QUIET RETURNS TO GLOBAL EARTHQUAKE ACTIVITY

SUMMARY

It has been nearly two days since the last earthquake of Mb>5
in the world. Most condition which might trigger such an earthquake
are presently quiet. However, SEC is expecting a geomagnetic
storm on March 22, and this may enhance global seismicity, so
enjoy the quiet while it lasts.

GLOBAL

The largest earthquake of the day was a Mb 5.0 in New Britain.
This event and an aftershock of Mb 4.7 occurred at 151 E, an area
where recent geomagnetic effects were expected to enhance seismicity.
The most unusual earthquake occcurred in the Republic of South
Africa this afternoon (Mb 4.6). Most seismicity in So. Africa
is mining-related, and moderate to large events are somewhat rare
in this region. The antipode of South Africa is the Hawaiian Islands,
it is not uncommon to see triggering in Hawaii following moderate
or large earthquakes in So. Africa.
Other events today were scattered. These include a Mb 4.3
in the South Sandwich Islands, an area which has seen a series
of such events since a Mw 6 earlier in the month of March. Earthquakes
also were recorded at: Hindu Kush (Mb 4.6); the Carlsberg Ridge
in the northern Indian Ocean (Mb 4.4), the Central Philippines (Mb 4.7);
the Near Islands in the western Aleutians (Mb 4.4). The Hindu
Kush event was followed by a second (as yet unlocated) regional
event of Mb about 5.

U.S./CANADA

There were no events in the U.S./Canada, Alaska or Hawaii today
which were recorded with Ml>=3.
California saw a quiet day after a number of events on the
San Andreas region in Central California yesterday. This (apparently)
strong reaction to the earlier geomagnetic storm may mean that
a moderate to strong earthquake is likely in this region in the
near future.
Since last report there has been one Ml>=2 event in Northern
California (Ml 2.0 at the Geysers); and six listed in southern
California. The So. California group included three north of
Santa Barbara Island, two aftershocks (Ml 4.6, 4.5) and one near
Ventura (Ml 2.2). These follow a similar shock yesterday near
Goleta (about 40 miles west of Ventura, CA). These events may
precede another swarm or moderate-sized mainshock about a month
and a half down the road. One shock was located in the Calexico/Baja
swarm region today (Ml 2.8).
The largest event in the U.S. reported outside California/Nevada
was registered at Kanosh in central Utah this afternoon (Ml 2.5).
A series of events continued in the Ml>=2 range in the Yellowstone-
Jackson Lake region (Ml 2.4, 2.5, 2.0, 2.3).

NEW ZEALAND

Several light shocks appear to have occurred under North Island
today, however no reports are currently available from IGNS
for these events.

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. SEC does expect a geomagnetic
storm to begin today (March 22), however from effects of a coronal
Mass Emission on March 19. We will keep you informed as conditions
warrant.

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/20020321events.txt

TIDAL EFFECTS

March 24 is the eleventh 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

So. Alaska MB>=3.0 9 2.7 0.02
Australia MB>=4.0 33 2.6 0.03
New Madrid MB>=0.0 34 3.4 0.01
So Indonesia MB>=4.0 42 3.1 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

Geysers MB>=0.0 -6 -2.2 0.05
NE Europe MB>=4.0 -10 -2.3 0.04
Tonga MB>=4.0 -29 -2.0 0.05

TOMORROW IN EARTHQUAKE HISTORY

GLOBAL:

No destructive earthquakes have occurred on this date (March 22)
in history. The most interesting sequence occurred in the Kuril
Islands in 1978 where a series of events of Ms>7 occurred over the
space of several days, apparently triggering another event in
Alma Ata (Ms 7+) in Central Asia. The following events have
occurred on this date with Ms>=7:

MO DA HR MN SC YEAR LATITU LONGIT DEP MW LOCATION

3 22 10 23 0 1894 42.500 146.000 60 7.9 North of Hokkaido, Japan
3 22 3 38 53 1905 51.280 174.830 0 7.2 Rat Islands, Aleutians
3 22 8 41 55 1925 -18.500 168.500 50 7.6 Vanuatu Islands
3 22 4 17 3 1928 16.230 -95.450 0 7.7 Oaxaca Mexico
3 22 0 43 18 1944 -8.500 123.500 220 7.5 Timor, Indonesia
3 22 14 5 6 1955 -8.700 91.600 10 7.1 So. Indian Ocean
3 22 14 21 11 1957 53.500 -165.000 0 7.5 Fox Islands, Aleutians
3 22 10 27 43 1972 49.120 153.570 136 7.0 Northern Kuril Islands
3 22 0 50 32 1978 44.020 149.010 37 7.2 Kuril Islands
3 22 21 34 33 1978 44.190 149.060 40 7.0 Kuril Islands

It would seem the Oaxaca, Mexico event of 1928 should have caused
extensive damage, but no reports are available here.

U.S./CANADA

In addition to moderate to strong earthquakes in the Aleutians
(1952, Mw 6.4); (1957, Mw 7.5); (1987, Mw 6.2); (1993; Mw 5.7) and
(1996, Mw 6.7) there have been several felt of damaging earthquakes
in the Continental U.S. on this date in history.
The largest earthquake occurred in the Aleutians in 1957 (Mw 5.7) and
was followed by the most damaging event on this date about 5 hours later
in the Daly City/San Mateo County California area. Needless to say,
a case could be made for far-field triggering here as the distance
between these two is 36 degrees a distance at which FFA are expected.
The earthquakes on March 22 and 23 in California caused property
damage of about $1 million and injured about 40 people. The first of
these (Mb 5.3) killed one. Minor damage was done to houses along the
ocean west of Daly City. Many chimneys were damaged at Daly City
as well. In San Francisco widespread damage to chimneys, plaster,
merchandise and windows occurred. Pavement along Lake Merced fell
off into the lake, and both ends of a pedestrian bridge collapsed.
Landslides blocked State Highway 1 near Mussel Rock and the shoulder
of the highway was cracked extensively. The shock on March 23 caused
slight damage at Menlo Park and San Francisco as well. This was
the strongest shock in the San Francisco bay since 1906 and was
felt over a 12,000 square mile area. The Westlake reservoir near
Daly City had a 4-foot crack on one side extending from the
ground to the top. Damage was also done at the San Francisco
Inernational Airport. There was extensive infrastruce damage
throughout the city of San Francisco. A special report was
issued on this earthquake.

Among the earthquakes in the U.S. preceding the Alaska Good
Friday event of March 28 (UT) was a Mb 5.0 on the California-Nevada
border region north of Mammoth Lakes on Mar 22, 1964. This event was felt
over 7500 square miles of eastern California and western Nevada. The only
report of damage was a crack in a patio near the epicenter, however
many were frightened or awakened by this early morning earthquake.
A similar earthquake had occurred on March 22 1953 in the MArkleeville,
CA region. This event also frightened many. Houses creaked and
objects were moved. A very loud rumbling soudn preceded and accompanied
the earthquake.

The only other damaging U.S/Canadian earthquake on this date occurred
in western Vancouver Island in 1953 (Mw 6.4). This event was felt
strongly on the Queen Charoltte Islands and up to the Alaskan panhandle.
Dishes rattled in Prince Rupert.