WESTERN U.S. SEISMICITY AT ML>=2 LEVEL NEARLY TRIPLES AFTER GEOMAGNETIC STORM

SUMMARY

A strong geomagnetic storm occurred this morning. The storm appears to
have begun at approximately 01:50 UT this morning and lasted for more than
12 hours at strong levels. For details of the GOES geomagnetic field see
the site below:

http://sec.noaa.gov/ftpdir/lists/geomag/20020324_G10mag_1m.txt

Look at the He (Field directed perpendicular to the earth) readings between
01:50 and 01:59- you will see an approximate doubling of the intensity
of the field during this time, the indication of the onset of the storm.

The areas most directly affected by such a sudden commencement storm are
facing the sun at the time of occurrence - that is areas where it is local
noontime, and areas which are on the opposite side of the earth - that is
areas where it is local midnight. I usually considering triggered activity
possible within 30 degrees of these longitude, although the most notable
events often occur within 5-15 degrees of this longitude. For this storm
the respective longitudes are 28W and 152E (anti- and sub-solar). A seismic
watch is automatically issued after a storm has continued for 6-8 hours
for areas within 30 degrees longitude of the sub- and anti-solar longitudes.

Although the region of the western U.S. was not within the area most
likely to be affected by this storm, a dramatic increase in seismicity did
occur in these regions after the geomagnetic storm began. Twenty-eight
earthquakes of Ml>=2 have been listed in the western U.S. today compared
with less than 24 in the previous 3 days combined. In Southern
California, SCSN has recorded 8 eventsOf Ml>=2 in the 24 hours since the
storm commencement. Likewised, NCSN in Northern California has recorded
8 events of Ml>=2 since the storm began. In Nevada five events of Ml>=2
have been recorded in the past 24 hours including a Ml 4.2 in southeastern
Nevada.
This totals 21 earthquakes of Ml>=2 in the California/Nevada region in
the past 24 hours. Compare this total with 5 such events on March 23;
6 on March 22 and 9 on March 21 in these three regions - a total of 20
events of Ml>=2 in the 3 days prior to the commencement of the geomagnetic
storm this morning. In other words the 21 such earthquakes today
compared to the 20 over the past 3 days represents a tripling of the
regional seismicity rate after the geomagnetic storm began.
In addition a swarm of earthquakes including the strongest earthquake
in the southwestern Wyoming area in more than a year (Ml 3.4) occurred near
Hoback Junction, WY after the storm commencement. This swarm
has contained 5 events of Ml>=2.
Two earthquakes were also recorded in the Pacific Northwest region
Of Ml>=2, the first such events in that area since March 13.

Earthquake data from these regions at Ml>=2 is listed at the following
sites:
Southern California:

http://www.scecdc.scec.org/scecusers/.plan

Northern California:

http://quake.geo.berkeley.edu/data/quake/plan.xerox_map.html

Nevada:

http://www.seismo.unr.edu/Catalog/nbe.html

Pacific Northwest:

http://www.geophys.washington.edu/recenteqs/Quakes/quakes0.html

Southwestern Wyoming:

http://www.seismo.usbr.gov/quake/Jlsn.txt

GLOBAL

The moderate earthquakes which have been listed since the storm
began are all about 15 degrees from the sub- and anti-solar longitudes
at the time of the storm commencement. These occurred in the Vanuatu
Islands (Mb 4.5 and 5.5) - this is sub-solar; and in the North
Atlantic Mid-Ocean ridge (Mb 4.8 and 5.2) - the is anti-solar.
Other events reported today occurred in Northern Italy (Ml 2.8);
the Gulf of Alaska (Ms 4.1) and the Central Mediterranean (Ml 4.1).
NEIS also reported a Mb 4.6 in the Central Aleutians last
night and the Mb 4.2 in southeastern Nevada.

Source:
http://seismo.ethz.ch/redpuma/redpuma_ami_list.html

U.S./CANADA

The largest earthquake in the U.S./Canada region since last report
was a listed event of Mb 4.5 last night in the Central Aleutians,
Alaska. An event of Mb 4.1 was also reported today in the
Gulf of Alaska near the coast of SE Alaska. A Ml 3.5 was also
recorded in Hawaii just as the geomagnetic storm was commencing.
The strongest event in the 48 contiguous United States occurred
in southeastern Nevada (Ml 4.2). This was preceded by several
foreshocks and followed by several aftershocks. The largest
previous event in this region had been a Ml 5.0 exactly 39 years
ago on March 25, 1963 (see history section below for details).
The 21 earthquakes of Ml>=2 today in this region represented
a substantial increase in seismicity over the past 3 days as
noted above. These events occurred as follows:
Nevada:
Ml 4.4 Southeastern Nevada
foreshock Ml 2.5; aftershocks of Ml 2.3, 1.6, 1.5, 1.4
Ml 2.4, 2.3 Hawthorne area, Nevada
Ml 2.0 Quincy area/Northwestern Nevada - 40N 121W

Northern California:
Ml 2.8 San Juan Bautista
Ml 2.8 Redding
Ml 2.3 Petrolia
Ml 2.6 Eureka
Ml 2.3 Weaverville
Ml 1.0 Geysers
Ml 2.2 Santa Rosa
Ml 2.5 Hawthorne

Southern California:
Ml 2.3 Olancha
Ml 2.2 Simi Valley
Ml 2.3, 2.7, 2.6, 2.4, 2.2, 2.1 Calexico Swarm area

The largest earthquake outside of California/Nevada today
in the lower U.S. was a Ml 3.4 at Hoback Junction, Wyoming,
near Jackson Lake. This is the largest event in the Jackson
Lake region since the U.S. Bureau of Reclamation began monitoring
the area for activity more than 5 years ago. This event was part
of a series of earthquakes which contained 6 earthquakes of Ml>=2
following the geomagnetic storm commencement. These earthquake
registered Ml of 3.4, 2.6, 2.5,
The storm also apparently affected the Pacific Northwest.
Two earthquakes of Ml>=2 were registered by the PNSN network
after storm commencement - at Canby Oregon (Ml 2.0) and Maple Valley
Washington (Ml 2.2). These were the first events of Ml>=2
in the Oregon/Washington region since March 13.
In sum, a total of 28 earthquakes have been reported in the
western U.S. in the past 24 hours including a Ml 4.4 and Ml 3.4.
It has been a VERY active day in this area.

NEW ZEALAND/AUSTRALIA

No events were reported from New Zealand today, however a Ml
4.7 was recorded near Burakin, Australia last night.
For further information on the Australian earthquake see:
http://www.agso.gov.au/bin/listQuakes

or

http://www.agso.gov.au/bin/earthquake.pl?title=Burakin+WA&magnitude=4.7&xy=117.4,-30.4&date=23,3,2002&time=13,16&bg1=eqrisk_lm&zoom=250&station=MORW

The IGNS on-line Seismometer can be found at:
http://www.gns.cri.nz/news/earthquakes/latest_drum.html

GEOMAGNETIC/SOLAR FIELDS

The strong geomagnetic storm this morning was the strongest recorded
Since November, 24, 2001, five months ago.
There were no M- or X- class solar flares recorded 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/20020324events.txt

TIDAL EFFECTS

March 27 is the fourteenth 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

Solomon Islands MB>=4.0 23 2.3 0.04
Spain MB>=4.0 38 2.7 0.02

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

Rocky Mountains MB>=4.0 -54 -2.1 0.05
China MB>=4.0 -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 25 0 0 0 1751 -36.900 -73.000 0 8.5 Central Chile
There were 25 reported killed in this earthquake near Conception,
Chile. A large tsunamis was generated which did damage locally.
There is one report this event occurred in March, however most
authorities believe this earthquake actually occurred in May
with the word Mayo mistranslated to March in English translation.
This is a common problem in historical seismicity studies and leads
to the appearance of many double events in the literature.

3 25 0 0 0 1806 18.900 -103.800 0 7.5 Michoacan, Mexico
Moderate damage occurred in this earthquake which struck the
Michoacan, Oaxaca and Jalisco areas. Destruction was worst at
in Zapotlan el Grande, Jalsico. May people were killed in
Colima where many houses were destroyed.

3 25 4 49 30 1912 -18.000 169.000 240 7.0 Vanuatu Islands
3 25 23 52 17 1916 24.000 124.000 60 7.4 Taiwan
3 25 18 27 15 1943 -60.000 -27.000 0 7.3 So. Sandwich Islands

3 25 20 32 15 1947 -38.920 178.240 12 7.0 North Island, N.Z.
A non-damaging event, this was felt along the east Coast of
North Island with MMI IV.

3 25 13 22 56 1990 9.959 -84.783 22 7.1 Costa Rica
This earthquake which was actually a double event (Ms 6.4 and 7.1)
was felt throughout Costa Rica, injured ten people slightly, and
damaged about sixty buildings. Several landslides blocked roads
fro some time. A small seismic sea wave was reported from Quepos
to Tambor. It was recorded within an observed amplitude of 30 cm at
Quepos. A rise of one meter was also observed at Punarenas. The
earthquake and wave occurred at low tide.

3 25 3 12 26 1998 -62.849 149.694 0 8.3 Macquarie Island Region
This event occurred near the Balleny Islands near Antarctica
south of New Zealand in an oceanic ridge area. This is the largeset
earthquake ever recorded in this area. A small tsunamis of 10
cm was recorded in southern Australia, but not in New Zealand.
Despite the large size, no damage resulted because of the remote
epicenter of this quake.

U.S/CANADA

The following events of Mw>=5 have occurred on this date in
recorded history:

3 25 23 58 31 1932 62.500 -152.500 25 6.9 Central Alaska

3 25 16 49 2 1937 33.400 -116.250 10 6.0 So. California
An earthquake in the Terwilliger Valley, San Diego county.
This did less damage than expected because it was located in
the mountains with few residents. Slight damage to chimneys,
windows and paster was reported. It was felot over most of
Southern California.

3 25 4 56 48 1949 42.000 -126.500 0 6.1 Off Coast of Oregon
3 25 14 13 35 1957 52.916 -166.836 33 6.1 Fox Islands, Aleutians
3 25 9 28 43 1963 36.018 -114.771 8 5.0 Nevada area
This event occurred near Boulder City, NV. It was felt over
a 9,000 square mile area. Considerable amount of minor damage
was done at Boulder City, consisting of cracked plaster and broken
dishes. Several rockslides onto roads occurred in the Boulder
City area. This was one of many earthquakes associated with
the filling of Lake Powell. Large reservoirs often induce seismicity
as they are filled because of loading and seepage of water into
surrounding earthquake-prone areas.

3 25 12 54 55 1966 51.300 -179.700 36 5.0 Andreanoff Islands, Aleutians
3 25 3 31 54 1971 50.524 -176.764 11 5.3 Andreanoff Islands, Aleutians
3 25 17 42 0 1971 59.000 -142.000 0 5.0 Southeast Alaska
3 25 22 42 3 1973 25.890 -109.878 33 5.5 Gulf of California
3 25 0 41 21 1976 35.590 -90.480 17 5.0 NW Arkansas area
Slight damage characterized by cracks in plaster and drywall,
downed ceiling tiles and broken windows occurred in towns in
Arkansas, Missouri and Tennessee. This event was felt in
Alabama, Arkansas, Illinois, Indiana and Kentucky.The quake
was felt over about 280,000 square km. One of the largest earthquake
in the region in the past 30 years.

3 25 7 49 34 1976 57.009 -153.705 28 5.0 Southern Alaska
3 25 16 5 13 1985 37.452 -118.609 7 5.1 California/Nevada area
An earthquake near Mammoth Lakes, CA., it was felt with MMI V
at Tom's place and with IV at Bass Lake to Yosemite National
Park. Felt from Nevada to Tulare, CA.

3 25 19 36 46 1988 62.154 -124.182 10 6.0 Northwest Terr., Canada
Felt at Wrigley, Whitehorse, Yukon Terriroty and Fort
Vermillion and Peace River and Edmonton, Alberta, Canada.

3 25 21 58 20 1988 54.776 -159.840 33 5.9 Alaska Peninsula

3 25 13 34 38 1993 45.110 -122.410 33 5.8 Oregon state, U.S.
Known as the Scott's Mill, Oregon earthquake, this event injured
numerous people. Damage to plaster, walls and windows was done
from Canby to Newberg, Oregon. Lesser damage elsewhere. Several
bridges were damaged in the McMinnville, Oregon area. Landslides
were reported at Mt. Hood. This earthquake was felt over a very
large area from Seattle, WA in the north to Coos Bay, Oregon in
the south.

3 25 13 45 14 1997 53.869 -163.581 33 5.0 Unimak Islands, Aleutians