FFA SEQUENCES FOLLOWING TAIWAN AND CHILE EARTHQUAKES DESCRIBED

SUMMARY

Apparent far-field aftershocks from the Taiwan, the Ryukyu Islands,
and northern and Central Chile earthquake have been numerous in the
past several days. A few statistics will be discussed here.
In general terms, using only NEIS data, 161 events have fallen
within expected FFA distances from the four mainshocks. A total
of 547 distances from these events are possible, so 161/547 inter-event
distances have fallen within FFA rings. This is 30% of the possible
occurring within 15% of the distances possible. This suggests that
about half of the 161 (or 80) of the distance relations may have
been affected by far-field triggering, a substantial effect from
relatively moderate mainshocks.
Some of the largest possible FFA events have occurred in the
regions where effects from Taiwan were expected. For example a
Mb 5.6, the largest event of the day occurred this evening in the
Hokkaido Islands, Japan. The FFA forecast from Taiwan had noted:

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

Hokkaido off East Coast of Honshu, Japan"

A complete report will be made after all time windows for FFA
have expired.

GLOBAL
(FFA distances in parenthses - CCH - Central Chile; NCH - Northern
Chile, TAI - Taiwan; RYU - Ryukyu Islands)

The major earthquakes of the past several days and their relations
to strong recent shocks occurred follows:

Mb 5.6 in Hokkaido, Japan (146 NCH)
MB 4.4 Nicaragua/Costa Rica (45 CCH)
MB 5.4, 5.0 Taiwan (aftershock)
Mb 4.8, 4.9 Northern Peru (19 NCH)
Ml 2.8 Southern California (Hemet area) (72 NCH)
MB 4.5 Bonin Islands (18 TAI)
MB 4.5 Hindu Kush (45 TAI, 142 NCH)
MB 4.2 Xizang China (44 TAI)
MB 5.6 Antarctic-Pacific Ridge (46 NCH)
MB 4.3, 4.5 South Sandwich Islands (43 CCH)
MB 4.7 Chile-Argentina Border (9 CCH)
MB 4.4 Mozambique (102 NCH, 101 CCH)
MB 4.6 North-Central Peru (18 CCH)
MB 6.5 Central Chile (9 NCH)
MB 4.1 Iran (60 TAI)
MB 4.1 Vanuatu (60 TAI, 106 CCH)
MB 4.7 Okhotsk (145 CCH)
MB 3.7 Colombia (35 CCH)

U.S./CANADA

The largest earthquake in the U.S./Canada region today was a Mb
4.3 in the eastern Aleutian Islands, Alaska. Four other earthquake
occurred in Alaska today of Ml>=3 as well, a considerable increase
in activity in Central Alaska over the past week. NORSAR reported
a Mb>=4 earthquake this evening in the Near Islands at the western
most extent Alaska, but has not yet been confirmed by other locators.
The largest event outside Alaska in the region was a Ml 3.5 last
night in the Vancouver Island region. This is the first event of
Ml>=3 in this area in nearly a month. It follows a slight increase
in local activity over the past 4 days.
In the California/Nevada area, it was relatively quiet today.
The largest events since the last summary occurred in the Banning/Hemet
region of southern California (Ml 2.8 and 2.1). In Central and
northern California four new events of Ml>=2 have been listed since
the last summary. These occurred in the Geysers (Ml 3.4), Mammoth
Lakes (Md 2.2), San Juan Bautista (Md 2.1) and Parkfield (Md 2.2)
areas. No events of Ml>=2 were recorded today in Nevada.
Besides the Ml 3.5 near Vancouver Island last night, other
areas of the Pacific northwest and Rocky mountain states were
relatively quiet today. The largest events were recorded in the
Jackson Lake region (Ml 2.4, 2.4, 2.3, 2.2) of Wyoming and in the
Cache, Idaho area (Ml 2.3) this evening (MST).
No events were reported today from the eastern U.S. or Canada.

NEW ZEALAND

A second moderate earthquake occurred on South Island today
after the Mb 5.6 near Te Anau yesterday. Today's event occurred
north of yesterday's in the Haast region, and was probably
felt between Haast and Milford Sound according to IGNS.

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 slightly disturbed levels today.
A light geomagnetic disturbance was recorded between 03:00 and 06:00 UT
this morning, but the field was quiet the rest of the day.
No M- or X- class solar flares were 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/20020403events.txt

TIDAL EFFECTS

April 05 is the twenty-third 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

Caribbean MB>=4.0 22 2.4 0.04
Central California MB>=0.0 32 2.1 0.05
Central California MB>=2.0 11 2.9 0.02
Central California MB>=3.0 23 2.9 0.02
Mammoth Lakes MB>=0.0 56 2.5 0.04
San Andreas MB>=0.0 14 2.4 0.04
San Andreas MB>=3.0 38 2.7 0.02
So Asia MB>=4.0 50 3.6 0.01
Canada MB>=2.0 26 2.2 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

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 4 0 0 0 1819 -27.300 -70.500 0 8.0 Coast Central Chile
A very violent earthquake occurred at Copiapo, Chile (Mw 8.0).
The whole city was destroyed by the shocks of this day and of the
4th and 11th. The inhabitants had barely time to save their lives.
No reports of deaths. (See also April 3, 1819)

4 4 10 13 3 1904 41.800 23.400 6 7.3 Bulgaria
Limited damage was suffered in Bulgaria and northern Greece

4 4 0 50 0 1905 33.000 76.000 60 8.6 India

The earthquake that struck the Dharamshala-Kangra area in Himachal Pradesh
on April 4th, 1905 is among the deadliest earthquakes in the history of
India. According to the provincial government of Punjab, 19,727 people
were killed at Sialkot. Many of the fatalities were from Dharamshala,
Kangra and neigbhouring towns and villages. Felt from Afghanistan to Bengal.
All the buildings were destroyed at Kangra including numerous churches
and temples.
One major difficulty in this event was that most government officials
were killed and there was no one to supervise the rescue and cleanup
efforts. Most of the deaths were due to the ground shaking.
Landslides, liquifaction and other earthquake effects caused
extensive damage throughout the region.

The Amateur Seismic Center has a much more detailed account of
This earthquake at:

http://asc-india.org/gq/kangra.htm

4 4 15 48 40 1911 36.500 26.500 140 7.2 Aegean Sea
4 4 18 44 14 1950 51.770 101.000 24 7.0 So. Siberia

U.S./CANADA

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

4 4 0 13 4 1957 58.170 -155.040 89 6.0 Alaska Peninsula

4 4 21 32 10 1961 33.800 -118.200 33 5.0 So. California
At Terminal Island, Long Beach Harbor. This shock was only
slightly felt in the Long Beach-San Pedro-Wilmington area, but
subsurface damage including major pipeline breakage and to
oil well pipes on Terminal Island was estimated at $4.5 million. More
than 40 wells were damaged and off normal production.

4 4 4 34 57 1964 60.300 -146.500 5 5.0 Central Alaska
4 4 4 54 2 1964 60.100 -146.700 40 5.6 Central Alaska
4 4 8 40 30 1964 56.500 -152.600 15 5.3 Southern Alaska
4 4 17 46 9 1964 56.300 -154.400 18 5.7 Southern Alaska
4 4 17 59 43 1964 56.400 -154.500 25 6.1 Southern Alaska
Aftershocks of the Great Alaska Earthquake of March 28, 1964.

4 4 18 15 52 1964 56.180 -154.490 22 5.0 Southern Alaska
4 4 22 16 54 1964 59.400 -145.200 10 5.1 Southern Alaska
4 4 13 45 11 1980 46.364 -122.182 4 5.0 Washington state, U.S.
Shocks associated with the eruption of Mt. St. Helen's in May 1980.

4 4 17 21 40 1993 53.980 -165.060 33 5.4 Fox Islands, Aleutians

RECENT EARTHQUAKE LOCATIONS

ASIA

O: 31MAR2002 21:23:07 36.2N 69.1E MB=4.5 NEI HINDU KUSH, AFGHANISTAN

O: 1APR2002 12:02:58 7.4S 128.4E MB=4.7 NEI BANDA SEA

O: 3APR2002 23:42:03 41.1N 142.5E MS=5.4 GSR HOKKAIDO, JAPAN REGION
O: 3APR2002 23:42 41.5N 142.0E Mj=5.4 NIED E_OFF_AOMORI_PREF, Japan

O: 31MAR2002 01:14:53 28.5N 141.9E MB=4.3 NEI BONIN ISL, JAPAN REGION

O: 3APR2002 08:38:20 27.3N 140.1E HB>4.0 NEI BONIN ISL, JAPAN REGION

O: 31MAR2002 02:08:02 45.7N 151.7E MB=3.7 NEI KURIL ISLANDS

O: 31MAR2002 02:19:15 0.8N 127.8E MB=4.6 NEI HALMAHERA, INDONESIA

O: 31MAR2002 06:33:11 23.4N 142.1E MB=4.2 NEI VOLCANO ISL, JAPAN REGION

O: 31MAR2002 12:40:31 29.9N 88.1E MB=4.4 NEI XIZANG

O: 3APR2002 02:24:30 39.2N 70.6E ML=4.1 ASC of Du-Oba, Tajikistan

O: 3APR2002 01:04:52 36.2N 69.3E ML=3.2 ASC NE of Zaryate Oluq (Baghlan),

O: 2APR2002 19:09:07 35.2N 77.0E ML=3.4 ASC NNE of Chulung (Jammu &

O: 3APR2002 14:48:06 24.2N 122.1E ML=5.2 TAI Ilan, Taiwan
O: 3APR2002 06:47:36 24.2N 122.4E MB=4.7 NEI TAIWAN REGION

O: 4APR2002 02:06:10 24.3N 121.9E ML=5.4 TAI Ilan, Taiwan

O: 1APR2002 10:00:10 25.8N 143.3E MB=4.4 NEI VOLCANO ISL, JAPAN REGION

O: 1APR2002 09:38:14 36.0N 69.3E MB=4.0 NEI HINDU KUSH, AFGHANISTAN

O: 1APR2002 05:06:40 39.5N 140.7E MB=4.1 NEI EASTERN HONSHU, JAPAN

O: 3APR2002 18:38:47 38.2N 89.5E ML=4.2 ASC W of Mandalik (Xinjiang),

O: 3APR2002 14:58:22 37.4N 72.3E ML=4.8 ASC NNE of Rubat, Tajikistan

O: 3APR2002 11:26:09 38.2N 82.2E ML=3.1 ASC SE of Tongguzbasti

O: 3APR2002 08:06:09 31.7N 71.4E ML=3.1 ASC NE of Bakhtawarwala (Punjab),

O: 3APR2002 07:19:00 39.7N 70.6E ML=4.2 ASC of Tubek, Kyrgyzstan
O: 3APR2002 02:24:30 39.2N 70.6E ML=4.1 ASC of Du-Oba, Tajikistan

O: 2APR2002 10:59:29 27.0N 128.4E MB=3.9 NEI RYUKYU ISLANDS, JAPAN

SOUTH PACIFIC ISLANDS

O: 2APR2002 12:24:18 5.2S 151.1E MB=4.3 NEI NEW BRITAIN REGION, P.N.G

O: 2APR2002 05:56:37 21.5S 174.3W MB=4.7 NEI TONGA ISLANDS

O: 1APR2002 20:53:23 12.2S 166.5E MB=4.8 NEI SANTA CRUZ ISLANDS

O: 1APR2002 13:49:39 6.0S 151.7E MB=4.5 NEI NEW BRITAIN REGION, P.N.G

O: 1APR2002 06:14:14 6.1S 147.5E MB=4.9 NEI E NEW GUINEA REG., P.N.G.

O: 31MAR2002 08:25:44 14.9S 174.8W MB=4.4 NEI SAMOA ISLANDS REGION

CARIBBEAN/CENTRAL/SOUTH AMERICA

O: 2APR2002 01:28:43 11.9S 72.2W MB=4.6 NEI CENTRAL PERU

O: 3APR2002 21:55:29 12.9N 88.6W MB=4.4 NEI OFF COAST OF CENTRAL AMER

O: 31MAR2002 03:31:23 15.8S 69.5W MB=4.5 NEI PERU-BOLIVIA BORDER REGIO

O: 3APR2002 10:38:21 10.5N 85.2W MC=3.7 CASC Costa Rica, Central America
O: 2APR2002 18:22:49 9.1N 84.9W MC=3.6 CASC Costa Rica, Central America

O: 2APR2002 14:26:56 17.0N 100.2W ML=4.3 SSN GUERRERO, MEXICO

O: 3APR2002 21:55:29 12.9N 88.6W MB=4.4 NEI OFF COAST OF CEN AMERICA
O: 3APR2002 01:11:29 11.9N 87.7W ML=2.9 SIS Nicaragua, Central America
O: 3APR2002 10:37:42 12.3N 87.3W ML=4.1 SIS Nicaragua, Central America

O: 3APR2002 14:08:58 7.1S 80.6W MB=4.8 NEI OFF COAST OF NORTHERN PERU
O: 3APR2002 11:45:47 7.1S 80.6W MB=4.6 NEI OFF COAST OF NORTHERN PERU

O: 3APR2002 03:05:59 34.3S 70.4W mb=2.8 DGF Santiago, Chile

O: 3APR2002 03:36:15 35.5S 71.4W mb=3.9 Dpt Talca, Chile

O: 2APR2002 04:10:58 22.0S 65.8W MB=4.7 NEI SOUTHERN BOLIVIA

NEW ZEALAND

O: 31MAR2002 22:42:54 59.7S 148.6E MB=4.4 NEI WEST OF MACQUARIE ISLAND

O: 3APR2002 16:56 44.0S 168.6E ML=4.5 IGNS SW of Haast, N.Z.

O: 1APR2002 20:14:24 45.8S 167.3E HB=5.7 NEI SOUTH ISLAND, NEW ZEALAND

OCEANIA

O: 31MAR2002 22:42:54 59.7S 148.6E MB=4.4 NEI WEST OF MACQUARIE ISLAND

O: 2APR2002 17:09:57 49.6S 116.0W MS=5.6 NEI SOUTHERN EAST PACIFIC RIS

O: 1APR2002 07:12:21 53.6N 35.5W MB=4.7 NEI REYKJANES RIDGE
O: 31MAR2002 22:49:09 53.9N 35.4W MS=5.3 NEI REYKJANES RIDGE
O: 31MAR2002 19:18:39 54.0N 35.1W MB=4.6 NEI REYKJANES RIDGE
O: 31MAR2002 19:14:20 53.8N 35.0W MB=4.5 NEI REYKJANES RIDGE
O: 31MAR2002 19:07:45 53.8N 35.3W MB=5.1 NEI REYKJANES RIDGE

O: 2APR2002 12:06:54 58.7S 25.0W MB=4.3 NEI SOUTH SANDWICH ISL REGION
O: 1APR2002 19:20:25 58.5S 24.8W MB=4.9 NEI SOUTH SANDWICH ISL REGION

O: 2APR2002 04:04:41 16.4S 41.4E MB=4.4 NEI MOZAMBIQUE CHANNEL

EUROPE/MIDDLE EAST/AFRICA

O: 3APR2002 12:00:20 36.1N 22.8E Ml=4.5 INGV SOUTHERN GREECE

O: 2APR2002 15:40:13 41.5N 17.6E MD=3.5 INGV ADRIATIC SEA

O: 2APR2002 04:24:25 51.4N 16.2E Ml=3.0 BGR POLAND

O: 4APR2002 01:57:50 37.8N 30.2E ML=4.2 KAN BURDUR, TURKEY

O: 1APR2002 20:34:55 37.7N 42.8E MB=4.1 NEI TURKEY

U.S/CANADA

CALIFORNIA/NEVADA

O: 3APR2002 02:33:38 36.6N 120.7W ML=2.0 NCSN NNW of New Idria, CA

O: 3APR2002 02:39:46 33.9N 116.9W ML=2.8 SCSN SSE of Banning, CA
O: 3APR2002 10:39:46 33.9N 116.8W ML=2.8 NEI SOUTHERN CALIFORNIA

O: 3APR2002 07:24:29 38.8N 122.8W ML=2.4 NCSN ESE of The Geysers, CA

O: 1APR2002 06:47:37 38.8N 122.8W ML=3.0 NEI NORTHERN CALIFORNIA

O: 3APR2002 08:51:18 37.4N 118.8W ML=2.2 NCSN SW of Toms Place, CA

O: 3APR2002 12:25:02 33.8N 116.9W ML=2.1 SCSN E of Hemet, CA

O: 3APR2002 12:52:46 35.8N 120.4W ML=2.3 SCSN SSE of Parkfield, CA

O: 3APR2002 18:02:27 37.0N 121.5W ML=1.9 NCSN ESE of Gilroy, CA

PACIFIC NORTHWEST/CANADA

O: 2APR2002 05:06:34 49.0N 129.1W ML=3.4 PGC SSW Pt. Hardy BC

O: 1APR2002 10:41:10 52.7N 132.1W ML=1.9 PGC SSW Sandspit BC

O: 29MAR2002 23:09:19 50.2N 127.8W ML=1.1 PGC SSW Pt. Hardy BC

O: 29MAR2002 13:56:08 55.1N 134.0W ML=2.6 PGC NW Massett BC

O: 29MAR2002 07:18:19 61.4N 140.1W ML=2.3 PGC WNW Haines Jct. YT

O: 28MAR2002 21:55:21 49.6N 127.5W ML=2.5 PGC W Gold R. BC

O: 2APR2002 17:19:22 47.7N 120.3W ML=1.6 PNSN WNW of Entiat, WA

ROCKY MOUNTAIN AREA

O: 3APR2002 03:23:20 43.2N 110.8W MD=2.4 USBR SSW of Hoback Jct, WY
O: 03APR2002 04:53:50 43.2N 110.8W MD=2.4 USBR SSW of Hoback Jct, WY
O: 03APR2002 05:37:10 43.2N 110.8W MD=2.0 USBR SSW of Hoback Jct, WY
O: 03APR2002 07:29:01 43.2N 110.8W MD=2.2 USBR SSW of Hoback Jct, WY

O: 31MAR2002 19:03:28 43.8N 105.3W ML=3.3 NEI WYOMING

O: 4APR2002 01:09:58 43.8N 111.2W MD=2.3 USBR SSE of Cache, ID

EASTERN U.S./CANADA

ALASKA

O: 3APR2002 13:27:27 51.5N 172.7W Ms=4.0 GSSC ANDREANOF ISLANDS, ALEUTIAN IS

O: 3APR2002 13:27:29 51.5N 173.4W MB=4.3 NEI ANDREANOF ISL, ALEUTIAN IS.

O: 1APR2002 19:00:17 51.3N 178.2E MB=4.4 NEI RAT ISL, ALEUTIAN ISLANDS

O: 3APR2002 07:14:33 60.6N 154.9W ML=2.9 AEIC Anchorage, Alaska

O: 3APR2002 05:02:02 62.1N 149.8W ML=3.0 AEIC Talkeetna, Alaska

O: 3APR2002 22:16:08 59.8N 145.2W ML=3.1 AEIC Valdez, Alaska

O: 4APR2002 03:14:06 59.8N 148.2W ML=3.6 AEIC Seward, Alaska

HAWAII