.2N   38.8E ML=4.4  EMSC   EASTERN TURKEY

O: 04AUG2020 18:40:03  38.2N   38.8E Mw=4.8  EMSC   EASTERN TURKEY

O:  4AUG2020 09:37:36  38.2N   38.7E Mw=5.5  EMSC   EASTERN TURKEY               

P:  7AUG2020 126116    39.0N   40.0E 3.5-5.2 BAAAA  Turkey                     

P: 26JUL2020 125835    38.0N   39.0E 3.5-5.0 CAAAA  Turkey                     

 

The strongest earthquake in the U.S. or Canada today was an M 5.2 aftershock in the Alaska Peninsula zone. It was reported by NEIC to have been felt with intensity III in King Cove, Alaska. This aftershock zone has been active with such events over the past week to 10 days. but this is the strongest aftershock in the area since an M 5.6 on July 29. Forecast 126177 had expected today's event was likely within about 10 km of this epicenter around August 7.

 

O:  4AUG2020 12:47:18  54.7N  161.1W Mw=5.2  EMSC   ALASKA PENINSULA             

P:  7AUG2020 126177    54.7N  161.2W 3.5-5.1 BAAAA  Unimak Islands, Aleutians  

 

An unusual earthquake in the Arctic Ocean north of Siberia in the area north of Severnaya Zemlya, Russia occurred today with M 4.6. It was not reported felt in this remote area. This continues activation of the Arctic area which has included mostly light to moderate sized quakes in the past several days. This may be related  to the geomagnetic storm which occurred yesterday. This summary had previously noted in this regard:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 16.  High latitude geomagnetic field active conditions  with AP at 26. This is the most active the geomagnetic field has been in the past month. The last period of more disturbance was on April 20, 2020 when AP was 18. Moderate geomagnetic storms such as this can help promote seismicity at high latitudes and near the geomagnetic equator within several days of the storm.." (August 3-5, 2020)

 

It may also be related to the full moon tidal stresses which maximized near this longitude on August 3 and occurred near local solar midnight, a prime time for high tidal stresses. Tidal stresses had been thought to be triggers for enhanced seismicity in previous issues at this time as:

 

"The full moon  arrived at 15:59 UT on August 3, 2020. Longitudes which were sub-solar (local solar noon) at this time are 60 West and 120 East and include in the west the Caribbean and Puerto Rico and portions of northern and western South America. Those in the east include the Philippines and central Indonesia near Sulawesi. These areas may see moderate seismic enhancement at this time. Many areas can see tidal enhancement with lunar-solar alignments so the seismicity of the earth is expected to be at active conditions through August 7." (August 2-5, 2020)

 

The last earthquake of similar size in the area within about 300 km of this epicenter was an M 4.7 on January 12, 2020. The last of larger magnitude was an M 5.1 on September 13, 2012. Forecast 126195 had expected this event within about 200 km was likely in early August.

 

O:  4AUG2020 14:52:14  83.5N  115.1E mb=4.6  EMSC   NORTH OF SEVERNAYA ZEMLYA    

P: 11AUG2020 126195    82.0N  119.0E 4.0-5.5 CrBAA  Arctic Ocean Region        

 

SO

GEOMAGNETIC DISTURBANCE ENHANCES SEISMICITY NEAR GEOMAGNETIC EQUATOR

 

EARTHQUAKE SUMMARY FOR AUGUST 3, 2020

 

A new geomagnetic storm began today near mid-day. It was accompanied by a series of B-class solar flares, the first since early June, 2020. It was followed by moderately large earthquake of M 5.5-5.6 near the geomagnetic equator in the Mariana Islands and in Northern Chile/Southern Peru. This summary had expected this activity as:

 

"The geomagnetic field saw disturbed conditions today. The AP level was 16.  High latitude geomagnetic field active conditions  with AP at 26. This is the most active the geomagnetic field has been in the past month. The last period of more disturbance was on April 20, 2020 when AP was 18. Moderate geomagnetic storms such as this can help promote seismicity at high latitudes and near the geomagnetic equator within several days of the storm." (August 3-4, 2020)

 

The strongest earthquake in the world today was an M 5.5 in northern Chile. NEIC reported it was felt in Northern Chile with IV in Iquique, Tarapaca and in Arica and Calama, Antofagasta and in wouthern Peru with II-III in Arequipa and Tacna. This area has been active with moderate earthquakes since the M 7.8 in the Alaska Peninsula of July 22. It is located at 102-104 degrees from that epicenter and is likely being promoted by concentrated energy from that source.

GUC reported this earthquake was felt with intensity V in  Tarapaca at Camina, La Tirana; IV in Alto Hospicio, Huara, Iquique, Mamina, Pica; III in Pisagua and Pozo Almonte; in Arica with IV in Codpa and Cuya and III in Arica, San Miguel de Azapa and Cocon Chile, Chile. An aftershock about 100 km to the south occurred later with M 4.5-4.7. GUC reported the earthquake of M 4.5 was felt with intensity IV in  Tarapaca at Pica; III in Alto Hospicio and Iquique and II in Camina and in Arica at Arica with intensity III, Chile. NEIC reported this earthquake of M 4.7 in northern Chile  was felt with intensity II-III in the area(s) of northern Chile at Iquique, Tarapaca. The only similar event within about 100 km of this epicenter in the past two years was an M 6.3 6.2 on November 1, 2018 near today's epicenter. Forecasts 126217 and 126203 had expected today's activity within this area was likely around August 4-5.

Other recent activity in southern Peru and northern Chile commented on in this summary may have been precursory to today's event.

 

O:  3AUG2020 11:56:51  19.6S   69.3W Mw=5.5  EMSC   TARAPACA, CHILE              

O:  3AUG2020 11:56     19.6S   69.2W mb=5.5  GUC    Tarapaca at Camina, La Tirana;

P:  4AUG2020 126217    20.0S   69.0W 4.0-5.9 AAAAA  So. Peru/Bolivia           

P:  5AUG2020 126203    19.0S   69.0W 4.0-5.7 AAAAA  So. Peru/Bolivia           

 

O:  3AUG2020 18:26     20.5S   69.0W mb=4.5  GUC    Tarapaca at Pica; III in Alto

P:  3AUG2020 126210    21.0S   69.0W 4.0-5.9 AAAAA  Coast No. Chile            

 

An M 5.5-5.6 also shook regions of the Northern Mariana Islands today. NEIC reported intensity II in Tinian to the south of the epicenter. This is the strongest earthquake in the northern Marianas within about 200 km of this epicenter since an M 5.9 on October 26, 2018. Forecast 125761 had expected today's activity was likely within about 50 km these epicenters in late July.

 

O:  3AUG2020 12:45:52  17.0N  147.5E mb=4.9  EMSC   MARIANA ISLANDS REGION       

O:  3AUG2020 08:31:10  17.1N  147.4E Mw=5.6  EMSC   MARIANA ISLANDS REGION       

P: 28JUL2020 125761    17.0N  147.0E 4.0-5.5 BAAAA  No. Marianas               

 

A light M 3.5 earthquake was felt widely in the Los Angeles, California area today. NEIC reported intensity IV in Anaheim, Placenta, Fullerton, Villa Park, Yorba Linda, Brea and III in Orange, among other communities. This is the largest earthquake in eastern Los Angeles since an M 3.6 on April 3, 2019. Earthquakes of M 3.8 and 4.2 hit the San Fernando Valley area west of Los Angeles on July 30, 2020. Forecast 126105 had expected today's activity within about 30 km of this epicenter was likely around August 4.

 

O:  3AUG2020 22:18:50  33.9N  117.8W ML=3.4  EMSC   GREATER LOS ANGELES AREA, CALI

O:  3AUG2020 22:20:05  33.9N  117.8W Ml=2.0  EMSC   GREATER LOS ANGELES AREA, CALI

P:  4AUG2020 126105    34.2N  117.8W 2.5-4.4 AAAAA  So. California             

 

 

UTHWEST PACIFIC REMAINS ACTIVE

 

EARTHQUAKE SUMMARY FOR AUGUST 2, 2020

 

The strongest earthquake in the world today was an M 5.8 in the Bismarck Sea. This is part of the regional activity which began yesterday in the area. This summary had noted with the M 6.0 yesterday in this regard:

 

"Earthquake of M 5.7 and 6.0 (in that order) also occurred in eastern Indonesia today in the region of the Bismarck Sea. They were not reported felt in this remote area. The  6.0 is the strongest in the Bismarck Sea since an M 6.4 on July 25, 2016. Forecast 126005 had expected today's activity was likely within about 50 km of this epicenter around August 6. Like the M 5.6 in the D'entrecasteaux Islands yesterday this epicenter is at the fifth node (72 degrees ) from the Alaska Peninsula and was probably promoted by energy from that source. Other such events today occurred at or near 72 degrees from Alaska in Mindanao, Philippines (M 6.4)," (August 1-2, 2020)

 

O:  2AUG2020 09:29:57   3.1S  149.0E Mw=5.8  EMSC   BISMARCK SEA                  

P:  6AUG2020 126005     3.0S  149.0E 4.0-5.4 BAAAA  New Ireland                

 

An M 5.4 was felt widely in eastern New Guinea today. NEIC reported felt intensity IV in the Eastern Highlands at Goroka and in Kindiawa and II-III in Madang, Kainantu, Mount Hage, Lalibu and Port Moresby, Papua New Guinea. This is the strongest earthquake in this area within about 200 km of this epicenter

since events of M 5.7 to the north on January 30, 2020 and M 5.9 on March 4, 2019. Forecast 126006 had expected today's activity was likely around August 5 within about 100 km.

 

O:  2AUG2020 14:15:48   5.0S  145.4E Mw=5.3  EMSC   EASTERN NEW GUINEA REG., P.N.G

O:  3AUG2020 02:35:19   5.0S  145.4E mb=4.4  EMSC   EASTERN NEW GUINEA REG., P.N.G

P:  5AUG2020 126006     4.0S  146.0E 4.0-5.6 AAAAA  New Ireland                

 

The strongest earthquake in the world today was an M 4.9 in the Alaska Peninsula area. This area has seen daily aftershocks of this size each day for the past week. Forecast 125905 had expected this event within about 25 km of this epicenter was likely around July 31.

 

O: 02AUG2020 07:44:52  54.7N  161.1W ML=3.0  EMSC   ALASKA PENINSULA

O: 02AUG2020 18:58:33  54.9N  160.3W ml=3.4  EMSC   ALASKA PENINSULA

O: 02AUG2020 12:16:09  55.1N  158.3W ML=3.4  EMSC   ALASKA PENINSULA

O: 03AUG2020 03:36:58  55.2N  159.5W mb=3.8  EMSC   ALASKA PENINSULA

O:  2AUG2020 14:39:23  54.6N  161.1W mb=4.9  EMSC   ALASKA PENINSULA             

P: 31JUL2020 125905    54.3N  161.4W 3.5-4.9 AAAAA  Unimak Islands, Aleutians  

 

A moderate earthquake also occurred today in the area south of Africa with M 4.7. This epicenter is in the antipodal area of the M 7.8 in the Alaska Peninsula of July 22 and was probably promoted by focused energy at the antipode of that event. The last earthquake in this area south of Africa with M>=4.7 was an M 5.1 on February 9, 2020 and prior to that an M 5.4 on January 10, 2020 and an M 5.6 on August 22, 2018. This forecast had expected this area would be active following the Alaska Peninsula quake at this time as:

 

"Far field triggering is likely with the earthquake in Alaska. The antipode is located south of South Africa in the Indian Ocean east of Bouvet Island and is a possible site for triggered activity." (July 22, 2020)

 

O:  3AUG2020 00:36:04  52.9S   27.7E mb=4.7  EMSC   SOUTH OF AFRICA              

 

Earthquakes at 103 degrees from the Alaska Peninsula epicenter today included the continuing swarm in southern Peru and northern Chile, Indonesia and an M 4.1 in the South Island of New Zealand. The New Zealand event had been expected in forecast 126234 within about 100 km of the epicenter was likely around August 3. This summary had expected in its far-field forecast that both of these areas would see enhanced seismicity at this time as:

 

"Far field triggering is likely with the earthquake in Alaska ... those near 103 degrees include northern Chile and southern Peru; South Island, New Zealand; Sumatra and southwestern Indonesia." (July 22, 2020)

 

O:  2AUG2020 21:40:15  45.1S  167.5E ML=4.1  EMSC   SOUTH ISLAND OF NEW ZEALAND  

P:  3AUG2020 126234    44.0S  169.0E 3.0-4.9 ABAAA  So. Island, N.Z.           

 

O:  2AUG2020 11:01:01  19.8S   69.9W mb=3.9  EMSC   TARAPACA, CHILE              

P:  4AUG2020 126217    20.0S   69.0W 4.0-5.9 AAAAA  So. Peru/Bolivia           

 

STRONG QUAKES SHAKE MINDANAO, PHILIPPINES; BISMARCK SEA

 

EARTHQUAKE SUMMARY FOR AUGUST 1, 2020

 

It was an active day in global seismicity. A series of moderately strong to strong earthquakes were recorded around the world.  Many of today's stronger events occurred in areas and at times suggesting tidal enhancement with the full moon of August 3 which effects on seismicity were expected as:

 

"The full moon will arrive at 15:59 UT on August 3, 2020. Longitudes which are sub-solar (local solar noon) at this time are 60 West and 120 East and include in the west the Caribbean and Puerto Rico and portions of northern and western South America. Those in the east include the Philippines and central Indonesia near Sulawesi. These areas may see moderate seismic enhancement at this time. Many areas can see tidal enhancement with lunar-solar alignments so the seismicity of the earth is expected to be at active conditions through August 7." (August 1-2, 2020)

 

The strongest earthquake in the world today was an M 6.4 in Mindanao, Philippines. It was reported by NEIC to have been felt with intensity IV in Mindano at Simuay and Taviran and with light intensity in Libertad. This earthquake is located at 124 East longitude, near the maximum tidal stress with this full moon.  This is the strongest earthquake in Mindanao within about

200 km of this epicenter during 2020 - the last such event was an M 6.8 on December 15, 2019. The area was in an active period with events of M 5.6 on July 31 and M 5.8 on July 27, 2020 recently occurring. Forecasts 125707 and 125991 had expected today's activity in late July or early August.

 

 

O:  1AUG2020 17:09:01   7.3N  124.1E Mw=6.4  EMSC   MINDANAO, PHILIPPINES        

P:  5AUG2020 125991     6.0N  125.0E 4.0-5.6 BBAAA  Mindanao, Philippines       

P: 24JUL2020 125707     7.0N  124.0E 4.0-5.6 CAAAA  Central Philippines        

 

Earthquake of M 5.7 and 6.0 (in that order) also occurred in eastern Indonesia today in the region of the Bismarck Sea. They were not reported felt in this remote area. The  6.0 is the strongest in the Bismarck Sea since an M 6.4 on July 25, 2016. Forecast 126005 had expected today's activity was likely within about 50 km of this epicenter around August 6. Like the M 5.6 in the D'entrecasteaux Islands yesterday this epicenter is at the fifth node (72 degrees ) from the Alaska Peninsula and was probably promoted by energy from that source. Other such events today occurred at or near 72 degrees from Alaska in Mindanao, Philippines (M 6.4), the Solomon Islands, Samoa, Poland, Tajikistan, Costa Rica, the Dominican Republic and Puerto Rico.

 

O: 01AUG2020 19:18:12   3.1S  148.9E mb=4.6  EMSC   BISMARCK SEA

O: 01AUG2020 19:08:50   3.2S  148.7E Mw=5.7  EMSC   BISMARCK SEA

O:  1AUG2020 19:22:06   3.3S  148.6E Mw=6.0  EMSC   BISMARCK SEA                 

P:  6AUG2020 126005     3.0S  149.0E 4.0-5.4 BAAAA  New Ireland                

 

Moderately large events also occurred today with M 5.6 in Tonga and M 5.7 in  southern Vanuatu. They were not reported felt. Forecasts 125956 and 126211 had expected this activity in late July or early August.

 

O:  1AUG2020 19:45:45  23.1S  175.9W Mw=5.6  EMSC   TONGA REGION                 

P: 29JUL2020 125956    23.0S  175.0W 4.0-5.4 AAAAA  Tonga Islands              

 

O:  2AUG2020 03:01:33  20.8S  173.5E Mw=5.7  EMSC   VANUATU REGION               

O:  2AUG2020 03:03:06  26.8S  174.7E ML=4.8  EMSC   SOUTHEAST OF LOYALTY ISLANDS 

P:  3AUG2020 126211    22.0S  171.0E 4.0-5.5 ABBAA  Loyalty Islands            

 

The strongest earthquake in the U.S. or Canada today was an M 4.9 aftershock in the Alaska Peninsula area. Aftershock of this size or greater have occurred each of the past five days in the area, but were absent for several days before that. NEIC reported this earthquake of M 4.9 in the Alaska Peninsula  was felt with intensity II-III in the area(s) of the Alaska Peninsula at Sand Point.  Forecast 125905 had expected today's activity within about 50 km was likely around July 31.

 

O: 01AUG2020 14:53:24  54.9N  160.3W ml=3.0  EMSC   ALASKA PENINSULA

O: 01AUG2020 21:05:12  55.0N  159.1W mb=3.5  EMSC   SOUTH OF ALASKA

O: 01AUG2020 23:28:10  55.2N  159.6W ML=3.0  EMSC   ALASKA PENINSULA

O:  1AUG2020 07:00:11  54.6N  160.4W mb=4.9  EMSC   ALASKA PENINSULA             

P: 31JUL2020 125905    54.3N  161.4W 3.5-4.9 AAAAA  Unimak Islands, Aleutians  

 

A moderate earthquake of M 4.4 also occurred today in Hawaii. NEIC reported this earthquake of M 4.2-4.4 in Hawaii  was felt with intensity II-III in the area(s) of Hawaii at Naalehu, Volcano, Captain Cook, Pahoa, Mountain View, Hilo, Holualoa, Kurtistown, Keaau and Kealakekua. This follows an M 4.6 on July 27 and events of M 4.5 and 4.7 on July 3, an active period in Hawaiian seismicity.

Forecast 125750 had expected today's event within about 25 km was likely around July 30.

 

O:  1AUG2020 20:03:06  19.3N  155.4W mb=4.4  EMSC   ISLAND OF HAWAII, HAWAII     

P: 30JUL2020 125750    19.2N  155.2W 3.0-4.4 AAAAA  Hawaii                     

 

The strongest earthquake today in South America was an M 5.1 in southern Peru.

 

NEIC reported this earthquake of M 5.1 in Southern Peru  was felt with intensity II-III in the area(s) of Southern Peru at Camana, Mollendo and Arequipa, Peru.  This area has been active for the past 10 days following the Alaska Peninsula quake of M 7.8 on July 22. It is located at 102-104 degrees from that epicenter a distance at which strong concentration of energy occurs due to internal  earth reflections of discontinuities. Today's event had been expected in early August in forecast 126202. More such activity in northern Chile and southern Peru may be expected in the coming days. This activity is near the longitude of maximum tidal stress with the upcoming full moon and may have been enhanced by stresses associated with that alignment. Other such earthquakes near 60 West longitude today included an M 4.0 in Puerto Rico; an M 5.0 in northern Venezuela and several moderate event in Sulawesi, Indonesia near 120 East longitude.

 

O:  1AUG2020 08:25:26  16.3S   72.6W Mw=5.1  EMSC   NEAR COAST OF SOUTHERN PERU  

P:  6AUG2020 126202    17.0S   71.0W 4.0-6.1 BAAAA  So. Peru/Bolivia           

P:  8AUG2020 126202    16.0S   72.0W 4.0-5.7 CAAAA  So. Peru/Bolivia           

 

 

NEIC reported the earthquake of M 3.5-4.0 in Southern Puerto Rico  was felt with intensity II-III in the area(s) of Southern Puerto Rico at Corozal.

 

O:  1AUG2020 20:07:58  18.0N   66.7W ML=4.0  EMSC   PUERTO RICO                  

P:  4AUG2020 126045    18.0N   67.0W 3.4-4.9 BAAAA  Puerto Rico                

 

NEIC reported the earthquake of M 5.0 in northern Venezuela  was felt with intensity II-III in the area(s) of northern Venezuela at Mucurapo Diego, Port of Spain, Tunapuna, Trinidad and Tobago and at Saint Georges and Saint Davids, Grenada.

 

O:  2AUG2020 00:03:47  10.8N   62.6W Mw=5.0  EMSC   OFFSHORE SUCRE, VENEZUELA    

P:  7AUG2020 126049    10.0N   63.0W 3.4-5.1 BAAAA  Windward Islands           

 

O:  1AUG2020 07:56:36   0.1S  122.9E mb=4.5  EMSC   SULAWESI, INDONESIA          

P:  6AUG2020 125990     0.0N  123.0E 4.0-5.6 BAAAA  Mindanao, Philippines      

 

O:  1AUG2020 20:28:20   2.1S  123.0E ML=4.0  EMSC   SULAWESI, INDONESIA          

P:  4AUG2020 126017     1.0S  124.0E 4.0-5.4 BBAAA  Sulawesi area              

 

ENHANCED SEISMICITY IN SOUTHWEST PACIFIC

 

EARTHQUAKE SUMMARY FOR JULY 31, 2020

 

The strongest seismicity today was in the Southwest Pacific where several events of M>=5.2 occurred in the D'entrecasteaux area. These were not reported felt in this remote area. The last earthquake of M>=5.6 in the D'entrecasteaux region occurred on March 10, 2019 with M 6.1. Today's event was followed by aftershocks of M 4.7 and 4.2. An earthquake of M 5.2 also occurred in the Solomon Islands and in New Britain  with M 5.3 today These events had been forecast in 125736 and 126016 in late July or early August. This activity is near the fifth node (72 degrees) from the M 7.8 in the Alaska Peninsula of July 22 and may have been promoted by energy from that source.

 

O: 31JUL2020 17:05:59   7.5S  156.8E Mw=5.2  EMSC   SOLOMON ISLANDS              

P:  3AUG2020 126016     7.0S  155.0E 4.0-5.4 BABAA  Solomon Islands            

P: 24JUL2020 125736     8.0S  155.0E 4.0-5.4 CABAA  Solomon Islands            

 

O: 31JUL2020 10:02:16   8.7S  152.7E Mw=5.6  EMSC   D'ENTRECASTEAUX ISLANDS REGION

O: 31JUL2020 16:17:15   8.8S  152.9E mb=4.7  EMSC   D'ENTRECASTEAUX ISLANDS REGION

P: 24JUL2020 125736     8.0S  155.0E 4.0-5.4 CABAA  Solomon Islands            

 

O: 31JUL2020 20:37:44  10.8S  151.0E mb=4.2  EMSC   D'ENTRECASTEAUX ISLANDS REGION

P:  3AUG2020 126199    10.0S  151.0E 4.0-5.4 BAAAA  New Ireland                

 

O: 31JUL2020 16:04:18   5.5S  151.9E mb=5.3  EMSC   NEW BRITAIN REGION, P.N.G.   

P: 31JUL2020 125726     6.0S  154.0E 4.0-5.5 BABAA  New Britain                

 

Two factors were setting up today which may help enhance global seismicity in the next several days. The first is an upcoming geomagnetic storm which is expected in early August, but has not yet begun. The other is the full moon expected August 3. This summary expects seismicity related to the full moon as:

 

"The full moon will arrive at 15:59 UT on August 3, 2020. Longitudes which are sub-solar (local solar noon) at this time are 60 West and 120 East and include in the west the Caribbean and Puerto Rico and portions of northern and western South America. Those in the east include the Philippines and central Indonesia near Sulawesi. These areas may see moderate seismic enhancement at this time. Many areas can see tidal enhancement with lunar-solar alignments so the seismicity of the earth is expected to be at active conditions through August 7." (July 31-August 1)

 

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Fox Islands, Aleutians, Alaska. It was not reported felt in this remote epicentral area. It was followed by an energetic aftershock sequence including two events of M 3.9. This is the strongest earthquake in the Fox Islands since an M 4.6 on July 12, 2020 and prior to that on June 15, 2020. Forecast 125895 had expected today's quake was likely within about 100 km of this epicenter around July 28.

 

O: 31JUL2020 18:43:56  51.3N  168.5W ml=3.3  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 31JUL2020 18:43:56  51.3N  168.5W ml=3.3  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 31JUL2020 19:10:03  51.3N  168.6W mb=3.9  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 31JUL2020 19:47:58  51.4N  168.6W mb=3.9  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 31JUL2020 19:51:41  51.4N  168.6W mb=4.4  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

O: 31JUL2020 07:45:29  51.3N  168.6W ml=3.4  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 28JUL2020 125895    52.4N  169.4W 3.5-5.1 BAAAA  Fox Islands, Aleutians     

 

 

 

WESTERN LOS ANGELES, CALIFORNIA VALLEYS SHAKE

 

EARTHQUAKE SUMMARY FOR JULY 30, 2020

 

A series of light to moderate earthquakes shook the valleys west of Los Angeles, California today. The largest of these was an M 4.2 near San Fernando. It was felt with maximum intensity V in San Fernando, California, Mission Hils, North Hills; IV in Pacoima, Granada Hills, Panorama City, Northridge, Porter Ranch, Sun Valley and III in Newhall. Moderate earthquakes in this series were reported felt with intensity V in Pacoima and IV in San Fernando, Van Nuys and II-III in Mission Hills, Granada Hills, Newhall, Panorama, Northridge, Sun Valley. An M 4.1 off the coast of northern California occurred minutes before the Los Angeles activity. It was possibly felt on the coast of Northern California with light intensity. This is the strongest earthquake in the San Fernando Valley, California area since an M 4.2-4.3 on January 4, 2015. At the time this summary noted in this regard:

 

"The last earthquake of similar or larger magnitude within 50 km of this epicenter in the Los Angeles area occurred as an M 4.4 on March 17, 2014 and as an M 4.3 on September 1, 2011. A foreshock to the south occurred on December 30, 2014 and was followed several hours later by a foreshock of M 3.1 at today's epicenter. A similar sequence preceded the 1994 Northridge earthquake." (January 4, 2015)

 

The effects of Hurricane Hanna which hit southern Texas over the past several days cannot be discounted in today's earthquake series. This summary had previously noted in this regard:

 

"Hurricane Hanna dissipated south of Southern Texas with winds up to 25 kts.  Some regional seismicity and some effects on the western edge of the North America plate may accompany landfall of this storm." (July 29, 2020)

 

Similar conditions accompanied the M 4.3 of September 1, 2011 as noted in this summary at the time:

 

"As noted in this summary over the past week, a series of unusually large earthquakes has been occurring in California and has been migrating to the south since Hurricane Irene hit the continental shelf in late August. This sequence began with an M 3.6 and 3.7 in San Francisco, then an M 4.6 near Hollister and an M 3.7 in the San Simeon area. Our summary speculated that this was likely to include an unusually large earthquake in southern California." (September 2, 2011)

 

Triggering effects from the Alaska Peninsula earthquake of M 7.8 of July 22 should also not be discounted in this case. The epicenters in Los Angeles area near the 10th node (36 degrees) from the western edge of that aftershock zone and at exactly 36.0 degrees from the M 6.1 of July 28 in Alaska.

 

This summary had previously expected this area was close to a strong local event as part of the approximately 22-year repeat cycle. Today’s events may help to elucidate where the progress towards that event is at this time.

 

O: 30JUL2020 11:31:07  34.3N  118.5W Ml=2.1  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 11:34:26  34.3N  118.4W Ml=2.1  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 11:38:38  34.3N  118.4W ML=2.9  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 11:39:19  34.3N  118.5W Ml=2.2  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 12:02:25  34.3N  118.4W Ml=2.1  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 13:48:18  34.3N  118.4W ML=3.8  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 13:59:17  34.3N  118.4W ML=2.3  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 14:24:50  34.3N  118.4W ML=2.3  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 21:11:02  34.3N  118.5W Ml=2.0  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 22:04:57  34.3N  118.4W Ml=2.3  EMSC   GREATER LOS ANGELES AREA, CALIF.

O: 30JUL2020 11:29:29  34.3N  118.4W Mw=4.2  EMSC   GREATER LOS ANGELES AREA, CALI

P: 27JUL2020 125826    34.4N  118.6W 2.5-4.5 AAAAA  So. California             

 

The M 4.1 off the coast of northern California that occurred about 40 minutes before the M 4.2 in San Fernando had been expected within about 15 km of that epicenter in forecast 125869.

 

O: 30JUL2020 10:50:23  40.5N  127.1W mb=4.1  EMSC   OFF COAST OF NORTHERN CALIFORN

P: 29JUL2020 125869    40.4N  127.2W 2.5-4.5 AAAAA  Off Coast of No. Calif     

 

The largest earthquake in the U.S. or Canada today was an M 4.9-5.0 in the Alaska Peninsula aftershock zone. NEIC reported it was felt with intensity II-III in Alaska at Chignik and Sand Point. This follows several days of enhanced seismicity in the Alaska Peninsula aftershock zone. This activity had been expected at this time in forecast 125887.

 

O: 30JUL2020 11:46:14  54.6N  161.1W ml=3.3  EMSC   ALASKA PENINSULA

O: 30JUL2020 13:11:22  54.6N  161.0W ml=3.6  EMSC   ALASKA PENINSULA

O: 30JUL2020 16:08:19  55.0N  158.4W Mw=4.9  EMSC   ALASKA PENINSULA             

P: 28JUL2020 125887    54.7N  157.9W 4.5-6.0 AAAAA  Alaska Peninsula           

 

The strongest earthquakes in the world today were an M 5.6 in Mindanao, Philippines. and an M 5.7 in the Tonga Islands. NEIC reported maximum intensity V for the Mindanao quake in Rosariao, Caraga, Philippines; IV in Bag-asa, Southern Mindanao and II-III in Butuan, Caraga and Davao and Mandawa, Central Visayas. This event near the fifth node (72 degrees) from the Alaska Peninsula continues quakes near this magnitude over the past several days including an M 5.8 on July 27. Forecast 125712 had expected today's activity was likely around July 30.

 

O: 31JUL2020 06:06:44   8.5N  126.6E Mw=5.6  EMSC   MINDANAO, PHILIPPINES        

P: 30JUL2020 125712     7.0N  127.0E 4.0-5.9 ABAAA  Halmahera                   

 

The last event in Tonga of larger magnitude than M 5.7 was an M 6.2 north of today's epicenter on July 18, 2020. The last such event within about 200 km of today's event was an M 5.8 on February 28, 2020. The last of M>=6 was aa November 11, 2019 with M 6.1. Forecast 125955 had expected today's activity at the end of July. NEIC reported this earthquake of M 5.7 in Tonga  was felt with intensity II-III in the area(s) of Tonga at Neiafu, Vava'u.

 

O: 30JUL2020 19:16:49  18.9S  173.5W Mw=5.7  EMSC   TONGA                        

P: 29JUL2020 125955    20.0S  175.0W 4.0-5.7 ABBAA  Tonga Islands              

 

An unusual M 4.7 quake hit the Falkland Islands off the east coast of southern Argentina today. The only other such earthquake in the area in the past year was an M 4.6 on July 8, 2020. This is an unusual epicenter. The last earthquake of M>=4.7 within about 300 km of this was an M 4.8 on December 8, 2018 but the last of larger magnitude occurred on November 25, 2013 with M 7.0 and several aftershocks of M 5.4-5.5. Hours before the San Fernando, California earthquake (M 6.9) of February 9, 1971 an M 7.1 occurred southwest of today's epicenter. The distance between the San Fernando quakes today and the M 4.7 in the Falkland Islands is 103 degrees.

 

O: 30JUL2020 07:09:40  54.4S   55.8W mb=4.7  EMSC   FALKLAND ISLANDS REGION      

 

An M 3.7 was also widely felt in northern New Mexico today. NEIC reported it was felt with intensity V in New Mexico at Coyote; IV in Lindrith and Ouba; and II-III in Gallina, Counselor, La Jara, Jemez Springs, El Rito, Abiqulu and Tierra Amarilla. This epicenter is at the ninth node (40.0 degrees) from the epicenter of the  M 7.8 in the Alaska Peninsula and was probably promoted by energy from that  source. Other areas at the ninth node include areas of Baja California.  Only two other such earthquakes within about 100 km of today's epicenter in Northern New Mexico have occurred in the past 30 years - an M 3.7 on June 4, 2008 and an M 4.3 on August 1, 2004.

 

O: 30JUL2020 15:04:11  36.2N  106.8W mb=3.7  EMSC   NEW MEXICO                   

P: 26JUL2020 125802    37.0N  105.2W 2.0-3.9 BABAA  Colorado area