ALASKA AND NEW ZEALAND SHOW FIRST SIGNS OF STRONG SEISMICITY INCREASE
FOLLOWING GEOMAGNETIC STORM/X-FLARE

SUMMARY

Seismicity at the Ml>=3 level was very high in the region of
Alaska today. Eleven separate epicenters in the state had events
of Ml>=3 since the storm subsided. On average there are events
of this size at between 2 and 3 epicenters on a given day.
Also at the end of the storm a strong earthquake rocked the
southern section of South Island, New Zealand. Preliminary magnitude
for this event is Ml 5.6. This earthquake was followed by a second
strong earthquake about an hour later about 100 km to the north.
The Ml 5.6 was felt throughout North Island.
The Space Environment Center (SEC) is expecting strong solar
and geomagnetic storms over the next several days. A polar
absorption event is current taking place. When this happens,
earthquakes at high latitudes (and often near the geomagnetic poles)
are common, however activity elsewhere is often subdued until after
the proton storm has passed. This temporary quiet is followed by strong
seismic activity throughout many areas of the world.
SEC has issued the following forecast at:
http://sec.noaa.gov/today.html

"Geophysical Activity Forecast: The geomagnetic field is expected to be at
major to severe storm levels beginning early on 26 September.
The cme/flare event of earlier today is expected to
spawn a strong disturbance expected to persist for 48 hours. The proton events
currently occurring are likely to continue for the next 24 hours. The Polar
Cap Absorption is expected to continue throughout the day on 25 September."

GLOBAL

Global seismicity was moderate today. An interesting swarm began
this afternoon in the region near Tokyo, Japan. This swarm could
develop into something larger over the next several days as the
region is often sensitive to strong geomagnetic activity. This afternoon's
earthquakes registered at Mb 4.6 and 4.8. NEIS has not listed any
earthquake with Mb>=5 since the Colombia (Mb 6.0) earthquake on
22 Sept. The largest was a Mb 4.9 in the Vanuatu Islands in the
SW Pacific ocean that occurred today.
The most unusual earthquake occurred in the East African Rift
in Kenya. Seismic activity in this region is often triggered
by geomagnetic/solar storms. This was an area where a seismic
event had been expected. The magnitude was Mb 4.5.
Other previously unreported earthquakes occurred yesterday in
Ecuador (Mb 4.6); Guatemala (Mb 4.7, 4.2); the North Atlantic
Ridge (Mb 4.7); the Fiji Islands (Mb 4.5, 4.6) and in the Ionian
Sea off of Greece (Mb 4.6).

U.S./CANADA

Seismicity in the lower 48 states and Canada remained at quiet
conditions today, however this is expected to change beginning late
tomorrow (25 September) due to the geomagnetic storms and cessation
of the polar cap absorption event.
In the California/Nevada region, there were only 3 earthquakes of
Ml>=2 again today. These occurred near Pine Flat (west of Coso Junction)
(Ml 2.4), Big Bear City (Ml 2.5) and Orange, East of Los Angeles (Ml 2.3).
The most unusual of these was the Orange CA event. Earthquakes of
Ml>=2.3 occur about once a month within 30 km of this epicenter.
There have been 29 such events since Jan 1, 1999. The largest this
year was a Ml 3.6 on April 13, 2001.
An earthquake of Ml 2.0 occurred near New Madrid, MO. last night.
This region was directly antisolar at the time of the geomagnetic
storm commencement on 23 September and seismicity near 90W was
expected to be high after that storm (see previous report).
The Pacific northwest was relatively quiet. The swarm near
Mt. St. Helens saw it's largest event thus far ( a Ml 1.8). Likewise
the Rocky mountain region, Canada and the eastern and central
U.S. saw no significant activity today.
Hawaii continued quiet as well. The last event of Ml>3 in that
state occurred with a Ml 4.4 on Sept. 13, 2001.

NEW ZEALAND

Two moderate to strong (Ml 5.6, Ml>4) earthquakes occurred in New Zealand
last night. Both were under North Island. The second appears
to be a regional aftershock of the first since it is about
same distance from the first as Big Bear was from Lander.
An earthquake (Mb 4.6) was also reported in the Kermadec
Islands over the weekend.

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 was at quiet conditions throughout
the day (September 24), however this is expected to change
within the next two days (see above SUMMARY).
A strong X2.6 class solar flare occurred this morning with
maximum output at around 10:08 UT April 24, 2001. This event
is likely to increase global seismicity with the largest events
expected in about 4 days. Regions most affected would be within
35 degrees longitude of 30E and 150W. These area include Hawaii
Alaska and the westernmost regions of the U.S. and New Zealand
(antisolar) and Turkey, Ethiopia, the east Africa rift valley
and the Iran/Pakistan subduction zone. Maximum magnitudes for
previously expected quakes in these areas can be expected
to be up to 1.0 units above previous forecasts.
This slightly overlaps the area under seismic warning from
yesterday's geomagnetic storm which began about 06:00 UT and
reintensified about 12:00 UT. In addition to the areas identified
the reintensification of that storm at 12:00 UT should enhance
seismicity in regions within 10 degrees of 180E and 0E, an area
that would also include Europe and New Zealand.
Strong earthquakes are most likely to occur in these areas
and high latitudes between September 27 and September 29.

Parameters of today's X2.6 solar flare are:

Flare # START MAX END CLASS

7650 + 0932 1038 1109 X2.6

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20010924events.txt

TROPICAL STORMS

Hurricane Juliette continued tracking along the west coast
of Mexico. It has reduced to a class 2 hurricane with winds
of 105 mph at this time. Seismicity could still be triggered
by this storm.
For tracking details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/ep200111.html

Hurricane Humberto continues to follow offshore of the
East U.S. Coastline. It is not expected to hit the mainland.
No seismicity is expected to be triggered by Humberto. For
tracking details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200110.html