SAN FRANCISCO SWARM REACHES LOCAL MAXIMIM

 

EARTHQUAKE SUMMARY FOR FEBRUARY 23, 2018

 

The San Francisco Bay swarm near Danville, California continued today with the strongest events in the current activity. An M 3.5 was the strongest event today but an M 3.3 also occurred. These larger earthquake were reported by NEIC to have been felt with intensity up to IV within about 10-15 km of the epicenter at Danville, Diablo and Alamo, California. Lesser shaking of intensity II-III was reported in San Ramon, Walnut Creek, Clayton, Moraga, Castro Valley, Concord, Lafayette, Dublin, Pleasant Hill, Oakland, Hayward, Orinda, San Leandro, Livermore and in general within about 50 km of the epicenter. It is likely the swarm will now reduce. An M 3.5 quake releases more energy by far than the series of events of M 2.5-2.9 which have been occurring and will probably damp these lower magnitude quakes at least until the full moon. These earthquakes were apparently promoted by strong tidal stresses as they tended to occur near local midnight (M 2.3 at 07:39 local time) and solar noon (M 3.5 at 12:19 local time) when these stresses maximize. The M 3.5, for example,  occurred within about 5-10 minutes of local solar noon and was followed two minutes later by an M 2.8. The swarm is likely to reduce until the next full moon on March 2. The last earthquake of M>=3.5 within about 50 km of these epicenters in the San Francisco Bay area occurred as an M 4.4 on January 4, 2018 with other events of M 3.8 on April 30, 2017 and September 13, 2016 of M 3.5.  Forecast 114638 had expected this earthquake within about 10 km of the epicenters was most likely to maximize around February 22.

 

 

O: 23FEB2018 20:31:43  37.8N  122.0W MD=2.0  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 09:12:54  37.8N  122.0W MD=2.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 11:01:20  37.8N  122.0W MD=2.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 10:52:47  37.8N  122.0W MD=2.2  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 07:39:33  37.8N  122.0W MD=2.3  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 10:32:10  37.8N  122.0W MD=2.7  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 11:24:57  37.8N  122.0W MD=2.8  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 20:21:59  37.8N  122.0W MD=2.8  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 20:19:39  37.8N  122.0W ML=3.5  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 13:28:40  37.8N  122.0W Mw=3.3  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P: 22FEB2018 114638    37.9N  122.0W 2.5-4.7 AAAAA  Central California         

 

 

Another area where a moderate earthquake occurred today near local solar noon was the area off the coast of Honshu, Japan. This area is near 103 degrees from the M 7.2 in Mexico of February 16 as well and may have been promoted from that

source. Local solar noon at this epicenter is 02:30 UT and this quake occurred at 02:43 UT. A similar quake of M 4.6 hit the region on February 18, but the last event of M>=5 in the area was an M 5.4 on October 6, 2017. Forecast 114661 had expected today's earthquake was likely within about 50 km of this epicenter around February 23.

 

O: 24FEB2018 02:43:51  37.3N  141.4E mb=4.6  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 23FEB2018 114661    37.0N  141.0E 4.0-5.8 AAAAA  Off East Coast Honshu      

 

The strongest earthquake in the U.S. or Canada today was an M 4.1 in the area south of the Fox Islands, Aleutians, Canada. It was not reported felt in this remote area. The last earthquake within about 150 km of this epicenter with M>=4.1 occurred on February 20, 2018 with M 4.8 and prior to that on November 22, 2017 with M 4.3. Forecast 114732 expected this earthquake within this area was likely around February 27.

 

O: 24FEB2018 01:04:42  52.7N  165.4W mb=4.1  EMSC   SOUTH OF ALEUTIAN ISLANDS    

P: 27FEB2018 114732    53.5N  165.8W 3.5-5.1 BAAAA  Fox Islands, Aleutians     

 

OTHER GLOBAL EARTHQUAKE ACTIVITY

 

For most events there are two listings. The first line is the observed event starting with "O:" for Observed. There follows the date, month and year, the time in UT hours:minutes:seconds, the latitude and longitude, the given magnitude and the reporting agency followed by the geographic location. The second line starts with "P:" This is the forecast event as forecast in our summaries normally more than a month in advance. Magnitudes may vary in response to updated seismic watches and daily variations due to tidal and other influences. This line has the forecast date, month and year, the forecast number, latitude, longitude and forecast magnitude range.  This is followed by a comparison between the forecast and the event. The comparison includes letters A-D. The first is number of days difference from predicted (A:up to 2, B3-5; C:6-10; D:more than 10), Difference in latitude (A:up to 1 degree; B:1-2 degrees; C:2-4 degrees; D:more than 4 degrees); longitude (same comparison as with latitude); magnitude (A: within forecast range; B: higher than forecast range; C: lower than forecast range; D: no comparison possible). The last letter is a stand in for a future comparison which needs to be done statistically after a large number of forecasts have been made. In previous data, an excellent match is generally AAAAA; a good match as one or two B's; a fair match has several B's and C's and a poor match is one which contains a number of C's or D's. 

 

ASIA

 

O: 23FEB2018 08:49:08  27.9N   67.7E mb=4.3  EMSC   PAKISTAN                     

P: 21FEB2018 114371    29.0N   68.0E 3.5-4.9 ABAAA  Pakistan                   

 

O: 23FEB2018 10:21:56  39.4N   72.8E mb=4.5  EMSC   KYRGYZSTAN                   

P: 24FEB2018 114646    39.0N   72.0E 3.8-5.4 AAAAA  Hindu Kush/Pakistan        

 

O: 24FEB2018 03:03:46  55.9N  161.1E mb=4.3  EMSC   NEAR EAST COAST OF KAMCHATKA 

P: 27FEB2018 114731    54.0N  160.0E 4.0-5.4 BBAAA  E. of Kamchatka            

 

No significant (M>=5) or unusual earthquakes were reported in Asia today.

 

INDONESIA AND PHILIPPINES

 

O: 24FEB2018 01:17:11   2.3N   98.7E mb=4.4  EMSC   NORTHERN SUMATRA, INDONESIA  

P: 23FEB2018 114567     2.0N  100.0E 4.0-5.6 AABAA  So. Sumatera               

 

O: 24FEB2018 06:51:14   3.1S   86.5E mb=4.7  EMSC   SOUTH INDIAN OCEAN           

 

O: 23FEB2018 10:42:33   3.2S  130.8E mb=4.5  EMSC   SERAM, INDONESIA             

P: 24FEB2018 114589     4.0S  131.0E 4.0-5.4 AAAAA  West Irian, PNG            

 

O: 23FEB2018 14:56:10   4.7S  139.5E mb=4.6  EMSC   PAPUA, INDONESIA             

P: 22FEB2018 114590     5.0S  139.0E 4.0-5.7 AAAAA  West Irian, PNG            

 

O: 23FEB2018 07:20:39   5.3S  129.7E mb=4.6  EMSC   BANDA SEA                     

P: 25FEB2018 114572     4.0S  129.0E 4.0-5.5 ABAAA  Ceram area                 

 

O: 23FEB2018 09:32:13   8.7S  115.5E ML=3.8  EMSC   BALI REGION, INDONESIA       

P: 21FEB2018 114516    10.0S  116.0E 4.0-5.7 ABAAA  Sumbawa Island area         

 

 

No significant (M>=5) or unusual earthquakes were reported in Indonesia or the Philippines today.

 

CENTRAL AND SOUTH AMERICA

 

O: 23FEB2018 18:49     34.5S   72.2W mb=4.6  GUC    Paredones, Pichilemu, Curico;

P: 23FEB2018 114784    35.0S   71.0W 4.0-5.6 AAAAA  Central Chile              

 

CSN reported this earthquake was felt with intensity IV in  Paredones, Pichilemu, Curico; III Chepica, Lolol, San Fernando, Constitucion, Curepto, Iloca, Rio Claro, Talco. Felt in O'Higgins, Chile.

NEIC reported this earthquake of M 4.9 in Central Chile was felt with intensity IV in San Vicente, O'Higgins; in Curico and Talca, Maule and in Valparaiso, Chile.

 

O: 23FEB2018 12:11:42   2.7N   84.3W mb=4.5  EMSC   OFF COAST OF CENTRAL AMERICA 

P: 28FEB2018 114560     4.0N   83.0W 4.0-5.6 BBAAA  Ecuador                    

 

O: 24FEB2018 01:50:53  12.7N   88.1W Mw=4.9  EMSC   OFFSHORE EL SALVADOR         

P: 25FEB2018 114606    12.0N   88.0W 3.5-5.6 AAAAA  Nicaragua                  

 

NEIC reported this earthquake of M 4.9 in El Salvador was felt with intensity IV in Santo Tomas, El Salvador and II-III in the area(s) of San Miguel, Jucuapa, El Rosario, Ilopango, Antiguo Cuscatland, Mejicanos, San Salvador, El Salvador.

 

O: 23FEB2018 12:24:26  13.1N   89.2W ML=4.4  EMSC   OFFSHORE EL SALVADOR         

P: 23FEB2018 114597    14.0N   90.0W 3.5-5.2 AAAAA  Guatemala                  

 

O: 23FEB2018 14:31:43  15.1N   94.3W ML=4.3  EMSC   OFF COAST OF CHIAPAS, MEXICO 

O: 23FEB2018 14:31:43  15.1N   94.3W ML=4.3  UNAM  al SUROESTE de TONALA, CHIS *: 15.

P: 24FEB2018 114594    16.0N   95.0W 3.5-5.1 AAAAA  Chiapas, Mexico            

 

O: 23FEB2018 05:43:41  16.4N   97.6W mb=4.8  EMSC   OAXACA, MEXICO               

O: 03FEB2018 05:39:18  15.7N   98.0W ML=4.1  UNAM  l SUROESTE de RIO GRANDE, OAX *: 1

O: 03FEB2018 05:37:57  15.6N   98.0W ML=4.2  UNAM  l SUROESTE de RIO GRANDE, OAX *: 1

O: 03FEB2018 05:43:35  15.6N   98.0W ML=5.0  UNAM  l SUROESTE de RIO GRANDE, OAX *: 1

O: 23FEB2018 20:39:45  16.4N   98.5W ML=4.0  UNAM  l SUROESTE de OMETEPEC, GRO *: 16.

O: 23FEB2018 20:39:45  16.4N   98.5W ML=4.0  EMSC   GUERRERO, MEXICO             

P: 23FEB2018 114609    17.0N   99.0W 3.5-5.4 AAAAA  Oaxaca, Mexico             

 

O: 23FEB2018 14:21:57  18.3N   64.4W MD=3.4  EMSC   VIRGIN ISLANDS REGION        

P: 22FEB2018 114600    18.0N   64.0W 3.0-5.0 AAAAA  Leeward Islands            

 

O: 23FEB2018 18:52:53  19.2N   67.5W Md=3.2  EMSC   PUERTO RICO REGION           

P: 25FEB2018 114610    19.0N   67.0W 3.4-4.9 AAAAA  Puerto Rico                 

 

O: 23FEB2018 18:27:00  19.4N  104.1W ML=4.3  EMSC   COLIMA, MEXICO               

O: 23FEB2018 18:27:00  19.4N  104.1W ML=4.3  UNAM  l NOROESTE de COQUIMATLAN, COL *:

P: 22FEB2018 114604    19.0N  104.0W 3.5-5.2 AAAAA  Michoacan, Mexico           

 

O: 24FEB2018 02:47:24  21.4S   68.5W mb=4.1  EMSC   ANTOFAGASTA, CHILE           

P: 27FEB2018 114772    21.0S   69.0W 4.0-5.4 BAAAA  Coast No. Chile            

 

O: 24FEB2018 02:19:59  24.3S   67.7W ML=4.0  EMSC   SALTA, ARGENTINA             

P: 22FEB2018 114770    24.0S   67.0W 4.0-5.5 AAAAA  Argentina                  

 

O: 23FEB2018 11:43:05  17.7N  101.5W ML=4.1  UNAM  l NORTE de ZIHUATANEJO, GRO *:

P: 24FEB2018 114609    18.0N  100.0W 3.5-5.1 AABAA  Oaxaca, Mexico             

 

No significant (M>=5) or unusual earthquakes were reported in Central or South America today.

 

AFRICA AND EUROPE

 

O: 24FEB2018 02:03:00  34.0N   26.1E mb=4.4  EMSC   EASTERN MEDITERRANEAN SEA    

P: 26FEB2018 114645    34.0N   27.0E 3.0-4.7 AAAAA  Crete                       

 

No significant (M>=5) or unusual earthquakes were reported in Europe today.

 

SOUTHWEST PACIFIC

 

O: 24FEB2018 02:16:57  21.4S  179.3W mb=4.8  EMSC   FIJI REGION                  

P: 23FEB2018 114780    21.0S  177.0W 4.0-5.5 AABAA  Tonga Islands               

 

No significant (M>=5) or unusual earthquakes were reported in the Southwest Pacific region today.

 

OCEAN RIDGES

 

O: 23FEB2018 23:07:54  12.1N   43.9W mb=4.8  EMSC   NORTHERN MID-ATLANTIC RIDGE  

P: 21FEB2018 114351    15.0N   45.0W 4.0-5.4 ACAAA  Mid-Atlantic Ridge         

 

O: 24FEB2018 05:16:27  29.5N   17.5W ML=4.0  EMSC   CANARY ISLANDS, SPAIN REGION 

P: 28FEB2018 114615    28.0N   16.0W 3.0-4.4 BBBAA  Canary Islands             

 

No significant (M>=5) or unusual earthquakes were reported on Ocean Ridges today.

 

 

ZEALANDIA AND AUSTRALIA REGION

 

No earthquakes of M>=4 were recorded in the regions of Zealandia or Australia

today. GeoNet did not report any felt events in the area.

 

JAPAN AND KURIL ISLANDS

 

No earthquakes of M>=4 were located in Japan or the Kuril Islands today.

 

U.S./CANADA*

 

WESTERN U.S./CANADA

 

CALIFORNIA

 

O: 23FEB2018 08:27:27  32.2N  116.4W ML=2.5  EMSC   BAJA CALIFORNIA, MEXICO      

P: 22FEB2018 114666    32.8N  116.0W 2.5-4.6 AAAAA  So. California             

 

NEIC reported this earthquake of M 2.5 in Baja California was felt with intensity II-III in the area(s) of Tecate, Baja, Mexico.

 

O: 23FEB2018 06:07:25  32.5N  115.6W ML=2.1  EMSC   BAJA CALIFORNIA, MEXICO      

P: 23FEB2018 114668    32.9N  115.6W 2.5-4.4 AAAAA  So. California             

 

O: 23FEB2018 15:56:42  33.5N  116.8W ML=2.6  EMSC   SOUTHERN CALIFORNIA          

P: 22FEB2018 114666    32.8N  116.0W 2.5-4.6 AAAAA  So. California             

 

O: 23FEB2018 22:55:40  34.1N  118.3W ML=2.2  EMSC   GREATER LOS ANGELES AREA, CALI

P: 22FEB2018 114671    34.4N  118.6W 2.5-4.7 AAAAA  So. California             

 

O: 23FEB2018 18:49:20  34.5S   72.3W mb=4.9  EMSC   OFFSHORE O'HIGGINS, CHILE    

P: 23FEB2018 114784    35.0S   71.0W 4.0-5.6 AAAAA  Central Chile              

 

O: 24FEB2018 02:39:20  36.2N  117.4W ML=2.8  EMSC   CENTRAL CALIFORNIA           

P: 22FEB2018 114631    37.2N  117.3W 2.5-4.4 AAAAA  California/Nevada area     

 

O: 23FEB2018 06:54:29  38.0N  115.3W ML=3.2  EMSC   NEVADA                        

P: 24FEB2018 114633    38.7N  115.4W 2.5-4.4 AAAAA  California/Nevada area     

 

O: 23FEB2018 09:53:00  40.2N  121.1W ML=2.0  EMSC   NORTHERN CALIFORNIA          

P: 23FEB2018 114709    40.0N  120.9W 2.5-4.8 AAAAA  Northern California         

 

 

O: 23FEB2018 20:31:43  37.8N  122.0W MD=2.0  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 09:12:54  37.8N  122.0W MD=2.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 11:01:20  37.8N  122.0W MD=2.1  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 10:52:47  37.8N  122.0W MD=2.2  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 07:39:33  37.8N  122.0W MD=2.3  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 10:32:10  37.8N  122.0W MD=2.7  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 11:24:57  37.8N  122.0W MD=2.8  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 20:21:59  37.8N  122.0W MD=2.8  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 20:19:39  37.8N  122.0W ML=3.5  EMSC   SAN FRANCISCO BAY AREA, CALIF.

O: 23FEB2018 13:28:40  37.8N  122.0W Mw=3.3  EMSC   SAN FRANCISCO BAY AREA, CALIF.

P: 22FEB2018 114638    37.9N  122.0W 2.5-4.7 AAAAA  Central California         

 

ALASKA

 

O: 24FEB2018 01:04:42  52.7N  165.4W mb=4.1  EMSC   SOUTH OF ALEUTIAN ISLANDS    

P: 27FEB2018 114732    53.5N  165.8W 3.5-5.1 BAAAA  Fox Islands, Aleutians     

 

O: 24FEB2018 00:25:29  56.3N  149.4W Ml=3.2  EMSC   GULF OF ALASKA               

P: 22FEB2018 114726    56.0N  149.7W 3.5-5.1 AAAAA  Gulf of Alaska             

 

O: 23FEB2018 07:21:29  58.2N  155.4W Ml=3.3  EMSC   ALASKA PENINSULA             

P: 21FEB2018 114469    54.7N  156.9W 3.5-5.0 ACAAA  Alaska Peninsula           

 

O: 23FEB2018 19:19:29  59.8N  136.8W ML=3.0  EMSC   SOUTHEASTERN ALASKA          

P: 23FEB2018 114739    59.0N  136.0W 3.0-4.7 AAAAA  Southeast Alaska           

 

PACIFIC NORTHWESTERN U.S./WESTERN CANADA

 

No events of M>=2 were located in the northwestern U.S. or western Canada today.

 

ROCKY MOUNTAINS REGION

 

O: 23FEB2018 05:24:50  44.8N  111.0W ML=2.7  EMSC   YELLOWSTONE NAT. PARK, WYOMING

P: 23FEB2018 114724    44.6N  110.8W 2.0-4.0 AAAAA  Yellowstone/Wyoming        

 

EASTERN U.S./CANADA

 

O: 23FEB2018 06:36:09  36.5N   90.8W MD=2.7  EMSC   ARKANSAS                     

P: 22FEB2018 114652    36.0N   91.0W 2.0-4.2 AAAAA  New Madrid area            

 

NEIC reported this earthquake of M 2.7 in Missouri was felt with intensity II-III in the area(s) of Maynard, Paragould, Harrison, Arkansas and in Columbia, Missouri.

 

O: 23FEB2018 06:51:48  36.5N   89.6W md=1.2  ANSS   ENE of Portageville Missouri 

P: 25FEB2018 114653    37.0N   90.0W 2.0-3.9 AAAAA  New Madrid area            

 

O: 22FEB2018 10:41:32  68.8N   69.0W ML=3.6  NRCA  187 km S from Clyde River     

P: 21FEB2018 114502    71.0N   75.0W 2.5-4.2 ACAAA  Baffin/Davis Strait Canada 

 

O: 22FEB2018 09:00:55  45.9N   75.1W ML=1.6  NRCA  19 km N from Saint-Andre-Avelli

P: 25FEB2018 114706    46.0N   74.0W 2.0-4.1 BAAAA  New York State             

 

O: 22FEB2018 05:16:58  52.4N   80.0W ML=2.1  NRCA  James Bay                     

P: 15FEB2018 114453    49.0N   81.0W 2.0-3.9 CCAAA  Ohio/Lake Erie             

 

HAWAII

 

No earthquakes of M>=3 were located in Hawaii.