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