MODERATELY STRONG QUAKE SOUTH OF AUSTRALIA

 

EARTHQUAKE SUMMARY FOR APRIL 21, 2018

 

The largest earthquake of the day was an M 5.8 on the Western Indian-Antarctic Ridge south of Australia. It was not reported felt in this remote area. It occurred within about 30 minutes of local solar midnight and may have been promoted from the geomagnetic storm and tidal effects which maximized near this hour. The high latitude (near Antarctica) suggests the geomagnetic storm was a major promoter of this event. This is the strongest earthquake within about 300 km of this epicenter since an M 5.9 on December 13, 2008, the only such event in the region with M>=5.8 in the past 25 years.  Forecasts 116090 and 116375 had expected this event within about 100 km of the epicenter between April 18 and 25. The antipode of this earthquake is in eastern Quebec at 49N 58W, an area where low-level seismicity occurs and may be promoted by energy concentrations from the Indian-Antarctic event today.

 

O: 21APR2018 19:44:20  49.1S  123.5E Mw=5.8  EMSC   WESTERN INDIAN-ANTARCTIC RIDGE

P: 18APR2018 116090    49.0S  122.0E 4.0-5.6 BAAAA  So. of Australia           

P: 25APR2018 116375    49.0S  122.0E 4.0-5.5 BAAAA  So. of Australia           

 

Seismicity in Hawaii was up today in concurrence with the geomagnetic storm which probably helped promote it. Two earthquakes of M>=3 were recorded in the region, an M of M 3.0 and 3.1 and were felt lightly in Hawaii at Kula, Wailuku and Lahaina. The largest of these of M 3.1 occurred within about an hour of local solar midnight and may also have been promoted by tidal stresses. Geomagnetic effects had been anticipated in this summary in previous issues as:

 

 

"The geomagnetic field saw minor storm conditions today. The AP level was 47. High latitude geomagnetic field was also stormy with AP at 56. KP levels at high latitude reached 7 mid-day on April 20. It is likely this was triggered by an undetected CME from the sun. This is the most active the geomagnetic field has been since it reached AP 47 on November 8, 2017 with high latitude AP 82. This could launch a new round of increased seismicity beginning April 21 with most likely strong quakes near the geomagnetic equator and at high latitudes around April 24-27,  but this may change depending on how long the storm lasts (it is not expected to be a long-lived event)." (April 20-21, 2018)

 

O: 22APR2018 09:21:02  19.5N  155.9W ml=3.1  ANSS   NNW of Honaunau-Napoopoo Hawai

P: 22APR2018 116142    19.9N  156.1W 3.0-4.5 AAAAA  Hawaii                     

 

O: 22APR2018 02:57:40  19.5N  156.4W ML=3.0  EMSC   HAWAII REGION, HAWAII        

P: 22APR2018 116142    19.9N  156.1W 3.0-4.5 AAAAA  Hawaii                     

 

An earthquake of M 4.0 occurred far off the Oregon coast today and may have been felt lightly in the areas of Neskowin and Nehalem, Oregon and possibly at Redding, California. This regional activation may have been promoted by an earthquake of M 6.0 south of Africa near the antipode on April 19 as noted in this summary at the time:

 

"  ... The antipode (of the Prince Edward Islands M 6.0) at 42 N 138W is off the coast of Oregon in an aseismic region, but regional seismicity off Oregon could follow." (April 20, 2018)

 

The last earthquake of M>=4.0 within about 150 km of this epicenter was an M 4.0

on March 16, 2018. A larger quake hit the area with M 5.5 on January 28, 2018. Forecast 116273 had expected today's event within about 25 km of the epicenter was likely around April 22.

 

O: 21APR2018 09:50:08  44.0N  128.6W mb=4.0  EMSC   OFF COAST OF OREGON           

P: 22APR2018 116273    44.1N  128.8W 3.0-4.6 AAAAA  Off Coast of Oregon        

 

The strongest earthquake in the U.S. or Canada today was an M 4.7 in the Unimak Island area of Alaska. It was not reported felt in this remote area. Two earthquakes in the region occurred to the east of this with M 4.5-4.6 on April 16 and 19, but the only events of larger size in the past half year were in late February, 2018 with M 4.8 and 5.1. Forecast 116305 expected today's event was likely around April 22. As the quake occurred within about 30 minutes of local solar noon, it is likely it was promoted by high tidal stresses which maximize at this hour.

 

O: 21APR2018 22:31:26  53.9N  164.0W mb=4.7  EMSC   UNIMAK ISLAND REGION, ALASKA 

P: 22APR2018 116305    54.5N  163.5W 3.5-4.9 AAAAA  Unimak Islands, Aleutians  

 

The strongest earthquake in California today was an M 3.3 in central California west of Parkfield. NEIC reported this earthquake of M 3.3 in Central California was felt with intensity II-III in the area(s) of San Ardo and King City, California.  This area often sees enhanced seismicity during and following strong geomagnetic storms. The last event of M>=3.3 within about 50 km of this epicenter occurred on August 12, 2017 (M 3.4) and prior to that an M 3.5 on April 13, 2017.  Forecast 115931 had expected an event in this ara around April 19.

 

O: 22APR2018 05:23:27  36.2N  120.8W ML=3.3  EMSC   CENTRAL CALIFORNIA           

P: 19APR2018 115931    36.1N  120.1W 2.5-5.0 BAAAA  Central California         

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: 21APR2018 22:41:14  18.4N   96.2E mb=4.7  EMSC   MYANMAR                       

P: 20APR2018 115876    19.0N   96.0E 4.0-5.4 AAAAA  Andaman Islands            

 

O: 21APR2018 10:56:54  23.0N  121.8E ML=4.4  EMSC   TAIWAN                       

O: 21APR2018 10:56:54  23.0N  121.7E ML=4.4  TAI    Hualien, Taiwan               

P: 23APR2018 116175    23.0N  121.0E 4.0-5.5 AAAAA  Taiwan                     

 

CWB reported this earthquake was felt with intensity III in Taitung and I in Hualien, Yunlin, Changhua and Taichung Counties, Taiwan.

 

O: 22APR2018 01:12:25  27.7N   53.5E mb=4.5  EMSC   SOUTHERN IRAN                

P: 22APR2018 116173    28.0N   52.0E 3.5-4.9 AAAAA  So. Iran/Persian Gulf      

 

NEIC reported this earthquake of M 4.5 in Iran was felt with intensity IV in the area(s) of Gerash, Fars, Iran.

 

O: 22APR2018 07:42:22  27.9N   67.3E mb=4.5  EMSC   PAKISTAN                     

P: 16APR2018 115916    29.0N   68.0E 3.5-5.1 CBAAA  Pakistan                   

 

O: 21APR2018 20:03:55  31.2N   56.4E mb=4.6  EMSC   CENTRAL IRAN                 

P: 24APR2018 116179    33.0N   60.0E 3.8-5.2 BBCAA  Afghanistan                

 

O: 21APR2018 14:18:12  33.7N   45.6E ML=3.7  EMSC   IRAN-IRAQ BORDER REGION      

P: 23APR2018 116232    33.0N   46.0E 3.8-5.6 AAAAA  So. Iran                   

 

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

 

INDONESIA AND PHILIPPINES

 

O: 22APR2018 05:46:05   0.5S  125.9E mb=4.2  EMSC   MOLUCCA SEA                  

P: 22APR2018 116105     0.0N  124.0E 4.0-5.6 AABAA  Mindanao, Philippines      

 

O: 21APR2018 15:16:48   1.7N   96.5E mb=4.6  EMSC   NIAS REGION, INDONESIA       

O: 21APR2018 15:16:48  01.8N  096.4E MS=5.1  BMG  Felt with intensity II in Simeulue, Aceh, Indonesia.

P: 18APR2018 115852     2.0N   98.0E 4.0-5.6 BABAA  So. Sumatera               

 

O: 21APR2018 16:16:48 01.8N 096.4E MS=5.1  BMG reported this earthquake was felt with intensity II in Simeulue, Aceh, Indonesia.

 

O: 22APR2018 02:55:23   2.2S  120.6E ML=4.6  EMSC   SULAWESI, INDONESIA          

O: 22APR2018 02:55:23  02.2S  120.6E MS=4.6  BMG  Felt with intensity II in Kolonodale, Sulawesi, TimorSimeulue, Aceh, Indonesia.

P: 29APR2018 116128     1.0S  120.0E 4.0-5.5 CBAAA  Sulawesi area              

 

O: 22APR2018 02:55:23 02.2S 120.6E MS=4.6  BMG reported this earthquake was felt with intensity II in Kolonodale, Sulawesi, TimorSimeulue, Aceh, Indonesia.

 

O: 22APR2018 00:31:50   2.8S  139.1E mb=4.7  EMSC   NEAR N COAST OF PAPUA, INDONES

P: 17APR2018 115874     2.0S  138.0E 4.0-5.5 BAAAA  West Irian, PNG            

P: 22APR2018 116122     4.0S  140.0E 4.0-5.6 ABAAA  Papua New Guinea           

 

O: 21APR2018 11:36:33   3.4S  101.6E mb=4.6  EMSC   SOUTHERN SUMATRA, INDONESIA  

O: 21APR2018 11:36:32  03.3S  101.7E MS=4.7  BMG  Felt with intensity II-III in Bengkulu Kota and II in Kepahiang, Bengkulu, Indonesia.

P: 19APR2018 115870     4.0S  102.0E 4.0-5.4 AAAAA  So. of Sumatera            

 

O: 21APR2018 12:36:32 03.3S 101.7E MS=4.7  BMG reported this earthquake was felt with intensity II-III in Bengkulu Kota and II in Kepahiang, Bengkulu, Indonesia.

 

O: 21APR2018 09:20:34   3.4S  147.0E mb=4.4  EMSC   BISMARCK SEA                 

P: 25APR2018 116117     3.0S  146.0E 4.0-5.6 BAAAA  New Ireland                

P: 25APR2018 116117     5.0S  147.0E 4.0-5.8 BBAAA  New Ireland                

 

O: 22APR2018 02:29:26   4.7N  127.6E mb=5.1  EMSC   KEPULAUAN TALAUD, INDONESIA  

P: 22APR2018 116104     4.0N  129.0E 4.0-5.6 AABAA  Halmahera                  

 

O: 21APR2018 11:19:40   7.2S  109.7E ML=3.4  EMSC   JAVA, INDONESIA              

O: 21APR2018 11:19:40  07.2S  109.6E MS=3.4  BMG  Felt with intensity II-III in Kalibening and Karangkobar, Java, Indonesia.

P: 24APR2018 116125     7.0S  107.0E 4.0-5.4 BACAA  So. of Java                

 

BMG reported this earthquake was felt with intensity II-III in Kalibening and Karangkobar, Java, Indonesia.

 

O: 21APR2018 05:06:47   7.4S  126.7E Mw=5.0  EMSC   KEPULAUAN BARAT DAYA, INDONESI

P: 28APR2018 116108     8.0S  127.0E 4.0-5.7 CAAAA  Banda Sea                  

 

O: 22APR2018 02:07:38  20.8N  145.1E mb=4.6  EMSC   MAUG ISLANDS REG, N. MARIANA I

P: 29APR2018 116177    22.0N  145.0E 4.0-5.7 CBAAA  Volcano Islands            

 

 

CENTRAL AND SOUTH AMERICA

 

O: 21APR2018 07:52     27.5S   69.3W mb=4.6  GUC    Copiapo, Tierra Amarilla, Felt

P: 24APR2018 116342    27.0S   63.0W 4.0-5.6 BAAAA  Argentina                  

 

CSN reported this earthquake was felt with intensity  III in  Copiapo, Tierra Amarilla, Felt in Atacama, Chile.

 

O: 21APR2018 09:16:00   8.9S   74.4W mb=4.2  EMSC   CENTRAL PERU                  

P: 17APR2018 116049    10.0S   75.0W 3.5-5.3 BBAAA  Brazil                     

 

O: 21APR2018 11:14:51  14.4N   90.3W mb=4.4  EMSC   GUATEMALA                    

P: 18APR2018 115885    15.0N   91.0W 3.5-5.3 BAAAA  Guatemala                  

 

O: 21APR2018 11:46:37  15.0N   94.4W ML=4.0  EMSC   OFF COAST OF CHIAPAS, MEXICO 

P: 20APR2018 115880    14.0N   94.0W 3.5-5.1 AAAAA  Chiapas, Mexico            

 

O: 21APR2018 19:26:59  15.6N   95.0W ML=4.0  EMSC   OFFSHORE OAXACA, MEXICO      

O: 21APR2018 11:46:37  15.0N   94.4W ML=4.0  UNAM  al SUROESTE de TONALA, CHIS *: 15.

O: 01APR2018 05:38:48  16.6N   95.0W ML=3.6  UNAM  l NORESTE de CD IXTEPEC, OAX *: 16

O: 21APR2018 19:26:59  15.5N   95.0W ML=4.0  UNAM  l SUR de SALINA CRUZ, OAX *: 15.57

O: 21APR2018 07:19:47  16.4N   95.1W ML=4.0  UNAM  l OESTE de JUCHITAN DE ZARAGOZA, O

O: 22APR2018 08:01:03  16.5N   95.9W ML=4.0  UNAM  l ESTE de MIAHUATLAN, OAX *: 16.5°

O: 22APR2018 08:01:03  16.5N   95.9W ML=4.0  EMSC   OAXACA, MEXICO               

P: 22APR2018 116136    16.0N   95.0W 3.5-5.2 AAAAA  Chiapas, Mexico            

 

O: 21APR2018 06:00:34  18.7N   68.7W Md=3.0  EMSC   DOMINICAN REPUBLIC           

P: 24APR2018 116155    18.0N   69.0W 3.4-5.1 BAAAA  Puerto Rico                

 

O: 21APR2018 10:10:14  23.4S   67.0W mb=4.3  EMSC   JUJUY, ARGENTINA             

P: 24APR2018 116341    22.0S   67.0W 4.0-5.4 BAAAA  Argentina                  

 

O: 21APR2018 07:52:53  27.3S   69.1W Mw=4.6  EMSC   ATACAMA, CHILE               

P: 24APR2018 116344    28.0S   69.0W 4.0-5.6 BAAAA  Coast Central Chile        

 

O: 21APR2018 21:06:17  31.6S   71.8W ML=4.0  EMSC   OFFSHORE COQUIMBO, CHILE     

P: 17APR2018 116076    33.0S   72.0W 4.0-5.4 BAAAA  Central Chile              

 

O: 21APR2018 07:31:33  38.8S   73.7W Mw=4.5  EMSC   OFFSHORE ARAUCANIA, CHILE    

P: 23APR2018 116357    36.0S   73.0W 4.0-5.6 ACAAA  Central Chile              

 

 

O: 21APR2018 09:22:02  18.2N  101.5W ML=4.0  UNAM  l NORTE de ZIHUATANEJO, GRO *:

P: 24APR2018 116147    18.0N  101.0W 3.5-5.4 BAAAA  Michoacan, Mexico          

 

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

 

AFRICA AND EUROPE

 

O: 22APR2018 08:18:04  40.3N   40.9E ML=3.2  EMSC   EASTERN TURKEY               

P: 26APR2018 116242    39.0N   41.0E 3.5-4.9 BBAAA  Turkey                     

 

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

 

SOUTHWEST PACIFIC

 

O: 21APR2018 18:07:11  11.8S  165.3E mb=4.7  EMSC   SANTA CRUZ ISLANDS           

P: 25APR2018 116339    11.0S  167.0E 4.0-5.6 BABAA  Vanuatu Islands            

 

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

 

OCEAN RIDGES

 

O: 21APR2018 19:44:20  49.1S  123.5E Mw=5.8  EMSC   WESTERN INDIAN-ANTARCTIC RIDGE

P: 18APR2018 116090    49.0S  122.0E 4.0-5.6 BAAAA  So. of Australia           

P: 25APR2018 116375    49.0S  122.0E 4.0-5.5 BAAAA  So. of Australia           

 

 

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

 

O: 21APR2018 17:01:56  26.4N  141.5E mb=5.0  EMSC   BONIN ISLANDS, JAPAN REGION  

P: 20APR2018 115906    26.0N  143.0E 4.0-5.6 AAAAA  Bonin Islands               

 

O: 22APR2018 07:56:30  34.7N  140.7E mb=4.3  EMSC   NEAR EAST COAST OF HONSHU, JAP

O: 21APR2018 09:47:16  35.5N  141.0E Mw=5.0  EMSC   NEAR EAST COAST OF HONSHU, JAP

P: 15APR2018 115952    35.0N  140.0E 4.0-5.4 CAAAA  Off East Coast Honshu       

 

NEIC reported this earthquake of M 5.0 east of Tokyo, Japan  was felt with intensity IV in Katsuura, Chiab, Japan and intensity II-III in the prefectures of Chiba, Ibaraki, Tokyo, Saitama, Kanagawa and Shizuoka, Japan.

 

U.S./CANADA*

 

WESTERN U.S./CANADA

 

CALIFORNIA

 

O: 21APR2018 14:05:39  34.2N  117.2W ML=2.3  EMSC   GREATER LOS ANGELES AREA, CALI

P: 25APR2018 116225    34.1N  117.4W 2.5-5.0 BAAAA  So. California             

 

O: 22APR2018 05:23:27  36.2N  120.8W ML=3.3  EMSC   CENTRAL CALIFORNIA            

P: 19APR2018 115931    36.1N  120.1W 2.5-5.0 BAAAA  Central California         

 

NEIC reported this earthquake of M 3.3 in Central California was felt with intensity II-III in the area(s) of San Ardo and King City, California.

 

O: 22APR2018 02:09:19  36.5N  121.1W MD=2.0  EMSC   CENTRAL CALIFORNIA           

P: 25APR2018 116188    36.8N  121.3W 2.5-4.8 BAAAA  Central California         

 

O: 22APR2018 03:37:08  37.5N  121.3W MD=2.2  EMSC   NORTHERN CALIFORNIA          

P: 24APR2018 116189    37.3N  121.6W 2.5-4.8 AAAAA  Central California         

 

O: 21APR2018 18:54:19  38.8N  122.8W MD=2.5  EMSC   NORTHERN CALIFORNIA          

O: 21APR2018 22:36:55  38.8N  122.8W ML=3.2  EMSC   NORTHERN CALIFORNIA          

P: 16APR2018 115935    38.7N  122.7W 2.5-4.4 BAAAA  Central California         

 

NEIC reported this earthquake of M 3.2 in Northern California was felt with intensity II-III in the area(s) of Kelseyville, Glenhaven California.

 

 

ALASKA

 

O: 21APR2018 22:31:26  53.9N  164.0W mb=4.7  EMSC   UNIMAK ISLAND REGION, ALASKA 

P: 22APR2018 116305    54.5N  163.5W 3.5-4.9 AAAAA  Unimak Islands, Aleutians  

 

O: 21APR2018 13:31:01  55.6N  149.2W ML=3.5  EMSC   GULF OF ALASKA               

O: 21APR2018 19:31:36  56.2N  149.4W ML=3.3  EMSC   GULF OF ALASKA               

O: 21APR2018 17:04:56  56.2N  149.4W mb=4.1  EMSC   GULF OF ALASKA               

P: 18APR2018 116011    56.0N  148.9W 3.5-5.0 AAAAA  Gulf of Alaska             

 

O: 22APR2018 06:12:45  56.2N  155.7W ML=3.4  EMSC   ALASKA PENINSULA             

O: 22APR2018 02:59:15  57.6N  155.3W ML=3.3  EMSC   ALASKA PENINSULA             

P: 21APR2018 116012    54.8N  158.7W 3.5-5.1 ACBAA  Alaska Peninsula           

 

O: 22APR2018 06:17:45  59.8N  153.2W ML=3.0  EMSC   SOUTHERN ALASKA               

O: 22APR2018 03:06:48  60.3N  153.0W Ml=3.4  EMSC   SOUTHERN ALASKA              

P: 24APR2018 116309    60.3N  153.0W 3.2-5.3 AAAAA  Central Alaska             

 

 

No events of M>=3 were located in Alaska today.

 

PACIFIC NORTHWESTERN U.S./WESTERN CANADA

 

O: 21APR2018 09:50:08  44.0N  128.6W mb=4.0  EMSC   OFF COAST OF OREGON          

P: 22APR2018 116273    44.1N  128.8W 3.0-4.6 AAAAA  Off Coast of Oregon        

 

O: 21APR2018 07:07:28  60.9N  138.3W mb=3.7  EMSC   SOUTHERN YUKON TERRITORY, CANA

P: 23APR2018 116307    61.0N  138.0W 3.2-4.9 AAAAA  Central Alaska             

 

ROCKY MOUNTAINS REGION

 

No earthquakes of M>=2 were located in the Rocky Mountain region today.

 

EASTERN U.S./CANADA

 

O: 21APR2018 11:42:37  34.4N   88.0W MD=2.3  EMSC   ALABAMA                      

P: 22APR2018 116203    35.0N   89.0W 2.0-4.2 AAAAA  New Madrid area            

 

O: 21APR2018 23:16:23  36.1N   89.7W MD=2.3  EMSC   SOUTHEASTERN MISSOURI        

P: 22APR2018 116203    36.0N   89.0W 2.0-3.9 AAAAA  New Madrid area            

 

O: 21APR2018 14:26:01  36.1N   97.3W mb=3.0  EMSC   OKLAHOMA                     

P: 23APR2018 116236    37.0N   97.0W 2.0-4.3 AAAAA  Southern Plains            

P: 24APR2018 116237    36.0N   97.0W 2.0-3.9 BAAAA  Southern Plains             

 

NEIC reported this earthquake of M 3.0 in Oklahoma was felt with intensity II-III in the area(s) of Stillwater and Crescent, Oklahoma.

 

HAWAII

 

O: 22APR2018 02:57:40  19.5N  156.4W ML=3.0  EMSC   HAWAII REGION, HAWAII        

P: 22APR2018 116142    19.9N  156.1W 3.0-4.5 AAAAA  Hawaii                     

 

O: 21APR2018 13:34:42  20.8N  156.4W MD=2.7  EMSC   MAUI REGION, HAWAII          

P: 26APR2018 116164    20.3N  156.6W 4.0-5.7 BAAAA  Hawaii area                

 

O: 22APR2018 09:21:02  19.5N  155.9W ml=3.1  ANSS   NNW of Honaunau-Napoopoo Hawai

P: 22APR2018 116142    19.9N  156.1W 3.0-4.5 AAAAA  Hawaii