GEOMAGNETIC STORM EXPECTED IN THE NEXT 24 HOURS

SUMMARY

The Space Environment Center (SEC) is forecasting a possible major
geomagnetic storm beginning in the next day. Since it has been some
time (January 10) since the last moderately strong (AP 45) geomagnetic
storm, seismic conditions may be affected by the sudden commencement
of this event. Areas within 30 km of sub-solar and anti-solar longitudes
are expected to see the most likely increase in seismicity along with
areas above 50 degrees latitude and within 10 degrees of the geomagnetic
equator.
While some increases in seismicity are common during the geomagnetic
storm, if it is a sudden commencement event, stronger events are
generally expected about 4 days later.

GLOBAL

Global seismicity has been quiet again today. The largest event
appears to have been a Mb 4.9 in the region of Peru this morning.
Earthquakes in the Mb>=4 range also appear to have hit in Pakistan
(Ms 3.5 GSC); Hokkaido, Japan (Ms 4.4, GSC); and in western Iran (Mb 4.4
GSC).
A swarm of earthquakes with Ml 4.6, 4.6 continued today in western
Taiwan after a Ml 4.8 yesterday was followed by 3 light aftershocks.
The largest event in Europe occurred in eastern Turkey this evening
as a Ml 4.2 (KAN). There are currently two active areas in Turkey
- in the eastern and western regions.

U.S./CANADA

The largest earthquake in the U.S./Canada today occurred off the
Coast of Oregon (Mb 4.2). This earthquake occurred southeast of
another event in the same region yesterday which registered Ml 4.6.
The area appears to be active, and more shocks in this magnitude
range are considered a possibility.
The second largest event occurred at the westernmost portion of
the U.S. in the Near Islands, Aleutians (Ms 3.9 GSR). No other
events of M>=3 were recorded in Alaska today.
Four earthquakes of Ml>=3 were recorded in the region of California
today. Two of these were aftershocks of the Baja/Calexico sequence of
Ml 3.4 and 3.1 which occurred after a full day of quiet in the area.
The third occurred near Likely, CA in northern California north of
Susanville. This was a rare regional event. There have been only
three events of Ml>=2.5 within 20 km of this epicenter ever recorded.
The largest was a Ml 3.8 on Nov. 27, 1976 following a strong Mw 6.8
earthquake off the Coast of No. California.
The fourth event of Ml>=3 occurred in the Baker, California area
this afternoon (Ml 3.0). This is an area which some seismologists
believe will be the next large event in the desert of SE California
following the Landers and Hector Mine earthquakes in the 1990's both
of which occurred on faults which should have increased the strain
in the Baker, CA area where today's earthquake occurred.
A Ml 2.9 event also occurred north of the Geysers in northern
California near Ukiah. Other events of Ml>=2 in the western U.S.
today included earthquake near Tres Pinos, Central California (Ml 2.2);
a Ml 2.3 near Westmoreland and a Ml 2.0 south of Idyllwild, both
in southern California.
A Ml 2.0 also was recorded in the Seattle, WA area south of Everett
this morning.

NEW ZEALAND

The IGNS on-line seismometer was relatively quiet today although
two teleseismic events (perhaps aftershocks in the Kermadec Islands)
were recorded around 20:00 UT today. IGNS did not report any
earthquake parameters today as they are off for the Sunday holiday.

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, however
SEC expects some storminess in the next several days due to a
recurrent coronal hole. This should start sometime tonight or
tomorrow. Since it has been some time since the last major geomagnetic
storms, this could lead to a change from quiet to active seismic
conditions throughout all study areas, depending upon when the
storm hits. Updates will be posted as appropriate.
There were no M- or X- class solar flares observed today.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20020302events.txt

TOMORROW IN SEISMIC HISTORY

The largest event recorded to have occurred on March 3 happened only
17 years ago in Central Chile. This earthquake (Ms 7.8) injured at least
2,500 people, killed about 175 and did extensive damage throughout the
cities of Valparaiso, Santiago and San Antonio, Chile. The maximum
felt intensity occurred at MMI VIII in the Valparaiso, Chile area.
Liquifaction occurred along dune sands in the San Antonio area.
There were reports of extensive ground cracking and subsidence
throughtout most of the region. It was felt as far away as Buenos
Aires, Argentina and Sao Paulo, Brazil.
A tsunami was generated which was one of the few Pacific-wide events
in the past 20 years, reaching Alaska, Hawaii and the islands of Japan.
The earthquake was followed less than an hour later by a Ms 7.0
aftershock.
The seismic history of this region of Chile shows a strongly
repetitive cyclic behaviour to the great quakes in the past 4 centuries.
On average the interevent time between great quakes within 200 km of the
Valparaiso, Chile event in 1983 is about 85 +/- 7 years. Table 1
shows the great quakes in this area and the associated interevent
times.

Table 1: Seismic History of the Valparaiso Chile area

Event Interevent time

May 14, 1647 Mw 8.5

83 years

July 8, 1730 Mw 8.5

92 years

Nov. 20, 1822 Mw 8.5

85 years

Aug. 18 1906 Mw 8.6

79 years

Mar. 3 1985 Mw 7.8

This would suggest the next such event is not due until about
2070 A.D. Howver, the last event was earlier and smaller than
expected, so there may still be pent-up strain in the region and
another great quake could occur before the middle of this century.

U.S./CANADA

The largst earthquake to hit the U.S./Canada region on March 3
occurred in 1954 in southern Alaska near Valdez. This earthquake
of Ms 6.2 tumbled stock from local grocery stores. The weather
Bureau Office in Anchorage reported movement of bookcases against
the wall, and at the peak of the quake there appeared to be a rotating
or wobbling of the building which was enough to cause persons
in the next room to stand in the doorway.

The most unusual earthquake on this date in the U.S. occurred
in the New Madrid Seismic zone in Missouri with Ms 5.5 in 1963.
This was the last large earthquake felt in this zone, although more
are expected in the future. The earthquake was felt from Arkansas
to Indiana and from Kansas to Mississippi. Plaster cracked and
fell; bricks fell from chimneys and cracks formed in walls,
foundations, sidewalks and chimneys. In Poplar Bluff MO. water
lines were damaged and many basements were flooded. Great earthquakes
occur with interevent times of about 500+ years in this area as
shown by trenching research.

In the region of the western U.S., the most unusual earthquake on this
day occurred in the eastern Pacific off the coast of California. This
Mw 5.4 earthquake had it's epicenter at 34.5N 128.1W - the only earthquake
ever recorded this far off shore from Southern California. This location
is about 800 km due west of Los Angeles. The cause of this earthquake
is unknown, however a strong solar storm was occurring at the time
of the flare.

A giant X 15 solar flare erupted on March 6 and led to
the strongest geomagnetic storm ever recorded on March 13, 1989. This
storm caused power severe blackouts throughout much of the northeast U.S.
and southeast Canada and the induced electrical currents in the
earth melted transformers in several power plants in New Jersey.