Older Summaries

MODERATE EARTHQUAKES SHAKE NORTHERN CALIFORNIA

EARTHQUAKE SUMMARY FOR SEPTEMBER 30, 2023

The strongest earthquakes in the U.S. or Canada today occurred off the coast of northern California. NEIC reported the largest of these - of M 4.7 was felt with maximum intensity V in California at Loleta and IV in Ferndale, Fortuna, Rio Dell, Hydesville, Eureka, Petrolia and Samoa. An aftershock of M 4.2 was felt with intensity IV in Ferndale, Loleta and III in Rio Dell, Fortuna, Petrolia, Hydesville and Scotia among others. An M 3.7 aftershock was also felt with intensity II-III in northern California in Hydesville, Eureka and Whitethorn.

The last earthquake off the coast of Northern California with M>=4.7 was an M 5.6 on May 21, 2023. A strong M 6.4 hit the area on December 20, 2022. At the time this summary noted:

"Today's M 6.4 is the strongest within about 200 km of this epicenter in Northern California since an M 6.8 on March 10, 2014 and an M 6.5 on January 10, 2010 and an M 7.1 on June 15, 2005, the only such earthquakes in this area in at least 25 years." (December 20, 2022)

Forecast 156791 had expected today's event off Northern California was likely within about 25 km of today's epicenter around September 26. Today's activity was timed near local solar noon and may have been promoted by tidal stresses with the full moon of September 29.

O: 30SEP2023 17:25:19 40.5N 124.5W md=2.1 ANSS OFF COAST OF NORTHERN CALIFORNIA

O: 30SEP2023 15:26:26 40.6N 124.3W mw=4.7 ANSS OFF COAST OF NORTHERN CALIFORNIA

O: 30SEP2023 17:25:19 40.5N 124.5W md=2.1 ANSS OFF COAST OF NORTHERN CALIFORNIA

O: 30SEP2023 17:16:47 40.5N 124.4W mw=4.2 ANSS OFF COAST OF NORTHERN CALIFORNIA

O: 30SEP2023 19:58:21 40.5N 124.5W md=2.0 ANSS OFF COAST OF NORTHERN CALIFORNIA

P: 26SEP2023 156791 40.4N 124.2W 2.5-4.6 AAAAA Off Coast of No. Calif

STRONG EARTHQUAKE IN MACQUARIE ISLANDS

EARTHQUAKE SUMMARY FOR SEPTEMBER 29, 2023

The strongest earthquakes in the world today occurred in the world's oceans

with an M 5.8 in the Macquarie Islands south of Australia, an M 5.2 in the Azores and an M 5.2 in the South Sandwich Islands. These occurred near local solar noon and midnight and may have been promoted by tidal stresses with the current full moon as noted in this and previous issues of this summary:

"The full moon arrived on September 29 at 09:57 UT. This is the last supermoon of the year. Supermoons occur when the moon is closest to the earth on its elliptical orbit. The considerably increases tidal stress and possibility of strong earthquakes. Longitudes which are at local solar noon at this time are located near 30 East longitude while those at local solar midnight are near 150 West longitude. In the east these include These include Hawaii and areas of eastern Alaska and western Canada and to a lesser extent areas off the coast of Oregon and California while in the east they include Eastern Turkey where an M 7.7 hit on February 6, 2023 as well as Ethiopia and areas off southern Africa and eastern Europe. These and surrounding areas are the most likely to see tidally enhanced seismicity at this time. A large to major earthquake is considered likely in the next week at this time." (September 28-30, 2023)

The last similar earthquake in the Macquarie Islands within about 300 km of today's epicenter was an M 5.7-5.8 on November 20, 2020. At the time this summary noted:

"The strongest earthquake in the world, and the only event of M>=5 today was an M 5.7 in the Macquarie Island area south of Australia. This continues a series of moderate to moderately strong earthquakes in this area which began several days ago and included event of M 4.6 on November 9; an M 5.7 on November 13 and an M 4.4 on November 14. These events occurred about 1000 km to the east of today's activity. The last activity within about 300 km of today's event with M>4 occurred on August 27, 2020 with M 4.8. The last earthquake of M>=5.7 within about 500 km of today's epicenter was an M 6.0 on August 21, 2019 and an M 6.5 April 18, 2019 and M 5.9 February 27, 2016." November 20, 2020)

O: 30SEP2023 00:32:00 52.8S 140.2E ML=5.8 AUS MACQUARIE IS

O: 30SEP2023 00:31:59 52.9S 140.2E mw=5.8 ANSS MACQUARIE ISLANDS

The event of M 5.2 in the South Sandwich Islands of larger magnitude than M 5.2 2as an M 5.7 on August 20, 2023. A regional foreshock of M 5.0 hit the South Sandwich Islands on September 25 following a series of such events in mid-September. Forecast 156892 had expected today's earthquake within about 25 km was likely in the South Sandwich Islands around September 27.

O: 29SEP2023 22:36:09 58.0S 25.5W mb=5.2 ANSS SOUTH SANDWICH ISLANDS

P: 27SEP2023 156892 58.0S 25.0W 4.0-5.8 AAAAA So. Sandwich Islands

The M 5.2 in the Azores follows a series in the Azores on September 23-25, 2023.

At the time this summary noted:

A swarm of earthquakes has been occurring in the Azores Islands region of Portugal over the past several days. The largest of these events occurred today with M 4.6 and M 4.1. This activity may be related to the passage of Hurricane Nigel through the region over the past several days as noted in previous issues of this summary. For example it was stated on September 22:

"Hurricane Nigel (15) continued today in the area of the central Atlantic north of the Azores and over the mid-Atlantic Ridge with winds up to 70 kts. It is expected to track to the northeast. Some seismic enhancement is possible in the Atlantic Ridge system as this storm passes through." (September 22, 2023)

The last earthquake with M>=4.6 within about 200 km of today's epicenters in the Azores occurred as an M 4.8 on January 27, 2020." (September 25, 2023)

Today's event was not part of that swarm having occurred about 200 km to the west of the events of September 25. Forecast 156730 expected today's event was likely in late September within about 150 km of this epicenter.

O: 29SEP2023 19:05:44 38.4N 30.2W mw=5.2 ANSS AZORES

P: 22SEP2023 156730 38.0N 32.0W 4.0-5.6 CABAA No. Mid-Atlantic Ridge

The strongest earthquake in the U.S. or Canada today was an M 4.7-4.9 in the eastern Andreanof Islands, Aleutians, Alaska. It was not reported felt in this remote area. Forecast 156814 had expected today's event was likely within about 100 km was likely to occur around September 26.

O: 29SEP2023 15:23:51 51.0N 170.2W ML=4.7 MOS ANDREANOF ISLANDS

O: 29SEP2023 15:24:21 56.7N 173.5W ML=4.9 GFZ ANDREANOF ISLANDS

O: 29SEP2023 15:23:51 51.1N 170.2W mb=4.2 ANSS ANDREANOF ISLANDS

P: 26SEP2023 156814 51.9N 169.2W 3.5-5.0 BAAAA Fox Islands, Aleutians

STRONG INCREASE IN SEISMICITY WITH FULL SUPER-MOON TIDAL STRESSES

EARTHQUAKE SUMMARY FOR SEPTEMBER 28, 2023

Seismicity was considerably higher in the world today than in the past week. Included in this activity was an M 6.1 in Vanuatu and an M 6.3 in New Ireland. These are near the equator and as noted in previous issues of this summary may have been promoted by strong tidal stresses associated with the overhead noon time sun at this time of year as In the previous summary this had been addressed as:

"A series of earthquakes occurred along the equator over the past several days.

These included moderate events in Gabon, the Central Atlantic, Ecuador, Indonesia and Rwanda among others. This summary has noted in previous issues that seismic enhancement often occurs at sub-solar latitudes due to the vertical tidal stresses. At the fall and spring equinox the sun is directly over the equator and can help promote seismicity along the equator as is currently being seen with the fall equinox." (September 28, 2023)

Among today's equatorial earthquakes were a series in Papua New Guinea and New Ireland which included events of MM 5.6, M 5.4-5.5 and M 5.0. The last earthquake of M>=5.4 in New Ireland was an M 6.0 on March 7, 2023 about 250 km north of today's events. A series of smaller events occurred in the past week as a regional activation of seismicity. This included an M 4.5 on September 27, an M 4.7 on September 24 and an M 5.0 on September 22, 2023. Forecast 156649 had expected today's activity within about 25 km was likely at the end of September.

This activity is at 148 degrees from the M 6.8 in Morocco of September 8 and at 103 degrees from the Prince Edward Islands M 6.8 of May 21, 2023 and at the fifth node (72 degrees) from the Alaska Peninsula and may have been promoted by energy from those sources.

O: 29SEP2023 01:53:17 5.2S 152.8E mb=5.0 ANSS NEW IRELAND

O: 29SEP2023 01:19:37 4.6S 153.2E mw=5.5 ANSS PAPUA NEW GUINEA

O: 29SEP2023 01:19:36 4.6S 153.1E ML=5.4 GFZ NEW IRELAND

O: 29SEP2023 00:14:36 5.3S 152.7E mb=4.7 ANSS PAPUA NEW GUINEA

O: 28SEP2023 19:39:04 5.3S 152.9E mb=4.5 ANSS PAPUA NEW GUINEA

O: 29SEP2023 01:19:36 4.6S 153.1E ML=5.4 GFZ NEW IRELAND

O: 28SEP2023 19:21:14 5.2S 152.7E ML=5.6 GFZ NEW BRITAIN

P: 26SEP2023 156649 7.0S 154.0E 4.0-5.6 ABBAA New Britain

P: 22SEP2023 156649 5.0S 153.0E 4.0-5.4 CAAAA New Britain

A strong earthquake also occurred today in the region of the Kuril Islands, Hokkaido, Japan with M 6.2. The last earthquake within the Kuril Islands and within about 200 km of today's epicenter was an M 7.0 on February 13, 2020 and an M 6.3 on July 7, 2015. On February 13, 2020 this summary noted in regard to the seismic history of this region:

"Today's event of M 7.0 in the Kuril Islands is the strongest quake recorded in the Southern Kuril Islands in near seven years - since an M 7.2 on April 19, 2013 and prior to that an M 7.3 on November 17, 2002. After the M 7.7 in Cuba region of January 28, it is the strongest earthquake in the world during 2020." (February 13, 2020)

Forecast 156774 had expected today's event was likely around September 27 within about 50 km. This epicenter is located at 102 degrees from the M 6.8 in Morocco of September 8, 2023 and may have been promoted by energy from that source.

O: 28SEP2023 17:40:04 44.3N 148.6E mw=5.8 ANSS KURIL ISLANDS

O: 28SEP2023 17:40:07 44.3N 148.5E ML=6.2 GFZ KURIL ISLANDS

P: 27SEP2023 156774 44.0N 149.0E 3.5-5.4 AAAAA Hokkaido, Japan

Another strong earthquake in the world today was an M 6.1 in Central Vanuatu. NEIC reported it was felt with intensity IV in Luganville, Sanma. The last earthquakes in Vanuatu of equal of greater magnitude than M 6.0 were an M 6.1 on September 21, 2023 about 200 km north of today's epicenter and a similarly placed M 6.5 on August 16, 2023. At the time of the August event this summary noted:

"The strongest earthquake in the world today was an M 6.5 in northern Vanuatu. The mainshock was reported by NEIC to have been felt with intensity VII in Vanuatu at Sola Torba and IV in Sanma at Port Olry and Luganville and possibly in the Solomon Islands and New South Wales, Australia. The mainshock was preceded by an M 5.2 regional foreshock several hours earlier. That event was

felt with intensity III in Luganville, Sanma, Vanuatu. An aftershock of M 4.3 was felt with intensity IV in Port Olry, Sanma, Vanuatu. The mainshock within minutes of local solar midnight and most likely was promoted by tidal stresses with the new moon which was completed within hours of the occurrence of this earthquake. This is the first earthquake of M>=6.5 in the world since an M 6.5 in El Salvador on July 19, 2023 with the last new moon. Other strong earthquakes with that new moon were an M 6.6 in Chile and an M 7.2 in the Alaska Peninsula.

…

Today's event of M 6.5 is the largest in northern Vanuatu since an M 7.0 about 150 km south of this epicenter on January 8, 2023. The last within 100 km at this magnitude level was an M 6.6 on January 15, 2019. Today's event occurred within several minutes of local solar midnight and was probably promoted by tidal stresses with today's new moon which maximize near this hour." (August 16, 2023)

Today's event also occurred near local solar midnight and may have been promoted by strong tidal stresses with the full moon as noted in this and previous issues of this summary:

"The full moon will arrive on September 29 at 09:57 UT. This is the last supermoon of the year. Supermoons occur when the moon is closest to the earth on its elliptical orbit. The considerably increases tidal stress and possibility of strong earthquakes. Longitudes which are at local solar noon at this time are located near 30 East longitude while those at local solar midnight are near 150 West longitude. In the east these include These include Hawaii and areas of eastern Alaska and western Canada and to a lesser extent areas off the coast of Oregon and California while in the east they include Eastern Turkey where an M 7.7 hit on February 6, 2023 as well as Ethiopia and areas off southern Africa and eastern Europe. These and surrounding areas are the most likely to see tidally enhanced seismicity at this time. A large to major earthquake is considered likely in the next week at this time." (September 28, 2023)

Forecast 156859 had expected this earthquake in Vanuatu was likely about 150 km south of today's epicenter around September 28.

O: 28SEP2023 14:40:27 15.5S 167.6E ML=6.0 GFZ VANUATU

O: 28SEP2023 14:40:26 15.6S 167.7E mw=6.1 ANSS VANUATU

P: 28SEP2023 156859 17.0S 168.0E 4.0-5.9 ABAAA Vanuatu Islands

The largest earthquake in the U.S. or Canada or vicinity today was an M 4.3 near Nuuk, Greenland. A similar M 4.3 hit this area on August 1, 2023. Other event of M>=4.3 in this area have occurred as an M 5.2 on July 12, 2022 and prior to that in 2005 and 2006 with M 4.4, 4.3 and 4.6. The M 5.2 in July, 2022 is the largest reported in this area in the past 35 years and was noted in this summary at the time as:

"A series of unusual earthquake today in many area of the western hemisphere appear to be related to strong tidal stresses associated with the super-moon which will be complete on July 13. ...

The M 5.1-5.2 in the Davis Strait near Greenland was the strongest event in the U.S. or Canada today. It may have been lightly felt in this remote epicentral area. This earthquake occurred within about an hour of local solar noon and was probably promoted by high tides associated with the full moon of July 13 and/or geomagnetic effects from today's geomagnetic storm as reported in this summary:

This is the strongest earthquake within about 300 km of this epicenter in at least 30 years. The only event in the region with M>4.6 since 1990 was an M 4.9 about 200 km to the east on July 29, 1999." (July 12, 2022)

Forecast 156827 had expected today's event within about 50 km was likely around September 23.

O: 28SEP2023 23:15:43 61.3N 59.5W MB=4.3 ECAN of Nuuk, GL

P: 23SEP2023 156827 61.0N 58.0W 2.5-4.0 BAAAA Baffin/Davis Strait Canada

An M 3.0 was also recorded in northern Greenland today. It was not felt in this remote epicentral area. This event occurred within minutes of local solar noon and may have been promoted by strong tidal stresses with the supermoon.

O: 28SEP2023 12:45:48 80.0N 1.2W ML=3.0 BER GREENLAND

An earthquake of M 3.5 was also felt in southeastern Alaska today. The last earthquake of larger magnitude within about 200 km of this epicenter was an M 4.0 on September 14, 2023. The last event of M>4 in the area was an M 4.4 on August 6, 2023. Forecast 156824 had expected today's event in this region was likely around September 30, 2023.

O: 29SEP2023 02:35:52 58.4N 133.5W ML=3.5 PGC SOUTHEAST ALASKA

O: 29SEP2023 02:35:52 58.4N 133.5W MB=3.5 ECAN of Juneau, Alaska, USA

P: 30SEP2023 156824 58.0N 136.0W 3.0-4.4 AABAA Southeast Alaska

MODERATE, UNUSUAL QUAKE NEAR NAPLES, ITALY RAISES CONCERNS

EARTHQUAKES IN DJIBOUTI LINKED TO SOLAR FLARES

EARTHQUAKE SUMMARY FOR SEPTEMBER 27, 2023

A pair of moderate earthquakes occurred in Djibouti, Africa today. NEIC reported these earthquakes of M 4.6 and M 4.7 in Djibouti were felt with intensity IV in the area(s) of Djibouti at Jibuti, Tajurah and Dorra.

The earlier event of M 4.7 in Djibouti was felt with intensity V in Jibuti, VI in Ta'izz, Yemen and III Tajurah and in Asmara, Eritrea. These occurred at the peak of C-class solar flares and were probably promoted by SFE associated with this flare. Readers can visit the "SOLAR FLARE" portion of this summary for details of these events.

When a similar set of events in Djibouti occurred in January, 2023, this summary noted:

"A moderate M 5.1 also occurred near 45 East longitude in the area of Djibouti today. A smaller foreshock preceded this event. This continues activation of this region in recent days much of which was promoted by strong solar and geomagnetic storms. Most of this including an M 5.5 on December 26, 2022 and an M 4.9 on January 9, 2023 occurred about 400 km west of today's event. The last event in Djibouti listed by EMSC was an M 3.8 on January 4, 2023. At the time this summary noted:

" ... an M 3.5 occurred in Djibouti, Ethiopia today. This possibility had been discussed on December 12 as being a possible triggering point from strong solar flares at this time as:

"The area of Africa was unusually seismic today. Moderate earthquakes were recorded in Djibouti (M 3.5), South Africa (M 4.4) and Morocco (M 4.5). The earthquake in Djibouti may be the beginning of stronger activity in that region and in Ethiopia. This usually peaks during high solar flare periods as it is located on the geomagnetic equator in areas of high heat flow." (December 12, 2022, December 26, 2022)

The only earthquake in Djibouti with equal or larger magnitude in the past

5 years was an M 4.4 on August 31, 2020. The last of significantly larger magnitude were of M 4.7 on April 14, 2017. The only event of M>=5 in the area was an M 5.6 on June 17, 2012, part of a strong regional activation with the last solar active period." (January 18, 2023)

Forecast 156669 had expected today's earthquake in the area was likely around

September 28.

O: 28SEP2023 01:22:05 11.7N 43.1E mb=4.7 EMSC GOLFE DE TADJOURA, DJIBOUTI

O: 28SEP2023 05:53:12 11.6N 43.3E mb=4.6 EMSC NEAR THE COAST OF DJIBOUTI

P: 28SEP2023 156669 12.0N 40.0E 3.5-5.4 AACAA Ethiopia

The strongest earthquake in the U.S. or Canada today was an M 4.8 in the Pribilof Islands of Alaska. The only event in the Pribilof Islands in the past three years of equal or larger magnitude occurred as an M 5.3 on July 4, 2022. At the time this summary noted:

"The M 5.3 in the Pribilof Islands is the strongest in that region since an M 5.3 on February 1, 2015 and a similar event on January 31, 2015. The only event in the region of larger magnitude in the past 35 years was an M 6.0 on August 14, 1991. At the time of the 2015 activity this summary noted in this regard:

"The swarm of moderate earthquakes in the Pribilof Islands north of the Fox Islands in the Bering Sea continued today and expanded. Two earthquakes of M 5.3 and one of M 5.0 today were the strongest events located within 200 km of this epicenter since an M 5.5 west of this epicenter on October 22, 1965." (February 1, 2015, July 4, 2022)

Today's activity follows a series of moderate quakes of M>=5 in the Fox and Unimak and Alaska Peninsula area and occurred near local solar midnight. It may have been promoted by today's strong geomagnetic storm as it occurred at the peak of this storm as noted in previous issues of this summary:

"The geomagnetic field saw stormy conditions today. The AP level was 32. High latitudes saw major storm conditions with AP 68. Middle latitudes were at stormy conditions with AP 26. This may enhance global seismicity at the end of September or in early October." (September 27-28,, 2023)

Forecast 156825 had expected enhanced seismicity in this area was likely around

September 24.

O: 27SEP2023 09:51:05 56.4N 168.2W mb=4.8 EMSC PRIBILOF ISLANDS, ALASKA REGIO

P: 24SEP2023 156825 54.1N 164.4W 3.5-4.9 BCBAA Unimak Islands, Aleutians

A series of earthquakes occurred along the equator over the past several days.

The strongest earthquake in the world today was an M 5.4 off the west coast of Northern Sumatra, Indonesia. The earthquake on the equator occurred at local solar midnight and may have been promoted by strong tidal stresses with the full moon as noted in this and previous summaries:

The last earthquake of M>=5.4 within about 200 km of today's event in Sumatra occurred on 5.7 occurred on May 14, 2013. An M 8.2 was recorded near today's epicenter on April 11, 2012. Forecast 156638 expected today's event was likely within this area around September 26. This epicenter is at 103 degrees from the M 6.8 in Morocco of September 8, 2023 and was probably promoted by energy from that source.

O: 27SEP2023 17:47:22 0.9N 93.2E Mw=5.4 EMSC OFF W COAST OF NORTHERN SUMATR

P: 26SEP2023 156638 3.0N 94.0E 4.0-6.0 ACAAA Nicobar Islands

O: 28SEP2023 00:14:01 0.8N 26.0W mb=4.9 EMSC CENTRAL MID-ATLANTIC RIDGE

P: 23SEP2023 156627 1.0N 28.0W 4.0-5.6 BAAAA Central Mid-Atlantic Ridg

O: 28SEP2023 00:08:02 2.6N 66.4E mb=4.5 EMSC CARLSBERG RIDGE

P: 30SEP2023 156647 1.0S 67.0E 4.0-5.6 ACAAA Indian Ocean

EARTHQUAKE SUMMARY FOR SEPTEMBER 26, 2023

An earthquake of M 4.2 near Naples, Italy occurred today and was accompanied by a swarm of minor quakes. This is the strongest earthquake in the region in about 40 years. The quake occurred in the Phlegraean Fields (Campi Flegrei) which is a vast volcano near Naples. Recent smaller events in the region have raised concern that this may be a precursory swarm to increased seismicity and volcanism in the are - a concern echoed by the National Institute of Geophysics and Volcanology (INGV). The area is populated by nearly half a million residents. The major eruption in the area was an eruption of lava and ash in 1538. Some believe that the extinction of the Neanderthal species was - in part - caused by major eruptions in this area.

Forecasts 156775 and 156721 had expected enhanced seismicity in this area was likely around September 28-29.

O: 27SEP2023 01:35:35 40.8N 14.2E ML=4.2 EMSC SOUTHERN ITALY

P: 28SEP2023 156775 43.0N 16.0E 3.0-5.4 ACAAA Italy

P: 29SEP2023 156721 38.0N 14.0E 3.0-4.9 ACAAA Mediterranean/Sicily

The strongest earthquake in the U.S. or Canada today was an M 5.1 in the Alaska Peninsula. NEIC reported it was felt with intensity II-III in Alaska at Sand Point and King Cove. This appears to be an aftershock of the M 5.4 in the Alaska Peninsula of September 21. At the time of that event this summary noted:

"The strongest earthquake in the U.S. or Canada today was an M 5.4 in the Alaska Peninsula Alaska. NEIC reported it was felt with intensity V in Sand Point and King Cove and III in False Pass, Alaska. This is the strongest earthquake in the region of the Alaska Peninsula since an M 5.6 on August 3, 2023. At the time this summary noted:

"The strongest earthquake in the world, the U.S. or Canada today was an M 5.6 in the Unimak Island area of Alaska. NEIC reported it was felt with intensity IV in Sand Point, King Cove and II-III in False Pass, Chignik Lagoon, Alaska. This is the strongest aftershock to date of the M 7.2-7.4 of July 16, 2023 in the Alaska Peninsula about 50 km east of today's epicenter. It is the second largest earthquake in this area since an M 6.1 on July 28 and July 29, 2020. In the past 15 years many of the strongest earthquakes in this region have occurred in mid- to late-July and early August, perhaps indicating a seasonal triggering component. All events in the region with M>=6 since 2008 have occurred in late July including an M 6.1 on July 16, 2011; an M 6.0 on July 19, 2018; an M 6.1 on July 28, 2020 and an M 7.2 on July 16, 2023." (August 3, 2023, September 21, 2023)

Forecast 156825 had expected today's earthquake within about 100 km was likely at the end of September.

O: 27SEP2023 02:14:27 55.0N 160.4W mb=5.1 EMSC ALASKA PENINSULA

P: 30SEP2023 156825 54.5N 161.8W 3.5-5.0 BAAAA Unimak Islands, Aleutians

An M 4.1 also occurred today off the coast of Washington State. NEIC reported this earthquake of M 4.1 off the coast of Washington may have been felt with intensity II-III in the area(s) of Washington in Everett and Bellevue and in British Columbia, Canada at Victoria and Walnut Grove. This is the strongest earthquake within about 150 km of this epicenter off the coast of Washington since an M 4.5 on February 22, 2021 and an M 4.1 on September 22, 2020.

Forecast 156803 had expected today's event in this region to the north was likely around September 26.

O: 25SEP2023 19:46:02 48.8N 128.2W MB=3.4 ECAN of Tofino, BC

O: 25SEP2023 13:31:47 47.4N 128.9W MB=4.1 ECAN of Tofino, BC

O: 26SEP2023 02:09:09 47.5N 129.2W MB=4.1 ECAN of Tofino, BC

P: 26SEP2023 156803 49.5N 127.2W 2.8-5.3 ABAAA Vancouver Island area

P: 30SEP2023 156803 49.3N 129.0W 2.8-5.4 BBAAA Vancouver Island area

STRONG QUAKE IN TALAUD ISLANDS

EARTHQUAKE SUMMARY FOR SEPTEMBER 25, 2023

The strongest earthquake today in the world was an M 5.9 in the Talaud Islands, Philippines. NEIC reported it was felt with intensity II-III in Southern Mindanao at Davao and Buayan. PHIVOLCS reported this earthquake was felt with intensity IV in Glan, Sarangani; II in Malapatan and Malungon, Sarangani; Don Marcelino and Malita, Davao Occidental and I in the City of General Santos and Polomolok, South Catabato; City of Davao, Philippines. Similar earthquakes of M 6.0-6.1 hit the Talaud Islands about 100 km south of today's epicenter on February 11, 2023 and January 22, 2022. Forecast 156634 had expected today's activity within about 100 km was likely around September 27.

O: 26SEP2023 01:39:45 4.7N 127.5E Mw=5.9 EMSC KEPULAUAN TALAUD, INDONESIA

P: 27SEP2023 156634 4.0N 128.0E 4.0-5.4 AAAAA Halmahera

The last earthquake with M>=4.6 within about 200 km of today's epicenters in the Azores occurred as an M 4.8 on January 27, 2020. Forecast 156523 and 156787

had expected this activity in the Azores region in mid- to late September.

O: 25SEP2023 16:47:26 38.7N 27.3W ML=4.1 EMSC AZORES ISLANDS, PORTUGAL

O: 25SEP2023 16:44:24 38.7N 27.3W mb=4.6 EMSC AZORES ISLANDS, PORTUGAL

P: 15SEP2023 156523 40.0N 30.0W 4.0-5.7 CBBAA No. Mid-Atlantic Ridge

P: 28SEP2023 156787 41.0N 30.0W 4.0-5.9 BCBAA No. Mid-Atlantic Ridge

An earthquake of M 5.4 also occurred today off the southern coast of Michoacan, Mexico. It was not reported felt in this area. This event occurred near local solar midnight and may have been promoted by strong tidal stresses at this hour or by geomagnetic/solar flares which maximize their seismic influence near this time. At M 5.4 this is the first event of this magnitude within about 150 km of this epicenter since an M 5.5 on March 29, 2022. Events of M 5.4 also hit the area on July 23, 2016 and January 22, 2011. The only earthquake in this area of significantly larger size in the past 35 years was an M 5.9 on October 28, 1994. At the time of the M 5.4 on March 29, 2022, this summary noted:

"NEIC reported this earthquake south of Michoacan Mexico was felt in Coahuayana, Michoacan, Mexico with intensity III. The last earthquake of M>=5.5 within about 200 km of this epicenter south of Michoacan, Mexico occurred on January 22, 2011, eleven years ago with M 5.5. The only other such event in the area in the past 30 years was an M 5.9 on October 28, 1994." (March 29, 2022)

Forecast 156411 had expected today's event was likely in mid- to late September.

O: 26SEP2023 06:21:40 15.1N 104.4W Mw=5.4 EMSC OFF COAST OF MICHOACAN, MEXICO

P: 16SEP2023 156411 15.0N 104.0W 3.5-5.2 CAAAA Michoacan, Mexico

The largest earthquake in the U.S. or Canada today was an M 4.1 off the coast of Washington. NEIC reported this earthquake of M 4.1 off the coast of Washington may have been felt with intensity II-III in the area(s) of Washington in Everett and Bellevue and in British Columbia, Canada at Victoria and Walnut Grove. This is the strongest earthquake within about 150 km of this epicenter off the coast of Washington since an M 4.5 on February 22, 2021 and an M 4.1 on September 22, 2020.

Forecast 156803 had expected today's event in this region to the north was likely around September 26.

O: 25SEP2023 13:31:50 47.7N 128.5W mb=4.1 EMSC OFF COAST OF WASHINGTON

P: 26SEP2023 156803 49.5N 127.2W 2.8-5.3 ABAAA Vancouver Island area

MODERATE QUAKES NEAR EQUATOR IN GABON AND RWANDA, AFRICA

EARTHQUAKE SUMMARY FOR SEPTEMBER 24, 2023

A pair of moderate earthquakes shook the equatorial zone of Africa today. These events occurred in Gabon (M 4.7) and Rwanda (M 4.5). An M 5.4 occurred on March 9, 2021 and on M 5.5 on December 4, 2022 was followed by an M 4.6 on January 10, 2023. At the time of the December, 2022 event this summary noted:

"The moderately strong earthquake of M 5.5 occurred in Gabon, West Africa today. NEIC reported it was felt with maximum intensity VIII in Gabon at Lambarene, Moyen-Ogooue; IV in Booue, Ogooue-Ivindo and III in Libreville Estuaire.

A series of islands apparently cause by the African Plate passing over a hot spot in the mantle aligns from southwest to northeast off the coast of western Africa and passes near this event in Gabon, which may be related to activity associated with this hot spot. The only similar event near Gabon within about 400 km of this epicenter in the past 35 years occurred as an M 5.5 on December 19, 2019 about 300 km northwest of today's epicenter." (December 4, 2022)

O: 25SEP2023 01:28:55 1.0S 10.3E mb=4.7 EMSC GABON

A series of events near M 4.5 occurred last in Rwanda in late May, 2021 and may have been related to volcanism. The last earthquake of significantly larger magnitude in the area of Rwanda within about 200 km of today's epicenter was an M i5.3 on October 20, 2019. Forecast 156386 had expected today's activity in Rwanda was likely in mid-September.

NEIC reported this earthquake of M 4.5 in Rwanda was felt with intensity II-III in the area(s) of Rwanda in Kibungo (IV), Cyangugu, Kigali and Byumba.

O: 24SEP2023 14:21:56 2.3S 29.5E mb=4.5 EMSC RWANDA

P: 16SEP2023 156386 2.0S 29.0E 3.0-4.8 CAAAA Lake Victoria area

The largest earthquake in the U.S. or Canada today was an M 5.0 in the eastern Andreanof Islands. NEIC reported it was felt with light intensity in Atka, Alaska. The last earthquake of M>=5 in the Fox Islands was an M 5.2 on August 20, 2023 with an epicenter about 250 km to the east of today's event. The last event in the Fox Islands within about 200 km of today's earthquake was an M 5.4 on May 13, 2023. At the time this summary noted in this regard:

"The strongest earthquake in the world today was an M 5.4 in the Fox Islands, Aleutians, Alaska. It was not reported felt in this remote area. The last earthquake in the Fox Islands with greater magnitude was an M 5.5 on November 21, 2022 but the last of significantly larger magnitude in this region was an M 6.8 on January 11, 2022 and aftershocks of M 6.1 on January 22, 2022. At the time this summary noted in this regard:

"Strong earthquakes of M 6.8 and M 6.4 shook the region of the Fox Islands, Aleutians, Alaska today. NEIC reported the M 6.8 was felt with intensity VI in Nikolski; IV in Dutch Harbor, Unalaska, False Pass and II-III in Akutan, Atka, Cold Bay, and Adak, Alaska. The M 6.4 aftershock was reported with intensity IV in Nikolski, Alaska and III in Unalaska. An aftershock of M 5.8 was also reported felt with intensity IV in Nikolski and Dutch Harbor, Alaska. The last earthquake within about 250 km of this epicenter in the Fox Islands with M>=6.8 was an M 6.9 on July 27, 2015 about 150 km west of today's epicenter." (January 11, 2022, May 13, 2023)

Forecast 156811 had expected enhanced seismicity within about 50 km of today's epicenter was likely around September 25.

O: 24SEP2023 15:01:37 52.6N 171.8W mb=5.0 EMSC FOX ISLANDS, ALEUTIAN ISLANDS

P: 25SEP2023 156811 52.4N 170.7W 3.5-5.2 AAAAA Andreanoff Isls, Aleutians

A series of aftershocks of M 3-4 continued in the Vancouver Island area of British Columbia today. These are apparently aftershocks of the M 5.6 on September 17. Most of this series occurred near local solar noon and may have been promoted by tidal stresses which maximize near this hour. Forecast 156812 had expected this activity was likely within about 25 km around September 22.

O: 23SEP2023 19:44:02 50.7N 130.4W MB=3.3 ECAN of Port Hardy, BC

O: 23SEP2023 19:32:36 50.6N 130.5W MB=3.2 ECAN of Port Hardy, BC

P: 22SEP2023 156812 50.7N 130.5W 3.0-4.9 AAAAA British Colombia

An earthquake of M 3.9 was also felt in southern Oklahoma today. NEIC reported this earthquake of M 3.7-3.9 in Oklahoma was felt with intensity II-III in the area(s) of Oklahoma with IV in Marlow, Comanche, Altus and lesser shaking in Duncan, Loco, Hennepin, Ryan, Altus, and in Texas at Lewisville and the Colony. This is generally south of the current moderate seismicity in the area. The last earthquake in Oklahoma within about 100 km of the M 3.9 today was an M 4.4 on October 13, 2010. The only event in the past 35 years closer than 100 km to today's epicenter with M>=3.9 occurred on January 18, 1995. Forecast 156755 had expected today's event was likely within 100 km around September 22.

O: 24SEP2023 19:15:00 35.0N 97.5W ML=2.2 EMSC OKLAHOMA

O: 25SEP2023 00:40:32 34.5N 97.8W mb=3.9 EMSC OKLAHOMA

P: 22SEP2023 156755 34.0N 97.0W 2.0-4.1 BAAAA Southeast U.S.

QUIET DAY WITH DISTURBED IONOSPHERE

EARTHQUAKE SUMMARY FOR SEPTEMBER 23, 2023

It was a quiet day in global seismicity. The largest quakes was an M 5.1 in the Loyalty Islands of the southwest Pacific and in Nias Indonesia. These events were not reported felt. This seismic lull occurred as a new geomagnetic storm was brewing with AP 21 on September 24. It is likely there is a relation between the seismic lull and this geomagnetic storm.

"The geomagnetic field saw disturbed conditions today. The AP level was 10. High latitudes saw active conditions with AP 24. Middle latitudes were at quiet conditions with AP 9. The geomagnetic field is expected to see major storm conditions September 25 with minor storms September 24 and active September 26. Solar activity is expected to be at disturbed levels September 24-26 with a moderate chance (60%) of an M-class flare and 10% chance of an X-class flare. A proton storm is expected with 20% probability in this time period." (September 23-24, 2023)

The M 5.1 in the Loyalty Islands has been relatively quiet in recent months with the only events of larger magnitude an M 5.3 on July 3 and an M 5.2 on September 13, 2023. Forecast 156865 had expected this event was likely within about 100 km around September 24.

O: 23SEP2023 15:51:21 22.2S 170.5E Mw=5.1 EMSC SOUTHEAST OF LOYALTY ISLANDS

P: 24SEP2023 156865 23.0S 170.0E 4.0-5.4 AAAAA Loyalty Islands

An earthquake of M 5.1 also occurred in Sumatra today in the Nias Region of Indonesia. A major M 7.3 hit the Nias area on April 24, 2023. This may be a regional aftershock of that event. Forecast 156638 expected today's event within about 100 km was likely around September 23.

O: 24SEP2023 01:27:34 2.0N 97.0E mb=5.1 EMSC NIAS REGION, INDONESIA

P: 23SEP2023 156638 1.0N 97.0E 4.0-5.5 AAAAA Nicobar Islands

NEIC reported this earthquake of M 4.0 in Georgia was felt with intensity II-III in the area(s) of Georgia in Samgori, Tbilisi, Zahesi, Mtskheta, Tskneti, Tianeti and in Balakhonovskoye, Russia. The last activity in Georgia of M>=4 occurred February 11-12, 2023 with maximum intensity M 4.4. At the time this summary noted:

"The earthquake of M 4.4 in the Caucasus was the strongest in that area since M 5.3 on September 27, 2022. At the time this summary noted in this regard:

"An M 5.3 was also felt in eastern Turkey near the Georgia border today. NEIC reported these earthquake of M 5.3 and 4.4 in Eastern Turkey was felt with intensity CI in Susuz, Kars, Turkey and II-III in the area(s) of in Tbilisi and Batumi, Ajaria, Georgia. A similar M 5.3 hit within about 200 km on February 13, 2022 but the only earthquake of larger magnitude in this area of eastern Turkey in the past thirty-two years was an M 5.5 on December 16, 1990." (September 28, 2022, February 11, 2023)

Forecast 156770 had expected today's event within about 200 km was likely around September 24.

O: 24SEP2023 04:00:07 41.8N 45.0E mb=4.0 EMSC GEORGIA (SAK'ART'VELO)

P: 24SEP2023 156770 40.0N 44.0E 3.5-5.2 ABAAA Caucasus/Caspian Sea

NEIC reported an earthquake of M 2.9 in Northern California was felt with intensity II-III in the area(s) of Northern California in Paradise, Lodi.

An earlier M 3.3 was felt with intensity II-III in Patterson, Newman, Tracy, Gustine, Manteca, San Jose, Sunnyvale, Aptos, Palo Alto. NEIC reported this earthquake of M 2.7 in San Francisco, California was felt with intensity II-III in the area(s) of San Francisco, California in Milpitas, San Jose, Sunol among others. These appear to be largest long-term aftershocks of the M 4.5 of September 19, 2023. This area appears to be promoted by geomagnetic storms and by solar flares as noted with the M 4.5 in this summary as:

"The strongest earthquake in the U.S. or Canada today was an M 4.5 in Northern California east of the San Francisco, California Bay. This event was widely felt throughout much of central and northern California. … The mainshock was preceded by an M 4.0 foreshock, among others of smaller magnitude and by a number of felt aftershocks of M>=3. ... This largest event in the series may have been triggered by an M1.1 class solar flare which coincided with it.

...

This is the first M-class solar flare in the past three days.

The earthquakes in California also occurred at the height of the strongest geomagnetic storm since September 2 and may have been promoted by changes in the geomagnetic field associated with that storm. This summary noted in this regard:

"The geomagnetic field saw minor storm conditions today. The AP level was 30. High latitudes saw major storm conditions with AP 49. Middle latitudes were at active conditions with AP 21. This is the strongest disturbance in the geomagnetic field since AP reached 38 on September 2 with high latitude AP 59 on that date. This storm is expected to intensity on September 19, 2023. Some initial seismic enhancement is likely with a stronger intense period around September 21-22." (September 19, 2023)

Today's event in Northern California is the first of M>=4.5 within about 100 km of today's epicenter since an M 5.1 about 50 km southwest of this on October 25, 2022 and may be a regional aftershock of that event." (September 19, 2023)

Forecast 156710 had expected this aftershock was likely within about 50 km around September 23.

O: 23SEP2023 22:02:35 37.4N 121.8W MD=2.7 EMSC SAN FRANCISCO BAY AREA, CALIF.

P: 23SEP2023 156710 37.4N 121.3W 2.5-4.4 AAAAA Central California

STRONG EARTHQUAKE IN NORTHERN VANUATU

EARTHQUAKE SUMMARY FOR SEPTEMBER 21, 2023

The strongest earthquake of the day in the world was an M 6.1 in northern Vanuatu. NEIC reported it was felt with intensity IV in Luganville, Sanma, Vanuatu. This may be an aftershock of an M 6.5 which occurred on August 16, 2023. At the time this summary noted in this regard:

...

Forecast 156858 had expected today's event within about 25 km was likely around September 22.

O: 21SEP2023 21:11:52 14.0S 167.2E Mw=6.1 EMSC VANUATU

P: 22SEP2023 156858 14.0S 167.0E 4.0-5.4 AAAAA Vanuatu Islands

Moderately large events of M 5.7 also occurred today in the Kermadec Islands and in the Izu Islands of Japan. These occurred in areas where moderately strong activity has been occurring in recent days.

The earthquake of M 5.7 in the Izu Islands, Japan was followed by an M 4.7 three hours later. follows a series of such events in the area including an M 5.8 on September 19. At the time this summary noted:

"An M 5.8 also occurred in the Izu Islands south of southeastern Honshu, Japan today. A similar M 5.8 occurred on February 5, 2023 and an M 6.3 in the Izu Islands was recorded on January 16, 2023. At the time of that event this summary noted:

"The strongest earthquake in the world today was an M 6.3 in the Izu Islands, Japan. NEIC reported it was felt with intensity II-III in Japan at Shizuoka, Kanagawa, Tokyo, Chiba, Fukushima and Okinawa Prefectures. This follows an M 5.2 in the area yesterday. In the previous summary it had been noted in this regard:

"The strongest earthquake in the world today was an M 5.2 in the Izu Islands of Southeastern Japan. Today's event was reported by JMA to have been lightly felt in southeastern Honshu, Japan. The last earthquake in the Izu Islands of significantly larger magnitude in this area of Izu Islands occurred on August 4, 2022 with M 5.7 after similar activity on July 31, 2022." (January 16, 2023, September 19, 2023)

Forecast 156732 had expected today's event within about 100 km was likely around September 24.

O: 22SEP2023 00:46:51 31.0N 142.0E mb=4.7 EMSC IZU ISLANDS, JAPAN REGION

O: 21SEP2023 21:22:13 31.0N 141.8E Mw=5.7 EMSC IZU ISLANDS, JAPAN REGION

P: 24SEP2023 156732 32.0N 142.0E 4.0-5.4 BAAAA Off East Coast Honshu

The M 5.7 in the Kermadec Islands is likely a regional aftershock of the M 6.6

south of this on September 8, 2023. It was not felt in this remote area. At the time of the September 8 event this summary noted:

"The M 6.6 in the Kermadec Islands, New Zealand today was widely felt in North Island, New Zealand - unlike most strong earthquakes in the Kermadec Islands. NEIC reported maximum intensity for the M 6.6 at IV in Gisborne at Te Karaka and II-III in the Bay of Plenty at Opotiki, Whakatane, in North Shore, Auckland, Napier, Hawke's Bay, in Manawatu-Wanganui at Palmerston North and Shannon, and more than 1000 km away in Wellington at Porirua, Lower Hutt and Wellington.

This is the strongest earthquake in the Kermadec Islands within about 200 km of this epicenter since an M 6.6 on August 14, 2022 and an M 7.4 on June 18, 2020." (September 9, 2023)

Forecast 156877 had expected today's event was likely within about 100 km around

September 22.

O: 21SEP2023 15:20:30 30.7S 178.0W Mw=5.7 EMSC KERMADEC ISLANDS, NEW ZEALAND

P: 22SEP2023 156877 30.0S 179.0W 4.0-5.6 AAAAA No. Kermadec Islands

The strongest earthquake in the U.S. or Canada today was an M 4.7 in eastern Greenland. It was not reported felt in this remote area. This is the strongest earthquake in eastern Greenland within about 300 km of this epicenter since an M 5.2 north of this epicenter on November 23, 2021. Similar events in the region occurred on January 16, 2018 with M 4.7 and August 15, 2008 with M 4.8.

Forecast 156842 had expected enhanced seismicity in this region was likely around September 22.

O: 21SEP2023 22:41:40 79.6N 18.4W mb=4.7 EMSC EASTERN GREENLAND

O: 21SEP2023 22:41:40 79.6N 18.6W mb=4.7 ANSS eastern Greenland"

P: 22SEP2023 156842 71.0N 8.0W 3.5-5.2 ACAAA Jan Mayen Isl. area

STRONG QUAKES IN EAST PACIFIC RISE; PRINCE EDWARD ISLANDS

EARTHQUAKE SUMMARY FOR SEPTEMBER 20, 2023

The largest earthquake in the world today was an M 6.0 in the northern East Pacific Rise south of Oaxaca, Mexico where was reported felt with intensity II. It was followed by a strong aftershock of M 5.7 and a moderate event of M 4.6 and preceded by an M 4.6 foreshock and an M 5.2 foreshock seconds before the mainshock. The last earthquake of M>=6 within about 200 km of today's epicenters occurred as an M 6.1 on March 22, 2020 and a similar event of M 6.0-6.1 on September 11, 2013. The only event of M>=6.0-6.1 in the area in the past 35 years was an M 6.33 on August 15, 1997. At the time of the event of March 22, 2020, this summary noted:

"The strongest earthquakes in the world today were an M 6.1 in the Central East Pacific Rise and an M 5.6 in the Central Mid-Atlantic Ridge. Neither of these were reported felt in these remote areas. The event in the Central East Pacific Rise is the largest within about 250 km of that epicenter since an M 6.1 on September 11, 2013 and a similar M 6.1 on August 4, 2007. The maximum sized earthquakes in the region in the past 30 years have been about M 6.1." (March 22, 2020)

Forecast 156391 had expected today's activity within about 100 km of these epicenters was likely around September 16. This activity is at the fifth node (72 degrees) from the M 7.7 in the Loyalty Islands of May 19, 2023 and near 103 degrees from the M 6.8 in Morocco of September 8, 2023 and may have been promoted by energy from those sources.

O: 20SEP2023 14:46:00 4.5S 105.8W Mw=6.0 EMSC CENTRAL EAST PACIFIC RISE

O: 20SEP2023 15:03:37 4.6S 105.9W Mw=5.7 EMSC CENTRAL EAST PACIFIC RISE

O: 20SEP2023 15:28:25 4.6S 106.2W mb=4.6 EMSC CENTRAL EAST PACIFIC RISE

O: 20SEP2023 14:45:29 4.5S 105.7W mb=5.2 EMSC CENTRAL EAST PACIFIC RISE

P: 16SEP2023 156391 5.0S 105.0W 4.0-5.5 BAAAA No. East Pacific Rise

An M 5.8 in the Prince Edward Island region of the South Indian Ocean also occurred today. It was not reported felt in this remote area. This epicenter is near the antipode of the M 6.0 in Vancouver, Canada of September 17, 2023 and may have been promoted by antipodal energy associated with that event. An earthquake of M 5.9 hit the Prince Edward Islands about 300 km east of today's epicenter on August 14, 2023. At the time this summary noted:

"An M 5.9 also occurred in the Prince Edward Islands of the south Indian Ocean. It was not reported felt in this remote area. Several hours earlier an M 4.9 occurred in the Southeast Indian Ridge. Neither of these event was reported felt. Both events occurred about an hour after local solar noon and may have been promoted by strong tidal stresses associated with the new moon of August 16. As noted in this and previous issues of this summary this event in the Prince Edward Islands is near the longitude of maximum tidal stress with today's new moon (see above).

The earthquake in the Prince Edward Islands is a aftershock of an M 6.8 on May 21, 2023. At the time this summary noted:

"The strongest earthquake in the world today was an M 6.8 in the Prince Edward Islands of the South Indian Ocean. It was not reported felt in this remote area.

This is the strongest earthquake in the Prince Edward Islands region within about 300 km of these epicenters in at least 35 years. The largest previous earthquake in this time frame in this area was an M 6.3 exactly 25 years ago today on May 21, 1998 within about 200 km of today's epicenter." (May 21, 2023, August 14, 2023)

Today's event is at 102 degrees from the M 7.7 in the Loyalty Islands of May 19 and may have been promoted by energy from that source.

O: 20SEP2023 19:22:34 44.9S 35.4E Mw=5.8 EMSC PRINCE EDWARD ISLANDS REGION

The strongest earthquake in the U.S. or Canada today was an M 5.4 in the Alaska Peninsula Alaska. NEIC reported it was felt with intensity V in Sand Point and King Cove and III in False Pass, Alaska. This is the strongest earthquake in the region of the Alaska Peninsula since an M 5.6 on August 3, 2023. At the time this summary noted:

This event occurred near local solar noon and may have been promoted by strong tidal stresses which maximize near this hour. forecast 156562 had expected enhanced seismicity in this region in mid-September.

O: 21SEP2023 01:14:00 55.0N 160.5W Mw=5.4 EMSC ALASKA PENINSULA

P: 14SEP2023 156562 54.3N 161.7W 3.5-4.9 CAAAA Unimak Islands, Aleutians

An unusually large earthquake of M 3.8 hit the central Nunavut, Canada region today. It was not reported felt in this remote area. The last earthquake with M>=3.8 within about 200 km of today's epicenter in Nunavut, Canada occurred more than 10 years ago on March 10, 2012 with M 4.2.

Forecast 156574 had expected today's event was likely in mid-September within

about 100 km of this epicenter. This activity is at 144 degrees from the Prince Edward Islands and at the third node (120 degrees) from the M 7.1 in Java of August 28, 2023 and at 103 degrees from recent strong earthquakes in Tonga and may have been promoted by energy from those sources.

O: 20SEP2023 14:22:14 64.9N 88.2W ML=3.8 EMSC NUNAVUT, CANADA

O: 20SEP2023 14:22:14 64.9N 88.2W MB=3.8 ECAN of Naujaat, NU

P: 12SEP2023 156574 65.0N 86.0W 2.5-4.0 CAAAA Nunavit/Hudson Bay, Canada

An earthquake of M 4.4 also shook the northern Dominican Republic today.

NEIC reported this earthquake of M 4.4 in the Dominican Republic was felt with intensity II-III in the area(s) of the Dominican Republic with V in Mao Valverde; IV in Moncion Santiago Rodriguez, Villa Bisono, Santiago and lesser shaking in Altamira, Villa Gonzalez, Imbert, Puerto Plata, among others. The last earthquake of larger magnitude within the Dominican Republic was an M 4.8 on May 18, 2023. Forecast 156422 had expected today's event was likely within about 50 km around September 20.

O: 20SEP2023 07:00:41 19.6N 70.8W mb=4.4 EMSC DOMINICAN REPUBLIC

P: 20SEP2023 156422 20.0N 71.0W 3.0-4.6 AAAAA Bahamas/No. Caribbean

STRONG EARTHQUAKE SHAKES CENTRAL SOUTH ISLAND, NEW ZEALAND

EARTHQUAKE SUMMARY FOR SEPTEMBER 19, 2023

The strongest earthquake in the world today was an M 5.6-6.2 in central South Island, New Zealand. NEIC reported it was felt with maximum intensity V in Canterbury at Rolleston and IV in Oamaru, Timaru, Lincoln, Christchurch with lesser shaking of II-III in Ashburton, Lyttelton, Te Puru-Thornton Bay, Waikato and Denedin Otago. GEONET reported it at M 6.2 and that it was felt with light intensity in the area of Central South Island, New Zealand. Of 14338 felt reports 4779 reports of light and 6786 of weak intensity with 1749 of moderate shaking and 169 with strong 2 with severe and 11 with extreme intensity came from the area. The last earthquake within about 150 km of this epicenter with M>=5.6 occurred on February 14, 2016 with M 5.8. The last of M>=6.2 was the Christchurch earthquake of M 7.0 of September 3, 2010 about 100 km north of today's epicenter. Forecast 156620 had expected a moderate earthquake in this area of South Island was likely around September 17.

O: 20SEP2023 01:18:23 43.7S 171.1E ML=3.8 EMSC SOUTH ISLAND OF NEW ZEALAND

O: 19SEP2023 21:14:49 43.7S 171.1E MS=6.2 GEONET South Island, New Zealand

O: 19SEP2023 21:14:50 43.7S 171.1E Mw=5.6 EMSC SOUTH ISLAND OF NEW ZEALAND

P: 17SEP2023 156620 44.0S 169.0E 3.0-5.1 AABAA So. Island, N.Z.

An unusual earthquake of M 4.5 hit near the northern coast of Libya today. This appears to be part of an activation of the northern African and Western Europe area which in the past several days included an M 6.8 in Morocco and an M 5.1 in northern Italy among others. Moderate earthquakes in this region of Libya area rare. The last earthquake in Libya within about 150 km of this epicenter was an M 4.5 on November 16, 2005, the only such quake in this area in at least 35 years. Forecast 156438 had expected today's event was likely in mid-September to the north of today's epicenter.

O: 20SEP2023 01:33:09 32.5N 24.6E mb=4.5 EMSC NEAR COAST OF LIBYA

P: 16SEP2023 156438 35.0N 25.0E 3.0-4.9 BCAAA Aegean Sea

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Alaska Peninsula Alaska. NEIC reported it was felt with intensity III in Sand Point, Alaska.

An earthquake of M 4.4 also shook the northern Dominican Republic today. The last earthquake of larger magnitude within the Dominican Republic was an M 4.8 on May 18, 2023. Forecast 156422 had expected today's event was likely within about 50 km around September 20.

O: 20SEP2023 07:00:41 19.6N 70.8W mb=4.4 EMSC DOMINICAN REPUBLIC

P: 20SEP2023 156422 20.0N 71.0W 3.0-4.6 AAAAA Bahamas/No. Caribbean

MODERATE QUAKE SHAKES NORTHERN CALIFORNIA EAST OF SAN FRANCISCO

EARTHQUAKE SUMMARY FOR SEPTEMBER 18, 2023

The strongest earthquake in the U.S. or Canada today was an M 4.5 in Northern California east of the San Francisco, California Bay. This event was widely felt throughout much of central and northern California. NEIC gave maximum intensity IV was felt in California in Patterson, Newman, Crows Landing, Modesto, Tracy with III in Livermore, Ceres, Manteca, San Francisco and as far as southern California. The mainshock was preceded by an M 4.0 foreshock, among others of smaller magnitude and by a number of felt aftershocks of M>=3. The aftershocks were generally felt in the Patterson, Newman, Livermore, Tracy, Morgan Hill, Modesto, Ripon and San Jose area with intensity II-III but the M 4.0 foreshock was felt with intensity IV in Patterson. This largest event in the series may have been triggered by an M1.1 class solar flare which coincided with it. The preliminary parameters from SWPC for this flare are:

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

-------------------------------------------------------------------------

XXXX 0344 0400 0410 M1.1 (September 19, 2023) 1.1E-02

This is the first M-class solar flare in the past three days.

"Another actor promoting this earthquake at this time was a Tropical Cyclone making slope-fall off Virginia at this time. This summary had noted the possible effect on the western edge of the North American plate in the previous issues as:

"A tropical cyclone may be forming in the North Atlantic east of Georgia and South Carolina. This system is expected by NHC to reach Tropical Depression status in the next day at 40% likelihood. It is not expected to make landfall but is near the continental slope and could affect seismicity in the western North American Plate. This system is currently near 35N 65W." (October 23-24, 2022)

The last earthquake in the San Jose/San Francisco, California area with equal or larger magnitude than M 5.1 occurred on October 31, 2007 with M 5.5. Other earthquakes of M>=5 hit the area with M 5.2 on August 12, 1998, January 16, 1993 and April 18, 1990. At the time of the M 5.5 on October 31, 2007 ..." (October 25, 2022)

"A strongly felt earthquake hit the San Francisco Bay region tonight with M 5.6. ... The earthquake in the San Francisco Bay region was preceded several hours earlier by an event of M 2.9 which hit to the northwest and may have set up the conditions for the larger earthquake. ... The earthquake was generally felt within about 300 km of the epicenter with lesser intensities. This was the strongest earthquake to hit the San Francisco area since the World Series earthquake in October, 1989 (M 7.0). While pictures fell from walls and items fell from shelves throughout much of the area no immediate reports of major damage or casualties were available. The earthquake appears to have occurred on the Calaveras Fault. A contributing factor for the occurrence of this earthquake at this time may have been the strong geomagnetic storms which occurred late on October 25 and again this morning. The storms occurred while San Francisco was sub-solar and the effects were maximized. It is common for storms such as this to have their maximum effect on seismicity 4.5-5.0 days following the onset. The earthquake in San Francisco did occur five days after the onset of this storm which was the strongest to occur at mid-latitudes in the past month and the second strongest to occur in the past three months (Kp 36)." (October 31, 2007)

The factors noted in the previous strong activity in this area were all prevalent today including the landfall of Hurricane Lee in the northeastern U.S. and eastern Canada and a strong geomagnetic storm and may be notable for triggering in this region.

Forecast 156444 had expected enhanced seismicity was likely in this region in mid-September.

O: 19SEP2023 00:15:32 37.4N 121.3W Mw=4.0 EMSC NORTHERN CALIFORNIA

O: 19SEP2023 03:44:30 37.4N 121.3W Mw=3.5 EMSC NORTHERN CALIFORNIA

O: 19SEP2023 04:40:58 37.4N 121.3W ML=3.1 EMSC NORTHERN CALIFORNIA

O: 19SEP2023 04:48:37 37.4N 121.3W MD=2.1 EMSC NORTHERN CALIFORNIA

O: 19SEP2023 05:25:20 37.4N 121.2W ML=3.2 EMSC NORTHERN CALIFORNIA

O: 19SEP2023 04:13:10 37.5N 121.2W Mw=4.5 EMSC NORTHERN CALIFORNIA

P: 13SEP2023 156444 38.0N 122.3W 2.5-4.4 CAAAA Central California

P: 16SEP2023 156444 36.4N 121.1W 2.5-4.5 BBAAA Central California

The earthquake in California was preceded by an M 3.4 in southern Nebraska. This event was reported felt with intensity II-III in Nebraska at Blue Hill, Guide Rock, Hastings, Grand Island, Fremont and South Sioux City. Earthquakes in Nebraska often precede significant earthquakes in northern and central California as previously noted in this summary. Fore example a slightly smaller event near this epicenter in Nebraska of August 22, 2023 caused the following note to be published in this summary:

"A pair of light earthquakes of M 2.9 and 2.7 occurred today south of Lincoln and Hastings, Nebraska. NEIC reported they were felt with intensity IV in Nebraska at Ashton. Earthquakes in this region of Nebraska often precede stronger events on the North American-Pacific tectonic plate boundary. In the current situation with Hurricane Hilary and accompanying M 5.1 in Southern California this possibility may be somewhat mitigated. This is the third earthquake of M 2.9 in this region of Nebraska in the current year. These follow an M 3.7 on July 17, 2022 southeast of today's epicenter - the only event of M>2.9 in Nebraska in the past 3 years. At the time of the M 3.7 this summary noted:

"An unusual M 3.8 earthquake occurred on the Nebraska-Kansas border south of Lincoln and Grand Island, Nebraska near Superior. NEIC reported this earthquake of M 3.8 in Nebraska was felt with intensity IV-V in the area(s) of Nebraska at Superior, Guide Rock and in Mankato Kansas, with lesser shaking in Hardy, Red Cloud, Deshler, Glenvil, Nebraska and in Kansas at Webber, Smith Center, Republic. This is the strongest earthquake in southern Nebraska within about 150 km of this epicenter since an M 3.8 on May 6, 2021. The only event of larger magnitude in this area in the past 30 years was an M 4.5 on June 22, 2019. Earthquakes in Nebraska and South Dakota often precede strong earthquakes along the western rim of North America and with a strong coming geomagnetic storm this is a possibility. When the event occurred on May 6, 2021 this summary noted in this regard:

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

Kansas. This included an M 3.8 and aftershocks of M 3.0, 3.1 and 3.1. An M 3.8 in northern Kansas today was widely felt. NEIC reported this earthquake and aftershocks of M 3.1 in Kansas was felt with intensity IV in the area(s) of Kansas at Formoso, Courtland, Burr Oak, Hope and II-III in Jewel, Randall, Webber, Mankato, Belleville, Concordia, and Bend, Herington and Ramona. Other aftershocks of M 3.1 and 3.0 in Kansas were felt with intensity IV in Formoso and possibly in Sylvan Grove and in Peru, Nebraska. This is the strongest earthquake within about 100 km of this epicenter in the past year. An M 4.5 occurred about 150 km southeast of this in Kansas on January 19, 2020. Forecast 133547 had expected today's activity in northern Kansas was likely around May 4." (May 7, 2021)

When the M 4.5 hit on June 23, 2019 it was noted as:

"As noted in previous issues of this summary, moderate earthquakes in the area of Kansas, Nebraska and South Dakota are often followed within hour by moderate to strong quakes along the western boundary of North America - often in the regions off the coast of Oregon and Washington and this appears to be the case in this instance." (June 23, 2019, July 17, 2022, August 22, 2023)

At M 3.4 this is the strongest earthquake in Nebraska recorded in the past three years. The last event in Nebraska with M>=3.4 within about 200 km of this epicenter was an M 3.6 on July 26, 2022.

Forecast 156493 had expected regional seismic enhancement was likely in Nebraska and northern Kansas around September 16.

O: 18SEP2023 14:34:40 40.2N 98.3W ML=3.4 EMSC NEBRASKA

P: 16SEP2023 156493 38.0N 98.0W 2.0-4.3 ABAAA Southern Plains

Three moderately strong earthquakes occurred in the region of Japan today - an M 6.4-6.8 in the Ryukyu Islands, an M 5.8 in the Izu Islands south of Tokyo and an M 5.5 off the coast of northeastern Honshu. The strongest earthquake of the day in the world was the M 6.4-6.8 in the Ryukyu Islands near Okinawa, Japan. NEIC reported it was felt with maximum intensity IV in Okinawa at Naha and Urasoe with III in Tomigusuku, Yomitan, Chatan, Okinawa, Ginowan, Ishikawa, Gushikawa and Nago among others. CWB reported this earthquake at M 6.8 was felt with intensity I in Hualien, Yilan, Nantou, Taichung, Changhua, Taitung, Yunlin, and Chiayi Counties, Taiwan. Only two earthquakes of M>=6.4 have been recorded within about 250 km of today's epicenter in the past 35 years - an M 6.5 on March 2, 2014 and an M 6.9 on November 8, 2011. Today's earthquake was simultaneous with the beginning of flare 190 and may have been promoted by SFE from that flare.

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

-------------------------------------------------------------------------

190 1321 1338 1359 C1.5 (September 18, 2023) 3.3E-03

Forecast 156431 had expected today's event within about 100 km was likely in mid-September. This epicenter is located near 103 degrees from the M 6.8 in Morocco of September 8 and was probably promoted by energy from that source.

O: 18SEP2023 13:21:24 26.5N 125.3E Mw=6.4 ANSS NORTHEAST OF TAIWAN

O: 18SEP2023 13:21:24 26.5N 125.3E Mw=6.3 EMSC NORTHEAST OF TAIWAN

O: 18SEP2023 13:21:19 26.8N 126.0E Mw=6.8 CWB NORTHEAST OF TAIWAN

P: 13SEP2023 156431 26.0N 125.0E 4.0-5.4 BAAAA Ryukyu Islands

P: 19SEP2023 156431 25.0N 124.0E 4.0-5.6 ABAAA Ryukyu Islands

An M 5.8 also occurred in the Izu Islands south of southeastern Honshu, Japan today. A similar M 5.8 occurred on February 5, 2023 and an M 6.3 in the Izu Islands was recorded on January 16, 2023. At the time of that event this summary noted:

Forecast 156469 ad expected today's activity within about 50 km was likely around September 18.

O: 18SEP2023 11:31:11 29.7N 139.1E mb=4.5 EMSC IZU ISLANDS, JAPAN REGION

O: 19SEP2023 06:22:38 31.0N 142.0E Mw=5.8 EMSC IZU ISLANDS, JAPAN REGION

O: 18SEP2023 21:33:29 31.5N 141.8E mb=4.5 EMSC IZU ISLANDS, JAPAN REGION

O: 19SEP2023 00:00:17 31.5N 142.0E mb=4.6 EMSC IZU ISLANDS, JAPAN REGION

P: 18SEP2023 156469 32.0N 141.0E 4.0-5.4 AAAAA Off East Coast Honshu

The earthquake off the northern coast of Honshu, Japan of M 5.5 followed a similar M 5.5 on September 8, 2023. At the time this summary noted in this regard:

"An M 5.5 was also reported off the east coast of northern Honshu, Japan today. NEIC reported it was felt with intensity II-III in Iwate, Miyagi, Fukushima, Aomori, Saitama and Tokyo Prefectures, Japan.

... Enhanced seismicity in Honshu and off eastern Honshu, Japan had been expected at this time in this summary due to the passage of Tropical Storm Kirogi through the area at this time. This was emphasized in the September 5, issue of this summary as:

"NEIC reported this earthquake of M 4.9 near Tokyo, Japan was felt with intensity II-III in the area(s) of Honshu, Japan in Chiba, Ibaraki, Tokyo, Saitama, Kanagawa Prefectures. This follows smaller events yesterday which was reported in this summary in the previous issue as:

"... An interesting earthquake of M 4.1 hit off the east coast of Honshu, Japan.

This event occurred near local solar noon and may have been promoted by geomagnetic and tidal stresses which maximize near this hour. Tropical Storm Kirogi passed over this epicenter at the time of the earthquake." (September 8, 2023)

Forecast 156471 had expected today's event within about 50 km was likely around September 18 off northern Japan.

O: 18SEP2023 19:33:04 38.5N 141.6E Mw=5.5 EMSC NEAR EAST COAST OF HONSHU, JAP

P: 18SEP2023 156471 39.0N 142.0E 4.0-5.5 AAAAA Off East Coast Honshu

The mainshock in the Vancouver area yesterday has been reanalyzed. The current magnitude is given as M 6.0. This event was probably promoted by strong geomagnetic and weather-related stresses (see previous issues of this summary. This summary noted this event in the previous issue as:

"The strongest earthquake in the world today was an M 5.6-5.9 west of Vancouver Island, British Columbia, Canada. NEIC reported it was felt with light shaking I-III in British Columbia at Parksville, Gibsons, Vancouver and perhaps as far as Oregon and Northern California. Foreshocks of M 4.5 and 4.3 preceded the mainshock and may have been felt lightly in the epicentral area." (September 18, 2023)

Forecast 156546 had expected this event within about 15 km was likely in mid-September.

O: 17SEP2023 11:28:08 50.6N 130.5W MB=6.0 ECAN of Port Hardy, BC

O: 17SEP2023 15:19:49 50.7N 130.5W MB=4.5 ECAN of Port Hardy, BC

P: 13SEP2023 156546 50.5N 130.4W 3.0-4.9 BAAAA British Colombia

MODERATELY STRONG QUAKE SHAKES VANCOUVER ISLAND, BRITISH COLUMBIA, CANADA

EARTHQUAKE SUMMARY FOR SEPTEMBER 17, 2023

The strongest earthquake in the world today was an M 5.6-5.9 west of Vancouver Island, British Columbia, Canada. NEIC reported it was felt with light shaking I-III in British Columbia at Parksville, Gibsons, Vancouver and perhaps as far as Oregon and Northern California. Foreshocks of M 4.5 and 4.3 preceded the mainshock and may have been felt lightly in the epicentral area.

This enhanced seismicity in British Columbia, Canada had been anticipated in this summary in the past several issues. It began two days ago with a strong series of moderate quakes as described at the time in this summary:

"A series of light to moderate earthquake with maximum events of M 4.2 occurred today in the region near Vancouver, British Columbia, Canada. These events centered near local solar noon and were probably promoted by the new moon tidal stresses today which maximized near this time as noted in this and previous issues of this summary:

"The New Moon will arrive at 01:40 UT on September 15. Longitudes which will be at local solar midnight at this time are near 25 West while those at local solar noon are near 155 East. These include the same areas identified as probable area of tidal triggering with the Full Moon of August 31. This forecast identified these at the time as: "These zones include the central Atlantic and Iceland and western Europe in the west and the Kuril Islands, Japan and portions of eastern Indonesia and the Vanuatu Islands in the east. These areas are the most likely to see tidal triggering in the next week. Such events often occur near local solar midnight and noon. A major earthquake is considered likely with this full moon in the next week." (September 13-15, 2023)

and continued in the previous issues of this summary as:

"The strong swarm of earthquakes yesterday in the area of Vancouver Island, British Columbia ceased abruptly today with only a minor earthquake recorded in the area. This swarm coincided with landfall of Hurricane Lee in Maine and Nova Scotia, Canada. This storm has been called a summer "nor'easter" because of its strength and characteristics. This summary has taken a clear stance on the likely connection between nor'easters and coincidental major activity in the northwestern U.S. and southwestern Canada as typified by the summary of January 29, 2022:

" ... a major nor'easter is beginning to progress up the eastern coast of the U.S. It may hit the Boston area with record snows today and on Saturday, January 29, 2022. Such nor'easters are often associated with a strong enhancement of seismicity along the western North American tectonic plate. A precautionary seismic watch is being called by this summary for this region through February 2, 2022." (January 27, 2022)

and more recently:

"The strongest earthquakes in the U.S. or Canada today occurred as an M 4.3 near Vancouver Island and as an M 3.8 in the Queen Charlotte Islands area of British Columbia. These were not reported felt. This may related to a nor'easter hitting the northeastern U.S. at this time. Larger earthquakes in the Vancouver and Queen Charlotte Island area of Canada often occur in conjunction with strong nor'easters on the opposite side of the North American Plate." (March 14, 2023)

A stronger earthquake in the Vancouver or Queen Charlotte region is possible with landfall of Hurricane Lee today in Nova Scotia and Newfoundland.

Hurricane Lee has been described in this and previous issues of this summary as:

"Hurricane Lee continued today in the area of north of Nova Scotia with winds up to 50 kts (category 1 hurricane). It is expected to track to the north and east and may enhance seismicity in the Northeast U.S and Quebec, Canada as it makes landfall in that area around of Nova Scotia on September 17 in the next week. Interactions with the North American Plate may also trigger moderate to strong seismic enhancement in areas of coastal western Canada and northwestern U.S. at this time. Coastal flooding in Maine is considered marginal by NHC but more intense effects are possible along the coasts of eastern Canada." (September 16-17, 2023)

The last earthquake of M>=5.9 within about 100 km of today's epicenters in Vancouver was an M 6.3 on December 25, 2019, part of a series of events in the area that started with two of M 6.0 on December 23, 2019. At the time this summary noted:

"Other factors which probably affected the timing of the activity in Vancouver, Canada probably included strong meteorological storms which dropped up to 12 inches on areas of the southeast U.S. and in Washington State and British Columbia and the geomagnetic storm of December 19-20.

...

The last earthquake in the Vancouver Island area of M>=6 was an M 6.5 on July 4, 2019 with the regional seismic activation of early July, 2019. A swarm hit southeast of today's events on October 22, 2018 (M 6.8, 6.5, 6.5) and in January, 2008 (M 6.4, 6.0 ..) and September 2013 (M 6.0, 6.0, 6.1)." (December 23, 2019)

An M 6.0 was also recorded in the Vancouver area about 150 km southeast of today's event on April 13, 2023.

Forecast 156546 had expected today's event within about 10 km was likely in mid-September.

O: 17SEP2023 11:28:13 50.8N 130.2W Mw=5.6 EMSC VANCOUVER ISLAND, CANADA REGION

O: 17SEP2023 11:28:08 50.6N 130.5W MB=5.9 ECAN of Port Hardy, BC

O: 17SEP2023 15:19:50 50.8N 130.3W ML=4.3 EMSC VANCOUVER ISLAND, CANADA REGION

O: 17SEP2023 15:19:49 50.7N 130.5W MB=4.3 ECAN of Port Hardy, BC

O: 17SEP2023 09:58:57 50.6N 130.5W MB=5.0 ECAN of Port Hardy, BC

O: 17SEP2023 09:59:03 50.8N 129.8W Mw=4.5 EMSC VANCOUVER ISLAND, CANADA REGIO

P: 13SEP2023 156546 50.5N 130.4W 3.0-4.9 BAAAA British Colombia

An unusually large M 5.1 struck the area of Northern Italy today. NEIC reported it was felt with maximum intensity IV in San Godenzo, Toscana, Brisighella Emilia-Romagna, Castrocaro Terme and Terra del Sole and Forli with lesser shaking in Borgo, San Lornzo, Scarperia, Riolo Terme, Pontassieve and Imola among others. This is the strongest earthquake in northern Italy within about 200 km of this epicenter since an M 5.6 about 200 km to the east on November 9, 2022 but the last within about 100 km of today's epicenter was an 6.1 on May 20, 2012 and an M 5.5 aftershock on May 29, 2012. At the time of the May 20, 2012 event this summary noted:

"Three strong earthquakes of M 5.8-6.1 hit in the world today and were probably triggered by tidal forces associated with the upcoming solar eclipse which will occur later today. The most widely felt and damaging of today's events occurred as an M 6.1 in northern Italy ...

The last earthquake in northern Italy of similar or larger magnitude (and the only such event in the past 22 years) was an M 6.4 on September 26, 1997." (May 20, 2012)

Today's event in Italy occurred near Florence but was reported by the press to have not caused any significant damage in the area. Forecast 156503 had expected today's event within about 100 km was likely around September 15.

O: 18SEP2023 03:10:14 44.0N 11.7E Mw=5.1 ANSS NORTHERN ITALY

O: 18SEP2023 03:10:14 44.0N 11.6E Mw=5.1 EMSC NORTHERN ITALY

P: 15SEP2023 156503 45.0N 12.0E 3.0-5.2 BAAAA Austria

LANDFALL OF HURRICANE LEE IN NOVA SCOTIA ASSOCIATED WITH VANCOUVER EARTHQUAKES

EARTHQUAKE SUMMARY FOR SEPTEMBER 16, 2023

The strong swarm of earthquakes yesterday in the area of Vancouver Island, British Columbia ceased abruptly today with only a minor earthquake recorded in the area. This swarm coincided with landfall of Hurricane Lee in Maine and Nova Scotia, Canada. This storm has been called a summer "nor'easter" because of its strength and characteristics. This summary has taken a clear stance on the likely connection between nor'easters and coincidental major activity in the northwestern U.S. and southwestern Canada as typified by the summary of January 29, 2022:

and more recently:

A stronger earthquake in the Vancouver or Queen Charlotte region is possible with landfall of Hurricane Lee today in Nova Scotia and Newfoundland.

Hurricane Lee has been described in this and previous issues of this summary as:

The strongest earthquake in the world today was an M 5.4 in the Mid-Indian Ridge. This is the first earthquake of this size or larger within about 200 km of this epicenter since an M 5.6 on March 27, 2022 and an M 5.5 on November 2, 2021. Today's activity in the mid-Indian Ridge may have been promoted by antipodal energy associated with Hurricane Jova which passed over the antipode of today's event on September 5, 2023 as noted at the time in this summary:

"HURR JOVA 2023-09-06 00:00 UT 13.3N 109.0W 90 kts South of Gulf of Mexico" (September 6, 2023)

Forecast 156319 had expected today's event in this region was likely around

September 10.

O: 16SEP2023 13:47:57 13.7S 66.3E Mw=5.4 EMSC MID-INDIAN RIDGE

P: 10SEP2023 156319 15.0S 67.0E 4.0-5.6 CBAAA So. Indian Ocean

The strongest earthquake in the U.S. or Canada today was an M 3.9 in the Fox Islands, Aleutians, Alaska. It was not reported felt in this remote area. The last event of significantly larger magnitude in the Fox Islands was an M 4.6 near today's epicenter on August 16, 2023. At the time this summary noted:

"The strongest earthquake in the U.S. or Canada today was an M 4.6 in the Fox Islands, Aleutians, Alaska. It was not reported felt in this remote epicentral area. This is the strongest earthquake in the Fox Islands since an M 4.8 on July 1, 2023 and is probably a regional aftershock of that event." (August 16, 2023)

Like the event of August 16, today's Fox Islands earthquake occurred with the new moon near local solar noon and was probably promoted by tidal stresses with that alignment. Forecast 156550 had expected today's event in the Fox Islands was likely within about 50 km around September 17. The Fox Islands are near 103 degrees from the M 6.8 in Morocco of September 8, 2023 and may have been promoted by energy from that source. Other events at this distance today from Morocco included moderate quakes in Sumatra, the West Chile Rise and Honshu, Japan.

O: 16SEP2023 23:59:20 52.4N 169.4W ML=3.9 EMSC FOX ISLANDS, ALEUTIAN ISLANDS

P: 17SEP2023 156550 51.9N 169.2W 3.5-4.9 AAAAA Fox Islands, Aleutians

O: 16SEP2023 19:14:14 41.2S 89.4W mb=4.8 EMSC SOUTHEAST OF EASTER ISLAND

P: 13SEP2023 156616 43.0S 83.0W 4.0-5.8 BBCAA Chile Rise

O: 17SEP2023 00:44:20 3.3N 97.9E ML=4.3 EMSC NORTHERN SUMATRA, INDONESIA

P: 12SEP2023 156376 3.0N 97.0E 4.0-5.7 BAAAA Nicobar Islands

O: 16SEP2023 18:28:21 44.9N 149.8E mb=4.5 EMSC KURIL ISLANDS

P: 14SEP2023 156535 45.0N 149.0E 3.5-5.5 AAAAA So. Kurils

STRONG QUAKE SHAKES ATACAMA, CHILE

EARTHQUAKE SUMMARY FOR SEPTEMBER 15, 2023

The strongest earthquake in the world today was an M 5.7-5.9 in the area off the coast of Atacama, Chile. GUC reported this earthquake was felt with intensity III in Atacama at Copiapo, Tierra Amarilla and Caldera, Chile. This earthquake occurred with the new moon within about an hour of local solar noon and was probably promoted by tidal stresses associated with that alignment as described in previous issues of this summary:

A similar M 5.9 hit Atacama with the full moon on April 4, 2023. At the time this summary noted:

"An M 5.9 also shook the region of Central Chile in Atacama today. NEIC reported it was felt with intensity VI in Copiapo with IV in Diego de Almagro and in La Serena, Coquimbo, Chile. This is the largest earthquake in the Atacama region of Chile since an M 6.0 on July 4, 2021. That earthquake was associated with an X1.2 solar flare and a strong activation of western North America. At the time this summary noted:

"A series of moderately large to large earthquake hit along the western coastline of North and South America today. These included an M 5.6-5.7 in Nayarit, Gulf of California; two events of M 5.8-6.0 in Atacama, Chile and a series of light, but widely felt quakes in southern and central California of M 3.4-3.6. Much of this activity may be related to an X1.5 solar flare which occurred when the region of Atacama was sub-solar at 14:30 UT (#6940). This is the strongest solar flare reported since X9 and X8 flares on September 6 and 10, 2017, nearly four years ago. ...

Two strong earthquakes of M 5.9-6.0 struck the Atacama area of Central Chile today. They were felt with maximum intensity IX (local damage) at Vallenar; V in Vicuna and Ovalle, Coquimbo and IV in Coquimbo at Coquimbo, Copiapo, and IV in Valparaiso at Vina del Mar and Quilpue, Chile. ... The last earthquake of M>=6 within about 200 km of today's activity was a series on September 1, 2020 including events of M 6.8, 6.5 and 6.3 and prior to that an M 6.9 on November 11, 2015." (July 4, 2021, April 4, 2023)

O: 15SEP2023 18:07:42 27.3S 71.4W Mw=5.7 EMSC OFFSHORE ATACAMA, CHILE

O: 15SEP2023 18:07:42 27.3S 71.7W Mw=5.9 GUC OFFSHORE ATACAMA, CHILE

P: 13SEP2023 156593 26.0S 71.0W 4.0-5.6 ABAAA Coast Central Chile

P: 13SEP2023 156593 28.0S 67.0W 4.0-5.6 AACAA Argentina

MODERATE QUAKES IN NEW BRITAIN, PNG; SOUTHEAST PACIFIC

EARTHQUAKE SUMMARY FOR SEPTEMBER 14, 2023

The strongest earthquake in the world today was an M 5.6 in New Britain, New Guinea. NEIC reported it was felt with maximum intensity V in New Britain at Kimbe and II in Port Moresby, PNG. A similar earthquake of M 5.6 occurred about 100 km west of this epicenter on August 13, 2023, but the last earthquake of larger magnitude in New Britain was an M 6.3 on April 19, 2023 which, like today's event occurred with the new moon. At the time this summary noted:

"The strongest earthquake in the world today was an M 6.3 in the area of New Guinea. This event was reported by NEIC to have been felt with intensity V in New Britain, Papua New Guinea in Kandrian and VI in Kimbe with intensity II-III in Kae, Morobe, Kainantu, Port Moresby and Mount Hagen, Papua New Guinea. This epicenter is located along the path of totality of the solar eclipse today (see discussion below and in "TIDAL" section of this summary. It is likely it was promoted by strong tidal stresses associated with this alignment. The last earthquake at shallow or intermediate focus with M>=6.3 within about 200 km of this epicenter was an M 6.3 on March 5, 2017. An M 6.5 hit at a depth of 600 km on March 1, 2023 outside this 200 km distance. An M 7.0 on October 10, 2018 was about 200 km from today's epicenter." (April 19, 2023)

Forecast 156389 had expected today's event within about 150 km was likely around September 14, 2023.

O: 14SEP2023 23:15:32 6.4S 149.5E mb=5.0 EMSC NEW BRITAIN REGION, P.N.G.

O: 14SEP2023 19:58:45 6.2S 149.6E Mw=5.6 EMSC NEW BRITAIN REGION, P.N.G.

P: 14SEP2023 156389 5.0S 150.0E 4.0-5.5 ABAAA New Ireland

A similar event of M 5.6 in the area southeast of Easter Island followed an M 4.9 earlier in the day. The foreshock occurred near local solar midnight and may have been promoted by the strong tidal stresses today with the new moon. This is probably a regional aftershock of an M 6.1 in the West Chile Rise about 200 km to the east of today's event on September 13. At that time this summary noted:

The strongest earthquake in the world today was an M 6.1 in the West Chile Rise.

It was not reported felt in this remote area. The only earthquake in the past 3 years of larger magnitude than M 6.1 in the West Chile Rise was an M 6.7 on February 3, 2021. At the time this summary noted in this regard:

"This earthquake is the strongest within about 400 km of this epicenter in at least the historical record for the area. Earthquakes in this area of M 6.5 hit on 1934, 1937, 1954, 1975, 1997 and 1999. It occurred within about an hour of local solar midnight, a time when geomagnetic effects are prominent and may have been related to those as well as to tidal stresses which maximize near this hour. Forecast 131093 had expected today's event within about 50 km was likely around February 8 in the Chile Rise area. The antipode of this epicenter is in China north of Nepal at 36N 83E" (February 3, 2021)

Forecast 156347 had expected today's event within about 100 km was likely around September 9, 2023. This epicenter is at 107 degrees from the M 6.8 in Morocco of September 8 and may have been promoted by energy from that source." (September 13, 2023)

These events in the south Pacific are near 103 degrees from the M 6.8 in Morocco of September 8 and may have been promoted by energy from that source.

O: 14SEP2023 07:19:50 36.3S 99.6W mb=4.9 EMSC SOUTHEAST OF EASTER ISLAND

O: 14SEP2023 22:51:27 36.5S 98.1W Mw=5.6 EMSC SOUTHEAST OF EASTER ISLAND

P: 9SEP2023 156347 36.0S 97.0W 4.0-5.9 BAAAA Chile Rise

An unusually strong earthquake of M 4.0 shook the Falls City area of Southern Texas today. NEIC reported it was felt with maximum intensity IV in Hobson, Karnes City and Falls City with II-III shaking in Gillett, Stockdale, Poth, Sutherland Springs, Floresville and Kenedy among others. This event may have been triggered by Solar Flare effects from flare #9230 (SWPC - which maximized within minutes of this earthquake with parameters from SWPC as:

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

-------------------------------------------------------------------------

9230 1840 1845 1850 C2.9 (September 14, 2023) 1.6E-03

The earthquake in Texas occurred within minutes of local solar noon and SFE re most prominent at this hour - reinforcing the suspicion this could have been promoted by flare 9230. Today's event in Texas follows a series of smaller events which began about two years ago with an M 3.5 on October 30, 2022 but is the strongest event in this series to date - the strongest prior to today in this series was an M 3.8 on July 19, 2023. Stronger regional events have been recorded as an M 4.8 on October 20, 2011 and an M 4.3 on April 9, 1993. At the time of the October 30, 2022 this summary noted:

"An earthquake of M 3.5 also shook Southern Texas today. NEIC reported intensity II-III in Texas at Westhoff, Smiley and Cotulla. This is the strongest earthquake within about 100 km of this epicenter since an M 3.5-3.6 on June 16, 2019 but the last event of significantly larger magnitude in this area was an M 4.8 on October 20, 2011." (October 30, 2022)

Forecast 156430 had expected today's event within this area was likely around

September 13, 2023.

O: 14SEP2023 18:50:41 29.1N 97.9W mb=4.0 EMSC SOUTHERN TEXAS

P: 13SEP2023 156430 28.0N 98.0W 3.0-4.6 ABAAA Northern Mexico

An M 4.6 aftershock in Morocco today was widely felt in the area. Like the event in Texas this event may have been triggered by SFE from flare #9160 with parameters from SWPC as:

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

-------------------------------------------------------------------------

9160 0548 0600 0611 C1.5 (September 14, 2023) 6.8E-04

NEIC reported this M 4.6 was felt with intensity IV in Morocco at Oulad Teima, Essaouira, Marrakech and III in Taroudannt, Agadir, Ouarzazate, Ben Guerir, Safi, Tiznit, and El Jadida. A major incidence of earthquake lights has been reported to have occurred in Morocco shortly before the M 6.8 there on September 8. This has been published in reliable sources. Earthquake lights are often observed in association with major earthquake and have been seen and reported for thousands of years. Many theories try to explain them but the exact cause of these phenomena is still unknown. Thanks to Pam, a reader of this summary for a good summary she sent in this regard. Similar summaries are available on the web for readers to peruse. The death toll from this earthquake is near 3000 with more than 5600 injured. Forecast 156458 had expected enhanced seismicity in this region of Morocco was likely around September 11.

O: 14SEP2023 05:53:16 31.0N 8.4W mb=4.6 EMSC MOROCCO

O: 13SEP2023 15:45:07 31.3N 8.2W ML=3.5 EMSC MOROCCO

O: 15SEP2023 04:55:40 31.6N 7.6W mb=3.7 EMSC MOROCCO

P: 11SEP2023 156458 30.0N 8.0W 3.5-5.3 AAAAA Morocco/Spain

The largest earthquake in the U.S. or Canada today was an M 4.4 in Southern Alaska. This is the strongest earthquake within about 150 km of this epicenter in Southern Alaska since an M 4.4 on August 6, 2023 and an M 5.0 on July 28, 2023. This earthquake occurred within minutes of local solar noon and was probably promoted by tidal stresses with today's new moon. Forecast 156568 had expected today's event in this area was likely around September 14.

O: 14SEP2023 22:35:04 59.3N 153.5W mb=4.4 EMSC SOUTHERN ALASKA

P: 14SEP2023 156568 60.0N 153.5W 3.2-5.1 AAAAA Central Alaska

A series of light to moderate earthquake with maximum events of M 4.2 occurred today in the region near Vancouver, British Columbia, Canada. These events centered near local solar noon and were probably promoted by the new moon tidal stresses today which maximized near this time as noted in this and previous issues of this summary:

Following is an abridged listing of earthquake in this swarm with M>=3.7. A more complete listing can be found under "PACIFIC CANADA" section of this report.

O: 14SEP2023 17:12:22 50.6N 130.5W ML=3.7 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 17:27:10 50.6N 130.5W ML=3.9 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 17:41:29 50.6N 130.5W ML=4.2 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 17:03:37 50.7N 130.4W ML=3.7 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 17:15:42 50.7N 130.5W ML=4.0 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 17:31:06 50.7N 130.4W ML=4.2 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 17:52:26 50.7N 130.5W ML=4.1 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 18:02:47 50.7N 130.5W ML=4.0 EMSC VANCOUVER ISLAND, CANADA REGION

O: 14SEP2023 18:02:47 50.7N 130.5W MB=4.0 ECAN of Port Hardy, BC

O: 14SEP2023 17:52:26 50.7N 130.5W MB=4.1 ECAN of Port Hardy, BC

O: 14SEP2023 17:41:29 50.6N 130.5W MB=4.3 ECAN of Port Hardy, BC

O: 14SEP2023 17:31:06 50.7N 130.4W MB=4.2 ECAN of Port Hardy, BC

O: 14SEP2023 17:27:10 50.6N 130.5W MB=3.9 ECAN of Port Hardy, BC

O: 14SEP2023 17:15:42 50.7N 130.5W MB=4.0 ECAN of Port Hardy, BC

O: 14SEP2023 17:12:22 50.6N 130.5W MB=3.7 ECAN of Port Hardy, BC

O: 14SEP2023 17:03:37 50.7N 130.4W MB=3.7 ECAN of Port Hardy, BC

P: 13SEP2023 156546 50.5N 130.4W 3.0-4.9 AAAAA British Colombia

Today's activity in Vancouver is the strongest in the region since M 4.6 and M 6.0 on April 19 and 13, 2023.

STRONG EARTHQUAKE IN WEST CHILE RISE

EARTHQUAKE SUMMARY FOR SEPTEMBER 13, 2023

The strongest earthquake in the world today was an M 6.1 in the West Chile Rise. It was not reported felt in this remote area. The only earthquake in the past 3 years of larger magnitude than M 6.1 in the West Chile Rise was an M 6.7 ion February 3, 2021. At the time this summary noted in this regard:

"This earthquake is the strongest within about 400 km of this epicenter in at least the historical record for the area. Earthquakes in this area of M 6.5 hit on 1934, 1937, 1954, 1975, 1997 and 1999. It occurred within about an hour of local solar midnight, a time when geomagnetic effects are prominent and may have been related to those as well as to tidal stresses which maximize near this hour. … The antipode of this epicenter is in China north of Nepal at

36N 83E" (February 3, 2021)

O: 13SEP2023 11:49:16 36.3S 97.9W Mw=6.1 EMSC WEST CHILE RISE

P: 9SEP2023 156347 36.0S 97.0W 4.0-5.9 BAAAA Chile Rise

A moderate M 5.0 also occurred in Eritrea today. It was not reported felt in this region. This may be an aftershock of an M 5.6 which hit the same region on August 1, 2023. At the time this summary noted:

"The most unusual earthquake of the day today was an M 4.6 in the border region between Eritrea and Ethiopia. This has been an active area especially during periods of active solar and geomagnetic periods, often showing synchronicity with major solar flares. During the current solar quiet period, however the area has see little moderate seismicity. The last earthquakes of M>=4.6 within about 300 km of this epicenter occurred September 11, 2019 and August 13, 2018. The last event of M>5 in this area was an M 5.6 on July 8, 2013." (June 5, 2022)

As expected today’s earthquake occurred at the height of the geomagnetic storm along with several moderate flares and may have been promoted by SFE and other geomagnetic effects. Forecast 156405 had expected enhanced seismicity in mid-September in this region.

O: 13SEP2023 17:51:07 15.2N 39.5E mb=5.0 EMSC ERITREA

P: 16SEP2023 156405 12.0N 40.0E 3.5-5.5 BCAAA Ethiopia

An M 4.6 aftershock shook Morocco today. NEIC reported it was felt with intensity IV in Morocco at Oulad Teima, Essaouira, Marrakech and III in Taroudannt, Agadir, Ouarzazate, Ben Guerir, Safi, Tiznit, and El Jadida.

A major incidence of earthquake lights has been reported to have occurred in

Morocco shortly before the M 6.8 there on September 8. This has been published in reliable sources. Earthquake lights are often observed in association with major earthquake and have been seen and reported for thousands of years. Many theories try to explain them but the exact cause of these phenomena is still unknown. Thanks to Pam, a reader of this summary for a good summary she sent in this regard. Similar summaries are available on the web for readers to peruse. The death toll from this earthquake is near 3000 with more than 5600 injured. Forecast 156458 had expected enhanced seismicity in this region of Morocco was likely around September 11.

O: 14SEP2023 05:53:16 31.0N 8.4W mb=4.6 EMSC MOROCCO

O: 13SEP2023 15:45:07 31.3N 8.2W ML=3.5 EMSC MOROCCO

P: 11SEP2023 156458 30.0N 8.0W 3.5-5.3 AAAAA Morocco/Spain

A minor swarm of earthquakes occurred in the region of Mt. St. Helens today. This was centered within minutes of local solar noon and may indicate tidal stresses moving magma. Forecast 156539 had expected enhanced seismicity in this region was likely September 11.

O: 13SEP2023 21:10:40 46.2N 122.2W MD=2.3 EMSC MT. ST. HELENS AREA, WASHINGTON

O: 13SEP2023 19:48:08 46.2N 122.2W MD=2.1 EMSC MT. ST. HELENS AREA, WASHINGTO

P: 11SEP2023 156539 46.9N 122.0W 2.0-4.1 AAAAA Washington state, U.S.

STRONG EARTHQUAKES SHAKES NORTHERN PHILIPPINES; TAIWAN

EARTHQUAKE SUMMARY FOR SEPTEMBER 12, 2023

The largest earthquake in the world today occurred in the Northern Philippines in the Luzon Strait between the Babyuan Region of the Philippines and Taiwan. NEIC reported it was felt with maximum intensity V in the Cagayan Valley at Aparii, Batal, amd om Cprdo;;era at Sagada, Baguio with lesser shaking of II in Tuguegarao, Cagayan Valley and in Taiwan in Kaohsiung and Taiwan. Strong seismic enhancement had been expected in this region at this time after Supertyphoon Saola passed directly over this epicenter with winds up to 170 kts in late August and early September, 2023 as noted in earlier issues of this summary:

"Super-Typhoon SAOLA (09W ) continued today in the area of southern Taiwan and northern Philippines with winds up to 165 kts. It is expected to reverse course and head towards southern Taiwan making landfall there around September 1. Enhanced seismicity in the northern Philippines and Taiwan is likely as Saola passes through the area." (September 1, 2023).

It is likely today's earthquake was promoted by stresses associated with Super-Typhoon Saola. It occurred near the height of today's geomagnetic storm when AP at 35 was near minor storm levels. It is likely this also had an effect on the occurrence of this event at this time.

PHIVOLCS reported it with M 6.3 while CWB in Taiwan reported it with M 6.7

CWB reported it was felt in Taiwan with intensity II in Kaohsiung, Changhua, Taitung, Yunlin, Tainan and I in Hualien, Nantou, Chiayi, and Penghu Counties, Taiwan. PHIVOLCS reported it was felt throughout northern Luzon, Philippines with maximum intensity VI in Calayan, Cagayan and V in Luna and Pudtol, Apayao; Bacarra, Bangui, Burgos, Demalneg, City of Laoag,Pagudpud, Paoay, Pasuquin, San Nicolas and Vintar, Ilocos Norte; Aparri, Baggao, Camalaniugan, Claveria, Lal-Lo, Pamplong, Sanchez-Mira, Santa Ana, Santa Praxedes and Santa Teresita, Cagayan, Philippines. A foreshock of M 5.0 hit this region yesterday. An earthquake of M 6.0 hit the Babuyan Islands on June 30, 2022, the last event of M>=6.3 in the area reported by NEIC occurred on May 18m 1993 with M 6.8. An M 7.0 hit south of this on July 27, 2022 with an aftershock of M 6.4 on October 25, 2022. The only other similar event in the region in the past 35 years was an M 6.4 on July 16, 2000. At the time of the M 7.0 in July, 2022, this summary noted:

"Today's event of M 7.0 is the strongest within about 300 km of this epicenter since an M 7.3 about 250 km southwest of this on December 11, 1999 and prior to that an M 7.7 about 200 km to the south on July 16, 1990." (July 27, 2022)

Forecasts 156136 and 156410 had expected today's event was likely around September 10-11 within about 25 km of today's epicenters. Today’s epicenter in the Babuyan Islands is near 103 degrees from the M 6.8 in Morocco of September 8 and may have been promoted by energy from that source.

O: 11SEP2023 17:30:12 19.2N 121.1E mb=5.0 EMSC BABUYAN ISL REGION, PHILIPPINE

P: 10SEP2023 156136 19.0N 121.0E 3.5-4.9 AAAAA Luzon, Philippines

P: 11SEP2023 156410 19.0N 121.0E 3.5-4.9 AAAAA Luzon, Philippines

O: 12SEP2023 11:03:18 19.3N 121.3E Mw=6.3 EMSC BABUYAN ISL REGION, PHILIPPINE

O: 12SEP2023 11:03:18 19.3N 121.3E Mw=6.7 BMGC BABUYAN ISL REGION, PHILIPPINE

O: 12SEP2023 11:03:17 19.3N 121.2E Mw=6.7 CWB BABUYAN ISL REGION, PHILIPPINE

P: 10SEP2023 156136 19.0N 121.0E 3.5-4.9 AAAAA Luzon, Philippines

P: 11SEP2023 156410 19.0N 121.0E 3.5-4.9 AAAAA Luzon, Philippines

The strongest earthquake in the U.S. or Canada today was an M 5.0 in the central Andreanof Islands, Aleutians, Alaska. NEIC reported it was felt with intensity III in Adak, Alaska. This earthquake occurred within minutes of local solar noon and was probably promoted by strong tidal stresses which maximize near this hour. The last earthquake with M>=5.0 in the Andreanof Islands was an M 5.2 on February 15, 2023. At the time this summary noted:

"The strongest earthquake in the U.S. or Canada today was an M 5.2 in the western Andreanof Islands. This is the strongest earthquake in the western Andreanof Islands, Aleutians, Alaska since an M 5.2 on June 6, 2022. The last event in the area of larger magnitude was an M 6.1 on September 24, 2021." (February 15, 2023)

Forecast 156543 had expected today's event in the Andreanof Islands within about 50 km of this epicenter was likely around September 12.

O: 12SEP2023 23:17:37 51.5N 176.4W mb=5.0 EMSC ANDREANOF ISLANDS, ALEUTIAN IS

P: 12SEP2023 156543 51.1N 175.8W 3.5-4.9 AAAAA Andreanoff Isls, Aleutians

An M 4.9 also occurred in the Unimak Islands, Alaska today. This event occurred about an hour before that in the Andreanof Islands and, like that event, occurred near local solar noon, probably being promoted by strong tidal stresses. An earthquake of M 5.0 hit the Unimak Island region on August 14, 2023 and was described in this summary at the time as:

The strongest earthquake in the U.S. or Canada today was an M 5.0 in Unimak Island, Aleutians, Alaska. NEIC reported and aftershock of M 4.2 in Unimak Island, Alaska was felt with intensity II-III in the area(s) of Unimak Island, Alaska in Akutan. This activity occurred within minutes of local solar noon and was probably promoted by high tidal stresses with the upcoming new moon. This is the strongest earthquake in the Unimak area since an M 5.1 on September 9 and January 11, 2021. No events of significantly larger magnitude have hit this area in the past 3.5 years." (August 14, 2023)

Forecast 156549 had expected today's event within about 100 km was likely in the Unimak Island area around September 15.

O: 12SEP2023 21:48:57 54.0N 164.1W mb=4.9 EMSC UNIMAK ISLAND REGION, ALASKA

P: 15SEP2023 156549 53.5N 165.8W 3.5-5.0 BAAAA Fox Islands, Aleutians

An unusually large M 3.3 hit the region of Morgan Hill, Central California today. NEIC reported this earthquake of M 3.3 in Central California was felt with intensity II-III in the area(s) of Central California in Morgan Hill, San Martin, San Jose, Gilroy. This event occurred within minutes of local solar midnight and may have been promoted by strong tidal stresses which maximize near this hour. The last earthquake of M>=3.3 within the region of Morgan Hill with M>=3.3 occurred on August 31, 2023 with M 3.3. At the time this summary reported:

"An unusually large M 3.6 earthquake was widely felt in the Morgan Hill area of Central California today. NEIC reported intensity II-III in San Jose, Morgan Hill, Coyote, Mount Hamilton, among others. This is the largest earthquake in this region of California within about 50 km since an M 3.6 on January 23, 2023. The last earthquake of greater magnitude in this area was an M 5.1 on December 5, 2022" (July 30, 2023)

Forecast 156174 had expected today's event was likely within this area around

September 9.

O: 12SEP2023 08:32:21 37.2N 121.6W ML=3.3 EMSC NORTHERN CALIFORNIA

P: 9SEP2023 156174 37.7N 121.9W 2.5-4.4 BAAAA Central California

STRONG QUAKES CONTINUE IN INDONESIA

EARTHQUAKE SUMMARY FOR SEPTEMBER 11, 2023

The strongest earthquake in the world today was an M 6.0-6.1 in Halmahera, Indonesia. NEIC reported it was felt in Sulawesi, Indonesia with III in Manado, Tomohon and Mobagu, Sulawesi and possibly in Southern Mindanao, Philippines. BMG reported it was was felt with intensity III-IV in Manado, Sangihe, Kotamobagu, Bitung, Talaud, Jaillil; III in Ternate, Halmahera, Sula, II-III in Gorontalo, Minahas, Ternate, Taliabu, Ambon, and II in Namlea, Tomohon, and Bone Bolango, Indonesia. The last earthquake in Halmahera of M>=6.0 occurred about 200 km northeast of today's epicenter in Halmahera as an M 5.3 on February 23, 2023. At the time this summary noted in this regard:

"This epicenter is about 150 km northeast of the M 7.0 in the Molucca Sea of January 18, 2023 and the strongest within about 150 km in the area since an M 6.4 on June 4, 2020. The only event within this region of M>=6.8 in the past 35 years was an M 6.8 on April 19, 1993." (February 23, 2023)

Forecast 156100 had expected today's event was likely within about 150 km was likely around September 10, 2023.

O: 11SEP2023 12:51:33 1.1N 127.5E Mw=6.0 EMSC HALMAHERA, INDONESIA

O: 11SEP2023 09:33:37 1.3N 126.2E ML=4.1 EMSC MOLUCCA SEA

P: 10SEP2023 156100 2.0N 126.0E 4.0-5.4 AABAA Mindanao, Philippines

An earthquake of M 5.9 also occurred today in the Central Mid-Atlantic Ridge area. It was not reported felt in this remote area. This is near the antipode of the M 6.0 in Indonesia today and may have been promoted by energy associated with that event. The last earthquake of M>=5.9 within about 200 km of this epicenter was an M 6.9 on September 18, 2020. At the time this summary noted in this regard:

"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." (September 18, 2020)

Forecast 156092 had expected enhanced seismicity in this area was likely around September 8, 2023.

O: 11SEP2023 09:20:57 0.8N 26.1W Mw=5.9 EMSC CENTRAL MID-ATLANTIC RIDGE

P: 8SEP2023 156092 1.0N 28.0W 4.0-5.4 BABAA Central Mid-Atlantic Ridg

The strongest earthquake in the U.S. or Canada today was an M 4.7 in the area

South of Alaska near the Alaska Peninsula. It was not reported felt in this remote area. This is the strongest earthquake within about 200 km of this epicenter since an M 4.8 on April 24, 2023 and an M 5.0 on January 10, 2023, the only such events in the region since September 2022. Forecast 156541 had expected today's event was likely around September 13 within about 50 km of this epicenter.

O: 12SEP2023 05:23:16 55.1N 156.4W mb=4.7 EMSC SOUTH OF ALASKA

P: 13SEP2023 156541 54.7N 156.9W 3.5-5.0 AAAAA Alaska Peninsula

An unusual earthquake of M 3.0 hit northern Nunavut, Canada today near Grise Fiord. It was not reported felt in this remote area where it occurred near local solar midnight, a time when tidal stresses may have helped promote enhanced seismicity. This is the first earthquake within about 300 km of this epicenter reported by NEIC since an M 4.0 on August 18, 2008. Forecast 156309 had expected today's event within about 25 km around September 5.

O: 10SEP2023 06:42:43 80.3N 89.6W MB=3.0 ECAN of Grise Fiord, NU

P: 5SEP2023 156309 80.0N 90.0W 4.0-5.7 BAAAA Arctic Ocean Region

ATERSHOCKS CONTINUE IN MOROCCO

EARTHQUAKE SUMMARY FOR SEPTEMBER 10, 2023

An aftershock of M 4.2 shook areas of Morocco today. NEIC reported it was felt with intensity II-III in Morocco at Taoudannt, Marrakech, Agadir, Ouarzazate. Safi, Casablanca and Bouznika. More than 3000 confirmed deaths occurred with the M 6.8 earthquake of September 8, 2023. In the previous issue of this summary the tolls from the earthquake Morocco had been noted as:

"Death tolls continued to rise in the M 6.8 earthquake in Morocco. The reported number of dead in this earthquake is now more than 2100. An earthquake in Morocco in 1960 killed more than 12,000. BBC reports total destruction in many remote villages, so the tolls are expected to rise. This is the most deadly earthquake in the world since the M 7.7 in Turkey of February 6, 2023 which reportedly killed 53560. The previous most deaths in recent earthquakes occurred in Sulawesi on September 28, 2018 (4340) and Nepal on April 25, 2-15 (8964), the only other comparable events in the past 10 years in the world.

Detailed description of the mainshock in Morocco can be found in the previous issue of this summary. Light aftershocks continued but did little damage today. Forecast 156187 had expected regional seismic enhancement in Morocco was likely in early September. Far field seismic enhancement today from Morocco appears to have hit Sulawesi (M 6.3) and Bali (M 5.8) in Indonesia (120 degrees - node 3); Sumatra (M 4.1, 4.2, 4.6) (103 degrees), Costa Rica (M 4.6 node 5 72 degrees); the Galapagos (m 4.5, 4.6, 4.7) (node 4 90 degrees); and the Virgin Islands M 3.9 node 7 - 52 degrees)." (September 10, 2023)

O: 10SEP2023 08:00:01 31.0N 8.5W mb=4.2 EMSC MOROCCO

P: 5SEP2023 156187 37.0N 10.0W 3.5-5.1 BCAAA Morocco/Spain

An eruption of Mt. Kilauea volcano in Hawaii today followed an M 3.5 near local solar noon. This is the third eruption of Kilauea this year and is substantial with many lava flow and ash. Forecast 1556131 had expected enhanced seismicity in Hawaii was likely around September 7.

NEIC reported this earthquake of M 3.5 in Hawaii was felt with intensity II-III in the area(s) of Hawaii in Hawaii National Park.

O: 11SEP2023 00:47:18 19.4N 155.3W ML=3.0 EMSC ISLAND OF HAWAII, HAWAII

O: 11SEP2023 00:48:22 19.4N 155.3W ML=3.5 EMSC ISLAND OF HAWAII, HAWAII

O: 11SEP2023 00:49:45 19.4N 155.3W ML=3.1 EMSC ISLAND OF HAWAII, HAWAII

O: 11SEP2023 01:26:58 19.4N 155.3W ML=3.1 EMSC ISLAND OF HAWAII, HAWAII

P: 7SEP2023 156131 18.8N 155.2W 3.0-4.6 BAAAA Hawaii

The largest earthquakes in the world today were of M 5.3 - in the Kermadec Islands and in the Ryukyu Islands, Japan. Neither is unusual nor felt in their respective regions. Forecasts 156160 and 156156 expected the activity in the Ryukyu Islands in early September while forecast 156334 had expected the event in the Kermadec Islands within about 25 km was likely around September 8.

O: 10SEP2023 17:58:27 31.1N 131.5E mb=4.7 EMSC KYUSHU, JAPAN

O: 10SEP2023 15:02:03 29.3N 129.5E Mw=5.3 EMSC RYUKYU ISLANDS, JAPAN

O: 10SEP2023 22:57:57 29.4N 129.3E ML=4.1 EMSC RYUKYU ISLANDS, JAPAN

P: 5SEP2023 156160 29.0N 128.0E 4.0-5.6 BAAAA Ryukyu Islands

P: 7SEP2023 156156 29.0N 131.0E 4.0-5.6 BABAA Kyushu Japan

O: 10SEP2023 15:03:18 29.0S 177.3W Mw=5.3 EMSC KERMADEC ISLANDS, NEW ZEALAND

P: 8SEP2023 156334 29.0S 177.0W 4.0-5.4 AAAAA No. Kermadec Islands

A series of three moderate earthquakes were felt in Iraq today. NEIC reported this earthquake of M 4.7 in Iraq was felt with intensity II-III in the area(s) of Iraq in Chamchamal and Mossul (IV) and in Kirkuk, Irbil, Baghdad, Mehabad and ash Shikhan. The last earthquake with M>=4.7 within about 150 km of this epicenter in Iraq was recorded on March 16, 2023 (M 5.1) and on February 4, 2023 (M 4.7) - two days before the massive earthquakes in Turkey of February 6 (M 7.7+) after a two-year hiatus of seismicity at moderate levels in the area. Today's activity occurred near local solar midnight and may have been promoted by tidal stresses which are new maximum at this hour. Forecasts 156219 and 156227 had expected today's activity Iraq was like in early September.

O: 10SEP2023 21:42:48 35.1N 44.7E ML=4.6 EMSC IRAQ

O: 10SEP2023 21:43:49 35.1N 44.8E mb=4.7 EMSC IRAQ

P: 6SEP2023 156219 33.0N 46.0E 3.8-5.3 BCAAA So. Iran

O: 10SEP2023 21:44:13 36.4N 43.8E ML=4.4 EMSC IRAQ

P: 1SEP2023 156227 38.0N 43.0E 3.5-4.9 CBAAA Turkey

The largest earthquake in the U.S. or Canada today was an M 4.9 in the region of the Alaska Peninsula. It was reported felt with intensity II in Sand Point, Alaska. Alaska Peninsula. This appears to be an aftershock of the M 5.1 which occurred August 30, 2023. At the time this summary noted:

"The largest earthquake in the U.S. or Canada today was an M 5.1 in the Alaska Peninsula. NEIC reported it was felt with intensity II-III in Alaska at Sand Point and King Cove. While a foreshock of M 4.6 hit this same area on August 28, 2023 near local solar noon, this may be an aftershock of the M 7.4 on July 16 and M 5.6 which hit the same area with the previous full moon on August 3, 2023 as noted in previous issues of this summary:

"The strongest earthquake in the U.S. or Canada today was an M 4.6 off the Alaska Peninsula where NEIC reported it was felt with intensity IV in King Cove. This is the largest earthquake in the Alaska Peninsula area within about 150 km of this epicenter since an M 5.6 on August 3, 2023.

and

Forecast 156295 had expected today's event within about 50 was likely around

September 10.

O: 10SEP2023 13:03:53 54.3N 161.0W mb=4.9 EMSC ALASKA PENINSULA

P: 10SEP2023 156295 54.6N 161.7W 3.5-5.1 AAAAA Unimak Islands, Aleutians

A moderate earthquake of M 4.4 also occurred today in the Northwest Territories, Canada. It was probably felt lightly in the epicentra area near Nahanni Butte but this has not been reported. The last earthquake with M>=4.4 within about 200 km of today's epicenter occurred on October 24, 2020 with M 4.7. Like today's event that earthquake occurred with an M 4.9 in the Alaska Peninsula. At the time this summary noted:

"The series of moderate earthquakes in the Northwest Territories, Canada continued today with events of M 4.5-4.7 and M 4.0. This continues recent activation of this epicenter which included an M 5.1 on October 14 and an M 4.3 on October 18. The only other event in the region in the past year with M>=4.7 occurred as an M 4.7 on July 25, 2020, three days after the M 7.8 mainshock in the Alaska Peninsula." (October 24, 2020)

and

The strongest earthquake in the U.S. or Canada today was an M 4.4 in the Northwest Territories of Canada. The only earthquake in the past six years within about 300 km of this epicenter with M>=4.4 was an M 4.7 on July 25, 2020. Prior to that earthquakes of M 4.4 and 4.5 occurred in March and July, 2014 in this area. The strongest earthquake in this area in the past 30 years was an M 5.6 on June 10, 1990." (October 24, 2020)

Forecast 156306 had expected today's event within about 25 km was likely in early September.

O: 11SEP2023 00:12:37 61.9N 124.1W MB=4.4 ECAN of Nahanni Butte, NT

O: 11SEP2023 00:12:37 61.9N 124.1W ML=4.4 EMSC NORTHWEST TERRITORIES, CANADA

P: 2SEP2023 156306 62.1N 124.2W 2.5-4.3 CAAAA Northwest Terr., Canada

STRONG EARTHQUAKE IN SULAWESI, INDONESIA

EARTHQUAKE SUMMARY FOR SEPTEMBER 9, 2023

The strongest earthquake in the world today was an M 6.0-6.3 in Sulawesi, Indonesia. NEIC reported it was felt with intensity VI in Palu, Indonesia.

BMG reported this earthquake with M 6.3 was felt with intensity IV in Palu; V-VI Donggala, III in Poso, Sigi, Tolitoli, II-III in Pohuwatu, Kab. Gorontalo and Timur. This may be a strong aftershock of the Sulawesi earthquake of September 28, 2018 of M 7.5. That event was reported to have killed more than 4340 people. This earthquake occurred near local solar midnight and may have been promoted by strong tidal stresses which are greatest near this hour. Forecast 156091 had expected today's event within about 200 km was likely around September 6, 2023. This epicenter is located near the third node (120 degrees) from the M 6.8 in Morocco and may have been promoted by energy from that source. An M 5.8 at this same distance from Morocco hit Bali yesterday.

O: 9SEP2023 14:43:24 0.0S 119.9E Mw=6.0 EMSC MINAHASA, SULAWESI, INDONESIA

O: 9SEP2023 14:43:24 0.0S 119.8E Mw=6.3 BMG MINAHASA, SULAWESI, INDONESIA

P: 6SEP2023 156091 0.0N 122.0E 4.0-5.4 BABAA Celebes Sea

Death tolls continued to rise in the M 6.8 earthquake in Morocco. The reported number of dead in this earthquake is now more than 2100. An earthquake in Morocco in 1960 killed more than 12,000. BBC reports total destruction in many remote villages, so the tolls are expected to rise. This is the most deadly earthquake in the world since the M 7.7 in Turkey of February 6, 2023 which reportedly killed 53560. The previous most deaths in recent earthquakes occurred in Sulawesi on September 28, 2018 (4340) and Nepal on April 25, 2-15 (8964), the only other comparable events in the past 10 years in the world.

O: 09SEP2023 13:58:05 31.3N 8.1W mb=3.5 EMSC MOROCCO

O: 10SEP2023 06:36:10 31.3N 8.1W mb=3.2 EMSC MOROCCO

O: 09SEP2023 13:48:51 31.4N 7.7W mb=3.6 EMSC MOROCCO

O: 09SEP2023 23:11:36 31.5N 8.2W mb=3.2 EMSC MOROCCO

O: 09SEP2023 20:09:23 31.0N 8.5W mb=3.2 EMSC MOROCCO

O: 9SEP2023 11:19:13 31.3N 8.2W ML=3.6 EMSC MOROCCO

P: 5SEP2023 156187 37.0N 10.0W 3.5-5.1 BCAAA Morocco/Spain

The strongest earthquake in the U.S. or Canada today was an M 4.8 in the Rat Islands, Aleutians, Alaska. It was not reported felt in this remote region. The last earthquake of larger magnitude in the Rat Islands occurred east of this epicenter with M 5.0 on July 19 and this may be a regional aftershock of that event. Forecast 156291 had expected today's event was likely within about 100 km of this around September 8, 2023.

O: 9SEP2023 18:06:00 51.6N 177.8E mb=4.8 EMSC RAT ISLANDS, ALEUTIAN ISLANDS

P: 8SEP2023 156291 51.0N 176.0E 4.0-5.7 AAAAA Rat Islands

An M 2.7 earthquake occurred today in Illinois and Indiana. NEIC reported it was felt with maximum intensity IV in Hazleton, Indiana with II-III shaking in Indiana at Bloomington, and in Illinois at Calhoun, Sumner, Claremont, Olney, Mount Carmel, Albion, Carterville and Springfield among others. This is the strongest earthquake in Illinois since an M 2.8 on April 13, 2022.

At the time this summary noted:

"An unusual earthquake of M 2.6-2.8 was widely felt today in southern Illinois. NEIC reported it was felt with maximum intensity IV in Springerton and II-III in Burnt Prairie, McLeanboro, Carmi, Fairfield and in Indiana at Evansville and Vincennes. This is the strongest earthquake in the region of Illinois within about 100 km of this epicenter since an M 2.6 on September 11, 2019 but the last of larger magnitude in this region was an M 3.8 on September 19, 2017." (April 13, 2022)

The event in Illinois in April, 2022, like today's accompanied moderate quake in the Rat Islands (M 4.6) and an M 4.9 in the Andreanof Islands.

Forecast 156190 had expected enhanced seismicity in this region of Illinois was likely in early September.

O: 10SEP2023 04:11:00 38.6N 88.0W ML=2.5 EMSC ILLINOIS

O: 10SEP2023 04:11:00 38.6N 88.0W ML=2.7 ANSS ILLINOIS

P: 5SEP2023 156190 37.0N 88.0W 2.0-4.1 BBAAA New Madrid area

P: 6SEP2023 156190 38.0N 91.0W 2.0-3.9 BABAA New Madrid area

SERIES OF STRONG EARTHQUAKES HITS AROUND THE WORLD

EARTHQUAKE SUMMARY FOR SEPTEMBER 8, 2023

World seismic map looks a bit red today? That is because a series of moderately large to large earthquakes shook up much of the world today. These began with an M 6.2 in Coquimbo, Chile yesterday which was followed today by events of M 6.6 in the Kermadec Islands, New Zealand, M 5.6 in Bali, Indonesia, M 5.5 off eastern Honshu, Japan; M 6.8-6.9 in Morocco, M 5.8 and 5.6 in Jalisco, Mexico.

an M 5.8 in the Central East Pacific Rise; and an M 6.0 in Minahaasa, Suawesi, Indonesia (Sept 9 - see tomorrow's summary for more details). In general the average magnitude of larger earthquakes in the world today was nearly 1.0 magnitude units above the average of the past three months.

These earthquakes followed a period of relative quiet in the world's seismicity documented in previous issues of this summary as likely associated with the strong geomagnetic storm of early September. Among these this summary noted:

"It was a very quiet day in global seismicity today. This occurred as a geomagnetic storm, the first of this intensity in nearly a month began. Storms such as this can disrupt the ring currents in the ionosphere and reduce subsequent induced seismicity. If this is the case, the next several days are also likely to see reduced seismicity as a minor geomagnetic storm is expected September 3 by SWPC. This will probably trigger a moderately long period of reduced seismicity ending around September 6-7 depending on how long this geomagnetic storm lasts. Aurora could be visible at middle latitudes such as the central portion of the U.S. with these storms. Enhanced seismicity is likely to return in the second week of September, 2023." (September 2, 2023)

and

"No earthquakes were reported felt in the world in the past 24 hours according to NEIC data. This is the first time this has occurred in at least 10 years with global AP of 36 and high latitude AP of 58. This occurred while the geomagnetic field was at its most disturbed condition since global AP reached 76 with high latitude AP at 58 on April 24, 2023. Strong disturbance in the geomagnetic field disrupts ring currents and resulting induced telluric currents under them while it is in effect. This can considerably reduce global geomagnetic triggering and larger earthquakes. The influx of particles associated with these storms eventually become incorporated into renewed ring currents and normally produce elevated seismicity several days after such disturbances begin." (September 3, 2023)

A rare earthquake of M 6.9 struck the area of Marrakech, Morocco today.

World press outlets reported at least 2000 were killed in this earthquake -

The strongest in Morocco in recorded history. At least 1832 people were initially reported by Morocco's Interior Ministry to have been injured in the quake among which were 1220 with critical injuries but this number is much higher now. Damage was considerable with many structures destroyed. Most of the deaths and destruction occurred in the province of Al Haouz near the epicenter but deaths were also recorded in Taroudant, Chichaaoua, Marrackesh, Agadir, Casablanca among others. Damage included extensive damage to the 12th sentruy Koutobia Mosque in Marakesh. It occurred near local solar noon and was followed by an M 4.9 19 minutes later. NEIC reported maximum intensity VII in Morocco at Marrakesh, El Kealaa and Taroudannt with VI in Oulad Teima, Quarzazate,, V in Youssoufia, Ben Guerir, Agadir, Essaouria, Ben Guerir, Agadir, Essauira, Safi, Sidi, Tisnit, Fquiah, Settat, Beni, Zagora, Berrechid, Oued Zem with IV in El Jadida, Khouribga, Azemmour, Kasba among other communities. It was also reported felt with light intensity II-III in Algeria, Spain, Portugal. Earthquakes in Morocco or Spain at this magnitude level are rare. The historical record shows no events of M>=6.8 within about 500 km of today's epicenter. The last significant earthquake in the area was an M 5.6 to the east of today's epicenter on October 23 and again on October 30, 1992. An M 6.0 hit near today's epicenter in Morocco on February 29, 1960 - the only event in the historical record which goes back 150 year of M>=6 in Morocco. NEIC reported the M 4.9 aftershocks was felt with maximum intensity VI in Morocco at Guelmim, Tiznit, Taroudannt, Quarzazate, V in Marracech, Agadir, Essaouira, Ben Guerir, and Khouriba among other communities.

The earthquake in Morocco followed an M 6.6 in the Kermadec Islands. These two epicenters are nearly antipodal and the quake in Morocco may have been triggered by antipodal stresses associated with the M 6.4 in the Kermadec Islands. It is also nearly antipodal to the M 7.7 in the Loyalty Islands earlier in the year. It is also likely the area was set up by the full moon of August 31, 2023 which reached fullness when it was near this longitude (note "Western Europe" and presumably northwestern Africa in the tidal forecast) as noted in previous issues of this summary:

"The full moon arrived at 1:35 UT on August 31, 2023. Longitudes which were at local solar midnight at this time are near 25 West and at local solar noon at 155 East. These zones include the central Atlantic and Iceland and western Europe in the west and the Kuril Islands, Japan and portions of eastern Indonesia and the Vanuatu Islands in the east. These areas are the most likely to see tidal triggering in the next week. Such events often occur near local solar midnight and noon. A major earthquake is considered likely with this full moon in the next week." (September 1--5, 2023)

Forecast 156187 had expected enhanced seismicity in the region of Morocco or Spain to the north of today's epicenter was likely around September 5.

O: 8SEP2023 22:30:39 30.7N 9.4W mb=4.8 EMSC MOROCCO

O: 8SEP2023 22:11:00 31.1N 8.5W Mw=6.8 EMSC MOROCCO

P: 5SEP2023 156187 37.0N 10.0W 3.5-5.1 BCAAA Morocco/Spain

The M 6.6 in the Kermadec Islands, New Zealand today was widely felt in North Island, New Zealand - unlike most strong earthquakes in the Kermadec Islands. NEIC reported maximum intensity for the M 6.6 at IV in Gisborne at Te Karaka and II-III in the Bay of Plenty at Opotiki, Whakatane, in North Shore, Auckland, Napier, Hawke's Bay, in Manawatu-Wanganui at Palmerston North and Shannon, and more than 1000 km away in Wellington at Porirua, Lower Hutt and Wellington. This is the strongest earthquake in the Kermadec Islands within about 200 km of this epicenter since an M 6.6 on August 14, 2022 and an M 7.4 on June 18, 2020. At the time of the August 14, 2022 event this summary noted:

"The strongest earthquake in the world today was an M 6.4-6.6 in the Kermadec Islands, New Zealand. It may have been felt lightly as far as North Island, New Zealand. This is the second strongest earthquake in the world in the past month following an M 7.0 in Luzon, Philippines on July 27. An M 6.6-6.8 also occurred in the Easter Island region on July 12, 2022 and an M 7.2 hit southern Peru on May 26, 2022, the last such events in the past three months. Today's event of M 6.6 is the strongest earthquake within about 200 km of this epicenter in the southern Kermadec Islands since an M 7.4 on June 18, 2020 and an M 6.9 on September 10, 2018 and an M 6.8 on December 9, 2008." (August 14, 2022)

Like that event today's earthquake also ended a long seismic quiet period. Forecasts 156350 and 156355 had expected this activity within about 100 km in the Kermadec Islands was likely around September 8.

O: 9SEP2023 02:38:47 32.7S 177.7W mb=4.9 EMSC SOUTH OF KERMADEC ISLANDS

O: 8SEP2023 09:09:48 33.0S 178.6W Mw=6.6 EMSC SOUTH OF KERMADEC ISLANDS

P: 8SEP2023 156350 33.0S 177.0W 4.0-5.6 AAAAA No. Kermadec Islands

P: 8SEP2023 156355 32.0S 178.0W 4.0-5.4 AAAAA So. Kermadec Islands

An M 5.5 earthquake occurred off the east coast of Honshu, Japan today. NEIC reported it was felt with intensity II-III in Japan in Miyagi and Aomori Prefectures, Japan. Enhanced seismicity in Honshu and off eastern Honshu, Japan had been expected at this time in this summary due to the passage of Tropical Storm Kirogi through the area at this time. This was emphasized in the September 5, issue of this summary as:

"... An interesting earthquake of M 4.1 hit off the east coast of Honshu, Japan.

"Tropical Storm Kirogi is near Tokyo at this time as reported in this and previous issues of this summary, but also does not appear strong enough to trigger a large earthquake in the region at this time. It is expected to veer off to the east and not to make landfall in Honshu, but may affect regional seismicity moderately. This summary noted this storm as:

"TS Kirogi (11W) continued today in the area of the of the Bonin and Izu Islands, Japan with winds up to 35 kts. It is expected to track to the west and north any may enhance seismicity the Bonin and Izu Islands of southern Japan as it passes through this area." (September 1-2, 2023)

Forecast 156197 had expected today's event within about 50 km was likely around September 3." (September 4, 2023)

The earthquake in Tokyo today had been expected within about 50 km to occur around September 8 in forecast 156197. It is the strongest event within about 100 km of Tokyo, Japan since an M 6.1 on May 26, 2023 and may be an aftershock of that event. Similar events within about 100 km of Tokyo in the past year with M>=4.9 occurred on May 10, 2023 (M 5.2); November 9, 2022 (M 5.0 and September 21. 2022 (M 5.0). Today's event occurred near local solar noon and may have been promoted by tidal stresses which maximize near this hour." (September 5, 2023)

The last earthquake of M>=5.5 in the area off eastern Honshu within about 150 km of today's epicenter occurred on May 1, 2021 with M 6.8 although a series of similar events have hit the region slightly more than 150 km from today's epicenter in recent months - including an M 7.3 on March 16, 2022.

Forecast 156220 had expected today's event within this area was likely

around September 7. This epicenter is at 104 degrees from the M 5.5 in Honshu, Japan and may have been promoted by energy from that source.

O: 8SEP2023 09:28:50 38.9N 142.2E mb=5.5 EMSC NEAR EAST COAST OF HONSHU, JAP

P: 7SEP2023 156220 38.0N 143.0E 4.0-5.5 AAAAA So. of Honshu

An M 5.8 and M 5.6 were also felt in the region of Jalisco, Mexico today. NEIC reported the M 5.8 was felt with damage and intensity VIII in Jalisco at Cihuatlan, and IV in Las Juntas, San Patricio and Autlan with lesser shaking in Colima, Puerto Vallarta, Ixtapa, Bucerias, Nayarit, Tecalitlan and Jocotepec among others. The foreshock of M 5.6 was felt with similar intensities in the same areas of Jalisco, Mexico. These events occurred near local solar noon and may have been promoted by tidal stresses which maximize near this hour. The last earthquake of M>=5.8 in Jalisco within about 200 km of this epicenter occurred on September 20, 2022 also with M 5.8 an on June 30, 2018 with M 5.9-6.0. A major earthquake of M 7.6 hit the area on January 22, 2003 and on October 9, 1995 an M 8.0 occurred east of these epicenters.

Forecast 156127 had expected this activity in Jalisco was likely around September 9.

O: 08SEP2023 15:53:20 19.4N 105.0W Mw=5.6 EMSC JALISCO, MEXICO

O: 8SEP2023 16:37:12 19.4N 105.0W Mw=5.8 EMSC JALISCO, MEXICO

P: 9SEP2023 156127 18.0N 106.0W 3.5-5.1 ABAAA Coast of Jalisco, Mexico

An M 5.8 south of Jalisco, Mexico also occurred today on the Northern East Pacific Rise. It was not felt in this epicentral area. Both these events are near the strongest Hurricane current active reaching wind speed up to 140 kts yesterday - Hurricane Jova which was described in the previous issue of this summary as:

"Hurricane Jova continued today in the area southwest of the Gulf of California as a category 4 hurricane (major storm) with winds up to 105 kts. It is expected to track to the west and north but not to significantly affect regional seismicity as this time." (September 8, 2023)

Stresses associated with this storm may have helped promote the activity in Jalisco and the East Pacific Rise today. Today's event in the East Pacific Rise is the first of M>=5.8 in that region within about 200 km since an M 5.8 on September 21, 2020 and an M 6.1 on March 22, 2020.

Forecast 156113 had expected today's event within about 100 km was likely around September 6. Like the M 5.5 in Honshu, Japan this epicenter is near 103 degrees from the M 6.8 in Morocco.

O: 9SEP2023 03:09:51 4.7S 105.4W Mw=5.8 EMSC CENTRAL EAST PACIFIC RISE

P: 6SEP2023 156113 5.0S 105.0W 4.0-5.7 BAAAA No. East Pacific Rise

QUIET PERIOD MAY BE ENDING

EARTHQUAKE SUMMARY FOR SEPTEMBER 7, 2023

It was a very quiet day in global seismicity. Recent earthquakes such as the M 6.2 in Coquimbo yesterday, however suggest there is plenty of seismic energy available to be released under the right circumstances. This summary expects this quiet period to end in the next day or two as reported in this and previous summaries:

"The geomagnetic field saw quiet conditions today. The AP level was 6. High latitudes saw quiet conditions with AP 3. Middle latitudes were at disturbed conditions with AP 11. This appears to conclude the strongest geomagnetic storm since August 1-2, 2023 and will probably decrease global seismicity through about September 5-6 when strong earthquakes may be further introduced with the return of strong ionospheric ring currents." (September 5-7, 2023)

Some of this is likely to occur in areas near the International Date Line (IDL) and antipodally at the Greenwich Meridian (0 degree longitude) as noted in previous issues of this summary in regard to the full moon of August 31:

The strongest earthquakes in the world today were an M 5.1 in the Talaud Islands, Indonesia, an M 4.9 in the Kermadec Islands, New Zealand and an M 5.0 in Kamchatka. None of these events were reported felt and they were not unusual for their regions.

O: 7SEP2023 19:20:13 4.4N 127.8E Mw=5.1 EMSC KEPULAUAN TALAUD, INDONESIA

P: 5SEP2023 156098 4.0N 129.0E 4.0-5.4 AAAAA Halmahera

O: 07SEP2023 23:07:48 56.2N 163.8E mb=4.8 EMSC NEAR EAST COAST OF KAMCHATKA

O: 7SEP2023 23:02:17 56.2N 163.9E mb=5.0 EMSC NEAR EAST COAST OF KAMCHATKA

P: 5SEP2023 156287 55.0N 166.0E 4.0-5.8 ABBAA Komandorsky Isl

O: 7SEP2023 23:27:03 31.4S 177.7W mb=4.9 EMSC KERMADEC ISLANDS REGION

P: 8SEP2023 156355 32.0S 178.0W 4.0-5.4 AAAAA So. Kermadec Islands

The strongest earthquake in the U.S. or Canada today was an M 3.3 off the coast of Oregon. This is the strongest earthquake within about 100 km of this epicenter since an M 4.0 on August 1, 2023. NEIC reported this earthquake of M 3.3 off the coast of Oregon was felt with intensity II-III in the area(s) of Oregon in Port Orford and Rockaway Beach. Forecast 1565258 had expected this event within about 25 km was likely around September 7.

O: 8SEP2023 00:36:35 43.1N 126.2W ML=3.3 EMSC OFF COAST OF OREGON

P: 7SEP2023 156258 43.1N 126.5W 3.0-4.4 AAAAA Off Coast of Oregon

TRONG EARTHQUAKE SHAKES COQUIMBO, CHILE

EARTHQUAKE SUMMARY FOR SEPTEMBER 6, 2023

The strongest earthquake in the world today was an M 6.2 in the Coquimbo, Chile area. NEIC reported it was felt with maximum intensity VI in Coquimbo and La Serena and V in Ovalle, Coquimbo with III in Vicuna. In Valparaiso, Chile it was felt with intensity II-III in La Ligua, Quillota, Vina del Mar, Valparaiso, Villa Alemana, and in Santiago, Chile. When a series of smaller foreshocks hit the region on September 4, this summary noted in this regard:

"A moderate earthquake of M 4.1 also was recorded near Coquimbo, Chile today. While other areas of Chile have been active in recent weeks, Coquimbo has been relatively quiet. Today's M 4.1 is the strongest in that area in more than a month - since an M 4.5 occurred on August 3, 2023. The only other such event in the region in the past two months was an M 4.7 about 150 km north of today's epicenter on July 27. Both these occurred at full and new moon alignments. Today's event occurred near local solar midnight near the full moon and all of these may be tidally reinforced." (September 4, 2023)

An earthquake of M 5.8 hit this region of Coquimbo on May 2, 2021 but the last event of M>=6.2 in Coquimbo within about 200 km of today's epicenter was an M 6.3 exactly three years ago on September 6, 2020 but the last event in the area of significantly larger magnitude was an M 6.7 on January 20, 2019. At that time this summary noted in regard to the history of the area:

"The last earthquake in the Coquimbo area of central Chile within about 200 km of today's M 6.7 with M>=6.7 occurred on November 11, 2015 with M 6.9. This was a regional aftershock about 200 km north of a great M 8.3 in the Coquimbo area which occurred September 16, 2015." (January 20, 2019)

Some effects of Super-Typhoon Saola and Typhoon Haikui which made landfall over the past two days near the antipode of Coquimbo may also have helped promoted today's event.

Today's event appears to break the seismic quiet which has persisted around the earth following the strong geomagnetic storm of early September and may be followed by more such events around the earth in coming days. Forecast 156348 had expected today's event within about 50 km was likely around September 6. This epicenter is at 143 degrees from the M 7.1 in Bali of August 28 and may have been promoted by energy from that source.

O: 6SEP2023 23:48:05 30.3S 71.4W Mw=6.2 EMSC COQUIMBO, CHILE

P: 6SEP2023 156348 30.0S 72.0W 4.0-5.6 AAAAA Coast Central Chile

An unusually large M 3.5 earthquake shook areas of Southern Idaho today. NEIC reported this earthquake of M 3.5 in Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho in Nampa. This is not part of the aftershock sequence of the M 6.5 of March 31, 2020 about 50 km to the west of this but appears to be a late aftershock of the Borah Peak earthquake of October 28, 1983, which has been described in this summary as:

"Known as the Borah Peak earthquake, this is the largest ever located in

Idaho. At least two were killed in Challis, Idaho with up to $13 million

damage. Maximum intensity was IX. Surface faulting occurred in Idaho along

a 35-km section of the fault and as wide as 100 meters. Scarps up to 1-2

meters high were observed. Rockfalls, water fountains and sand boils occurred.

A temporary lake was formed south of Dickey. More than 200 homes and buildings

were damaged at Challis. Chimneys were damaged as was the high school at

Challis." (October 28, 2022)

The last earthquake within about 50 km of today's epicenter with M>=3.5 was an M 3.9 on August 6, 2023. At the time this summary noted in this regard:

"NEIC reported this earthquake of M 3.9 in Southern Idaho was felt with intensity II-III in the area(s) of Southern Idaho in Ellis, Shoup, May, Salmon, North Fork, Cascade and Nampa and in Victor, Montana." (August 6, 2023)

The last significantly larger event in this region was an M 4.9 on January 3, 2015 at which time this summary noted:

"The M 4.9 in Idaho was reported by NEIC to have been felt with intensity IV in Ellis and May, Idaho. … Initial reports were of property damage to houses and power outages in Custer County, Idaho. A number of rockslides were also reported. Motorists have been warned to watch for falling or loose rocks which could be dislodged in numerous aftershocks." (January 3, 2015)

Forecast 156247 had expected today's event was likely within about 50 km around September 5.

O: 06SEP2023 19:58:06 44.7N 114.4W ML=2.3 EMSC SOUTHERN IDAHO

O: 6SEP2023 19:54:12 44.7N 114.4W ML=3.5 EMSC SOUTHERN IDAHO

P: 5SEP2023 156247 44.5N 114.8W 2.0-3.9 AAAAA Montana/Idaho

An unusual earthquake also occurred today in Alabama. The last earthquake within about 100 km of this epicenter within Alabama with any magnitude was an M 2.5on October 15, 2020. Forecast 156189 had expected today's event was likely in this area around September 5.

O: 6SEP2023 11:00:23 34.3N 87.4W MD=2.3 EMSC ALABAMA

P: 5SEP2023 156189 35.0N 89.0W 2.0-4.3 AABAA New Madrid area

STRONG QUAKE IN NEW GUINEA FOLLOWED BY ANTIPODAL QUAKE IN TANZANIA

EARTHQUAKE SUMMARY FOR SEPTEMBER 5, 2023

The largest earthquake in the world today was an M 5.8 in Papua New Guinea. NEIC reported it was felt with intensity II-III in Papua at Porgera Enga, Mount Hagen and Kiunga Fly River, PNG. The last earthquake within about 200 km of this epicenter in New Guinea with equal of larger magnitude was an M 6.3 on April 7, 2018 and more recently an M 7.0 about 150 km northeast of this on April 2, 2023. Today's event may be an aftershock of that event. At the time this summary noted:

"The last earthquake of M>=7.0 within about 200 km of today's epicenter occurred as an M 7.2 on September 8, 2002 and an M 7.0 on July 17, 1998, the only such regional events in the past 35 years." (April 2, 2023)

This epicenter is located near the geomagnetic equator and was probably promoted by strong geomagnetic stresses associated with the geomagnetic storm of September 2-5. Forecasts 156116 had expected enhanced activity within about 150 km of this epicenter was likely in early September, 2023.

O: 5SEP2023 15:03:17 5.3S 142.9E Mw=5.8 EMSC NEW GUINEA, PAPUA NEW GUINEA

P: 1SEP2023 156116 5.0S 144.0E 4.0-5.4 BAAAA Papua New Guinea

P: 9SEP2023 156116 4.0S 143.0E 4.0-5.6 BBAAA Papua New Guinea

About 40 minutes after the M 5.8 in New Guinea, an M 5.2 occurred in Tanzania.

Tanzania is near the antipode of the event in New Guinea and apparently was triggered by seismic waves from that M 5.8 which arrived as reflected waves at the antipode coincident with the earthquake in Tanzania. An earthquake of M 5.5 hit this region of Tanzania on August 8, 2023 and this may be an aftershock of that mainshock. At the time this summary noted in this regard:

"The most unusual earthquake in the world today was an M 5.5 in Tanzania. NEIC reported this event was felt with intensity IV in Mombasa, Kenya and in Tanzania at Dodoma and Tabora. An M 4.8 aftershock was felt with intensity II in Magugu, Manyara, Tanzania. A foreshock of M 4.5 occurred on August 2, 2023 about 100 km north of today's epicenter. The last earthquake of M>=5.5 in the region of Tanzania within about 300 km of this epicenter occurred on November 4, 2002, the only such event in this region in the past 35 years. Three days ago an M 4.9 hit the Lake Tanganyika area west of today's epicenter. At the time this summary noted:

"An unusual quake of M 4.9 occurred today in the region of Tanzania. NEIC reported maximum intensity IV in Gitega, Burundi and Kigali Ville de Kigali, Rwanda and III in Kigoma, Tanzania at Kigoma and Kasulu. The only earthquake of M>4.9 in Tanzania or Lake Tanganyika areas within about 250 km of this epicenter occurred with M 5.0 about 250 km northwest of today's epicenter. Today's event occurred within minutes of local solar midnight and may have been promoted by high tidal stresses which maximize near this hour." (August 4, 2023, August 8, 2023)

Forecast 156111 had expected enhanced activity within about 100 km of this epicenter in Tanzania was likely between September 3 and 7, 2023.

O: 5SEP2023 15:42:22 5.4S 34.9E Mw=5.2 EMSC TANZANIA

P: 3SEP2023 156111 5.0S 36.0E 4.0-5.6 AAAAA Indian Ocean

P: 7SEP2023 156111 6.0S 36.0E 4.0-5.9 AAAAA Indian Ocean

A moderate earthquake of M 4.9-5.5 was also felt widely in southern Taiwan today. NEIC reported maximum intensity V in Chiayi and Kaohsiung and IV in Tainan with II-III shaking in Taichung, Taoyuan, and Taipei Counties, Taiwan.

CWB reported this earthquake of M 4.4 was felt with intensity V in Chiayi, IV in Tainan, Changhua and Yunlin; III in Nantou, Taichung, Kaohsiung, Miaoli, and II in Hualien, Taitung, Hsinchu, Penghu and Pingtung Counties, Taiwan. The M 4.3 was reported by CWB to have been felt with intensity IV in Kaohsiung II in Pingtung, Tainan, Chiayi and I in Taitung and Yunlin Counties, Taiwan. NEIC reported an earlier quake of M 4.8 in the Southwest Ryukyu Islands, Japan was also felt in Taiwan with intensity III. In previous issues of this summary this possibility had been noted as:

"An M 4.4 also occurred today in the area of southern Taiwan. CWB reported the M 4.4 was felt with intensity IV in Pingtung and Taitung, and I in Kaohsiung Counties, Taiwan. The last earthquake in Taiwan of M>=5.5 was an M 4.5 on July 8, 2023. At the time this summary noted this as:

"The activity in Taiwan was reported by CWB to have been felt with intensity IV

in Taitung, II in Pingtung and I in Hualien, Nantou, Kaohsiung, Changhua, Yunlin, Chiayi and Tainan Counties and probably throughout most of Taiwan. The last earthquake in Taiwan of M>=5.6 occurred as an M 6.0 on December 15, 2022." (July 8, 2023)

This event may be part of an enhanced seismicity in Taiwan as Typhoon Haikui moves through the area. A larger event may still follow. This summary had noted this possibility in this and previous issues as:

"Typhoon Haikui (10W) continued today in the area west of Taiwan with winds up to 40 kts where it made landfall today. It is expected to track to the west and north any may enhance seismicity in Taiwan as it passes through this area." (September 5, 2023)

and

"Typhoon Haikui (10W) continued today in the area of Taiwan with winds up to 130 kts where it made landfall today. It is expected to track to the west and north any may enhance seismicity in Taiwan as it passes through this area." (September 3-4, 2023)

One of today’s events occurred within about an hour of local solar noon and may have been promoted by strong tidal stresses.

Forecast 156163 had expected this activity up to a possible moderately large event around September 2 within about 50 km of the epicenter." (September 4-5. 2023)

O: 6SEP2023 05:21:38 22.9N 120.7E ML=4.3 EMSC TAIWAN

O: 6SEP2023 05:21:38 22.9N 120.7E ML=4.3 CWBC TAIWAN

O: 5SEP2023 09:30:41 23.6N 120.4E Mw=4.9 EMSC TAIWAN

O: 5SEP2023 09:30:41 23.5N 120.4E Mw=5.5 CWB TAIWAN

P: 2SEP2023 156163 22.0N 121.0E 4.0-5.6 BAAAA Taiwan

UNUSUAL, MODERATE QUAKE IN FIJI

EARTHQUAKE SUMMARY FOR SEPTEMBER 4, 2023

The strongest earthquake in the world today was an M 5.7 in the area of Fiji. It was not reported felt in this remote region. Most moderate to large earthquakes in this region occur more than 200 km northwest of today's epicenter. The last earthquake within about 250 km of this epicenter south of the Fiji Islands with M>=5.7 occurred more than 35 years ago, so this is a significant local earthquake. Today's event occurred within minutes of local solar noon and may have been promoted by geomagnetic and/or tidal effects which maximize near this hour.

Forecast 156069 had expected enhanced seismicity in this area was likely at the end of August or early September.

O: 5SEP2023 00:55:24 23.9S 175.4E Mw=5.7 EMSC SOUTH OF FIJI ISLANDS

P: 30AUG2023 156069 23.0S 173.0E 4.0-5.5 BABAA Tonga/Fiji

NEIC reported this earthquake of M 4.9 near Tokyo, Japan was felt with ntensity II-III in the area(s) of Honshu, Japan in Chiba, Ibaraki, Tokyo, Saitama, Kanagawa Prefectures. This follows smaller events yesterday which was reported in this summary in the previous issue as:

"... An interesting earthquake of M 4.1 hit off the east coast of Honshu, Japan.

Forecast 156197 had expected today's event within about 50 km was likely around

September 3." (September 4, 2023)

O: 05SEP2023 04:33:06 35.7N 140.1E ML=4.0 EMSC NEAR EAST COAST OF HONSHU,

O: 5SEP2023 04:27:16 35.7N 140.2E mb=4.9 EMSC NEAR EAST COAST OF HONSHU,

P: 8SEP2023 156197 36.0N 140.0E 4.0-5.4 BAAAA Off East Coast Honshu

O: 4SEP2023 21:12:40 37.0N 141.8E ML=4.0 EMSC NEAR EAST COAST OF HONSHU, JAP

P: 3SEP2023 156197 37.0N 142.0E 4.0-5.6 AAAAA Off East Coast Honshu

An M 4.4 also occurred today in the area of southern Taiwan. CWB reported the M 4.4 was felt with intensity IV in Pingtung and Taitung, and I in Kaohsiung Counties, Taiwan. This event may be part of an enhanced seismicity in Taiwan as Typhoon Haikui moves through the area. A larger event may still follow. This summary had noted this possibility in this and previous issues as:

and

One of today’s events occurred within about an hour of local solar noon and may have been promoted by strong tidal stresses.

Forecast 156163 had expected this activity up to a possible moderately large event around September 2 within about 50 km of the epicenter.

O: 04SEP2023 13:57:11 22.4N 120.2E mb=4.4 EMSC TAIWAN

O: 5SEP2023 03:13:51 22.3N 121.0E mb=4.4 EMSC TAIWAN

O: 5SEP2023 03:13:48 22.3N 120.9E mb=4.4 CWBC TAIWAN

P: 2SEP2023 156163 22.0N 121.0E 4.0-5.6 AAAAA Taiwan

MODERATE QUAKE SHAKES VIRGIN ISLANDS

EARTHQUAKE SUMMARY FOR SEPTEMBER 3, 2023

A moderate earthquake of M 4.3-4.8 was widely felt in the northern Virgin Islands today. NEIC reported intensity IV in the British Virgin Islands at Road Town, Tortola and IV in the U.S. Virgin Islands at Saint John and Saint Thomas with lesser shaking in Frederiksted, and in Puerto Rico at Culebra, Fajardo, Luquillo, Loiza, Punta Santiago, Carolina, among others. NEIC reported aftershocks of M 3.6, 3.4 in the Virgin Islands were felt with intensity II-III in the area(s) of the Virgin Islands in Saint Thomas and an M 3.9 felt with IV in Saint John. The Virgin Islands do not see earthquakes of M>=4.8 often. In the past three years three such earthquakes have been recorded - with M 5.2 on October 7, 2020; M 5.1 on February 6, 2021 and M 4.9-5.5 on May 8, 2022. At the time of the last such event this summary noted in this regard:

"A moderately strong M 4.9-5.5 shook the U.S. Virgin Islands today. NEIC eported it was felt with intensity IV in the U.S. Virgin Islands at Saint John and Saint Thomas and in Tortola, British Virgin Islands. Intensity III was also felt in Culebra, Vieques, Fajard, Celca, Puerto Rico and in the U. S. Virgin Islands at Christiansted, Frederiksted. The last earthquake in the Virgin Islands within about 150 km of this epicenter with equal or greater magnitude was an M 6.1 on October 11, 2008.

"The Virgin Islands is also a region which often shows strong triggering due to geomagnetic effect and this earthquake was likely triggered by the geomagnetic storm. The timing of the maximum effects of this geomagnetic storm is such as to coincide with the period of greatest danger of large earthquakes ...

The earthquake in the Virgin Islands of M 6.1 today was reported by NEIC

to have been felt with maximum intensity V in Puerto Rico at Naranjito,

... It was the most widely reported earthquake (by NEIC) in the region of Puerto Rico in at least the last 10 years and the second most widely felt in the area in that time period after an M 7.3 on November 29, 2007 that occurred south of this in Dominica." (October 12, 2008, May 8, 2022).

Forecast 156144 had expected today's event with magnitude up to M 5.3 was likely in the Virgin Islands around September 1.

O: 03SEP2023 08:36:08 18.8N 64.4W MD=3.3 EMSC VIRGIN ISLANDS REGION

O: 03SEP2023 07:49:41 18.9N 64.5W Mw=4.8 EMSC VIRGIN ISLANDS REGION

O: 03SEP2023 07:49:41 18.9N 64.5W Mw=4.3 ANSS VIRGIN ISLANDS REGION

O: 03SEP2023 22:23:48 19.0N 64.6W MD=3.9 EMSC VIRGIN ISLANDS REGION

O: 04SEP2023 03:34:13 19.0N 64.7W MD=3.4 EMSC VIRGIN ISLANDS REGION

O: 03SEP2023 12:18:52 19.1N 64.5W MD=3.6 EMSC VIRGIN ISLANDS REGION

O: 03SEP2023 13:10:16 19.1N 64.5W MD=3.4 EMSC VIRGIN ISLANDS REGION

O: 03SEP2023 16:34:19 19.1N 64.6W MD=3.5 EMSC VIRGIN ISLANDS REGION

O: 04SEP2023 03:05:16 19.1N 64.6W MD=3.9 EMSC VIRGIN ISLANDS REGION

O: 03SEP2023 21:26:38 19.2N 64.6W MD=3.9 EMSC VIRGIN ISLANDS REGION

O: 04SEP2023 04:43:20 19.2N 64.6W MD=3.7 EMSC VIRGIN ISLANDS REGION

O: 3SEP2023 12:13:36 18.1N 64.0W MD=3.9 EMSC VIRGIN ISLANDS REGION

P: 1SEP2023 156133 18.0N 64.0W 3.0-5.3 AAAAA Leeward Islands

Globally seismicity remained at quiet levels as anticipated in this summary. An interesting earthquake of M 4.1 hit off the east coast of Honshu, Japan. This event occurred near local solar noon and may have been promoted by geomagnetic and tidal stresses which maximize near this hour. Tropical Storm Kirogi passed over this epicenter at the time of the earthquake. Moderately enhanced seismicity in this region of Japan had been expected in this summary in the previous issue as:

Forecast 156197 had expected today's event within about 50 km was likely around September 3.

O: 4SEP2023 03:54:30 37.4N 141.4E ML=4.1 EMSC NEAR EAST COAST OF HONSHU,

P: 3SEP2023 156197 37.0N 142.0E 4.0-5.6 AAAAA Off East Coast Honshu

A moderate earthquake of M 4.1 also was recorded near Coquimbo, Chile today. While other areas of Chile have been active in recent weeks, Coquimbo has been relatively quiet. Today's M 4.1 is the strongest in that area in more than a month - since an M 4.5 occurred on August 3, 2023. The only other such event in the region in the past two months was an M 4.7 about 150 km north of today's epicenter on July 27. Both these occurred at full and new moon alignments. Today's event occurred near local solar midnight near the full moon and all of these may be tidally reinforced. Forecasts 156348 had expected today's event within this area was likely around September 4.

O: 4SEP2023 06:01:41 31.8S 71.4W ML=4.1 EMSC COQUIMBO, CHILE

P: 4SEP2023 156348 31.0S 70.0W 4.0-5.8 AAAAA Central Chile

SEISMIC QUIET CONTINUES

EARTHQUAKE SUMMARY FOR SEPTEMBER 2, 2023

No earthquakes were reported felt in the world in the past 24 hours according to NEIC data. This is the first time this has occurred in at least 10 years with global AP of 36 and high latitude AP of 58. This occurred while the geomagnetic field was at its most disturbed condition since global AP reached 76 with high latitude AP at 58 on April 24, 2023. Strong disturbance in the geomagnetic field disrupts ring currents and resulting induced telluric currents under them while it is in effect. This can considerably reduce global geomagnetic triggering and larger earthquakes. The influx of particles associated with these storms eventually become incorporated into renewed ring currents and normally produce elevated seismicity several days after such disturbances begin. This summary reported the geomagnetic storm today as:

"The geomagnetic field saw major storm conditions today. The AP level was 38. High latitudes saw major storm conditions with AP 59. Middle latitudes were at active conditions with AP 25. This is the strongest geomagnetic storm since August 1-2, 2023 and will probably decrease global seismicity through about September 5-6 when strong earthquakes may be further introduced with the return of strong ionospheric ring currents." (September 2-3, 2023)

Today marks 100 years since the great M 8.3 in Tokyo, Japan of September 1-2, 1923. This was a landmark earthquake for Japan and was discussed in this summary as:

"The great Tokyo earthquake. This event caused up to $3 billion (U.S. Dollars) damage. More than 142,000 were killed. A tsunami was generated. This earthquake is usually referred to as the Kwanto earthquake. Up to 38,000 residents of Tokyo were burned to death in an open area where they had congregated following the earthquake for safety. The firestorm which followed the quake destroyed libraries, museums, at collections, archives and scientific data among other irreplaceable structures and items. The earthquake was located in Sagami Bay southwest of Tokyo. At least 15 lines of vertical faults were found with displacement up to 6 feet. Leveling showed uplifts up to 2 meters along the Sagami Bay. The tsunami reached up to 10 meters. Many groundwater effects were observed including pulsating earthquake fountains. More than 128,000 houses were destroyed in the quake and up to 450,000 were burned in the ensuing fire. A hotel built one year earlier with great ability to move (architect: Frank Lloyd Wright) survived with only a few cracks and was used as hospital and first aid station following the earthquake. Building techniques in Tokyo contributed to the firestorm. These included building close to the ground and paper thin walls." (September 1-2, 2023)

Although a tropical cyclone is moving up to Honshu from the south at this time,

it is not expected to make landfall for another 5-7 days in Honshu. It is probably

not powerful enough to trigger a major earthquake in Japan at this time.

Tropical Storm Kirogi is near Tokyo at this time as reported in this and previous issues of this summary, but also does not appear strong enough to trigger a large earthquake in the region at this time. It is expected to veer off to the east and not to make landfall in Honshu, but may affect regional seismicity moderately. This summary noted this storm as:

The strongest earthquake in the world, and the only event of M>=5 today was an M 5.3 in Central Peru. This is the strongest earthquake in Central Peru in at least three years. An M 5.5 hit about 250 km south of this on October 30, 2020.

Forecasts 155842 and 156313 had expected today's event in this area was likely in late August or early September, 2023.

O: 02SEP2023 09:00:36 8.3S 74.4W ML=4.2 EMSC CENTRAL PERU

O: 2SEP2023 11:11:02 8.3S 74.3W Mw=5.3 EMSC CENTRAL PERU

P: 1SEP2023 156313 10.0S 75.0W 3.5-5.1 ABAAA Brazil

P: 25AUG2023 155842 9.0S 75.0W 3.5-5.3 CAAAA Brazil

The strongest earthquake in the U.S. or Canada today was an M 3.8 in the Queen Charlotte Islands region of Canada. It was not reported felt in this remote area. This may be a regional aftershock of the M 4.4 of August 15 in the Queen Charlotte Islands about 100 km southeast of today's epicenter. At the time this summary noted in this regard:

"An earthquake of M 4.4-4.7 also occurred today in the Queen Charlotte Islands region, Canada. It was reported to have been lightly felt in the epicentral area. The last earthquakes of equal or greater magnitude in the Queen Charlotte Islands Region were of M 5.1 on June 4, 2022 and July 26, 2022. Today's epicenters which began with an M 3.4 near local solar midnight are near the expected longitude of maximum tidal stress with the new moon of August 16 and were probably promoted by stresses associated with that tidal alignment" (August 15, 2023)

Forecasts 156282 and 156013 had expected this enhanced seismicity in the Queen Charlotte area at the end of August or early September, 2023.

O: 02SEP2023 13:49:23 53.2N 132.8W MB=3.8 ECAN of Village of Queen Charlotte, BC

O: 2SEP2023 13:49:23 53.2N 132.8W ML=3.8 EMSC QUEEN CHARLOTTE ISLANDS REGION

P: 6SEP2023 156282 54.0N 134.0W 3.0-5.2 BAAAA British Colombia

P: 29AUG2023 156013 52.0N 132.0W 3.0-5.0 BBAAA British Colombia

QUIET SEISMIC PERIOD BEGINS AFTER M 6.1 IN KURIL ISLANDS

EARTHQUAKE SUMMARY FOR SEPTEMBER 1, 2023

It was a very quiet day in global seismicity today. This occurred as a geomagnetic storm, the first of this intensity in nearly a month began. Storms such as this can disrupt the ring currents in the ionosphere and reduce subsequent induced seismicity. If this is the case, the next several days are also likely to see reduced seismicity as a minor geomagnetic storm is expected September 3 by SWPC. This will probably trigger a moderately long period of reduced seismicity ending around September 6-7 depending on how long this geomagnetic storm lasts. Aurora could be visible at middle latitudes such as the central portion of the U.S. with these storms. Enhanced seismicity is likely to return in the second week of September, 2023.

The strongest earthquake in the world today was an M 6.1 in the northern Kuril Islands. It was not reported felt in this remote area near Kamchatka. It follows a swarm of moderate quakes south of this epicenter on August 16, 2023 which included an M 5.3. An event of M 4.4 closer to today's quake showed migration to the north of this series on August 27 but this is the strongest earthquake in this region of the Kuril Islands within about 200 km since an M 6.5 on October 10, 2018. A series of strong earthquakes hit the are on February 28 and March 1, 2031 with mainshock of M 6.9. and an M 7.5 major quake occurred about 300 km southeast of this on March 25, 2020. At the time of that event this summary noted:

"A major earthquake of M 7.7 struck off the Kuril Islands north of Japan today. PTWC issued a tsunami warning, but it was later cancelled for the Island of Hawaii. JMA indicated that minor tsunami waves may occur in eastern Japan.

Tsunami waves are expected in Hawaii, Japan, Russia, the Pacific Islands of Midway, the northern Mariana Islands and Wake Island with heights up to 0.3 meters (about a foot). The China Earthquake Information Center reported M 7.4 while the Russians M 7.5. JMA reported light shaking from the M 7.8 event in some areas of Hokkaido and Honshu but not shaking of intensity III or greater was reported. NEIC reported maximum intensity V in Severo-Kurilsk, Russia and IV in Petropavlovsk and Mohovaja, Kamchatka. It was also reported felt lightly in Adak, Alaska. This earthquake was probably promoted by tidal stresses. It occurred on the day of the new moon within about an hour of local solar noon - a time when tidal stresses are maximized. The history of strong earthquakes in this area of the Kuril Islands (see below) indicates a strong relation with past new moon alignments." (March 25, 2020)

The remnants of Typhoon Damrey were near today's epicenter and may also have helped trigger today's earthquake. Damrey was over Hokkaido, Japan on August 28 and moved northeastward from ther over the past two days. The last mention of Damrey in this summary was on August 28 as:

"Tropical Storm Damrey (Depression 08W) continued today in the area east of northern Honshu, Japan with winds up to 55 kts. It is expected to track to the northeast and not to make landfall at this time. Some enhanced seismicity in northern Japan may occur with TS Damrey including the M 5.8 under they eye two days ago." (August 28, 2023)

Forecast 156249 had expected today's earthquake in the Kuril Islands was likely in this area around September 2. Today's epicenter is at 104 degrees from the M 6.6 in northern Colombia of May 25, 2023 and at 102 degrees from the M 6.6 in the Virgin Islands of July 10, 2023 and may have been promoted by energy from those sources.

O: 1SEP2023 20:49:55 50.8N 156.3E Mw=6.1 EMSC KURIL ISLANDS

P: 2SEP2023 156249 49.5N 155.0E 3.5-6.0 ABAAA NE Pacific

The unusual series of earthquake in the area of Ohio continued today. These included events of M 2.2, 2.3 and 2.5. The last of these occurred within minutes of local solar noon and was likely promoted by tidal stresses with the full moon of August 31 which maximize near this hour. This continues a series of events in this region which began on August 24 with an M 2.3 and continued on August 28, 2023 with an M 3.7. At the time this summary noted in this regard:

"An unusually large earthquake of M 3.7-4.3 shook areas of Ohio today. NEIC reported it was felt with intensity IV in Ohio at Geneva, Madison, Rock Creek, Austinburg, Thompson, Perry, Montville, Rome, Ashtabula, Jefferson and as far as New York, Ontario, Indiana with intensity II-IV. It follows a series of foreshocks in the region on August 24, 2023. Included in this activity was an M 2.3-2.8 foreshock on August 24, 2023 as reported at the time" (August 28, 2023)

The only comparable event in the area of Ohio in the past 3 years was an M 4.2 on July 17, 2021 in the Lake Erie, Ohio area which was noted in this summary as:

"... an M 4.2 occurred in Lake Erie, Ohio and was lightly felt in the area. Two earthquakes of equal or larger magnitude have occurred in the Lake Erie area of Ohio in the past 30 years - an M 4.4 on January 26, 2001 and an M 4.5 on September 25, 1998." (July 17, 2021)

A series of three spinning lights above Dayton Ohio followed these earthquakes on September 4. This was reported on the web by numerous witnesses. Any relation between these spinning lights and the recent earthquakes in Ohio is speculative.

Forecast 156260 had expected today's event in Ohio was likely in early September within about 25 km of this epicenter. This activity is at the seventh node (51.5 degrees) from the M 7.2 in the Alaska Peninsula of July 16, 2023 and at 103 degrees from the M 7.6 in Tonga of May 19 and may have been related to energy from this and other recent strong events in those regions.

O: 1SEP2023 16:33:13 41.7N 81.0W ML=2.4 EMSC OHIO

O: 01SEP2023 16:53:39 41.8N 81.0W ML=2.2 EMSC OHIO

O: 01SEP2023 17:16:39 41.8N 81.0W ML=2.3 EMSC OHIO

P: 5SEP2023 156260 41.8N 81.4W 2.0-4.0 BAAAA Ohio/Lake Erie

MODERATE QUAKE SHAKES TIMOR, INDONESIA

EARTHQUAKE SUMMARY FOR AUGUST 31, 2023

The strongest earthquake in the world today was an M 5.4 in the Timor region of Indonesia. NEIC reported it was felt with intensity VI in Kupang Nusa, Timur and IV in Dili, East Timor and II in Liquica and in Darwin Northern Territory, Australia. This is the strongest earthquake in Timor since an M 5.5 on July 25, 2023. At the time this summary noted in this regard:

"An M 5.5 was also felt in Timor, Indonesia today. NEIC reported it was felt in East Timor at Dili. The only earthquake of equal or larger magnitude in the region of Timor in the past three years was an M 6.2 about 400 km to the east of this on May 27, 2022. The last comparable earthquake within about 200 km of this epicenter was an M 5.3 on December 12, 2020." (July 25, 2023)

A major M 7.3 hit about 300 northwest of today's epicenter on December 14, 2021. It was summarized here at the time as:

"A major earthquake of M 7.3-7.6 occurred today in the Flores Sea of Central Indonesia. NEIC reported maximum intensity IX (damage) in Timur at Ende Nusa Tenggara; … This event occurred within minutes of local solar noon and was probably promoted by tidal stresses which maximize near this hour. It was followed by a strong aftershock series. A tsunami warning was issued but later withdrawn when no significant increases in sea level were observed. Residents fled from their homes during the earthquake which was strongest in the Sulawesi and Flores areas near the town of Larantuka. At least one person was injured in Manggarai on Flores in the quake and some minor damage was reported in South Sulawesi to a school and several homes on Selayar island. This is the strongest earthquake in the Flores Sea area within about 300 km since an M 7.9 at great depth on June 17, 1996. A shallow focus event (like today's) occurred southwest of today's epicenter on December 12, 1992. Earthquakes of M 7.3-7.5 occurred about 300 km from today's epicenter on November 11, 2003 and October 19, 2001." (December 14, 2021)

Forecast 155846 had expected today's event was likely around August 27 near

August 27 within about 50 km of this epicenter. This may be a regional aftershock of the M 7.1 in Bala about 500 km west of this epicenter which occurred on August 28, 2023.

O: 31AUG2023 10:29:30 9.5S 123.9E Mw=5.4 EMSC TIMOR REGION, INDONESIA

P: 27AUG2023 155846 9.0S 124.0E 4.0-5.6 BAAAA Flores Island area

The most unusual earthquake in the world today was an M 4.8 in Angola. It was not reported felt. This is the largest earthquake within about 300 km of this epicenter in Angola since a similar M 4.8 on March 23, 2003 - the only other event of this size or larger in the region in at least 35 years. That event was not reported by NEIC till later and was not noted in this summary at the time.

The earthquake occurred near local solar noon and may have been promoted by the full moon today as noted in this and previous issues of this summary:

O: 31AUG2023 09:27:44 13.4S 17.2E mb=4.8 EMSC ANGOLA

An earthquake of M 4.1 also shook the region of Mayotte in Southern Africa today directly to the east of Angola. Like the event in Angola this occurred near local solar noon and may have been promoted by the full moon. The last earthquake in the Mayotte area with larger magnitude was an M 4.5 on March 3, 2021 and an M 4.8 on November 10, 2020. The only other such event in the area in the past three years. This is part of a volcanic eruption near this site which began May 13, 2018 with extended seismicity for several years afterwards.

O: 31AUG2023 08:10:04 12.8S 45.6E ML=4.1 EMSC MAYOTTE REGION

The largest earthquake in the U.S. or Canada today was an M 4.6 in the western Andreanof Islands, Aleutians, Alaska. It was not reported felt in this remote area. The last earthquake in this area of the Andreanof Islands of equal or larger magnitude was an M 5.3 on June 13, 2023. At the time this summary noted in this regard:

"The strongest earthquake in the U.S. or Canada today was an M 5.3 in central Andreanof Islands, Aleutians, Alaska. NEIC reported it was felt with maximum intensity V in Adak, Alaska. This appears to be the strongest earthquake in the Andreanof Islands since an M 6.1 and M 5.5 on September 24, 2021 about 50 km west of today's epicenter." (June 13, 2023)

Forecasts 156279 and 156010 had expected today's event within about 50 km

was likely around August 29 to September 3, 2023.

O: 31AUG2023 07:13:25 51.3N 178.5W mb=4.6 EMSC ANDREANOF ISLANDS, ALEUTIAN IS

P: 3SEP2023 156279 51.8N 178.0W 3.5-5.1 BAAAA Andreanoff Isls, Aleutians

P: 29AUG2023 156010 51.6N 177.6W 3.5-4.9 AAAAA Andreanoff Isls, Aleutians

MODERATE AFTERSHOCK IN ALASKA PENINSULA WITH FULL MOON

EARTHQUAKE SUMMARY FOR AUGUST 30, 2023

The largest earthquake in the U.S. or Canada today was an M 5.1 in the Alaska Peninsula. NEIC reported it was felt with intensity II-III in Alaska at Sand Point and King Cove. While a foreshock of M 4.6 hit this same area on August 28, 2023 near local solar noon, this may be an aftershock of the M 7.4 on July 16 and M 5.6 which hit the same area with the previous full moon on August 3, 2023 as noted in previous issues of this summary:

Today's M 4.6 occurred within minutes of local solar noon and may have been promoted by strong tidal stresses which maximize near this hour especially near the time of the full moon which arrives on August 30-31." (August 28, 2023)

Forecast 156027 had expected enhanced seismicity within about 50 km of this epicenter was likely with the full moon around August 27, 2023.

O: 30AUG2023 18:59:25 54.9N 161.3W Mw=5.1 EMSC ALASKA PENINSULA

O: 30AUG2023 20:27:53 54.7N 161.1W ML=3.8 EMSC ALASKA PENINSULA

P: 27AUG2023 156027 54.3N 161.4W 3.5-4.9 BAAAA Unimak Islands, Aleutians

An earthquake of M 4.9 also occurred today in the Bering Strait of Alaska. It was not reported felt in this remote area. A series of three foreshocks shook the area with M 3.1-3.2 on August 26, 27 and 28, 2023 but the last earthquake in the Bering Strait within about 300 km of this epicenter with M>=4.9 was an 5.3 on February 21, 2012. At the time this summary noted in this regard:

"The strongest earthquake in the world today was an M 5.4-5.6 in the Bering Strait region off Alaska's northwest coast. It may have been felt in the Point

Hope and Kotzebue regions on the coast of Alaska but there have been no reports of damage associated with this earthquake. This earthquake was likely promoted by the new moon tidal alignment which was maximized in this region today as noted in our summary yesterday. The earthquake occurred near local midnight when tides were the highest. The last moderate earthquake in the Bering Strait, an M 4.4 on August 8, 2010 occurred a day before the New Moon as did an M 4.3 on June 20, 2009. Today's earthquake is the strongest recorded in the Bering Strait region in at least 22 years. We have noted this tidal relation for the area in the past." (February 21, 2012)

Today's event in the Bering Strait, not unlike conditions with previous moderate events in the area, was closely associated with the full moon of August 31, 2022 as noted in this and previous issues of this summary:

"The full moon will arrive at 1:35 UT on August 31, 2023. Longitudes which are at local solar midnight at this time are near 25 West and at local solar noon at 155 East. These zones include the central Atlantic and Iceland and western Europe in the west and the Kuril Islands, Japan and portions of eastern Indonesia and the Vanuatu Islands in the east. These areas are the most likely to see tidal triggering in the next week. Such events often occur near local solar midnight and noon. A major earthquake is considered likely with this full moon in the next week." (August 27-31, 2023)

O: 30AUG2023 17:58:51 67.5N 168.3W mb=4.9 EMSC BERING STRAIT

An M 3.7 was also felt in the Great Salt Lake area of northern Utah today. NEIC reported intensity II-III was felt in Utah at Huntsville, Eden, Paradise, Ogden, Croydon, Hyrum, Logan among others. The last earthquake of M>=3.7 in Utah was an M 3.8 on May 31, 2022 about 300 km south of today's epicenter, but this is the largest event within about 200 km of this epicenter in Utah since an M 3.7 on June 9, 2021. An M 5.7 hit this region of Utah on March 18, 2020 and this may be a regional aftershock of that event. Forecast 156006 had expected today's activity in Utah was likely within this arwa around August 28.

O: 31AUG2023 00:11:18 41.4N 111.7W ML=3.7 EMSC UTAH

P: 28AUG2023 156006 43.2N 111.0W 2.0-4.1 BBAAA Yellowstone/Wyoming

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

It was associated with a strong activation of the region within hours and was probably promoted by stresses from the full moon today. These included moderate events from northern Chile south to BioBio, Chile. GUC reported an earthquake in Antofagasta, Chile was felt with intensity IV in Antofagasta at Calama; III in Sierra Gorda and II in Baquedano, Chile. Forecast 156058 had expected this event was likely around August 28.

O: 30AUG2023 16:35:37 22.4S 69.1W ML=4.1 EMSC ANTOFAGASTA, CHILE

O: 30AUG2023 16:35 22.4S 69.1W mb=4.1 GUC Antofagasta at Calama; III in

P: 28AUG2023 156058 23.0S 69.0W 4.0-5.9 AAAAA Coast No. Chile

GUC reported the earthquake in Coquimbo was felt with intensity V in Coquimbo at La Serena, La Higuera, Coquimbo; IV in Andacollo, Vicuna, Rio Hurdado, Paiguano and III in Ovalle; in Atacama with IV in Alto del Carment, Freirina, Huasco, Vallenar; III in Copiapo and Tierra Amarilla, Chile. NEIC reported this earthquake of M 5.3 in Coquimbo, Chile was felt with intensity II-III in the area(s) of Coquimbo, Chile in La Serena, Andacollo (IV) and in Calera, Valparaiso. This event occurred near local solar noon and may have been promoted by strong tidal stresses with the full moon. Forecast 15606 had expected this event was likely within about 150 km around August 27. This epicenter is at 103 degrees from Bali, Indonesia where an M 7.1 hit on August 28 and was probably promoted by energy from that source.

O: 30AUG2023 14:17 29.5S 71.3W mb=5.3 GUC Coquimbo at La Serena, La Higu

O: 30AUG2023 14:35:12 29.5S 71.4W mb=4.8 EMSC OFFSHORE COQUIMBO, CHILE

P: 27AUG2023 156060 28.0S 71.0W 4.0-6.0 BBAAA Coast Central Chile

GUC reported the earthquake in Biobio Chile was felt with intensity IV in Biobio at Concepcion, Hualpen, Santa Juana; III in Chiguayante; in Maule with IV in Cauquenes; in Nuble with IV in Chillan and in La Araucania with III in Padre las Casas and Temuco, Chile. NEIC reported this earthquake of M 4.6 in Biobio, Chile was felt with intensity IV-V in the area(s) of Chillan, Bio Bio; Parral, Maule and II in Concepcion, Bio Bio. Forecast 156072 had expected this activity within about 100 km was likely at the end of August.

O: 30AUG2023 13:15 36.4S 72.5W mb=4.8 GUC Biobio at Concepcion, Hualpen,

O: 30AUG2023 13:15:01 36.3S 72.5W Mw=4.6 EMSC BIO-BIO, CHILE

P: 25AUG2023 156072 35.0S 72.0W 4.0-5.6 BBAAA Central Chile

P: 22AUG2023 156072 37.0S 74.0W 4.0-5.8 CAAAA Central Chile

GUC reported the earthquake in Valparaiso was felt with intensity IV in Valparaiso in Quillota, Limache; III in Villa Alemana and Vina del Mar, Chile. NEIC reported this earthquake of M 4.3 in Valparaiso, Chile was felt with intensity II-III in the area(s) of Valparaiso, Chile in Vina del Mar and Calera.

Forecast 156071 had expected this event within about 150 km was likely at the end of August.

O: 30AUG2023 09:07 32.8S 71.6W mb=4.2 GUC Valparaiso in Quillota, Limach

O: 30AUG2023 09:07:16 32.8S 71.7W mb=4.3 EMSC OFFSHORE VALPARAISO, CHILE

P: 27AUG2023 156071 33.0S 70.0W 4.0-5.6 BABAA Central Chile

P: 30AUG2023 156071 32.0S 70.0W 4.0-5.8 AABAA Central Chile

UNUSUAL EARTHQUAKES OFF SOUTHEASTERN AUSTRALIA CONTINUE

EARTHQUAKE SUMMARY FOR AUGUST 29, 2023

A pair of moderate earthquakes of M 4.3 and 4.4 hit off the coast of southeastern Australia today. They were not reported felt. These follow an M 4.6 at this same epicenter which occurred on August 22, 2023. At the time this summary noted in regard to this unusual epicenter:

"The most unusual earthquake in the world on a quiet day in seismicity today occurred in the region southeast of Australia. This is the strongest earthquake within about 300 km of this epicenter in at least 35 years. Earthquakes within about 500 km of today's epicenter of equal or larger magnitude occurred with M 4.6-4.7 on May 27, 2012, June 13, 2011 and M 4.6 on January 17, 1992. No larger earthquakes in this region have occurred since 1990. At the time of the M 4.6-4.7 on May 27, 2012 this summary noted this unusual epicenter as:

"An unusual earthquake of M 4.7 also hit the area southeast of Australia today. This is the strongest earthquake to occur within 500 km of this epicenter in at least 22 years. Earthquake of M 4.6 on January 17, 1992 and of M 4.0 on April 18, 1995 were the only events in this area of M>4 in the this time period. There is no evidence that these previous quakes were "canary quakes" announcing an upcoming large event but unusual earthquakes such as this often do seem to precede some of the largest global events." (May 27, 2012, August 22, 2023)

This activity is near the antipode of an M 4.5 in the Azores of August 24 - the largest in that area since an M 5.1 on January 17, 2023. This antipodal pair may be related.

O: 29AUG2023 18:20:03 43.6S 159.8E mb=4.3 EMSC SOUTHEAST OF AUSTRALIA

O: 29AUG2023 18:11:29 43.4S 159.8E mb=4.4 EMSC SOUTHEAST OF AUSTRALIA

The strongest earthquake in the world today was an M 5.2 in the region of Guam.

NEIC reported this earthquake of M 5.2 in Guam was felt with intensity II-III in the area(s) of Guam in Hagatna (IV), Santa Rita, Talofofo, Sinajana, Barrigada, Tamuning and Mangilao. This may be an aftershock of an M 5.6 near Guam of August 9, 2023. At the time this summary noted:

"One of the largest earthquakes in the world today was an M 5.3 in the area of Guam. NEIC did not report it as felt. This earthquake follows the passage of Typhoon Mawar over this epicenter several days ago and probably indicates a causal relationship. This has been previously noted in the relation between Typhoons in Guam in this summary and elsewhere.

...

While an M 5.4 hit near this epicenter on May 12, 2023, the last event of significantly larger magnitude in the Guam region was an M 5.7 on August 29, 2022." (August 9, 2023)

Today's event followed the passage of several typhoons near Guam over the past week which included Typhoon Damrey and a new storm (11W) which formed near Guam today as reported in this summary:

"TS 11W formed today in the area of the North Pacific east of the Mariana Islands and Guam with winds up to 45 kts. It is expected to track to the west and north any may enhance seismicity in the Mariana Islands, the Ryukyu Islands and southern Japan as it passes through this area." (August 29, 2023)

The current elevated seismicity in Guam is likely to have been promoted by stresses associated with these tropical cyclones.

Forecast 155887 had expected enhanced seismicity in the region of Guam was

likely around August 27.

O: 29AUG2023 10:15:26 13.2N 143.8E mb=5.2 EMSC GUAM REGION

P: 27AUG2023 155887 12.0N 141.0E 4.0-5.6 ABCAA So. Marianas/Guam

An earthquake of M 3.6-3.9 shook the area of Southern California near San Clemente Island today. NEIC reported it was felt with intensity II-III in San Clemente, Oceanside, Capistrano Beach, Dana Point, Carlsbad. While an M 3.3 hit near this epicenter to the north on July 17, 2022, the last earthquake of M>=3.9 within the Gulf of Santa Catalina was an M 4.3 on June 5, 2019. Events of M 3.6 occurred near this on July 17, 2022 and as an M 3.7 on October 26, 2017. At the time of the M 4.3 on June 5, 2019, this summary noted in this regard:

"Two earthquakes of M 4.3 in the Channel Islands southwest of Los Angeles, California were widely felt today. NEIC reported intensity II-III in California at Avalon, Rancho Palos, San Pedro, Newport, Corona del Mar, Dana Point, Palos Verdes, and Capistrano, California among others. Several light aftershocks were also felt in this area. These included an M 3.3 aftershock. The M 4.3 is the strongest earthquake in the region of the Channel Islands and Los Angeles, California since an M 5.3 on April 5, 2018 in the Channel Islands and prior to that an M 4.4 on December 30, 2015 in eastern Los Angeles." (June 5, 2019)

This earthquake occurred within minutes of local solar midnight and may have been promoted by strong tidal stresses associated with the full moon of August 31 as reported in this and previous summaries as:

“The full moon will arrive at 1:35 UT on August 31, 2023. Longitudes which are at local solar midnight at this time are near 25 West and at local solar noon at 155 East. These zones include the central Atlantic and Iceland and western Europe in the west and the Kuril Islands, Japan and portions of eastern Indonesia and the Vanuatu Islands in the east. These areas are the most likely to see tidal triggering in the next week. Such events often occur near local solar midnight and noon. A major earthquake is considered likely with this full moon in the next week.” (August 27-30, 2023)

Forecast 155944 had expected today's event within about 50 km was likely around August 30, 2023.

O: 29AUG2023 08:05:32 33.0N 117.9W ML=3.9 EMSC GULF OF SANTA CATALINA, CALIF.

P: 30AUG2023 155944 32.6N 118.1W 2.5-4.6 AAAAA So. California

MAJOR EARTHQUAKE SHAKES BALI AND JAVA, INDONESIA

EARTHQUAKE SUMMARY FOR AUGUST 28, 2023

The strongest earthquake in the world today was a deep focus event in the Bali Sea, Indonesia. It is also the strongest quake in the world since July 17 nearly 40 days ago. The mainshock was reported by NEIC to have been felt widely in the Bali area about 500 km to the southwest of the hypocenter with intensity V in Java at Banyuwangi, IV in Bali at Kuta, Denpasar, Rabanan, Ubud, Klungkung, Singaraja, Karangasem and in Praya Nusa and Mataram Nusa, among others.

An aftershock of M 5.6 was reported by NEIC to have been felt with intensity III in Kuta Bali, Indonesia.

This activity follows an M 5.7 in Colombia which occurred on August 27 near the antipode of Java, Indonesia. The possibility of triggered antipodal activity at this time was noted in the previous issue of this summary as:

"It is likely that this M 5.7 in Colombia will be followed in the next couple of days by similar or stronger antipodal activity from Sumatra to Java and Bali, Indonesia. This could be enhanced by strong tidal stresses with the full moon of August 31 as noted in this summary:

The last earthquake in the Bali Sea within about 250 km of today's events with M>=7.0 occurred more than 35 years ago. Only three earthquakes in the area of equal of larger magnitude have been historically recorded - an M 7.3 on August 6, 1984; an M 7.2 on August 11, 1937 and an M 7.5 on December 29, 1820. The only major events immediately following these included an M 7.5 in the Manila, Philippines area on August 20, 1937 and an M 5.5 on August 6, 1984 in the Molucca Sea south of the Philippines. Similar regional seismicity may be seen in the next several days.

Forecast 155861 had expected today's event within about 100 km was likely around

August 27.

O: 28AUG2023 20:06:53 6.8S 116.6E mb=5.4 EMSC BALI SEA

O: 28AUG2023 20:08:06 7.0S 117.2E mb=5.6 EMSC BALI SEA

O: 28AUG2023 19:55:32 6.8S 116.6E Mw=7.0 EMSC BALI SEA

O: 28AUG2023 19:55:32 6.8S 116.6E Mw=7.1 ANSS BALI SEA

P: 27AUG2023 155861 8.0S 117.0E 4.0-5.6 AAAAA Sumbawa Island area

A strong earthquake of M 5.9 also occurred in the Banda Sea, Indonesia today. NEIC reported it was felt with intensity II in Northern Territory, Australia in Darwin and Howard Springs. This may be a regional aftershock of the M 7.1 in the Bali Sea eight hours earlier. It occurred near local solar noon and may have been promoted by strong tidal stresses with the full moon. The last event of M>=5.9 within about 200 km of today's event was an M 6.2 on May 24, 2023 and an M 6.3 on November 1, 2020. Forecast 155863 had expected today's event was likely within about 50 km of today's epicenter around August 26.

O: 29AUG2023 04:34:44 5.5S 130.0E Mw=5.9 EMSC BANDA SEA

P: 26AUG2023 155863 6.0S 130.0E 4.0-5.4 AAAAA West Irian, PNG

The strongest earthquake in the U.S. or Canada today was an M 4.6 off the Alaska Peninsula where NEIC reported it was felt with intensity IV in King Cove. This is the largest earthquake in the Alaska Peninsula area within about 150 km of this epicenter since an M 5.6 on August 3, 2023. At the time this summary noted in this regard:

Forecast 156027 had expected today's event within about 50 km was likely around August 27.

O: 28AUG2023 22:01:31 54.8N 161.2W mb=4.6 EMSC ALASKA PENINSULA

P: 27AUG2023 156027 54.3N 161.4W 3.5-4.9 AAAAA Unimak Islands, Aleutians

MODERATELY STRONG QUAKE DAMAGES COLOMBIA

EARTHQUAKE SUMMARY FOR AUGUST 27, 2023

The strongest earthquake in the world today was an M 5.7 in western Colombia. NEIC reported it was felt with damage and intensity IX in Colombia in Choco area at Tado and Quibdo and IV in Santa Rosa de Cabal, Manizales, Armenia, Itagui, Antioquia, Sabaneta (V) with lesser shaking in Envigado, Pereira and Cartago Valle del Cauca among other localities. This continues enhanced seismicity in Colombia which began earlier in August and was noted in this summary on August 11 as:

"The strongest earthquake in the world today was an M 4.9 in Northern Colombia.

NEIC reported this earthquake of M 4.8 in Colombia was felt with intensity II-III in the area(s) of Colombia in Antioqua at Medellin and Envigado. This event occurred near local solar noon and may have been promoted by strong tidal stresses which maximize near this hour. Recent moderate earthquakes in Colombia were recorded with an M 5.3 on July 30 and M 5.1 on August 3, 2023. Earthquakes of M 4.8 and M 4.9 hit near the antipode (in Sumatra) of this epicenter on

August 8 and 9. Antipodal pairs are not uncommon in these two areas and could occur at this time." (August 11, 2023)

An M 6.6 hit Colombia on May 25, 2023 as described in this summary at the time:

"The strongest earthquake in the world today was an M 6.6 on the Panama-Colombia border. NEIC reported it was felt in Colombia with maximum intensity IV in Acandi Choco and in Necocli, Antioquia and in Panama with VI in Meteti, Darien. Intensity V in Panama was felt in Las Cumbres with IV in Santa Fe, Darien. Intensity III was reported in Colombia at San Bernardo Viento Cordoba, Cartagena, Bolivar and in Panama at San Miguelito and Panama City among other communities. Residents of Medellin and Cali also reported feeling the earthquake. This earthquake is located in the Darien Gap where thousands of migrants congregate on their migration to the north. While the area is densely populated with migrants and is dense jungle, some damage and injuries may have been incurred in this quake. The antipode of this earthquake is in southern Sumatra, Indonesia at 7S 103E, an active seismic zone near the M 7.3 in Sumatra of April 24, 2023 and the M 7.0 in Java of April 14, 23 and this activity may have been promoted by energy from that source. In recent days the antipode south of Sumatra has been active and a triggered moderate to large earthquake in this area in the next several days is possible." (May 25, 2023)

It is likely that this M 5.7 in Colombia will be followed in the next couple of days by similar or stronger antipodal activity from Sumatra to Java and Bali, Indonesia. This could be enhanced by strong tidal stresses with the full moon of August 31 as noted in this summary:

Forecast 155831 had expected this event within about 100 km in Colombia was likely at the end of August, 2023.

O: 27AUG2023 21:44:59 5.3N 76.6W Mw=5.7 EMSC COLOMBIA

P: 21AUG2023 155831 5.0N 78.0W 4.0-5.6 CABAA Colombia

An unusually large earthquake of M 3.7-4.3 shook areas of Ohio today. NEIC reported it was felt with intensity IV in Ohio at Geneva, Madison, Rock Creek, Austinburg, Thompson, Perry, Montville, Rome, Ashtabula, Jefferson and as far as New York, Ontario, Indiana with intensity II-IV. It follows a series of foreshocks in the region on August 24, 2023. Included in this activity was an M 2.3-2.8 foreshock on August 24, 2023 as reported at the time:

O: 24AUG2023 12:43:52 41.7N 81.0W ML=2.3 EMSC OHIO

O: 24AUG2023 12:48:39 41.8N 81.0W MB=2.5 ECAN of Cleveland, OH

O: 24AUG2023 12:43:53 41.8N 81.0W MB=2.8 ECAN of Cleveland, OH

O: 24AUG2023 17:27:29 41.8N 81.0W MB=2.5 ECAN of Cleveland, OH

P: 22AUG2023 155828 41.8N 81.4W 2.0-4.0 AAAAA Ohio/Lake Erie

Today's event of M 3.6-4.3 is the strongest in the region of Ohio within about

200 km of this epicenter since an M 4.0 on June 10, 2019. At the time this summary noted:

"The strongest earthquake in the U.S. or Canada outside Alaska today occurred in Lake Erie, Ohio. NEIC reported maximum intensity IV in Ohio at Eastlake, Wickliffe, Euclid, Mentor, Willoughby and II-III in Cleveland, and within about 60 km of the epicenter in Ohio. Two days ago when an M 3.0 occurred in Quebec, Canada east of today's epicenter this summary noted:

"Half a day after the event in Quebec, an M 5.0 occurred in the antipodal

area of Quebec in the southeast Indian Ridge, Indian Ocean. It is notable as it occurred within about 300 km of the exact antipode (compare 47S 103E with 47S 105E) in an area of generally light seismicity, The exact nature (if any) of this antipodal pair is not clear at this time. This is the strongest earthquake within about 300 km of the epicenter in the Southeast Indian Ridge since an M 5.3 on December 10, 2017 and prior to that an M 5.1 on May 29, 2015." (June 8-9, 2019)

It is likely the event in Ohio was likely affected by the event in the South Indian Ridge. The last earthquake within about 150 km of this event in Ohio with M>=4 was an M 4.4 on January 26, 2011. The only other such event in Ohio in the past 30 years was an M 4.5 on September 25, 1998." (June 10, 2019)

Forecast 155995 had expected this earthquake in Ohio was likely within about 25 km around August 22, 2023.

O: 28AUG2023 03:02:12 41.8N 81.0W ML=2.3 EMSC OHIO

O: 28AUG2023 02:43:25 41.8N 81.0W MB=4.3 ECAN ENE of Cleveland , OH

O: 28AUG2023 02:43:26 41.7N 81.0W Mw=3.6 EMSC OHIO

O: 28AUG2023 02:43:26 41.7N 81.0W Mw=3.7 ANSS OHIO

P: 22AUG2023 155995 41.8N 81.4W 2.0-4.0 CAAAA Ohio/Lake Erie

NEIC reported an earthquake of M 4.1 in the Alaska Peninsula was felt with intensity II-III in the area(s) of te Alaska Peninsula at Sand Point. This event occurred near local solar noon and may have been promoted by strong tidal stresses which maximize near this hour. Forecast 156027 had expected this event was likely within about 50 km around August 27.

O: 27AUG2023 21:56:06 54.7N 161.2W ML=3.7 EMSC ALASKA PENINSULA

O: 27AUG2023 21:56:06 54.7N 161.2W ML=4.1 ANSS ALASKA PENINSULA

P: 27AUG2023 156027 54.3N 161.4W 3.5-4.9 AAAAA Unimak Islands, Aleutians

A pair of unusual earthquakes of M 4.6 and 4.7 occurred in Tanzania today. These may be aftershocks of an M 5.5 of August 8, 2023. At the time this summary noted:

Forecast 155848 had expected this activity in Tanzania was likely within about 100 km around August 26.

O: 27AUG2023 11:00:20 5.4S 34.9E mb=4.6 EMSC TANZANIA

O: 27AUG2023 13:53:38 5.3S 34.9E mb=4.7 EMSC TANZANIA

P: 26AUG2023 155848 5.0S 36.0E 4.0-5.7 AAAAA Indian Ocean

COLORADO EARTHQUAKE RECALLS BEGINNING OF SERIES

EARTHQUAKE SUMMARY FOR AUGUST 26, 2023

A moderate earthquake of M 4.1 shook southern Colorado today. NEIC reported this earthquake of M 4.0 in Southern Colorado was felt with intensity II-III in the area(s) of Southern Colorado at Westong, San Pablo, Trinidad, and Sanford and in New Mexico at Cimarron, Raton, Costilla among other communities. An earthquake of M 3.4 near Stonewall Gap, Colorado occurred about an hour earlier as a foreshock. NEIC reported it felt with intensity II-III in San Pablo, Aguilar and Trinidad, Colorado. The mainshock was preceded by an M 3.4 foreshock which occurred within minutes of local solar midnight and may have been promoted by strong tidal stresses which maximize at this hour. The last earthquake of M>=4.1 in southern Colorado was an M 4.3 on June 19, 2023. At the time this summary noted:

"The strongest earthquake in the U.S. or Canada today was an M 4.3 in southern Colorado. It was preceded by an M 3.8 foreshock. The M 4.3 was reported by NEIC to have been felt with intensity IV in Colorado in Trinidad and La Junta and in Capulin, New Mexico. Intensity II-III was also felt in Colorado at Model, Branson, Las Animas, Granada, Denver and in New Mexico at Raton. The foreshock was reported with intensity IV in Trinidad and Aguilar, Colorado and III in Raton, New Mexico. The M 4.3 is the strongest earthquake in this series of events since an M 4.3 on March 10, 2023. The series began several days before September 11, 2001 (trade towers collapse) on September 5, 2001 with an M 4.5 and has continued off and on since that time. The strongest earthquakes in the area in the past 35 years occurred on August 22 and 23, 2011 and were accompanied by an M 5.9 in Virginia and Washington D.C. which did considerable damage and by one of the strongest Gamma Ray Bursts ever recorded. When the M 4.3 occurred on March 10, 2023, this summary noted the past history of the area as:

"A moderate earthquake of M 4.3 occurred today in the area of Trinidad, southern Colorado. These were reported by NEIC to have been felt with maximum intensity IV in Colorado in Weston and in Raton, New Mexico and III in Colorado at Aguilar, Trinidad, Walsenburg, Fort Garland, Blanca and in New Mexico at Cimarron and Questa among others. This swarm which began in September, 2001 several days before the attack on 9-11-2001 of the Trade Center in New York City also is off and on and has been extensively investigated. No definitive conclusions on the cause of these earthquakes (or earth disturbances) has been found to this time. Today's M 4.3 occurred within about an hour of local solar midnight and may have been promoted by high tidal stresses. The last event in this region of M>4 was an M 5.3 on August 23, 2011 and occurred in conjunction with an M 5.8 near Washington D.C. on the same day which did extensive damage in the Washington area, including to the National Cathedral and the Washington Monument. This was also associated with one of the strongest Gamma Ray Bursts (GRB) recorded. The temporal relation is clear but the physical relation of these events is still fuzzy. The only other event of M>4.3 in this series occurred as an M 4.9-5.0 on August 10, 2005 and as an M 4.5 on September 5, 2001 with the initial start of these events. These events occur with approximate 11-year intervals and could be related to solar cycles of the same length. At the time of the M 5.3 on August 22, 2011, this summary noted:

"Earthquakes of M 5.2-5.4 and M 4.6-5.0 hit southern Colorado near the New Mexico border today. These events were felt throughout most of Colorado and in much of northern New Mexico and as far as Kansas, Nebraska, Oklahoma, Texas and Wyoming. The larger event has only two predecessor earthquakes in Colorado of stronger magnitude in historic times. One of these was an artificially induced earthquake caused by water injection which occurred with M 5.4 in the Denver area on October 10, 1960. An earthquake in 1973 may have occurred in northwestern Colorado with M 5.7 but this is not listed in the "Seismicity of the United States 1568-1989" and may have had its epicenter in Wyoming as well where it is given an M 4.8 magnitude. While a geophysicist with the USGS is reported as stating there was an M 5.7 in Colorado in 1973 this is clearly an error. There is no such event listed in the definitive catalog of historical Colorado earthquake - "Colorado Earthquake Data and Interpretations 1967 to 1985" by Kirkham and Rogers. The only natural event of larger magnitude in Colorado history occurred near Denver on November 8, 1882 and while this event was felt strongly in northern Colorado, it is possible the epicenter was actually in southern Wyoming.

Initial reports indicated that a few homes were damaged and rockslides hit highways in the epicenral region.

...

Most of the lighter events in the series today also were felt lightly in the epicentral zone.

When the light precursor hit the region earlier this morning we discussed this series of events leading up to today's moderately strong earthquake in this summary as follows:

"An earthquake of M 2.9 was lightly felt in southern Colorado near the New Mexican border today. This series of unexplained earthquakes began exactly 10 years ago in late August (28), 2001 and has continued off and on since that time. The strongest earthquakes in the sequence typically occur in August and September with an M 5.0 on August 10, 2005, the largest to date and an M 4.5 on September 5, 2001 the second to date. The last event of M>=2.5 in the area was an M 3.8 on May 11, 2011 and an M 3.2 on March 12, 2011 shortly after the great Japanese earthquake. Since today's event followed a strong aftershock of the Japanese event by about the same time as the earthquakes in March, some triggering may be considered in these cases." (August 22, 2011, March 10, 2023, June 19, 2023)

Forecast 155921 had expected today's event within about 50 km was likely around August 25, 2023.

O: 26AUG2023 07:35:29 37.0N 105.0W ML=3.4 EMSC COLORADO

O: 26AUG2023 08:38:45 37.0N 104.9W Mw=4.1 EMSC COLORADO

P: 25AUG2023 155921 37.4N 104.7W 2.0-3.9 AAAAA Colorado area

The strongest earthquake in the U.S. or Canada today was an M 4.5 in the Fox Islands, Aleutians, Alaska. A foreshock of M 3.7 occurred 6 hours earlier. Neither of these events were reported felt in this remote area. This may be regional aftershocks of the M 5.2 in the Fox Islands about 100 km to the east on August 20. At the time of the M 5.2 on August 20, this summary noted:

"The strongest earthquake in the U.S. or Canada today was an M 5.2 in the Fox Islands, Alaska. This is the strongest earthquake in the Fox Islands since an M 5.4 on May 13, 2023. At the time this summary noted in this regard:

Forecast 156015 had expected today's event was likely within about 50 km around

August 25.

O: 26AUG2023 19:46:41 52.0N 168.6W ML=3.7 EMSC FOX ISLANDS, ALEUTIAN ISLANDS

O: 27AUG2023 01:47:29 52.3N 168.8W mb=4.5 EMSC FOX ISLANDS, ALEUTIAN ISLANDS

P: 25AUG2023 156015 52.4N 169.4W 3.5-5.2 AAAAA Fox Islands, Aleutians

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