ML 5.0 NEAR VANCOUVER ISLAND LARGEST IN REGION IN NEARLY TWO YEARS

SUMMARY

An earthquake of Ml 5.0 southwest of Vancouver Island this morning
was the largest in the region 49-52N 131-125W in nearly two years.
The previous events which were larger were Ml 5.4 and 5.3 on
April 30, 2000. For details on today's earthquake see:

http://www.pgc.nrcan.gc.ca/seismo/table.htm

Last year a series of earthquake of Ml>4 with several Ml>=5
did occur south of Vancouver Island in early to mid-September.
For more details on that swarm see:

http://www.pgc.nrcan.gc.ca/seismo/mstrec/local/sept01_swarm-info.htm

GLOBAL

Activity in the rest of the world today was relatively quiet again.
The other earthquakes listed by NEIS today also occurred in the
Alaska/Kamchatka area but magnitudes were not assigned except to a
Ml 4.1 at Near Island in the western Aleutians.
Earthquakes occurring yesterday (April 3), but not yet listed at
the time of that summary occurred south of Honshu (Mb 4.1); in the
Mariana Islands (Mb 4.4); in Irian Jaya (Mb 4.3); off the east coast
of Honshu (Mb 4.5); in Crete (Mb 4.5) in the Kermadec Islands (Mb 4.4);
and at West Irian (Mb 5.1).

U.S./CANADA

The largest earthquake in the U.S./Canada region today was the
Vancouver Island event discussed in the summary above. Only two
earthquakes of Ml>2 occurred in California/Nevada today - at
Mammoth Lakes (Ml 2.6) and in Central California near Gilroy (Ml 2.4).
The largest events outside of Alaska in the U.S/Canada was a Ml 2.8
near Palisades, Idaho and as a Ml 2.9 in the Baffin Island area
of Northern Canada. The Idaho event occurred west of the on-going swarm
near Jackson Lake WY, but may be related in an unknown way. A Ml 2.1
also occurred this morning (UT) near Cache, Idaho.
No events of Ml>=2 were reported from other areas of the U.S. or
Canada today.

NEW ZEALAND

The strongest earthquake in the New Zealand region listed since
the last daily summary was a Mb 4.4 in the Central Kermadec Islands
region.
The IGNS on-line seismometer did show a light "red-line" event
this afternoon, probably on southern North Island, but no parameters
have yet been assigned.

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 condition throughout
the day. Two rapid M-class events occurred, but neither is
expected to immediately influence terrestrial seismicity as they did not
last long enough to trigger much reaction in the ionosphere. SEC
however, expects both to trigger Coronal Mass Emission (CME) events
which may impact the earth in two to three days and could trigger
further geomagnetic storminess at that time. Parameters of these
events follow:

Flare # START MAX END CLASS

7170 1041 1048 1054 M1.4
7270 1524 1532 1538 M6.1

The only event which may have been associated was a Ml 1.5 at
15:34 UT near Rancho Cucamongo, CA which hit at the height of flare
7270. An unlocated event (LDG says Iran) with moderate magnitude
was also registered at about 15:44 UT.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20020404events.txt

TIDAL EFFECTS

April 06 is the twenty-fourth 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

China MB>=4.0 21 2.5 0.04
Antarctica MB>=4.0 343 2.8 0.02
India MB>=4.0 58 2.5 0.04
Yellowstone MB>=1.0 31 3.3 0.01

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 5 0 0 0 1690 17.500 -61.500 33 8.0 Leeward Islands
The correct date is probably April 16 (Gregorian) wile April
5 is the Julian date. Intensities of this event were as high as
IX in the islands of Antigua, Monserrat, St. Kitts and Nevis.
At Antigua, stone houses suffered much, most houses were shaking
down or were so split and cracked that they had to be leveled.
A spit at Redonda called Rockadunda was split and turned into
the sea. Landslides occured on Nevis Peak. The sea withdrew
about 500 feet from Charlestown before returning after two minutes
in a tidal wave. The earth opened up to 9 feet in some places and
buried solid timber sugar mills. This is one of the two largest
earthquakes recorded in this region of the West Indies.

4 5 23 30 45 1901 45.000 148.000 60 7.9 So. Kurils
4 5 16 42 40 1939 -19.500 168.000 70 7.1 Vanuatu Islands
4 5 9 27 0 1949 42.000 131.500 550 7.0 NE China
4 5 21 12 40 1990 15.530 147.580 33 7.5 No. Marianas
Felt at Guam and Saipan (V). It generated an observed tsunami
at the dock at Tinian, but no dmage. Maximum tshnami height
was probably less than the reported 3-4 meters.

4 5 4 19 52 1991 -5.900 -77.150 34 7.3 No. Peru
53 killed and 252 injured and extensive damage to 8.063 homes
in the Riojo-Moyabamba-Nueva Cajamarca area. Strongly felt
throughout Ecuador.

4 5 11 8 7 1999 -5.681 149.717 164 7.4 New Ireland

U.S./CANADA

No damaging or destructive earthquakes have been recorded in the
U.S. or Canada on April 5.

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

4 5 23 11 0 1915 38.580 -119.500 0 5.0 California/Nevada area
Coleville area. At Coleville CA., rocks rolled down the hillside.

4 5 19 26 56 1954 47.620 -129.230 0 5.0 Vancouver Island area
4 5 2 49 40 1957 52.000 -172.100 33 6.4 Andreanoff Islands, Aleutians
4 5 1 22 14 1964 56.280 -153.340 24 6.0 Southern Alaska
4 5 1 41 45 1964 56.200 -153.300 35 5.9 Southern Alaska
4 5 2 36 11 1964 60.030 -145.980 15 5.0 Central Alaska
4 5 17 42 13 1964 59.580 -144.700 56 5.2 Southeast Alaska
4 5 19 28 18 1964 60.200 -146.700 16 5.8 Central Alaska
4 5 20 13 25 1964 57.200 -152.200 33 5.2 Southern Alaska
4 5 9 27 32 1965 43.900 -127.800 33 5.1 Off Coast of Oregon
4 5 9 4 43 1971 53.359 -170.553 153 5.9 Andreanoff Islands, Aleutians
4 5 14 53 6 1971 66.800 -157.300 100 5.3 Northern Alaska
4 5 17 41 51 1986 54.055 -161.961 33 5.0 Unimak Islands, Aleutians
4 5 22 32 54 1988 50.836 -178.146 33 5.0 Andreanoff Islands, Aleutians
4 5 9 35 47 1994 51.360 -178.160 33 5.8 Andreanoff Islands, Aleutians

RECENT EARTHQUAKE OCCURRENCES

ASIA

O: 2APR2002 13:13:11 36.9N 139.1E MB=4.4 NEI EASTERN HONSHU, JAPAN

O: 2APR2002 13:13 37.1N 138.8E Mj=4.1 NIED MID_NIIGATA_PREF, Japan

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

O: 3APR2002 23:42:12 41.7N 141.7E MB=4.3 NEI HOKKAIDO, JAPAN REGION

O: 3APR2002 10:44:10 1.6S 134.0E MB=4.3 NEI IRIAN JAYA REGION, INDONE

O: 04APR2002 16:27:47 23.7N 120.7E ML=4.0 TAI Yunlin, Taiwan
O: 4APR2002 21:04:48 24.3N 121.8E ML=4.9 TAI Ilan, Taiwan
O: 4APR2002 21:19:40 24.3N 121.8E ML=4.2 TAI Ilan, Taiwan
O: 4APR2002 21:29:56 24.3N 121.8E ML=4.2 TAI Ilan, Taiwan

O: 4APR2002 10:00:19 37.2N 77.0E ML=3.2 ASC NE of Akmeqit (Xinjiang),

O: 4APR2002 09:18:30 35.0N 68.2E ML=3.0 ASC N of Lhargarak (Parwan),

O: 3APR2002 21:17:32 29.1N 139.2E MB=4.1 NEI SOUTHEAST OF HONSHU, JAPA

O: 2APR2002 19:34:15 29.1N 86.9E MB=4.2 NEI XIZANG

O: 2APR2002 10:59 26.8N 128.4E Mj=4.0 NIED NEAR_OKINAWAJIMA_ISLAND, Japan

SOUTH PACIFIC ISLANDS

O: 2APR2002 19:00:45 21.2S 177.7W MB=4.3 NEI FIJI ISLANDS REGION

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

CARIBBEAN/CENTRAL/SOUTH AMERICA

O: 3APR2002 21:55:29 12.9N 88.6W MB=4.1 NEI OFF COAST OF CENTRAL AMER

O: 3APR2002 00:36 15.8S 73.3W mb=4.4 IGP Caraveli

O: 3APR2002 10:37:42 12.4N 87.2W MB=4.1 NEI NEAR COAST OF NICARAGUA

NEW ZEALAND

O: 3APR2002 12:25:48 28.7S 178.2W MB=4.4 NEI KERMADEC ISLANDS REGION

O: 2APR2002 08:18:39 45.1S 167.6E MB>4.0 QED SOUTH ISLAND, NEW ZEALAND.

O: 2APR2002 07:13:06 43.3S 170.6E MB=4.0 QED SOUTH ISLAND, NEW ZEALAND.

O: 2APR2002 04:40:44 39.8S 174.5E MB>4.0 QED NORTH ISLAND, NEW ZEALAND.

OCEANIA

O: 4APR2002 15:44:18 25.0N 55.1E MS=4.2 GSR EASTERN ARABIAN PENINSULA

EUROPE/MIDDLE EAST/AFRICA

O: 3APR2002 12:00:10 35.6N 23.6E MB=4.7 NEI CRETE, GREECE

U.S/CANADA

CALIFORNIA/NEVADA

O: 4APR2002 14:34:08 37.1N 121.5W Md=2.4 NCSN NE of Gilroy, CA

O: 4APR2002 06:29:04 32.4N 115.4W ML=2.2 SCSN SSE of Calexico, CA

O: 5APR2002 00:38:19 37.5N 118.8W Md=2.6 NCSN SSE of Mammoth Lakes, CA

PACIFIC NORTHWEST/CANADA

O: 4APR2002 04:29:11 50.8N 129.9W MB=4.5 NEI VANCOUVER ISLAND REGION
O: 4APR2002 04:29:08 50.5N 130.4W ML=5.0 PGC W Pt. Hardy BC
O: 4APR2002 04:29:47 49.7N 126.9W ML>4.0 PNSN Vancouver Island
Note: For more information see:

http://www.pgc.nrcan.gc.ca/seismo/mstrec/local/4Apr02-locmap.htm

O: 3APR2002 03:13:48 48.2N 127.5W ML=2.6 PGC SW Tofino BC

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

O: 4APR2002 13:09:61 47.5N 122.9W ML=1.7 PNSN Washington State

O: 3APR2002 10:23:59 47.2N 121.6W ML=1.3 PNSN E of Enumclaw, WA

ROCKY MOUNTAIN AREA

O: 4APR2002 12:18:23 43.4N 111.2W MD=2.8 USBR NNW of Palisades Dam,

EASTERN U.S./CANADA

ALASKA

O: 3APR2002 10:37:15 51.2N 177.6E MB=4.5 NEI RAT ISLANDS, ALEUTIAN ISL

O: 1APR2002 19:00:17 51.3N 178.2E MB=4.0 NEI RAT ISLANDS, ALEUTIAN ISL

O: 4APR2002 09:27:38 58.0N 139.0W ML=2.5 PGC SSE Yakutat AK

HAWAII