NEW GEOMAGNETIC STORM BRINGS SEISMIC QUIET

 

EARTHQUAKE SUMMARY FOR SEPTEMBER 25, 2016

 

After two days of highly activated global seismicity, especially near the geomagnetic equator, today was a very quiet day. This sudden change may be related to conditions in the geomagnetic field. After a strong geomagnetic storm when began on September 19 the field disturbance declined to very low levels by September 21. This enabled ionospheric ring currents near the geomagnetic equator and at high latitudes to become organized. The resultant currents can induce telluric currents in the earth underneath them. These currents, in turn, can help promote seismicity. When the ionospheric currents are disrupted, the cycle comes to a halt and such promotion ceases. Today a minor storm occurred in  the geomagnetic field which probably disrupted the ionospheric ring currents.

With initial AP 23, this storm could continue for several days according to SWPC. While there often is immediate triggering of seismicity from Solar Flare Effects (SFE) this is generally limited to major flares. The sudden drop in seismicity with the onset of this storm is likely related. Generally, this is followed by several days of quiet and then several days of elevated seismicity with the potential for a major quake about five days after the end of the geomagnetic storm after ring currents have reformed.

 

The strongest earthquake in the world today was an M 5.0 south of Hokkaido, Japan. NEIC reported this earthquake of M 5.0 off Hokkaido, Japan  was felt with intensity II-III in the area(s) of Shizunai, Hokkaido and Misawa, Aomori, Japan.

Forecast 101534 had expected this earthquake within about 100 km of this epicenter was likely around September 23. The last earthquake within about this zone with M>=5 occurred on June 16, 2016 with M 5.2. The only other such event in the area during the year 2016 occurred on January 14, 2016 with M 6.7. Today's earthquake occurred within about 10 minutes of local solar noon, a prime time for tidal triggering, and this was probably a factor in the timing of this earthquake.

 

O: 26SEP2016 02:24:37  41.9N  142.2E mb=5.0  EMSC   HOKKAIDO, JAPAN REGION       

P: 23SEP2016 101534    41.0N  143.0E 3.5-5.8 BAAAA  Hokkaido, Japan            

 

The strongest earthquake in the U.S. or Canada today was an M 4.6 in the Fox Islands, Aleutians, Alaska. This is a remote area and this event was not reported felt in the epicentral region. Forecast 101574 had expected a moderate sized earthquake within about 100 km of this epicenter was likely around September 28. The last earthquake of M>=4.6 in the Fox Islands within this region of 100 km was an M 4.8 on September 18, 2016 and prior to that an M 4.7 on July 27, 2016. On average, about one such event hits this region per month.

 

O: 26SEP2016 00:40:39  52.8N  167.2W mb=4.6  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 28SEP2016 101574    53.7N  167.0W 3.5-5.4 AAAAA  Fox Islands, Aleutians     

 

An M 4.6 aftershock off the coast of northern California also occurred today.

This event occurred within about one hour of local solar midnight and is consistent with triggering promoted by tidal stresses which maximize near this time of day. This aftershock follows the M 4.9-5.0 in the same area earlier in the day. This summary noted this event in the previous issue as:

 

 

"The strongest earthquake in the U.S. or Canada today was an M 5.0 off the coast of Northern California. It was felt widely with low intensity along the coast of California and Oregon. NEIC reported intensity II-III in Oregon at Gold Beach, Brookings, Bandaon, Coquille, Central Point, Springfield, Toledo, Tualatin, Clatskanie, and as far as Vancouver, British Columbia and Monroe and Yakima, Washington. It was also felt on the California coastline at Smith River, Eureka, Fortuna, California. This is the strongest earthquake within about 150 km of this epicenter since an M 5.2 on March 13, 2016. Other similar activity occurred in this area on December 1, 2013, May 13, 2010 and May 4, 2008 (M 5-5.5). A strong earthquake of M 7.2 hit south of this on June 15, 2005.  Forecasts 101551 and 101295 had expected this activity within about 50 km of this epicenter was likely at the end of September. Like a similar event off  northern California earlier in the month, this earthquake is located at 103 degrees from the M 7.1 which hit the mid-Atlantic on August 29. Seismic energy reflects off the core-mantle boundary and returns to the surface in a concentrated form at a distance around 103 degrees from the mainshock. This energy can help promote further seismicity at this distance." (September 24-25, 2016)

 

NEIC reported the aftershock of M 4.6 off the coast of northern California was felt with intensity II-III in the area(s) of Brookings, Corvallis, Oregon and possibly in communities in Washington State.

 

O: 25SEP2016 09:50:49  41.9N  126.1W mb=4.6  EMSC   OFF COAST OF NORTHERN CALIFORN

P: 27SEP2016 101551    42.5N  126.8W 3.0-4.6 AAAAA  Off Coast of Oregon        

 

O: 25SEP2016 05:01:50  41.9N  126.2W mb=5.0  EMSC   OFF COAST OF NORTHERN CALIFORN

O: 25SEP2016 05:01:50  41.9N  126.1W mb=5.0  ANSS   Gold Beach Oregon

P: 27SEP2016 101551    42.5N  126.8W 3.0-5.0 AAAAA  Off Coast of Oregon        

P: 21SEP2016 101295    41.8N  126.9W 2.5-5.0 BAAAA  Off Coast of No. Calif     

P: 30SEP2016 101551    41.8N  126.9W 2.5-5.2 BAAAA  Off Coast of No. Calif     

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: 25SEP2016 08:00:29  29.6N  102.2E mb=4.0  EMSC   WESTERN SICHUAN, CHINA       

P: 27SEP2016 101468    28.0N  101.0E 4.0-5.8 ABAAA  Myanmar                    

 

O: 26SEP2016 00:13:40  36.6N   71.3E mb=4.4  EMSC   HINDU KUSH REGION, AFGHANISTAN

P: 25SEP2016 101490    36.0N   71.0E 3.8-5.4 AAAAA  Hindu Kush/Pakistan        

 

O: 25SEP2016 21:52:01  54.2N  111.1E mb=4.1  EMSC   LAKE BAYKAL REGION, RUSSIA   

P: 20SEP2016 101326    56.0N  110.0E 3.0-4.4 BBAAA  So. Siberia                

 

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

 

INDONESIA AND PHILIPPINES

 

O: 25SEP2016 19:30:55   0.0S  125.9E mb=4.1  EMSC   MOLUCCA SEA                  

P: 26SEP2016 101401     1.0N  128.0E 4.0-5.4 AABAA  Halmahera                   

 

O: 25SEP2016 05:31:35   6.7N  126.5E mb=4.4  EMSC   MINDANAO, PHILIPPINES        

P: 24SEP2016 101401     7.0N  127.0E 4.0-5.6 AAAAA  Halmahera                  

 

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

 

CENTRAL AND SOUTH AMERICA

 

O: 26SEP2016 02:57     34.0S   72.2W mb=4.4  GUC    La Estrella, Litueche; II San

O: 26SEP2016 02:57:39  34.0S   72.2W Mw=4.2  EMSC   OFFSHORE O'HIGGINS, CHILE    

P: 22SEP2016 101631    35.0S   70.0W 4.0-5.9 BABAA  Central Chile              

 

CSN reported this earthquake was felt with intensity III in  La Estrella, Litueche; II San Antonio, Santo Domingo. Felt in Valparaiso and O'Higgins, Chile.

 

O: 25SEP2016 18:23      3.4S   81.0W mb=5.0  IGP    Zorritos, Tumbes, Mancora  Per

O: 25SEP2016 18:24:00   3.2S   80.7W mb=4.7  EMSC   PERU-ECUADOR BORDER REGION   

P: 26SEP2016 101412     4.0S   80.0W 4.0-5.5 AAAAA  Ecuador                    

 

IGP reported this earthquake was felt with intensity II in  Zorritos, Tumbes, Mancora  Peru.

NEIC reported this earthquake of M 4.7 in Northern Peru was felt with intensity IV in Tumbes, Peru and II-III in the area(s) of Playas, Guayas, Machala, El Oro, Ecuador.

 

 

O: 25SEP2016 12:10:41   8.4S   75.0W mb=4.6  EMSC   CENTRAL PERU                  

P: 27SEP2016 101409     8.0S   74.0W 3.5-5.1 AAAAA  Brazil                     

 

O: 25SEP2016 12:31:30   9.5N   84.8W Mw=4.1  EMSC   COSTA RICA                   

P: 24SEP2016 101399     9.0N   85.0W 3.5-5.1 AAAAA  Costa Rica                  

 

O: 26SEP2016 01:25:29  19.1N   65.3W Md=3.1  EMSC   PUERTO RICO REGION           

P: 25SEP2016 101444    19.0N   65.0W 3.0-5.0 AAAAA  Leeward Islands            

 

O: 25SEP2016 23:12:41  20.0N   65.0W Md=2.7  EMSC   NORTH OF THE VIRGIN ISLANDS  

P: 25SEP2016 101444    19.0N   65.0W 3.0-5.0 AAAAA  Leeward Islands            

P: 25SEP2016 101458    20.0N   63.0W 3.0-4.6 AABAA  Bahamas/No. Caribbean      

 

O: 26SEP2016 02:35:52  14.4N   92.7W ML=4.0  UNAM  SUROESTE de CD HIDALGO, CHIS *:

P: 24SEP2016 101436    14.0N   93.0W 3.5-5.3 AAAAA  Chiapas, Mexico            

 

O: 25SEP2016 13:41:23  16.7N   94.3W ML=4.3  UNAM  OESTE de CINTALAPA, CHIS *: 16.

P: 23SEP2016 101437    16.0N   94.0W 3.5-5.3 AAAAA  Chiapas, Mexico            

 

O: 25SEP2016 11:31:06  19.3N  109.0W ML=4.3  UNAM   SUR de CABO SAN LUCAS, BCS *:

P: 22SEP2016 101462    20.0N  109.0W 3.5-5.1 BAAAA  Gulf of California         

 

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

 

AFRICA AND EUROPE

 

O: 25SEP2016 07:33:55  37.5N    2.6W ML=3.7  EMSC   SPAIN                        

P: 18SEP2016 101237    37.0N    3.0W 3.5-5.3 CAAAA  Morocco/Spain              

 

EMSC reported this earthquake was loudly heard in El Contador and Albox, Spain and then

slight shaking occurred.

 

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

 

SOUTHWEST PACIFIC

 

O: 25SEP2016 15:15:06  17.8S  178.7W mb=4.5  EMSC   FIJI REGION                  

P: 23SEP2016 101614    17.0S  178.0W 4.0-5.6 AAAAA  Tonga Islands              

P: 27SEP2016 101614    18.0S  179.0W 4.0-5.6 AAAAA  Tonga Islands              

 

O: 25SEP2016 19:19:37  21.1S  178.6W mb=4.3  EMSC   FIJI REGION                  

P: 27SEP2016 101626    20.0S  179.0W 4.0-5.4 ABAAA  Tonga Islands              

 

OCEAN RIDGES

 

O: 25SEP2016 12:34:41  29.2S   61.0E mb=4.6  EMSC   SOUTHWEST INDIAN RIDGE       

P: 11SEP2016 101117    29.0S   62.0E 4.0-5.4 DAAAA  So. Indian Ocean           

P: 27SEP2016 101635    32.0S   59.0E 4.0-5.6 ACBAA  So. Indian Ocean           

 

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

 

NEW ZEALAND AND AUSTRALIA REGION

 

O: 25SEP2016 23:46:49  32.7S  178.5W mb=4.6  EMSC   SOUTH OF KERMADEC ISLANDS    

P: 22SEP2016 101636    32.0S  178.0W 4.0-5.4 BAAAA  So. Kermadec Islands       

 

JAPAN AND KURIL ISLANDS

 

O: 26SEP2016 02:24:37  41.9N  142.2E mb=5.0  EMSC   HOKKAIDO, JAPAN REGION       

P: 23SEP2016 101534    41.0N  143.0E 3.5-5.8 BAAAA  Hokkaido, Japan            

 

U.S./CANADA*

 

WESTERN U.S./CANADA

 

CALIFORNIA

 

O: 26SEP2016 03:23:43  34.0N  116.8W ML=2.1  EMSC   SOUTHERN CALIFORNIA          

P: 25SEP2016 101510    33.4N  116.7W 2.5-4.6 AAAAA  So. California             

 

O: 26SEP2016 00:06:29  36.8N  121.4W MD=2.1  EMSC   CENTRAL CALIFORNIA           

O: 26SEP2016 00:06:29  36.8N  121.4W md=2.1  ANSS   WSW of Ridgemark California

O: 26SEP2016 00:06:01  36.8N  121.4W md=2.1  ANSS   WSW of Ridgemark California

P: 27SEP2016 101483    36.9N  121.7W 2.5-4.4 AAAAA  Central California         

 

O: 25SEP2016 15:15:19  38.3N  122.6W MD=2.1  EMSC   NORTHERN CALIFORNIA          

P: 25SEP2016 101484    38.0N  122.3W 2.5-4.4 AAAAA  Central California         

 

O: 25SEP2016 14:03:53  38.4N  115.9W ML=2.0  EMSC   NEVADA                        

P: 21SEP2016 101222    38.7N  115.4W 2.5-4.4 BAAAA  California/Nevada area     

 

O: 25SEP2016 22:27:23  38.8N  122.8W MD=2.1  EMSC   NORTHERN CALIFORNIA          

O: 25SEP2016 06:36:54  38.8N  122.8W MD=2.5  EMSC   NORTHERN CALIFORNIA          

P: 24SEP2016 101485    38.8N  122.8W 2.5-4.4 AAAAA  Central California         

 

O: 25SEP2016 17:23:20  39.3N  122.8W MD=2.3  EMSC   NORTHERN CALIFORNIA          

P: 27SEP2016 101485    39.3N  123.2W 2.5-4.5 AAAAA  Central California         

 

O: 25SEP2016 09:50:49  41.9N  126.1W mb=4.6  EMSC   OFF COAST OF NORTHERN CALIFORN

P: 27SEP2016 101551    42.5N  126.8W 3.0-4.6 AAAAA  Off Coast of Oregon        

 

ALASKA

 

O: 26SEP2016 00:40:39  52.8N  167.2W mb=4.6  EMSC   FOX ISLANDS, ALEUTIAN ISLANDS

P: 28SEP2016 101574    53.7N  167.0W 3.5-5.4 AAAAA  Fox Islands, Aleutians     

 

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: 25SEP2016 17:50:15  44.8N  111.1W ML=2.5  EMSC   WESTERN MONTANA              

O: 25SEP2016 16:46:34  44.8N  111.1W ML=2.6  EMSC   WESTERN MONTANA              

P: 29SEP2016 101565    45.6N  111.9W 2.0-4.2 BAAAA  Yellowstone/Wyoming        

 

EASTERN U.S./CANADA

 

O: 25SEP2016 17:34:53  35.8N   98.5W mb=2.6  EMSC   OKLAHOMA                     

P: 24SEP2016 101520    37.0N   98.0W 2.0-4.1 ABAAA  Southern Plains            

P: 29SEP2016 101520    36.0N   97.0W 2.0-4.1 BAAAA  Southern Plains            

 

NEIC reported this earthquake of M 2.6 in Oklahoma was felt with intensity II-III in the area(s) of Geary and Tulsa, Oklahoma.

 

HAWAII

 

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