MODERATE SEISMICITY HITS SW PACIFIC (BALLENY Ms 5.4), (SANTA CRUZ IS. Ms 5.6)

SUMMARY

Seismic activity today continued in the regions which have been
active in the past several days. These included mostly areas where
FFA were expected from the recent series of Ms>=6.5 events in
the Ryukyu Is. Taiwan and northern and central Chile.
Two more events of Mb 4.9 and 4.7 occurred in the Revillo Gigedo
Islands off the west coast of Mexico. These epicenters lie at
61 degrees from Central Chile.
A moderate earthquake also occurred this evening in the southern
Balkans near northern Greece (Ml 4.5). This event lies at 103 degrees
from the northern Chile event and joins a group (see yesterday's
report) of events in the mid-4 magnitude range over the past
two days in this region.

GLOBAL

Other earthquakes recorded today occurred in Oaxaca, Mexico
(Ml 4.4); the Central Aleutians (Mb 4.6) and the northern Vanuatu
Islands (Mb 5.6) today.

U.S./CANADA

The strongest earthquake of the day occurred in the Alaska
region with the aforementioned Andreanoff Island (Mb 4.6) and
two in the southern (Ml 4.2) and southeastern (Ml 4.1) portions
of the state.
In the California/Nevada region, three earthquakes of Ml>=3
were listed today. The largest was a Ml 3.3 in the Geysers region.
This event was followed by aftershocks of Ml 1.9 and 2.2. Several
events also occurred along the northern Coast of California including
a Ml 2.1 west of Petrolia and a Ml 2.0 east of Rio Dell.
Four shocks also occurred in the region south of California -
a Ml 3.4 in the Calexico swarm and a Ml 3.2, 2.5 and 2.5 in the
Ocotillo area SW of the Calexico swarm. The strongest quake
within the boundaries of southern California occurred tonight
near Beaumont (Ml 2.5).
Due to the weekend reports from other areas of the U.S. and
Canada were not available at this time.

NEW ZEALAND

Two events were of interest in the New Zealand region today.
IGNS reported a Ml 3.5 on the southeast coast of South Island.
The other event was a Ms 5.4 near the Balleny/Macquarie Island
region. This is part of the fault system which has seen moderately
strong earthquakes in three separate localities of South Island
since the Chile earthquake. Seismic wavefronts arrive parallel
to the fault azimuth in this region and affect the entire fault
simultaneously. This may lead to strong or moderately strong
earthquakes which rupture more than a small portion of the fault
in a single earthquake.

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 quiet today. There were no
solar flares of M- or X-class observed. The strongest flare
of the day occurred with the following parameters:

Flare # START MAX END CLASS

7920 0220 0236 0246 C9.6

This flare was followed about 2 hours later by the Ml 3.3 in
the Geysers region.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20020407events.txt

TIDAL EFFECTS

April 09 is the twenty-seventh 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

New Britain MB>=4.0 23 2.3 0.04
Puerto Rico MB>=4.0 28 3.1 0.01
So. California MB>=3.0 59 2.0 0.05
Hindu Kush MB>=4.0 17 2.4 0.04
Utah MB>=2.0 19 1.9 0.05
Aleutians MB>=4.0 35 2.7 0.03

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

No Regions

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 8 15 0 0 1858 36.040 137.020 0 7.0 No. Honshu, Japan
203 were killed and there was moderate damage at Hida, Japan.

4 8 15 40 24 1942 13.500 121.000 60 7.9 Luzon, Philippines
Five violent tremors occurred around midnight. Fiften others followed.
Building were slightly damaged in Manila where electical lines snapped.
Fires broke out at 2:40 due to grounded wire connections. The first
tremor was so violent that the seismograph needle at the Weather
Bureau in Manila jumped off the sheet. Cracks were sustained in
a number of buildings.

4 8 2 40 27 1976 40.311 63.773 33 7.1 Uzbekistan
Damage (VII) in Gazli-Bukhara area. Felt at Ashkhabad and
Samarkand.

4 8 13 10 36 1999 43.649 130.460 580 7.1 NE China

U.S./CANADA

No damaging earthquakes have been recorded in the U.S. or Canada
on April 8.

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

4 8 0 14 15 1958 65.400 -154.900 0 5.7 Northern Alaska
4 8 19 33 19 1964 59.600 -147.000 15 5.1 Southern Alaska
4 8 19 50 17 1964 60.380 -145.940 10 5.3 Central Alaska
4 8 22 10 57 1966 56.500 -152.500 33 5.6 Southern Alaska
4 8 19 51 31 1970 56.219 -156.591 23 5.0 Alaska Peninsula
4 8 6 24 14 1972 42.646 -126.320 11 5.6 Off Coast of Oregon
4 8 20 32 25 1975 51.899 -166.207 33 5.4 Fox Islands, Aleutians
4 8 19 29 3 1980 46.210 -122.196 0 5.1 Washington state, U.S.
4 8 13 1 23 1988 51.948 -173.271 54 5.0 Andreanoff Islands, Aleutians
4 8 1 22 19 1989 57.320 -143.460 3 5.2 Southeast Alaska
4 8 15 14 21 1997 52.000 -171.400 33 5.3 Andreanoff Islands, Aleutians

EARTHQUAKE EPICENTERS

ASIA

O: 7APR2002 07:59:42 24.9N 122.3E ML=5.0 TAI Ilan, Taiwan

O: 7APR2002 01:03:58 7.4N 116.9E MS=4.5 GSR BORNEO
Note: This event was not forecast but occurred 17 degrees from the
Taiwan earthquake of March 31, at a distance and in a general
region where FFA activity was expected in the FFA forecast:

"17-19 degrees: ... Celebes"

Only 10 events have been previously been located within 200 km of this
earthquake in Borneo.

O: 6APR2002 19:30:00 10.6S 118.7E MR=4.8 AEIC1 125 km SW WAIKABUBAK

O: 6APR2002 17:10:00 8.9S 117.6E MR=5.4 AEIC1 S SUMBAWABESAR

O: 6APR2002 11:33:20 9.9S 119.1E MR=4.7 AEIC1 SW WAIKABUBAK

O: 6APR2002 11:26:30 9.9S 121.8E MR=5.1 AEIC1 S ENDE

SOUTH PACIFIC ISLANDS

O: 7APR2002 12:09:40 10.8S 164.2E MB=5.6 NEI SANTA CRUZ ISLANDS REGION

CARIBBEAN/CENTRAL/SOUTH AMERICA

O: 7APR2002 11:30:03 12.9N 90.1W MC=4.2 SIS Guatemala, Central America

O: 6APR2002 14:29:44 15.3N 96.2W ML=4.4 SSN COSTA DE OAXACA, MEXICO

O: 6APR2002 09:56:40 17.0N 100.1W ML=3.9 SSN COSTA DE GUERRERO, MEXICO

O: 7APR2002 20:19:21 19.6N 109.2W MB=4.6 NEI REVILLA GIGEDO ISL REGION
O: 07Apr2002 18:34:37 19.6N 109.3W MB=4.9 NEI REVILLA GIGEDO ISL REGION

NEW ZEALAND

O: 5Apr2002 22:19 45.0S 170.9E ML=3.5 IGNS NW of Oamaru, N.Z.

OCEANIA

O: 7APR2002 01:41:28 63.1S 155.2E MS=5.4 GSR BALLENY ISLANDS REGION

EUROPE/MIDDLE EAST/AFRICA

O: 7APR2002 01:20:16 39.4N 26.2E ML=3.2 KAN AEGEAN SEA, TURKEY

O: 8APR2002 01:20:47 42.3N 20.0E Ml=4.4 INGV NORTHWESTERN BALKAN PEN.

O: 8APR2002 01:20:25 41.2N 21.8E Mb=4.5 SED NORTHWESTERN BALKAN PEN.

U.S/CANADA

CALIFORNIA/NEVADA

O: 7APR2002 01:03:15 38.0N 118.6W ML=2.2 REN California/Nevada Border

O: 7APR2002 01:03:15 38.0N 118.6W ML=2.2 REN California/Nevada Border
O: 7APR2002 01:03:14 38.0N 118.6W ML=2.4 NCSN S of Qualeys Camp, NV

O: 6APR2002 06:42:57 32.6N 117.5W ML=2.4 SCSN WSW of Mission Beach, CA

O: 6APR2002 21:25:35 40.3N 124.5W ML=2.1 NCSN WNW of Punta Gorda, CA

O: 6APR2002 22:01:26 38.8N 122.8W ML=3.3 NCSN NNE of The Geysers, CA
O: 6APR2002 22:03:19 38.8N 122.8W ML=1.9 NCSN NE of The Geysers, CA
O: 7APR2002 06:01:26 38.8N 122.8W MB=3.1 NEI NORTHERN CALIFORNIA

O: 6APR2002 23:21:43 34.5N 116.3W ML=2.4 SCSN SSW of Ludlow, CA
O: 7APR2002 00:01:09 34.5N 116.3W ML=2.6 SCSN SSW of Ludlow, CA

O: 7APR2002 10:03:15 39.1N 123.1W ML=2.2 NCSN SSE of Ukiah, CA

O: 7APR2002 13:58:43 32.1N 115.5W ML=3.4 SCSN S of Calexico, CA

O: 7APR2002 15:57:33 31.8N 116.0W ML=2.5 SCSN S of Ocotillo, CA
O: 7APR2002 23:32:21 31.7N 116.3W ML=3.1 SCSN SSW of Ocotillo, CA
O: 08APR2002 00:14:37 31.9N 116.3W ML=2.5 SCSN SSW of Ocotillo, CA

O: 7APR2002 15:36:12 35.3N 118.5W ML=1.9 SCSN NNW of Tehachapi, CA

O: 7APR2002 19:33:52 40.5N 123.9W ML=2.0 NCSN E of Rio Dell, CA

PACIFIC NORTHWEST/CANADA

O: 6APR2002 22:04:40 45.6N 122.8W ML=2.2 PNSN NNE of Newberg, OR

ROCKY MOUNTAIN AREA

EASTERN U.S./CANADA

ALASKA

O: 8APR2002 00:45:00 57.6N 142.9W ML=4.3 AEIC Valdez, Alaska

O: 7APR2002 08:41:03 61.7N 150.6W ML=4.4 AEIC Anchorage, Alaska

O: 7APR2002 13:10:46 51.2N 177.9W MB=5.0 GSSC ANDREANOF ISLANDS, ALEUTIAN IS
O: 07Apr2002 13:10:38 51.2N 178.2W MB=4.7 NEI ANDREANOF ISL, ALEUTIAN

HAWAII