GLOBAL SEISMICITY SLIGHTLY HIGHER THAN BACKGROUND
UNUSUALLY STRONG SEISMICITY IN EAST CANADA/NE U.S.

SUMMARY

Global seismicity was slightly higher than background over the
past 24 hours with earthquakes of Mb 5.2 in Kamchatka, and the Central
East Pacific Rise; of Mb 5.4 south of Vancouver Island and of
MB 5.5 in the Banda Sea region of Indonesia tonight. The Central
Weather Bureau of Taiwan (CWB) is also reporting a Mb 5.4 in Taiwan
tonight and Obninsk, Russia (GSSC) reported a Mb 5.2 earlier today
in the Molucca Sea south of Mindanao, Philippines.

GLOBAL

In addition to the six events of Mb>=5.0 earthquakes of Mb 4.7
and 4.8 also occurred in the region of Japan (at Kyushu and near
Tokyo today). A series of microearthquakes has also been located
in eastern France this evening.

U.S./CANADA

The largest event in the U.S./Canada region since the last report
was a Mb 5.4 in the swarm current affecting the region south of
Vancouver Island. The Mt. Hood swarm appears to be diminishing at
this time.
In California/Nevada, the 6-day drought of earthquakes of Ml>=3
was broken with a Ml 3.1 NNE of Yorba Linda. This earthquake was
slightly felt. The swarm in the L.A. area moved to the west over
the past several days with two Ml 2.2 events in the Isla Vista
area yesterday and one Ml 2.2 in the Frasier Park region today.
Seismicity also picked up in central and Northern California. Events
of Ml>=2.4 were reported near San Benito and the Stony Gorge
Reservoir.
The most unusual earthquake in the U.S. today may have been related
to the passage of Hurricane Gabrielle off the northeast coast. This
earthquake occurred on the Vermont-New Hampshire border and has
been given Ml 1.8 (Northeast Seismic Net) or Ml 2.2 (Canadian Seismic
Net). The event occurred nearer the Canadian net, so the Ml 2.2 is
probably the more correct. If the event was Ml 2.2, the last
earthquake within 50 km of this epicenter which was larger occurred
on August 8, 1990 more than 10 years ago. If Ml 1.8 events of similar
size occurred on August 13, 2001 and September 16, 1997.
The largest earthquake in Alaska occurred in the Fox Islands
with Mb 4.4.
There were no earthquakes in Hawaii today of Ml>=3. No earthquakes
were reported from the region of the recent swarm near Lo'ihi
Seamount. This swarm appears to have ceased on 14 September after
only 4 days.
A series of moderate M4-5 earthquakes has been reported by GSC
in the James Bay/No. Quebec region over the past two days. These
measured Ml 2.7 at James Bay; 4.1 W of Aupaluk, QUE and a Ml 3.7
N of Havre-St. Pierre QUE. and SE of Pond Inlet, Nunavut. This
is highly unusual activity for this region of NE Canada.
For epicentral details see:
http://www.seismo.nrcan.gc.ca/recent_canadian_eq/recent_canadian_eq_e.html
GEOMAGNETIC/SOLAR FIELDS

The geomagnetic field remained quiet yesterday and today, however
a geomagnetic storm may be brewing at about 03:30- 04:00 UT on 18 September.
Electron flux showed a strong decrease at this time. This is usually
a sign of an impending geomagnetic storm. Two M-class flares
were observed on the sun today. The second was nearly X-class,
large enough to have minor effects on the terrestrial systems.
The parameters of these flares are:

Flare # START MAX END CLASS
4730 0818 0825 0834 M1.5
4830 + 1544 1550 1554 M8.1

A ml 1.8 earthquake occurred at 15:53 during flare 4830 in the
Mammoth Lakes region. This area often sees events coincident with
strong solar flares. An event of Mb 5.2 occurred about an hour
later in the East Pacific Rise. Mid-ocean ridges often respond to
strong flares with increased seismic activity during the following
4-5 days.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20010831events.txt

TROPICAL STORMS

Felix and Gabrielle have been downgraded to tropical storm
status. Felix has stalled in the Central Atlantic, but not before
it was associated with a seimic event in the region. NEIS
shows the following event:

15Sep2001 23:34:41 31.0N 47.4W MB=4.6 NEIS NORTH ATLANTIC OCEAN

This event was likely triggered by the passage of Hurricane
Felix over this epicenter about a day before. Felix was a Category
3 Hurricane (111-130 mph winds) as it passed over 31N 45W on September 14
at 21:00 UT. Seismicity is often seen as hurricanes pass over
active mid-ocean ridges in this manner.

For trackline details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/at200107.track.html
For trackline map see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200107.html

Gabrielle became a class 1 Hurricane yesterday before returning
to tropical storm status. Conditions leading to a series of microearthquakes
in the northeast U.S. and SE Canada including an unusual event of Ml 2.2 on
the Vermont-New Hampshire border may have been affected by this Hurricane.

For trackline details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200108.html