Ms 5.8 HITS OFF WEST COAST, SOUTH ISLAND, N.Z., AFTERSHOCK CHANGE IN BAJA

SUMMARY

Events on opposite sides of the Pacific may be of interest today.
An Ms 5.8 off South Island, New Zealand and a change in the aftershock
pattern and position from the current sequence in Baja California
may be the most interesting developments over the past 24 hours.
These are discussed in more detail below.

GLOBAL

The largest earthquakes of the day were limited to areas around the
Greenwich Meridian and the International Date Line. This may be related
to the M-class flares several days which concentrated at when these
two regions were sub- and anti-solar. The largest earthquake of the
day was an Ms 5.8 off the west coast of South Island, New Zealand.
The most active area was southern Greece where events of 4.3 and 4.5
occurred at two separate epicenters today. Historically Feb. 24 has
seen several strong destructive earthquakes in this area of Greece
(see this day in History section below). Earthquakes of Mb 5.2 and
Mb 5.5 were also observed in the Java and Banda regions of Indonesia.
To minor tremors were reported near Honshu, Japan.

U.S./CANADA

Earlier today, following an increase in seismic activity in the
Bombay Beach area northwest of the current aftershock activity in Baja,
a note was posted stating:

"The aftershock sequence in the area of Baja/Calexico has moved!! Most of the events
today were occurring in the Bombay Beach/North Shore region. This may be a development
to watch, as this is the area where many seismologists expect the next big earthquake to
begin. Earthquakes in the primary Calexico aftershock zone have now apparently reached
the tail end of the initial aftershock sequence as they are few and far between at this time.
But watch out for the Bombay Beach area - something could be brewing there."

After that note two earthquakes of Ml 3.3 and 3.4 occurred in the
Obsidian Butte area this evening. The region north of the Baja
Aftershock zone has been more active than the aftershock zone since
about noon local time today with the Ml 3.3 and 3.4, the largest events
to occur in the U.S./Canada region on this date.

A Ml 3.0 earthquake also occurred on the border between Quebec and
Upstate New York state. This is the largest earthquake in this region
In more than half a year, although a similar sized earthquake of Ml 3.0
Did occur in this region on Feb. 11, 2002.

Most areas of the U.S. and Canada did not report local events today.

NEW ZEALAND

A Mb 5.4 (or 5.8) earthquake hit off the west coast, South Island
last night. There had been weak signals noted in previous daily
reports that this area should be watched for subsequent seismicity
increases. These were related to the many M-class flares which
occurred while the regions of Europe, Africa and New Zealand were
either sub-solar or anti-solar between 18 and 20 February. There
is often a 4-day delay between flares and subsequent seismic activity.
The report sent on Feb. 21 had stated following a discussion of the
unusual events in Europe:

"On the other side of the world at the international Date Line (180E) two
Mb 5.0 earthquakes occurred in the Fiji Islands near the anti-solar
longitude of the first flare."

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. The largest
solar flare was a C9.0 which occurred while California was sub-solar.
Following the solar flare, activity in the original Baja aftershock
zone became weak and swarms of events began in the Obsidian Butte and
in the Bombay Beach regions. Parameters for the C9.0 flare follow:

Flare # START MAX END CLASS
7770 + 2031 2038 2048 C9.0

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20022402events.txt

THIS DAY IN EARTHQUAKE HISTORY

U.S./Canada

The largest earthquake to occur in the U.S./Canada region on Feb.
24 occurred in 1892 along the California-Mexico border region (Mw 6.9).
This event occurred on the evening of Feb. 23 (local time). At the Carizzo
station in San Diego County all the adobe buildings were destroyed.
In Paradise Valley a church and schoolhouse which had been built on
stilts were thrown down. Ground fissures were observed throughout the
McCain and Jewel valleys. The earthquake was followed by more than
150 strong aftershocks. Aftershocks continued on into April 1892 and
were felt as far away as San Diego Bay. The event was felt as far
away as Visalia about 700 km north of the epicenter.

WORLD

Only three earthquakes of Mw>=7 have occurred on Feb. 24 which
are listed in seismic catalogs. The two largest of these were Ml 7.7
and occurred in Ecuador in 1913 and in off the E. Coast of Kamchatka
in 1923. The third, an Mw 7.1 occurred last year (2001) in the Molucca
Sea area. None of these earthquakes was particularly damaging as they
all occurred in underpopulated regions.
The most destructive earthquake in recent times on Feb. 24 occurred
in 1981 when a Mw 6.8 hit the area of Athens-Corinth, Greece. Sixteen
were killed and more than 600 were injured. There was extensive damage
throughout the area. A strong earthquake also struck the same region
of southern Greece on Feb. 24, 1919. That event had Mw 6.4 but did not do
extensive regional damage that was recorded in seismicity catalogs.