THE WINDS THEY ARE A'BLOWIN'

SUMMARY

A strong solar storm hit the earth this evening at 20:25 UT.
Seismicity is expected to be affected in the western U.S. among
other regions. Maximum Kp for this storm is thus far 6-7 making
it a very strong storm. SEC is expecting periods of severe
geomagnetic storms for the next two days.
Hurricane Juliette is still tracking along the west coast of
Mexico. This hurricane has now reach Class 5, the highest
hurricane classification. For the moment, it appears it will
continue to move offshore and not to make landfall.

GLOBAL

It was an active day in global seismicity. The largest event
of the day occurred in the Bay of Bengal, India (Mb 5.5). This
is the largest earthquake located in the Bay of Bengal (9-14N 77-83E)
since a M 5.7 on July 3, 1867 (yes that is not a typo - 1867).
and the second largest ever recorded in that region. The last event of
Mb>=5 was an Mb 5.0 on July 29, 1972.
The Bay of Bengal is situated on the geomagnetic equator where
geomagnetic effects are greatly enhanced. The earthquake occurred while
the area was under a seismic watch (within 20 degrees of 90E) from the
geomagnetic storms of 23 September - the Bay of Bengal was sub-solar at the
time of the commencement of that storm. The earthquake in the Bay of Bengal
on July 29, 1972 was also associated with a strong geomagmetic
storm on July 25-26, 1972. This storm preceded one of the most
active periods every recorded on the sun beginning on July
30-31, 1972 and culminating with a massive geomagnetic storm on Aug. 4, 1972.
The geomagnetic storms and solar flares of late July - early
August 1972 were accompanied by an earthquake of Ms 7.6 on
July 30 in southeastern Alaska, a Ms 6.2 (Aug 3) in the Andreanoff
Islands; a swarm of large earthquakes in the Solomon Isl. (6.1, 6.1,
6.1, 6.2, 6.5; the Vanuatu Isl. (6.2); Samoa (6.1) Iceland, the
Congo and the Arabian Sea among others. This is typical of seismic
activity associated with extreme geomagnetic events. The storm of
August 4, 1972 was the second largest geomagnetic storm since 1960,
the largest (and the largest ever recorded) occurred on March 13, 1989.

A strong earthquake (Mb 5.4) also occurred in the Leeward Islands,
Caribbean this evening. This area has been quiet at this magnitude
level since October, 2000 when a Mb 5.8 occurred near today's
epicenter. This event lies slightly outside the seismic watch area
which was 70-110 E and W. An earthquake (Ml 4.3) in Guatemala (along with
two late on 23 Sept., however did lie within this watch area.

Moderate earthquakes also occurred in southwestern Turkey (Ml 4.6)
and the Aegean Sea (Ml 4.6) which were sub-solar at the time of the
X-flare yesterday and the Kermadec Islands (Mb 5.0/5.6) which was
anti-solar to that flare, all of which were under seismic watch today.

U.S./CANADA

Seismicity was up in the California/Nevada region today as expected
following the recent geomagnetic and solar disturbances. Two events
of Ml>=3 occurred in California in the Coso Junction /Olancha area.
This is an area where seismicity commonly increases following geomagnetic
storms, as previously noted.
SCSN has reported 14 events of Ml>=2 in the two days since the end of the
last geomagnetic storm. Compare this was the 5 earthquakes of Ml>=2
in the two days prior to that storm to get an idea of the effect.
For SCSN listing see:
http://www.scecdc.scec.org/scecusers/.plan
Other earthquakes in California/Nevada today which exceeeded Ml 2.0
occurred south of San Luis Obispo (Ml 2.2, 2.6); at Bodie CA (Ml 2.6);
at Ludlow (Ml 2.2) and Arvin (Ml 2.1). The swarm continued in the
area near L.A. with events of Mlk 1.8, 1.8, 1.4, 1.4 and 1.2 today.
The swarm of events under Mt. St. Helens WA is also continuing.
Seismograms show that in addition to the Ml 1.4 and 1.2 listed events,
a stronger event occurred there this evening. The swarm also continued
offshore south of Vancouver Island.
The largest earthquake in Alaska was a Ml 4.3 off the western coast
in the Bristol Bay region. Earthquakes of this size are quite
uncommon in the Bristol Bay area.
This is the first earthquake of M>=4 recorded within 100 km of
this epicenter since a Ml 4.7 on Sept. 2, 1988. There have been only
5 earthquakes recorded of M>=4 in this region in the past 100 years.
The region was under seismic watch at the time of the earthquake from
a X-class flare that had occurred while the region was sub-solar
earlier on Sept. 25 (high latitude and within 35 degrees of 150W).
The largest earthquake in the U.S./Canada on 24 September occurred
in Ontario north of Lake Erie. A Ml 3.1 event hit SE of Elliot Lake
ONT. This area was also under seismic watch from the geomagnetic
storm of Sept. 23 (within 20 deg of 90W).
This is the largest earthquake within 100 km of this epicenter
since a Ml 3.5 on Dec. 18, 1984. Only 4 earthquakes have been
recorded within 100 km of this event of Ml>=3.

NEW ZEALAND

Seismicity was also high in the New Zealand region, which was
under seismic watch also from the X2.3 solar flare yesterday.
A Ml 4.0 earthquake occurred south of Wanganui, North Island,
and a Mb 5.0 was recorded by NEIS (5.6 GSSC) in the Kermadec
Islands region.
The on-line seismometer also shows a number of non-reported
events in the region today.

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

GEOMAGNETIC/SOLAR FIELDS

A very strong sudden commencement geomagnetic storm began today
at 20:25 UT. This storm has now lasted for 9 hours, so a seismic
watch is being called for the region within 20 degrees longitude
of the sub- and anti-solar locations at the time of the storm
commencement. These areas are 126W and 54E. The areas covered
include high latitudes and regions of western U.S. and Canada
east to the plains and west to southern Alaska - these regions
were sub-solar at the time of the sudden commencement. Anti-
solar regions include areas of Turkey, Iran east to Afghanistan
and along the East African Rift zone. Magnitudes of maximum expected
events in these regions should be increased by up to 1.0 magnitude
units over the next 4 days. The alert will cease 4 days after the
end of the geomagnetic storm which is continuing at this time.
In the California/Nevada region earthquakes occurred in the
Ludlow (Ml 2.2), Gilroy (Ml 1.6) and the Geysers (Ml 0.9) regions
within minutes of the onset of this storm.
One strong M-class solar flare was identified on the sun today.
The parameters are:

Flare # START MAX END CLASS

8100 0424 0440 0452 M7.6

In California/Nevada earthquakes in Hawthorne, CA (Ml 1.8)
(21:35 PST/04:35 UT) and Midway NV (Ml 1.1) occurred during this flare
and may have been affected by it.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20010925events.txt
For geomagnetic field details see:
http://sec.noaa.gov/ftpdir/lists/particle/20010925_G10part_5m.txt

TROPICAL STORMS

Hurricane Humberto is currently at 40N 60W about 1500 km east
of New York City. Tracking expects this storm to move into the
Atlantic and to have no effect on the coastline. No seismicity
is expected to be associated with this storm on the No. American
continent.
For tracking details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200110.html

Hurricane Juliette is now a class 5 Hurricane with maximum sustained
winds of 145 mph, gusts to 180 mph. It continues to track along
the west coast of Mexico. By Thursday it should begin to weaken.
Seismicity along the region of Jalisco and into the Gulf of California
could be enhanced by the presence of this hurricane.
For tracking details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/ep200111.html