SECOND MODERATE QUAKE HITS VANUATU IN AS MANY DAYS

SUMMARY

A second strong quake hit the Vanuatu region today. This event
in the northern Vanuatu Islands registered Ms 5.9-6.0 (NEIS) and was
well forecast by far-field triggering techniques. Yesterday a Ms 5.9
hit southern Vanuatu. Let us review the Far-field effects operating
on the epicenter of today's earthquake for a moment.
The event occurred at 107-108 degrees from the Central Chile
mainshock; at 44 degrees from the event south of Australia two
days ago and at 59 degrees from Taiwan. The corresponding FFA
forecasts had stated:

From Central Chile:

"103-106 degrees***: ... No. Vanuatu Is."

From Taiwan:

"59-61 degrees: NO. and Central Vanuatu,"

and

"The most likely events of Mw>=5 in the next 10 days appear to be:

Northern Vanuatu Islands"

and from South of Australia:

"43-45 degrees:.. Santa Cruz,"

GLOBAL

In other news from global earthquakes, two events were listed
in the South Sandwich Islands, another area where FFA were expected
(Ml 4.5 and 4.6). This was also a triple junction with effects from
three events - Central Chile (45 deg); Taiwan and Ryukyu (142 deg)
and South Australia (72 deg). A double junction occurred at 46 degrees
from the South Australian event and 145 from the Northern Chile mainshock
in the Aru Islands area, Indonesia where a Mb 4.7 occurred today.
A Mb 4.6 in Puerto Rico was also at 142 degrees from the South
Australian event, another FFA. In Iran another double junction
say an earthquake of Ml 4.5 in southern Iran (106 deg from So. Australia)
and 60 deg. from Taiwan. Near the Taiwan antipode a Mb 4.4 was
recorded in Argentina.
Last, but not least a Ml 4.8 occurred off the northern coast of
Honshu, a FFA from the northern Chile earthquake at a distance of
147 degrees.

Local networks also recorded a Ml 4.4 in Taiwan; a Ms 3.5 in
Kyrgyzstan, and earthquakes of 4.0 and 4.1 in Michoacan and
Oaxaca Mexico respectively and a Mb 3.9 in the northern Caucasus.

U.S./CANADA

The largest earthquake in the U.S./Canada region today occurred in
Alaska in the Fox Islands and was a FFA from the Ryukyu and Taiwan
earthquakes at 58 degrees from both. No other earthquakes of Ml>=3
were recorded in either Alaska or Hawaii today.

The strongest quake in the California/Nevada region occurred
in the Calexico swarm (again) with Ml 3.3. In northern California
a Ml 2.8 occurred in the Burney area near Tennant; a Ml 2.2 near
Fort Ross and a Ml 2.1 near Bishop. Other events of Ml>=2 in southern
California were listed at Panorama City (Ml 2.1); Joshua Tree (Ml 2.2)
and Calipatria north of Calexico (Ml 2.1).

Activity may begin to pick up along the Central San Andreas
and associated faults in the next several days. This is expected
to maximize around the 3rd week of April and the end of the first
week of May. A moderate event is possible in this time period
in the region from the Pinnacles to the area north of San Francisco.
The Los Angeles basin and the region near Simi Valley may also see
increased activity towards the end of the first week or the beginning
of the second week of May, 2002.

In the Rocky Mountain sector a Ml 2.7 was recorded tonight near
Redmond, Utah, the strongest in the Rockies in nearly a week.

No significant (Ml>2) events were located in the Pacific Northwest,
Canada or the eastern U.S. or Canada thus far in today's listings.

NEW ZEALAND

IGNS located two felt earthquakes on North Island today. The
largest of these occurred as a Ml 4.7 south of Tauranga (north of Taupo)
this afternoon and the other was a Ml 3.7 south of Hawke's Bay
near Porangahau about 45 minutes later.

The IGNS on-line Seismometer can be found at:
http://www.gns.cri.nz/news/earthquakes/latest_drum.html

GEOMAGNETIC/SOLAR FIELDS

The expected geomagnetic disturbance began about 15:00 UT, but
was short-lived, reintensifying later at about 21:00. A strong
gust of solar wind about 00:20 UT on 12 April temporarily reduced
the intensity of the Hp geomagnetic field sharply and increased
the intensity of the storm. The disturbance is still moderate
at this writing, however. If it should become stronger a seismic
alert will automatically go into effect for areas within 30 degrees
longitude of 180 E and 0 W.
There were no X- or M-class solar flares observed today.

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/20020411events.txt

TIDAL EFFECTS

April 13 is the first day after the beginning of the new 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

Lowell Whiteside
April 11, 2002

TOMORROW IN EARTHQUAKE HISTORY

GLOBAL:

The following events of Mw>=7 have occurred on this date in
recorded history:

MO DA HR MN SC YEAR LATIT LONGIT DEP MW LOCATION

4 12 0 22 13 1910 25.500 122.500 200 8.3 Ryukyu Islands
No damage was reported due to this great earthquake.

4 12 8 32 28 1926 -10.000 161.000 60 7.5 No. of Santa Cruz Islands
4 12 0 52 45 1962 38.200 142.500 50 7.5 Off East Coast Honshu
4 12 4 1 44 1970 15.100 122.100 24 7.2 Luzon, Philippines
An aftershock of the strong tremor on April 7 which shook Luzon.
This event was North of Polilio Island. Maximum felt intensity V.

4 12 23 19 56 1988 -17.192 -72.305 33 7.0 So. Peru/Bolivia
Felt at Arequipa. Also felt in the Ica area and at Arica, Chile.

U.S./CANADA

Following are events of Mb>=5 which have occurred in this region on
this date.

4 12 4 5 0 1885 36.500 -121.000 0 6.2 Central California
This event was strong at Marinez, Santa Rosa, Healdsburg
and may have originated on the San Andreas. In the thinly settled
region east of King City, Monterey county, although the actual
location is uncertain. Chimneys were thrown down at Las Tablas
north west of San Luis Obispo. Slight damage was done
to buildings at Salinas and Monterey.

4 12 4 17 52 1957 51.500 -178.500 0 5.0 Andreanoff Islands, Aleutians
4 12 22 37 11 1958 48.000 -120.000 0 5.0 Washington state, U.S.
This earthquake was centreed in north-central Washington state
near the town of Pateros. Cracked plaster and broken dishes constituted
most of the damage. There were rockslides near Chelan. Loud subterannean
noises accompanied the earthquake. An aftershock had about the same effects.

4 12 1 24 31 1964 56.600 -152.200 22 6.5 Southern Alaska
4 12 9 34 44 1964 56.600 -152.100 20 5.1 Southern Alaska
4 12 12 36 23 1964 56.400 -151.400 30 5.0 Southern Alaska
4 12 12 48 2 1964 56.600 -151.300 33 5.1 Southern Alaska
4 12 14 35 39 1964 61.200 -151.100 28 5.0 Central Alaska
4 12 17 22 2 1964 60.200 -145.600 16 5.0 Central Alaska
Strong aftershocks of the great Alaska earthquake of March 28, 1964.
No additional damage was reported with these events.

4 12 3 59 40 1965 56.600 -152.700 33 5.3 Southern Alaska
4 12 4 36 12 1965 52.700 -167.400 16 5.1 Fox Islands, Aleutians
4 12 4 43 10 1965 52.700 -167.500 22 5.3 Fox Islands, Aleutians
4 12 2 10 36 1970 51.510 -178.510 42 5.2 Andreanoff Islands, Aleutians
4 12 4 41 51 1976 52.405 -170.189 38 5.2 Andreanoff Islands, Aleutians
4 12 3 42 4 1978 56.423 -152.691 14 6.6 Southern Alaska
In the Kodiak Island region. Intensity V at Sitkinak Island.

4 12 3 48 55 1978 56.678 -153.568 19 5.2 Southern Alaska
4 12 5 22 29 1978 56.460 -152.548 22 5.0 Southern Alaska
4 12 9 12 1 1978 57.240 -152.040 33 5.0 Southern Alaska
4 12 9 33 38 1978 56.576 -152.841 27 5.1 Southern Alaska
4 12 14 23 59 1984 60.471 -141.229 15 5.0 Central Alaska

EARTHQUAKE EPICENTERS

ASIA

O: 11APR2002 16:06:41 37.0N 71.5E ML=3.4 ASC E of Avdzh, Tajikistan KHZ

O: 12APR2002 09:13:43 23.0N 120.7E ML=4.4 TAI Tainan, Taiwan

O: 11APR2002 09:04:46 38.0N 71.9E ML=3.2 ASC NW of Dana, Tajikistan KHZ

O: 11APR2002 12:04:13 40.1N 142.8E MB=4.8 NEI NEAR E COAST OF HONSHU, JAPAN
O: 11APR2002 12:04:13 40.2N 142.8E MS=4.6 GSR NEAR EAST COAST OF HONSHU

O: 11APR2002 20:19:46 40.0N 73.7E MS=3.5 GSR KYRGYZSTAN

O: 11APR2002 06:05:48 27.7N 56.7E MB=4.5 NEI SOUTHERN IRAN

O: 11APR2002 14:16 34.9N 137.1E Mj=4.3 NIED MIKAWA_BAY_REGION, Japan

O: 11APR2002 00:48:59 36.4N 71.1E ML=3.2 ASC NW of Sanglish KHZ

O: 10APR2002 19:48:35 5.3S 134.2E MB=4.7 NEI ARU ISLANDS REGION, INDONESIA

SOUTH PACIFIC ISLANDS

O: 11APR2002 21:56:56 14.4S 167.6E MB=5.9 NEI VANUATU ISLANDS

CARIBBEAN/CENTRAL/SOUTH AMERICA

O: 11APR2002 14:36:55 7.0N 82.5W MC=3.7 CASC Panama, Central America

O: 11APR2002 06:29:22 16.5N 94.4W ML=4.1 SSN ISTMO DE TEHUANTEPEC, MEXICO

O: 11APR2002 01:42:29 18.1N 102.5W ML=4.0 SSN COSTA DE MICHOACAN, MEXICO

O: 11APR2002 02:19:14 19.2N 66.7W MB=4.5 NEI PUERTO RICO REGION

NEW ZEALAND

O: 11APR2002 08:01 40.4S 176.5E ML=3.7 IGNS SW of Porangahau

O: 11APR2002 07:17 37.8S 176.1E ML=4.8 IGNS South of Tauranga, N.Z.

OCEANIA

O: 10APR2002 12:17:36 56.1S 27.5W MB=4.6 NEI SOUTH SANDWICH ISLANDS REGION

O: 10APR2002 14:44:15 60.1S 27.0W MB=4.5 NEI SOUTH SANDWICH ISLANDS REGION

EUROPE/MIDDLE EAST/AFRICA

O: 11APR2002 16:38:24 41.6N 44.7E MS=3.9 GSR NORTHWESTERN CAUCASUS

U.S/CANADA

CALIFORNIA/NEVADA

O: 11APR2002 11:50:18 41.4N 122.1W ML=2.8 PNSN ENE of Mount Shasta

O: 11APR2002 06:39:30 37.5N 118.4W ML=2.1 NCSN N of Bishop, CA

O: 11APR2002 06:39:56 39.3N 122.7W ML=1.9 NCSN NNE of Nice, CA

O: 11APR2002 11:50:18 41.4N 122.1W ML=2.8 PNSN ENE of Mount Shasta

O: 11APR2002 06:43:16 32.3N 115.3W ML=3.3 SCSN SSE of Calexico, CA

O: 11APR2002 10:29:01 38.6N 123.3W ML=2.2 NCSN ESE of Stewarts Point, CA

O: 11APR2002 11:50:18 41.4N 122.1W ML=2.8 NCSN SW of Tennant, CA

O: 11APR2002 13:40:46 34.6N 116.3W ML=2.2 SCSN SW of Ludlow, CA

PACIFIC NORTHWEST/CANADA

O: 10APR2002 19:40:06 45.1N 122.6W ML=1.6 PNSN ESE of Woodburn, OR

ROCKY MOUNTAIN AREA

O: 11APR2002 19:26:53 39.0N 111.9W ML=2.7 UUSN NNW of Redmond, UT

O: 9APR2002 13:35:10 41.1N 112.9W ML=1.9 UUSN SSW of Lakeside, UT

O: 9APR2002 15:17:43 39.7N 110.7W ML=2.1 UUSN ENE of Helper, UT

O: 10APR2002 10:23:59 38.2N 112.6W ML=0.8 UUSN SSE of Beaver, UT

EASTERN U.S./CANADA

ALASKA

O: 11APR2002 11:16:39 52.4N 169.3W MB=4.1 NEI FOX ISLANDS, ALEUTIAN ISLANDS

HAWAII

O: 10APR2002 21:15:49 19.3N 155.4W ML=2.4 HVO NE of Pahala, Hawaii