Posted by Lowell on October 16, 2001 at 14:19:23:
VERY UNUSUAL EARTHQUAKE (MS 5.6) OCCURS IN VIRGIN ISLANDS, CARIBBEAN SUMMARY A highly unusual earthquake occurred this morning in the Virgin Islands, Caribbean with Ms 5.6 (NEIS) shortly after a Mb 4.5 had occurred north of the Dominican Republic. The last two events of M>=5.5 within 100 km of this epicenter were on June 26, 1985 (Ms 5.6) and June 12, 1965 (Ms 5.5). Since 1900, 10 earthquakes of Ms>=5.5 have been recorded in the Virgin Islands, about one every 10 years. While no tsunami is likely with this event, destuctive tsunamis in the north and eastern Caribbean occur on average with interevent times of about 23 yeasrs with a standard deviation of 15 years. The last destructive tsunami in the region occurred on August 8, 1946 more than 55 years ago. A deadly tsunami in the region, therefore is way overdue as is a great earthquake. The region has become a highly popular tourist area since the last destructive earthquake or tsunami with a great deal of near-shore development. This is the second moderate earthquake in the northern Caribbean subduction zone near the Virgin Islands in the past three years - the other occurred on Dec. 8, 1998 (Ms 5.6). This may indicate regional activation prior to a strong or great earthquake. This is an area which should be carefully observed for warning signs. This earthquake may be a Far-Field Aftershock (FFA) from the Guam and Kamchatka events. A Mb 4.4 occurred two days ago in the Leeward Islands as well. Both forecasts had indicated that the region of the eastern Caribbean was likely to see FFA. This epicenter is 99 degrees from Kamchatka, 142 from Guam. From the Guam aftershock forecast: "142-146 degrees: ... Windward Islands" The Virgin Islands lie north of the Windward Islands. and from the Kamchatka FFA forecast: "103-106 degrees***: ... Leeward Islands, Puerto Rico" The Virgin Islands lie between the Leeward Islands and Puerto Rico. HURRICANE EFFECTS? These events may also be related to delayed triggering from Hurricane Jerry which passed over the region on 9 October. The report on the 9th of October had said: " Tropical Storm Jerry is hitting the Windward/Leeward Islands in the Caribbean today. It is expected to track northwestward south of Puerto Rico, Hispaniola and Cuba becoming a category 1 hurricane on Tuesday. Related seismicity is likely to be relatively minor because the path follows directly on Hurricane Iris, and Jerry is expected to be the weaker of the two storms. For trackline data see: http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200112.html " and on October 8, this report had said: "A new tropical depression (twelve) is following behind Iris by about 3-4 days. Current projections suggest it will follow approximately the same path through the Caribbean as Iris. This storm should hit the Windward/Leeward Islands on Monday. The effect on local seismicity is not expected to be great, however some activity is likely along the Antilles arc. This storm will push the Caribbean plate to the west, relieving some normal stress between this plate and the North American plate along the Antilles subduction zone. Watch for seismic activity at about 14N 60W in the Leeward Island or Puerto Rico at 18N 68W over the next three days or seismicity or related volcanism near Guadeloupe (17N 61W) around the 11th of October. Volcanism generally takes several days to manifest after hurricane passage." The three earthquakes of Mb>=4.4 in the area had parameters of: 13Oct2001 16:15:29 17.1N 60.3W MB=4.4 NEIS LEEWARD ISLANDS and 16Oct2001 15:27:27 19.3N 64.9W MS=5.6 NEIS VIRGIN ISLANDS and 16OCT2001 08:05:33 19.9N 69.2W MB=4.5 NEIS DOMINICAN REPUBLIC REGION GLOBAL The largest earthquake around the world today was the Ms 5.6 in the Virgin Islands. This is discussed in the summary above. Ocean ridges continued active with two events in the northern Mid-Atlantic ridge (Mb 4.8 and 4.5) and the Easter Islands (Mb 5.2). Two moderate earthquakes also occurred near Valparaiso Chile (Mb 4.9, 4.5). Other earthquakes of Mb>=4.5 occurred in the Vanuatu Islands (Mb 4.5); southern Sumatera (Mb 4.7) and the Alaska Peninsula (Mb 4.5). U.S./CANADA The largest earthquake registered in the U.S./Canada region today was a Mb 4.9-5.1 in the Unimak/Alaska Peninsula region. This followed a small foreshock in the area of Ml 3.8 yesterday. This was probably a FFT from Guam as it lies at the same distance from that event as the Ml 5.8 on North Island, N.Z. did (59.9 degrees), a distance at which FFTs are expected. The forecast had stated: "59-61 degrees: Alaska Peninsula (Unimak area)," In the contiguous 48-states, the largest event was an Ml>3 earthquake off the coast of Oregon at about 43N 129W. Events in this region are not well located or parameterized by local networks as they fall outside the net of seismometers. PNSN gives this event Ml 2.8, but it is likely 1.0+ units of magnitude higher based on past recordings from PNSN compared with subsequent NEIS data for the area off the coast of Oregon. It was another quiet day in the California/Nevada region. Two events of Ml>=2 were recorded in the Pinnacles, CA area last night (Ml 2.8, 2.5) and a Ml 2.2 near Cloverdale also occurred. SCSN is reporting events of MC>=2 at Ventura (Mc 2.1); Ocotillo (Mc 2.3); Baker (Mc 2.2); Twenty-nine Palms (Mc 2.0) and Coso Junction (Mc 2.0) today. Minor swarms are in progress in two areas of Montana/Wyoming today. These are occurring in the Norris Junction area of Yellowstone N.P. and in northwestern Montana. Several events of Ml>=2 have accompanied these swarms. For current Montana data see: http://mbmgquake.mtech.edu/earthworm/cgi-bin/getlist?ClickEffect=4&StationClickE ffect=4&MapName=Montana&LastDaysOnly=0&Start_Date=2001/09/06&Start_Time=02:45:45 &Lat=47.00&Lon=-110.00&LonWidth=14.00&LatHeight=9.00&&MaxZ=100.00&MinZ=0.00&MaxM ag=10.00&MinMag=0.00&Start_Date=2001/09/06&Start_Time=02:45:45&Finish_Date=2050/ 12/31&Finish_Time=23:59:59 For Utah/Yellowstone data see: http://www.quake.utah.edu/req2webdir/recenteqs/Quakes/quakes0.html An unusual earthquake occurred on October 14 in Saskatchewan, Canada. This event was felt WNW of Saskatoon, SK. This is the largest earthquake recorded within 100 km of this epicenter since July 21, 1987 (Ml 2.7) and one of only four ever recorded in the area of Ml>=2.5. The others occurred on Nov. 8, 1993 (Ml 2.5) and April 6, 1995 (Ml 2.9). NEW ZEALAND IGNS did not report any earthquakes today. The swarm which followed the Guam and Kamchatka events appears to have diminished. Five minor regional earthquakes could be found on the on-line seismometer. The IGNS on-line Seismometer can be found at: http://www.gns.cri.nz/news/earthquakes/latest_drum.html GEOMAGNETIC/SOLAR FIELDS The geomagnetic field remained at relatively quiet conditions today. There were not X- or M- class flares observed on the sun today. SEC expects the field to remain quiet for the next three days. Flare # START MAX END CLASS For general space weather conditions see: http://sec.noaa.gov/today.html For Solar flare data see: http://sec.noaa.gov/ftpdir/indices/events/20011016events.txt TROPICAL STORMS Tropical Storms Karen and Manuel are no longer threats to North America. Little to no associated seismicity is expected with either of these storms. For tracking information on Karen see: http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200113.html
For tracking information on Manuel see: http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/ep200115.html Typhoon Haiyan has reversed course and will not make landfall in Taiwan or Asia as previously expected. Haiyan is now moving NE away from Taiwan. Associated seismicity is no longer expected. in the region of Taiwan, however some activity may occur in the Ryukyu Islands between now and October 18. For a trackline map (in Chinese see): http://www.cwb.gov.tw/V3.0e/index-e.htm TIDAL TRIGGERING (LUNAR)
Statistics have been done on many regions of the world in terms of relationship of significant regional earthquakes with respect to lunar cycle. Each report will summarize the most likely areas for tidal triggering for the next day based on these statistics. It is expected that tidal triggering will add an additional 0.5 - 1.0 units of magnitude to events which are about to occur or will move these events forward in time by up to seven days in the regions where there is a statistical correlation between lunar phase and earthquakes. October 17 is one day after the beginning the lunar month. Regions most likely to experience tidal triggering on this day (With associated magnitude ranges; the percent change in seismicity rate over background seismicity rate on this day of the lunar month; statistical z-value and significance level) are: Region Magnitude range %change z-value Significance level Caucasus MB>=4.0 18 2.3 0.04 Idaho MB>=1.0 20 2.6 0.03 Italy MB>=4.0 43 2.8 0.02 Kuriles MB>=4.0 34 2.9 0.01 Tonga MB>=4.0 27 1.9 0.05 Mammoth Lakes MB>=0.0 46 2.0 0.05 Mammoth Lakes MB>=2.0 37 1.9 0.05 Regions expected to experience reverse triggering (i.e. they are unlikely to experience a significant event at this period of the lunar cycle) are:
Region Magnitude range %change z-value Significance level Central America MB>=4.0 -10 -2.0 0.05 Canada MB>=0.0 -29 -2.5 0.03 So. Alaska MB>=3.0 -7 -2.2 0.05 EARTHQUAKE LISTINGS
GLOBAL CARIBBEAN O: 16OCT2001 15:27:27 19.3N 64.8W MB=5.5 NEIS VIRGIN ISLANDS O: 16OCT2001 15:27:32 20.3N 64.9W Ms=5.3 GSSC NORTH ATLANTIC OCEAN O: 16OCT2001 08:05:33 19.9N 69.2W MB=4.5 NEIS DOMINICAN REPUBLIC REGION OCEANIA O: 15OCT2001 13:42:57 47.8N 27.7W MB=4.5 NEIS NORTHERN MID-ATLANTIC RIDGE O: 16OCT2001 05:43:31 47.8N 27.6W MB=4.8 NEIS NORTHERN MID-ATLANTIC RIDGE SOUTH PACIFIC ISLANDS O: 15OCT2001 16:13:33 14.7S 167.5E MB=4.9 NEIS VANUATU ISLANDS AUSTRALIA O: 13OCT2001 04:42 36.8S 147.7E Ml=3.9 MEL Victoria, Australia Note (MEL): This is the largest earthquake to occur in Victoria this year, its epicentre about 35 kilometres north of Omeo in northeast Victoria. ASIA O: 13OCT2001 04:25 33.9N 141.7E Mj=3.7 NIED FAR_SE_OFF_BOSO_PEN, JAPAN O: 12OCT2001 20:58 29.2N 130.0E Mj=3.9 NIED NEAR_AMAMI-OSHIMA_ISLAND, JAPAN O: 15OCT2001 05:00:40 45.4N 147.6E MB=4.5 NEIS KURIL ISLANDS O: 15OCT2001 05:00:51 46.0N 146.4E Mb=4.7 MIX NW. KURIL ISLANDS, RU O: 15OCT2001 05:00:37 45.2N 147.8E M =4.5 GSSC KURIL ISLANDS, RUSSIA O: 16OCT2001 15:49:21 43.3N 139.3E Ms=4.6 GSSC EASTERN SEA OF JAPAN O: 16OCT2001 16:37:06 48.3N 155.2E MB=4.6 NEIS KURIL ISLANDS O: 16OCT2001 16:37:16 49.2N 155.7E Ms=4.7 GSSC KURIL ISLANDS, RUSSIA O: 16OCT2001 04:46:29 0.0S 98.4E MB=4.7 NEIS SOUTHERN SUMATERA, INDONESIA CENTRAL/SOUTH AMERICA O: 16OCT2001 02:00:09 12.2N 88.3W MC=3.9 SIS OFF COAST CENTRAL AMERICA O: 15OCT2001 13:07:53 33.1S 71.8W MB=4.5 NEIS NEAR COAST OF CENTRAL CHILE O: 15OCT2001 15:19:50 33.1S 71.8W MB=4.9 NEIS NEAR COAST OF CENTRAL CHILE O: 15OCT2001 13:07:53 33.1S 72.1W ML=4.8 DGF W of VALPARAISO, CHILE O: 15OCT2001 15:19:49 33.1S 72.2W ML=4.8 DGF W of VALPARAISO, CHILE O: 14OCT2001 18:38 10.5S 78.4W ML=4.5 IGP Huarmey, Peru EUROPE O: 15OCT2001 17:30:33 43.2N 1.0W ML=2.0 STR WNW ARAMITS(64) O: 16OCT2001 04:18:31 45.2N 6.4E M =3.4 LDGM FRANCE O: 16OCT2001 04:18:31 45.1N 6.4E ML=3.1 STR S SAINT-JEAN-DE-MAURIENNE O: 14OCT2001 23:18:32 38.4N 25.4E ML=3.6 NOA AEGEAN SEA, GREECE O: 15OCT2001 03:53: 6 38.6N 25.8E ML=3.6 NOA AEGEAN SEA, GREECE O: 15OCT2001 08:51:10 36.0N 21.9E ML=4.6 NOA SO. GREECE O: 15OCT2001 08:51:09 36.1N 21.9E Ms=3.6 GSSC SOUTHERN GREECE O: 15OCT2001 08:51:08 36.3N 22.4E Mb=4.3 MIX SOUTHERN GREECE U.S/CANADA CALIFORNIA/NEVADA O: 16OCT2001 00:02:04 34.3N 119.2W MC=2.1 SCSN NNE of Ventura, CA O: 16OCT2001 2:12:27 38.9N 123.2W ML=2.2 NCSN NW of Cloverdale, CA O: 16OCT2001 1:06:34 36.5N 121.0W ML=2.5 NCSN ENE of Pinnacles, CA O: 15OCT2001 23:46:41 36.6N 121.0W ML=2.8 NCSN ENE of Pinnacles, CA O: 15OCT2001 23:56:36 37.3N 121.7W ML=1.5 NCSN E of San Jose City Hall, CA O: 16OCT2001 01:25:05 32.6N 116.2W ML=2.1 SCSN WSW of Ocotillo, CA O: 16OCT2001 04:51:33 34.8N 116.3W MC=2.2 SCSN SSW of Baker, CA O: 16OCT2001 14:23:32 34.3N 116.1W MC=2.0 SCSN NNW of Twentynine Palms, CA O: 16OCT2001 18:11:13 36.0N 117.8W MC=2.0 SCSN NE of Coso Junction, CA PACIFIC NORTHWEST/CANADA
O: 16OCT2001 5:14:23 42.9N 129.5W ML>2.8 PNSN OFF COAST OF OREGON O: 16OCT2001 14:32:18 47.5N 120.7W ML=1.2 PNSN W of Wenatchee, Wa O: 14OCT2001 09:35:36 52.2N 106.9W ML=2.6 FELT WNW Saskatoon SK ROCKY MOUNTAIN AREA O: 10OCT2001 01:29:11 47.2N 112.6W ML=1.8 MBMG SW of Augusta, MT O: 10OCT2001 10:05:36 45.7N 112.1W ML=1.9 MBMG S of Whitehall, MT O: 11OCT2001 03:18:56 45.7N 112.1W ML=1.3 MBMG S of Whitehall, MT O: 11OCT2001 04:33:28 45.7N 112.1W ML=2.5 MBMG S of Whitehall; Felt, MT O: 11OCT2001 10:32:56 45.7N 112.1W ML=1.2 MBMG S of Whitehall, MT O: 11OCT2001 11:35:44 45.6N 112.1W ML=1.4 MBMG S of Whitehall, MT O: 12OCT2001 06:12:32 45.7N 112.1W ML=1.0 MBMG S of Whitehall, MT O: 15OCT2001 3:43:42 44.8N 110.8W ML=2.0 UUSN WNW of Norris Junc., WY O: 15OCT2001 3:26:48 44.8N 110.8W ML=1.9 UUSN W of Norris Junc., WY O: 15OCT2001 3:20:58 44.7N 110.8W ML=1.4 UUSN W of Norris Junc., WY O: 15OCT2001 3:16:14 44.8N 110.8W ML=1.0 UUSN WNW of Norris Junc., WY O: 14OCT2001 20:41:54 44.8N 110.8W ML=1.2 UUSN NW of Norris Junc., WY O: 15OCT2001 9:08:07 44.8N 110.8W ML=1.3 UUSN NW of Norris Junc., WY O: 15OCT2001 9:08:07 44.8N 110.8W ML=1.3 UUSN NW of Norris Junc., WY O: 11OCT2001 10:59:05 44.7N 110.7W ML=1.7 MBMG N-Central Yellowstone WY O: 11OCT2001 20:59:50 47.0N 113.0W ML=2.3 MBMG near Ovando, MT O: 12OCT2001 06:35:49 44.8N 112.8W ML=1.5 MBMG Red Rock Valley, MT ALASKA O: 15OCT2001 11:58:00 54.2N 162.2W MB=3.8 NEIS ALASKA PENINSULA O: 16OCT2001 06:17:53 53.8N 159.8W MB=4.9 NEIS SOUTH OF ALASKA O: 16OCT2001 06:17:57 54.5N 160.6W Mb=5.1 MIX ALASKA PENINSULA. O: 16OCT2001 06:17:53 54.0N 159.7W Ms=4.5 GSSC SOUTH OF ALASKA O: 16OCT2001 06:18:03 54.2N 160.7W ML=4.5 AEIC S of Sand Point, Alaska
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