ANOTHER VERY QUIET DAY - GOOD TIME FOR A SPRING BREAK BUT TAKE YOUR SUNSCREEN

SUMMARY

It was another quiet Spring day in earthquake land today.
No moderate or large earthquake were reported.
A break seemed called for after several days of extreme quiet,
especially in the California region. Then tonight, a strong
geomagnetic change in the Hn field occurred about 22:30
followed by a moderate (so far) geomagnetic storm. This storm
has been accompanied by the return of seismicity to California,
including a Ml 3.1 in the Calexico swarm and events of 2.1, 2.8,
2.4 and 2.1 in Central California and the Mammoth Lakes area.
Your sunscreen may be called for on that spring break this
weekend.

GLOBAL

Two light to moderate earthquakes were reported by teleseismic
agencies today. They occurred in the Santa Cruz Islands (Ml 4.9)
and in the Northern Mariana Islands (Ml 4.8). Both were at distances
identified in the FFA forecast from the Ryukyu event as likely
sites of FFA - 19 degrees to northern MAriana Is. and 60 degrees
to the Santa Cruz. Islands.
No other events of Mb>=4.5 were reported today.

U.S./CANADA

March 29 was also a very quiet day in the U.S./Canada region,
although a few quakes began to occur as March 30 arrived.
In the California region, one event each occurred in
northern and southern California - a Ml 2.1 near the Geysers
and a Ml 2.9 in the Calexico swarm region. A Ml 3.0 was reported
from the Dixie Valley area of northern California as well, but
has not been confirmed.
In Utah, a minor swarm began this morning in the Yellowstone
Park region (Wyoming). This swarm contained about 20 events
of Ml>=1 in the first several hours, but no moderate events
were reported.
Alaska saw only one Ml 3.0 today in the Prince William Sound
area of southern Alaska. Canada did not report any events of
Ml>=2; neither did any of the other regions of the U.S.
All this changed this evening following the occurrence of
a strong change in the geomagnetic field. The field change
was recorded at 22:35 UT with a more than doubling of the
geomagnetic Hn field intensity in less than 3 minutes. This
signaled the onset of a geomagnetic storm which was beginning
by about 03:00 UT and had reached light storm status by 06:00 UT.
The first signs that a change in the quiet seismicity pattern
of the past two days were two events in Calexico and then
slightly to the north of Ml 2.9 and 3.1 as the magnetic field
began it's fluctuations. As the geomagnetic storm actually
began a number of small earthquake began to occur in Central
California first at Mammoth Lakes (Ml 2.8); then Danville (Ml 2.1)
and next at Pacifica (Ml 2.1 and 2.6).

NEW ZEALAND

IGNS identified a Ml 4.0 in the Queenstown area of South Island
this morning, however the location is not well established at this
point. Queenstown is a resort area (like Mammoth Lakes) nestled
in the mountain - lake area of southern South Island and does not
experience a lot of moderate or strong earthquake activity - that
is usually to the west of Queenstown.

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 through March 29, but
began to fluctuate toward the end of the day. By 02:00 UT on
March 30, a moderate geomagnetic storm was in progress. If this
storm continues and reaches major proportions, a seismic watch
will be issued for regions withing 30 degrees longitude of
158W and 22E (sub- and anti-solar respectively).
An extreme depression in the intensity of the geomagnetic
field occurred this morning at approximately 02:55 UT. Areas
where seismicity is most likely to be affected by this geomagnetic
field change would be within 20 degrees of 45W and 135E.
This depression was followed by the continuing geomagnetic
storm currently in progress.

No M- or X-class solar flares were observed or cataloged 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/20020329events.txt

TIDAL EFFECTS

April 01 is the nineteenth 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

Arctic MB>=4.0 30 1.9 0.05
India MB>=4.0 68 2.9 0.02
Hindu Kush MB>=4.0 14 2.0 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

Mammoth lakes MB>=3.0 -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

3 30 10 45 0 1796 -27.350 -70.350 0 7.7 Coast Central Chile
Destructive at Copiapo and Vallenar.

3 30 12 35 0 1828 -12.100 -77.800 50 8.2 Central Peru
The earthquake extended from Lima to Callao. Felt at Arequipa
but not at Arica. A very violent earthquakelasted 40 seconds, with
many aftershocks. Great damage was done, Scarcely a house in
Lima or Callao remained uninjured and walls of 6 and even 9 feet thick
were thrown down. The cloud of dust which arose from the ruined
buildings of Lima was seen at Callao before the shock itself
was felt there. At Surras streams of water burst forth from the
earth. At Truxillo and elsewhere in the northern part of the
district shake, hte most extraordinary and violent rain followed,
lasting four days and produced mos tdisastrous inundations. On
board the ship 'Volant' the shock is said to have been felt
before it was perceived on shore, while the accounts from other
vessels agree in saying the earthquake was first felt on land.
An interesting phenomena, which might have also been observed
in the Izmit Turkey quake of 1999 related to a ship at sea.
Some of the phenomena observed on board the ship in the harbor
of Callao were remarkable. On board the 'Volant' about half past
seven, a noise like distant thunder was heard, and then came a
shock, comparted to jolting over a rough road in a poorly constructed
cart or to the vessel striking upon rocks of sandbanks (a seaquake).
The water which was 25 fathoms deep , hissed and boiled as if red hot
iron had been thrown into it, and the surface was covered with
bubbles of gas of a sulphurous odour and quantities of dead fish.
The sea had been quite clear, but was now distrubed and muddy.
The ship swung to the extent of 14 inches on either side. On weighing
anchor, the chain cable on one of the anchors was found to be half
melted in a considerable part of its lenght, the links being
drawn out and also lengthways. The chain of the second anchor
was quite uninjured as were those of all other ships in the bay.
Note the similarity to the story of the fishermen in the sea
of Marmara - melted nets, fried fish, bubbling sea.
Could this be a case of sonoluminescence?

3 30 16 55 48 1910 -21.000 170.000 80 7.2 Loyalty Islands
3 30 0 41 0 1914 16.800 -92.200 150 7.5 Chiapas, Mexico
Much damage in Chiapas

3 30 0 0 0 1965 51.300 -179.000 0 7.5 Andreanoff Islands, Aleutians
3 30 2 27 3 1965 50.320 177.930 20 7.5 Rat Islands
Aftershock of the great Rat Islands earthquake of Feb. 4, 1965.

U.S./CANADA

No reports of damaging earthquakes were made on this date (March 30)
from the U.S. or Canada. Following are events of Mb>=5 which have
occurred in this region on this date.

3 30 0 8 56 1924 50.000 -130.200 0 6.0 British Colombia
3 30 21 7 28 1943 39.430 -120.400 0 5.3 Central California
3 30 9 17 0 1957 51.900 -175.100 0 6.2 Andreanoff Islands, Aleutians
3 30 2 18 6 1964 56.600 -152.900 8 5.8 Southern Alaska
3 30 16 9 2 1965 53.700 -165.600 30 5.1 Fox Islands, Aleutians
3 30 12 39 56 1966 49.800 -129.899 0 5.0 Vancouver Island area
3 30 11 30 39 1971 51.191 -177.485 20 5.7 Andreanoff Islands, Aleutians
3 30 18 54 25 1979 51.192 -168.178 37 5.6 Fox Islands, Aleutians
3 30 13 49 37 1980 43.391 -127.205 15 5.1 Off the Coast of Oregon
3 30 18 6 16 1983 61.410 -140.383 0 5.4 Central Alaska
3 30 3 13 41 1987 74.611 -130.471 10 5.5 Yukon Territory, Canada
3 30 13 33 19 1989 58.349 -137.318 10 5.6 Southeast Alaska
3 30 12 12 1 1994 59.880 -153.050 108 5.1 Southern Alaska
3 30 17 42 46 1994 66.460 -147.980 33 5.0 Northern Alaska
3 30 12 55 53 1996 51.000 -169.000 0 5.5 Fox Islands, Aleutians
3 30 13 5 17 1996 52.214 -168.734 33 6.3 Fox Islands, Aleutians
3 30 15 19 60 1996 52.091 -168.540 33 5.2 Fox Islands, Aleutians
3 30 23 5 57 1997 51.100 -178.100 33 5.5 Andreanoff Islands, Aleutians