STRONG (MW 6.2) EARTHQUAKE REPORTED FROM PACIFIC-ANTARCTIC RIDGE

SUMMARY

In a belated listing, NEIS is reporting a MW 6.2 earthquake that
occurred yesterday (April 24) in the Pacific-Antarctic Ridge. This event
is given the following parameters by NEIS:

O: 24APR2002 11:00:00 56.2S 122.1W MW=6.2 NEI SOUTHERN EAST PACIFIC RIS

This earthquake is 46 degrees from the Chile mainshock of Apr. 18.
It lies in a region where FFA were expected as noted in the Chile FFA
forecast:

"43-45 degrees: ... Pacific-Antarctic Ridge (120W)"

It also lies within the watch area for larger events expected following
the geomagnetic storm of April 17-19. The watch from that storm
had stated:

" As is usual for strong geomagnetic storms, a seismic watch is being
issued for a possible moderate or strong earthquake within 30 degrees
longitude of 120W or 60E or at high latitudes (>45 N or S) for the
next three days. Small events in these regions may be foreshocks."

This watch was updated on April 23 when a strong geomagnetic storm
again hit while 120W and 60E were anti- and sub-solar. Emphasis had
also been made in the daily reports to the incidence of larger events
occurring 3-5 days after strong geomagnetic storms at regions which
are sub- and anti-solar; at high latitudes or on mid-ocean ridge.
All of these conditions apply to this event. The epicenter appears
to have been ideally located for extensive triggering at the time
of the earthquake.

GLOBAL

The strongest earthquake of the day appears to occurred about an
hour ago in the Fiji-Tonga area. Initial magnitudes appear to be
about Ms 5.7, but details are currently sketchy.
Otherwise, it was a fairly quiet day on the global earthquake front.
Moderate activity continued in the Kosovo area with aftershocks of
yesterday's Ms 5.7 mainshock. A Mb 4.8 was also recorded in the NW
Caucasus area.
Earthquakes of Ml>=4.5 were also recorded in Central America off the
coast of El Salvador (Mb 4.5); in northern Chile (Mb 4.6); the Mariana
Islands (Mb 4.7); Mindanao (Mb 5.2); and Tajikistan (Mb 4.9).

U.S./CANADA

The largest earthquake of the day in the U.S./Canada area was a Ml 3.1
in the Louiseville, Quebec, Canada area this morning. This event was
not a classical aftershock of the Mn 5.5 event in the northern Adirondacks
in New York, but may have been a regionally triggered event. The epicenter
is an unusual one. Since 1800 only 7 events of Ml>=3 have been recorded
within 50 km of this epicenter. The largest was a Ml 5.0 on Nov. 9, 1842.
Earthquakes of comparable magnitude to today's have occurred in April 2000,
Feb. 1998; April 1997, April 1990; Jan 1981 and Sept. 1946. A second
unusual earthquake in the region within days of the Plattsburg, N.Y.
event suggests some kind of triggering process.
No events of Ml>=3 were reported from Alaska or Hawaii today.
In the California/Nevada area, light activity appears to be sprouting
up in the southland. The larger events today occurred in southern
California south of 36N at Idyllwild (Ml 2.6); Calexico (Ml 2.2);
Coso Junction (Ms 2.4); and Oxnard (Ml 2.2). Two Ml 2.7 events
were also recorded in Central California at Madera and along the
California-Nevada border at Mammoth Lakes.
A ml 2.7 was also listed in the Jackson Lake, WY area this morning.
Otherwise, no regionally significant earthquakes have been identified
in other regions of the U.S. or Canada today.

NEW ZEALAND

Two earthquakes have been noted by NEIS and IGNS in the region
of New Zealand since last report. These events occurred in the
southern Kermadec Islands yesterday (Mb 4.4) and along the eastern
coast of North Island SE of Napier (Ml 3.6) early on the morning
(UT) of April 26 (afternoon local time).

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 quiet conditions today. No
M- or X-Class solar flares were observed.

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/20020425events.txt

TIDAL EFFECTS

April 27 is the fourteenth 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

Solomon Islands MB>=4.0 23 2.3 0.04
Spain MB>=4.0 38 2.7 0.02

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

Rocky Mountains MB>=4.0 -54 -2.1 0.05
China MB>=4.0 -18 -2.1 0.05

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 26 2 30 0 1721 37.900 46.700 0 7.7 No. Iran
The city of Tabriz was entirely ruined and more than 8000
persons lost their lives. This figure varies from 8,000 to
250,000 killed. The most credible figure from an original
source appears to be about 80,000 killed. A writer (Morier)
stated the following:
"The danger of earthquakes has taught the inhabitants of Tabriz
to build their houses generally as low as possible and to employ
more wood than brick in their construction. For the same reason,
the bazaars have only wooden roofs and are not arched ... Yet
I am told that in earthquakes the domed buildings have invariably
stood, where others, the strongest walls have been rent asunder"

4 26 21 43 0 1905 -21.000 -70.000 60 7.0 Coast No. Chile
4 26 2 21 30 1916 10.000 -85.000 0 7.3 Honduras
4 26 1 54 15 1944 -1.000 134.000 50 7.2 West Irian, PNG
4 26 20 40 38 1959 24.810 122.700 127 7.5 Taiwan
East Taiwan. One person killed, 9 houses destroyed, 4 damaged.

4 26 7 26 33 1962 -17.700 -179.100 650 7.5 Tonga Islands
4 26 9 37 19 1990 36.100 100.230 33 7.3 So. China
At least 128 people killed, many injured, extensive damage and
landslides in the Ganghe-Xinghai area. Also felt in Gansu
Province. A second event followed.

U.S./CANADA

The following events of Mw>=5 have occurred on this date in
recorded history:

MO DA HR MN SC YEAR LATIT LONGIT DEP MW LOCATION

4 26 1 57 16 1965 58.780 -142.440 37 5.1 Southeast Alaska
4 26 20 29 8 1965 54.250 -162.510 51 5.8 Unimak Islands, Aleutians
4 26 7 18 22 1967 31.140 -114.547 33 5.0 Baja California
4 26 12 9 28 1981 33.098 -115.631 3 6.3 So. California
Property damage in the Calipatria/Westmoreland area was estimated at
$1-3 million. 12 buildings sustained damaged, 30 minor damage and about
70% of the 900 dwellings were also damaged. Razing of 10 downtown buildings
was completed and 5 dwellings were condemned.
The main effects in Calipatria and Westmorland were downed chimneys,
cracked and destroyed foundaations and collapse of exterior adobe and
wood walls. Some underground pipes were also damaged.
In the rural areas broken concrete-lined irrigation canals
were broken. Concrete in several bridges was also cracked and chipped.
This was the largest in a swarm of about 40 shocks between April 24-28.
It was felt over a large portion of southern California into Arizona
and Mexico.

4 26 23 23 24 1985 57.000 -152.100 0 5.0 Southern Alaska
4 26 1 47 35 1988 57.534 -143.073 10 5.6 Southeast Alaska
4 26 6 16 43 1991 61.250 -150.153 38 5.4 Central Alaska
4 26 7 41 40 1992 40.415 -124.603 20 6.6 Off Coast of No. California
This earthquake caused additional damage in the Ferndale, Fortuna
and Petrolia area. Felt throughout much of northern California from
Salinas to San Francisco and into southern Oregon.

4 26 12 6 40 1996 52.816 -168.364 21 5.4 Fox Islands, Aleutians
4 26 10 37 34 1997 34.373 -118.646 46 5.1 So. California
Felt at Acton, Calipatria, Culver City and Northidge with MMI V.
No injuries or damage.

EARTHQUAKE LISTINGS

ASIA

O: 25APR2002 01:46:07 37.9N 72.6E MB=5.0 GSSC TAJIKISTAN
Note: This earthquake falls at 147 degrees from the Chile mainshock
(Mw 6.7) in an area where FFA were expected. The FFA forecast from
Chile/Mexico had stated:

"Other areas where an earthquake of Mb>=4.5 may be and FFA.

...Hindu Kush area"

and

"142-146 degrees: Afghanistan, Hindu Kush"

O: 24APR2002 15:49:41 40.9N 73.1E MB=4.1 NEI KYRGYZSTAN

O: 25APR2002 01:46:03 37.4N 72.6E MB=4.9 NEI TAJIKISTAN

O: 24APR2002 10:46:01 15.0N 147.0E MB=4.5 NEI MARIANA ISLANDS

O: 24APR2002 12:47:06 30.0N 142.4E MB=4.5 NEI SOUTHEAST OF HONSHU, JAPA

O: 24APR2002 17:17:26 27.7N 76.0E Ml=3.6 IMD Rajasthan-Haryana border, Indi
Note: This earthquake falls at 146 degrees from the Chile mainshock
(Mw 6.7) in an area where FFA were expected. The FFA forecast from
Chile/Mexico had stated:

"142-146 degrees: ... So. Pakistan"

O: 25APR2002 03:07:22 6.9N 126.7E mb=5.6 GSR MINDANAO, PHILIPPINE ISLA

O: 25APR2002 03:16:30 14.8N 147.1E MB=4.7 NEI MARIANA ISLANDS REGION

O: 25APR2002 17:41:24 41.8N 44.8E MB=4.8 NEI NORTHWESTERN CAUCASUS

SOUTH PACIFIC ISLANDS

O: 24APR2002 11:46:56 21.6S 173.7E MB=4.4 NEI VANUATU ISLANDS REGION

O: 25APR2002 02:56:04 10.5S 165.9E MB=4.7 NEI SANTA CRUZ ISLANDS

CARIBBEAN/CENTRAL/SOUTH AMERICA

O: 25APR2002 01:03:10 16.6N 95.0W ML=4.4 SSN ISTMO DE TEHUANTEPEC, MEXICO

O: 25APR2002 00:55:23 16.7N 93.8W ML=4.2 SSN CHIAPAS, MEXICO

O: 24APR2002 10:50:01 15.5N 93.5W ML=4.1 SSN COSTA DE CHIAPAS, MEXICO

O: 25APR2002 06:36:52 22.0S 70.2W MB=4.6 NEI NEAR COAST OF N CHILE

NEW ZEALAND/AUSTRALIA

O: 26APR2002 01:55 39.6S 177.1E ML=3.6 IGNS SE of Napier, N.Z.

O: 24APR2002 20:48:53 33.2S 179.1W MB=4.4 NEI SOUTH OF KERMADEC ISLANDS

OCEANIA

O: 24APR2002 15:08:18 56.2S 26.5W MB=4.5 NEI SOUTH SANDWICH ISL REGION

O: 24APR2002 19:28:03 56.2S 26.6W MB=4.2 NEI SOUTH SANDWICH ISL REGION

O: 24APR2002 23:21:50 7.2N 59.7E MB=4.5 NEI CARLSBERG RIDGE

O: 24APR2002 11:00:00 56.2S 122.1W MW=6.2 NEI SOUTHERN EAST PACIFIC RIS
Note: This earthquake is 46 degrees from the Chile mainshock of Apr. 18.
It lies in a region where FFA were expected as noted in the forecast:

"43-45 degrees: ... Pacific-Antarctic Ridge (120W)"

EUROPE/MIDDLE EAST/AFRICA

O: 24APR2002 23:38:04 43.3N 20.9E mb=4.2 GSR NORTHWESTERN BALKAN REGIO

O: 25APR2002 07:28:44 41.6N 17.7E Ml=3.7 INGV ADRIATIC SEA
Note: This earthquake falls at 106 degrees from the Chile mainshock
(Mw 6.7) in an area where FFA were expected. The FFA forecast from
Chile/Mexico had stated:

"Other areas where an earthquake of Mb>=4.5 may be and FFA.

Sicily, Italy"

and

"103-106 degrees***: ... No. Italy, Italy, ..."

O: 23APR2002 21:30:27 53.5N 2.5E ML=2.7 BGS SOUTHERN NORTH SEA, U.K.
Note: This earthquake is 102 degrees from the Chile Mw 6.7 event of
18 April in an area and distance where FFA were expected. It is the
largest earthquake in the region of the United Kingdom since April 14, 2002.
The FFA forecast had stated:

" 103-106 degrees***: ... U.K. North Sea"

O: 24APR2002 23:37:57 42.5N 21.5E MB=4.3 NEI NORTHWESTERN BALKAN REGIO
O: 25APR2002 03:43:34 42.5N 21.8E MB=4.4 NEI NORTHWESTERN BALKAN REGIO

U.S/CANADA

CALIFORNIA/NEVADA

O: 25APR2002 01:13:04 35.9N 120.5W ML=1.9 SCSN NW of Parkfield, CA

O: 24APR2002 21:20:39 33.9N 118.4W ML=1.9 SCSN SSW of Hawthorne, CA

O: 24APR2002 21:45:25 34.5N 116.5W ML=1.6 SCSN E of Lucerne Valley, CA

O: 25APR2002 02:12:22 37.5N 118.8W ML=2.7 NCSN SW of Toms Place, CA
O: 25APR2002 12:05:20 37.6N 118.9W ML=1.3 REN California/Nevada Border
O: 25APR2002 09:12:22 37.4N 118.9W ML=1.9 REN California/Nevada Border
O: 25APR2002 06:55:31 37.5N 118.4W ML=1.2 REN California/Nevada Border

O: 25APR2002 10:44:23 38.8N 119.5W ML=1.5 REN California/Nevada Border
O: 25APR2002 10:44:23 38.8N 119.5W ML=1.5 NCSN WSW of Smith, NV

O: 25APR2002 05:48:53 39.4N 120.2W ML=1.3 REN California/Nevada Border

O: 25APR2002 00:01:47 40.2N 123.8W ML=1.5 NCSN NNE of Redway, CA

O: 25APR2002 03:38:07 39.7N 123.9W ML=1.8 NCSN SSW of Cape Vizcaino, CA

O: 25APR2002 04:21:48 33.9N 119.7W ML=2.5 SCSN SW of Santa Cruz Is., CA (E e

O: 25APR2002 07:37:49 37.0N 120.0W ML=2.7 NCSN E of Madera, CA

O: 25APR2002 08:48:19 38.8N 122.5W ML=1.7 NCSN SE of Lower Lake, CA

O: 25APR2002 09:08:24 36.0N 117.9W ML=2.4 SCSN SE of Coso Junction, CA

O: 25APR2002 11:21:57 34.2N 119.2W ML=2.2 SCSN E of Oxnard, CA

O: 25APR2002 18:11:27 32.3N 115.3W ML=2.2 SCSN SSE of Calexico, CA

O: 26APR2002 02:49:01 33.7N 116.8W ML=2.6 SCSN WSW of Idyllwild, CA

PACIFIC NORTHWEST/CANADA

O: 25APR2002 07:47:12 44.7N 126.1W ML>3.0 PNSN Off Coast of Oregon

O: 24APR2002 20:14:17 50.3N 114.7W ML>2.0 PNSN Alberta, Canada

ROCKY MOUNTAIN AREA

O: 25APR2002 05:04:03 44.8N 111.7W ML=1.0 MBMG S Gravelly Range

O: 25APR2002 13:11:30 47.9N 114.3W ML=1.4 MBMG near Elmo

O: 24APR2002 08:06:16 38.8N 112.1W ML=1.4 UUSN ENE of Richfield, UT
O: 24APR2002 10:56:23 39.5N 112.2W ML=1.9 UUSN W of Levan, UT

O: 24APR2002 10:56:23 39.5N 112.2W ML=1.9 UUSN W of Levan, UT

EASTERN U.S./CANADA

O: 25APR2002 12:51:04 46.2N 72.7W MN=3.1 GSC E FROM LOUISEVILLE, QUE.

ALASKA

O: 25APR2002 04:32:12 63.0N 150.4W ML=3.1 AEIC Kantishna, Alaska

O: 25APR2002 14:18:58 63.0N 149.3W ML>3.0 NEI CENTRAL ALASKA

HAWAII