MINDANAO FAR-FIELD AFTERSHOCKS BEGIN WITH MB 5.5+ in NORTHERN KURILS

SUMMARY

The largest earthquake in the world today was an event variously
calculated from Mb 5.2 to 5.8 which occurred in the northern or
Central Kuril Islands this evening. This is an area where the
far-field forecast from the Mindanao earthquake had stated far-field
triggering was extremely likely. The forecast had stated:

" The most likely location for a large earthquake in the next 10 days
appears to be in the Central to Northern Kuril Islands. This area
was also on the Hindu Kush FFA list, and has a record of very
strong activity following events in Mindanao. A Mw 6.5+ is possible,
with about 0.5 probability in the next two weeks in this general
region."
"
and

"43-45 degrees: ..Central Kuril Islands"

The second largest earthquake occurred off of Northern Japan
with Mj 4.8 in an area where FFA from the Hindu Kush earthquake
had been especially anticipated.

GLOBAL

In general, seismicity was relatively slow today. The earthquakes
that were listed occurred in areas where FFA were expected from
either Hindu Kush or Mindanao. The most unusual event of the
day occurred along the south-Mid Atlantic ridge system, an area
where FFA from the Mindanao earthquake had been expected as follows:

"Secondary location where event tend to occur but are not
as large or as likely . MB>=4.8 considered likely in next
10 days.

South Atlantic Ocean (2)"

Another Mb 4.8 occurred in the Central Vanuatu Islands at a distance
of 106 degrees from the Hindu Kush event, a distance and region
where FFA had been expected in that far-field forecast.

"103-107 degrees***: ...Central Vanuatu Islands"

This is the second such earthquake in this region since the
Hindu Kush mainshock.
Regional aftershocks in the Mb 4.8-5.0 range also occurred
throughout the island of Mindanao, Philippines.

U.S./CANADA

Two minor shocks occurred in the New Madrid, Missouri fault
zone yesterday (Ml 1.7 and 1.5). These were anticipated as
FFA from the Hindu Kush mainshock as they fall at the p- and
s- wave shadow zone boundary where seismic energy is concentrated
after a large earthquake (105 degrees distance).
All other areas except California had no significant regional activity
(Ml>=2 in the mountains and east or Ml>=3 in Alaska or Hawaii).
California (outside of the Calexico swarm) experienced
three earthquakes of Ml>=2 in northern California - Geysers (Ml 2.6);
Parkfield (Ml 2.5) and Fortuna (Ml 2.3); southern California saw
two small events near Independence (Ml 2.1, 2.0) in addition to
the 17 Calexico swarm events in the Ml>=2 range.
UNR lists a Ml 3.5 in northern Nevada at 00:16:11 UT, but this is
clearly a mis-reading of the p-wave from the Mb 5.7? earthquake in the
northern Kuril Islands about 10 minutes earlier. No new earthquakes
were reported from the Northeast or southeast or Canada today.

The swarm of earthquake in the Baja/Calexico region is beginning
to look more and more like a swarm and less and less like an
aftershock sequence. As noted in this report when the sequence
began, aftershock sequences in the region typically run only a
few days. This swarm has now been going on for nearly two weeks.
Daily counts of events of Ml >= 2 for this swarm follow:
Source: SCSN
Table 1: Numbers of events of Ml>=2 in the Calexico/Baja Swarm
for the past two weeks.

#EVEN DATE
YR MN DA

58 02/02/22
192 02/02/23
88 02/02/24
77 02/02/25
7 02/02/26
16 02/02/27
24 02/02/28
4 02/03/01
23 02/03/02
31 02/03/03
29 02/03/04
6 02/03/05
17 02/03/06

In a typical aftershock sequence the numbers would gradually decline
until reaching background levels. This appears to have followed a
typical Omori aftershock decay sequence for the first 3 - 4
days, but then something happened either on Feb. 26 or March 1
which shifted the aftershock sequence to swarm-like behavior.
Swarm-like behavior occurs when the number of events at a particular
magnitude level does not decline monotonically with time, but remains
relatively constant as it has in this area since Feb 27.
The difference is not trivial. Aftershock sequences show the
decline of available energy and weaknesses in the area as the
weak faults gradually break and older faults harden with stress
hardening. Aftershocks are normally broken by a large event or
decline to background seismicity levels. On the other hand,
swarm-like behavior could mean a fault trying to break and much
available strain available and could suggest a second mainshock
is not far off. Alternatively it could indicate motion of magma
in a local magma chamber(s). In any case the change from an
aftershock decay pattern to swarm-like behavior could be important
in the near-term activity of the area.

NEW ZEALAND

While the IGNS on-line seismometer continued to show much noise
in the region, no new earthquake parameters were available from
IGNS.

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

GEOMAGNETIC/SOLAR FIELDS

There was a short and moderate geomagnetic storm from about
15:00 UT to 21:00 UT. This was not a sudden impact events and
would tend to inhance seismicity only slightly. No solar
flares of M- or X- class were 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/20020306events.txt

TIDAL EFFECTS

March 07, is the twenty-second day after the beginning of the new lunar month.
Regions most likely to experience tidal triggering
on this day (With associated magnitude ranges; the percent change in
seismicity rate over background seismicity rate on this
day of the lunar month; statistical z-value and
significance level) are:

Region Magnitude range %change z-value Significance level

Aleutians MB>=4.0 27 2.0 0.05
Geysers MB>=2.0 5 1.9 0.05
Greece MB>=4.0 8 2.0 0.05
Indian Ocean MB>=4.0 17 2.1 0.05
Mammoth Lakes MB>=0.0 55 2.4 0.04
Mammoth Lakes MB>=2.0 70 3.6 0.01
Siberia MB>=4.0 38 2.1 0.05
Utah2 MB>=2.0 27 2.7 0.02
Washington MB>=0.0 95 3.2 0.01
Central California MB>=2.0 10 2.5 0.04
Central California MB>=3.0 20 2.5 0.03
Global MB>=5.0 7 2.4 0.04
Hawaii MB>=2.0 20 2.9 0.02
Iran MB>=4.0 30 2.2 0.05
San Andreas MB>=0.0 14 2.3 0.05
San Andreas MB>=2.0 43 1.9 0.05
San Andreas MB>=3.0 40 2.8 0.02
So Asia MB>=4.0 46 3.3 0.01
Turkey MB>=4.0 11 2.1 0.05

Regions expected to experience reverse triggering (i.e. they are
unlikely to experience a significant event at this period of the
lunar cycle) are:

Region Magnitude range %change z-value Significance level

NW Europe MB>=4.0 -9 -1.9 0.05

TOMORROW IN EARTHQUAKE HISTORY

Two great earthquakes (Mw>8) have occurred on March 7. These
occurred in the Fox Islands, Aleutians in 1929 (Mw 8.3) and in eastern
Peru on March 7, 1950 (Ms 8.3). The Fox Island earthquake is addressed
below, the Peru quake occurred at 550 km depth and did little
damage to surface facilities, although it was felt with MMI V
along the Peru-Brazil border. The most destructive and deadly
event on this date occurred in northern Japan in 1766 (Ms 7.3). This
earthquake killed 1334 people add did extreme damage in the Hirosaki
area of northern Japan/Hokkaido. and at Oshiu, Aeomori and Tsuruga.
Other areas where strong earthquakes have occurred on this date
are Lake Baykal, Russia (1829, Ms 7.5); the Kermadec Isl. (1961; Mw 7.5);
the northern Mariana Islands (1962, Ms 7.0) and Kyushu Japan (Ms 7.6, 1978).
All of these were either in unpopulated areas or occurred at great
depth and were not destructive.

U.S./CANADA

At Mw 8.6, the earthquake on March 7, 1929 in the Fox Islands,
Aleutians was one of the largest ever to hit the U.S. or Canada.
This earthquake was felt aboard a number of ships at sea and at
Dutch Harbor in the Aleutian Islands. Two Japanese ships were near the
Island of Four Mountains. They reported shocks as severe and lasting
nearly a minute. The steamer Shihara Maru reported that strong
vibrations caused the belief that the ship had struck bottom at
41.2N 171.3W. The Yokohama Maru felt the earthquake strongly at 51.5N 169.5W
and the President Madison felt the shock at 50N 165W. A small
tsunami was generated and observed at Hilo Hawaii, however no damage
occurred from this earthquake.
For more than a century, the region within 500 km of the 1929
earthquake recorded it's strongest earthquakes approximately every
28 years. Since the middle of the 1800's when reliable record first
began to be kept, the strongest earthquakes in this area have occurred with
the interevent times shown in Table 2:

Table 2: Recurrence of great earthquakes in the Fox Islands, Alaska region

Earthquake Date Location Magnitude Time to next strong EQ *years

1872 Aug 23 Fox Islands 52N 170W MW 8+ 29 years
1901 Dec 31 Fox Islands 51N 171W Mw 7.8 28 years
1929 Mar 7 Fox Islands 51N 170W Mw 8.6 28 years
1957 Mar 9 Fox Islands 52N 170W Mw 7.0 29 years
This event accompanied one of the greatest earthquakes recorded
in the Central Aleutians of Mw about 8.9+ slightly further west in
the Andreanoff Islands.
1986 May 7 Fox/Andreanoff 52N 174W Mw 8.0

Twenty-eight to 29 years from the 1986 Andreanoff Islands event
will bring us up to the year 2014-2015. It seems likely that
a great event will occur in that region around that time.

The most damaging earthquake in the western U.S. to fall on March
y occurred in 1949 near Salt Lake City, Utah. This sharp local
event (Mb 5.0) broke a pipeline, cracked walls and broke windows
at Salt Lake City. The shock, located on the Wasatch Fault, also moved
furniture and caused dishes to fall from shelves.