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Posted by Lowell on March 05, 2002 at 22:48:11:
FAR-FIELD AFTERSHOCK FORECAST FOR MINDANAO, PHILIPPINES MW 7.2+ (PRELIMINARY)
(MARCH 05, 2002) A strong Mw 7.6 earthquake occurred in the Mindanao region of
the Philippines today. NEIS gives the event parameters as: O: 05MAR2002 21:16:09 6.10N 124.15E MW=7.2+ MINDANAO, PHILIPPINES (shallow) GEOMAGNETIC PRECURSORS: The earthquake followed a moderate geomagnetic storm which had
begun at about 14:45 UT and reached it's maximum at approximately
15:36 UT, a time which was exactly solar midnight at the epicenter (that
is, the epicenter was antisolar at the time of the geomagnetic storm).
It was at this time that the total and Hp field showed the strongest
Fluctuation. For detailed information on the field see: http://sec.noaa.gov/ftpdir/lists/geomag/20020305_G10mag_1m.txt The field change was accompanied by a sudden increase in electron
Flux (nearly tripling from 14:45 to 15:35 UT). Details on electron flux
At >0.6 MEV levels can be found at: http://sec.noaa.gov/ftpdir/lists/particle/20020305_G10part_5m.txt These factors disturbed the geomagnetic field (and the field change
Is especially pronounced at midnight and noon longitudes (120E and 60W
And near the geomagnetic equator), triggering a moderate geomagnetic
Storm. For 15-minute Kp -indices see: http://sec.noaa.gov/ftpdir/lists/costello/ace_pkp_15m.txt For general information and graphics see: http://sec.noaa.gov/today.html The Mindanao epicenter was ideally located to take the brunt of such a
Geomagnetic storm as it lies near the geomagnetic equator at exactly
The anti-solar longitude during the storm.
TIDAL TRIGGERING
The region of South Asia typically shows increased activity at this
date in the lunar month (the 22th day). In the forecast from Dec 5, 2001
it was noted (and is noted in today's tidal effects as well):
Dec 5 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
Global MB>=5.0 7 2.4 0.04
So Asia MB>=4.0 46 3.3 0.01 South Asia (including southern Philippines/Mindanao) has seen a 46%
Increase in overall seismicity on this day of the lunar month compared with
Background. This is statistically significant at a 0.01 level meaning that
We can reject the null hypothesis that there is no relation between the seismicity of this region and tidal effects 1% of the time. Note that this
Lunar day is apparently especially prone to tidal triggering in a large number
Of regions of the world as there is a strong statistical increase in global
Activity on the 22th day of the lunar month as well. FAR-FIELD EFFECTS FROM HINDU KUSH (HISTORY REPEATS FOR THE OBSERVANT) Two days ago on March 3, a strong earthquake (Mw 7.2) occurred in the region
Of Hindu Kush. At the time a far-field aftershock forecast was produced which
Suggested that the region of Mindanao would be likely to experience strong
Far-field aftershocks on the basis of its location at approximately 60 degrees
From Hindu Kush. The forecast had read: "The following areas are expected to see increased seismicity
from March 3 through March 11, 2002. Maximum event size for
these regions is expected to increase by 0.8 magnitude units in this period.
59-61 degrees: ...Mindanao ... "
and in the summarized conclusions:
" The most likely events of Mw>=6 in the next 10 days appear to be:
(Number in paranthesis indicated number of times and event of M>=6
has followed a Hindu Kush mainshock within 2-3 weeks).
...
Mindanao/Mindoro Philippines (3) ..." It should be noted that in this case there is a very close case of repeating
History which was cited in the Far-field forecast - the case of the
Hindu Kush earthquake of 1985 followed by the Mindanao earthquake. The
Forecast had cited: MAIN AUG 02 1985 36N 70.7E 120 6.5 (Aftershock) AFTEREVENTS Aug 04 7N 126E Mw 6.4 Mindanao This was merely the best example of a large earthquake in Hindu Kush
Followed by a large event in Mindanao. The FF Forecast also cited other
Examples in 1911 when a Mw 7.6 Hindu Kush event was followed 8 days later
By a Mw 7.7 Mindanao earthquake; 1962 a Mw 7.0 followed by a Mw 6.0 in Mindanao
7 days later; and in 1965 a Mw 7.5 in Hindu Kush followed by an Mw 6.5 just south of Mindanao in the Celebes 7 days later. Indeed, history does repeat itself - over and over. SEISMIC HISTORY OF AREA: At Mw 7.2+, today's earthquake ranks as the largest in the 200 km
area in nearly 26 years, since August, 1976 at which time an event of Mw 8.0 occurred within a few tens of km of today's epicenter. That event killed 5,000
to 10,000 people and left near 90,000 homeless by the effects of the
earthquake and the tsunami. There was extensive damage along coastal areas
of Moro Gul. The maximum tsunami height was 4.3 meters. It was followed
half a day later by a Mw 7.0 aftershock. The mainshock was the only
great earthquake that is known to have afflicted the region within 200 km
of the epicenter in historical times.
The only other great earthquake in the area was recorded on Aug 15, 1918.
This event of Mw 8.5 kill more than 102 people, triggered a deadly
tsunami and did severe damage at Cotabato, Glan and Sarangani, Mindanao.
Nine previous earthquakes of Mw>=7 have been recorded within 200 km of
this epicenter since 1900 (see Table 1). The event of Dec 19, 1928 killed 93
and did moderate damage in Cotabato and the north Coast of Illana Bay. Other
shocks in the region are not known to have caused damage, perhaps because
many (3) of them were at intermediate and deep focus. Table 1 lists the parameters of earthquake of Mw>=7 within 200 km of
today's NEIC epicenter. MO DA HR MN SE YEAR N LAT E LONG DEPKM MW
8 15 12 18 22 1918 5.500 123.000 60 8.5
3 2 16 48 52 1923 6.500 124.000 60 7.2
12 19 11 37 10 1928 7.000 124.000 60 7.3
6 4 15 15 58 1929 6.500 124.500 380 7.0
4 30 1 23 32 1949 6.500 125.000 130 7.4
8 16 16 11 52 1976 6.300 124.000 33 8.0
8 17 4 19 27 1976 7.200 122.900 22 7.2
12 12 11 44 16 1978 7.330 123.492 33 7.3
11 20 8 15 11 1984 5.400 125.400 140 7.3 FAR-FIELD FORECAST:
The following areas are expected to see increased seismicity
from March 5 through March 13, 2002. Maximum event size for
these regions is expected to increase by 0.8 magnitude units in this period. 0-5 degrees: Regional triggering- Mindanao, Luzon, Mindoro, Philippines,
Celebes areas
9-10 degrees: Northern Luzon, westernmost West Irian, Seram, Banda Sea,
Sulawesi
17-19 degrees: Ryukyu Islands, Papua, New Guinea, South of Sumatera
34-36 degrees: Bengladesh, eastern Nepal, Northern Honshu off E. Coast,
Eastern Solomon Isl. SW Australia
43-45 degrees: Central Kuril Isl, Santa Cruz, Northern Vanuatu Islands,
westernmost Nepal
59-61 degrees: Hindu Kush/Afghanistan, Near, Rat Islands, Aleutians, Fiji
71-73 degrees: SW Iran, Gulf of Aden, Reunion Isl. Indian Ocean, Unimak
Isl. Fox Islands, Aleutians
103-107 degrees***: So and Central California from L.A. to Parkfield, north
to California-Nevada Border to Salt Lake Utah; Iceland, U.K., France,
No. Italy
142-146 degrees: Nicaragua, So. Chile
176-180 degrees: A-seismic zone in central Brazil south of the Amazon River
(6S 56W) ***: The strongest triggering is always expected to be along the
shadow zone boundary between 103-107 degrees from the epicenter. HISTORICAL SEISMICITY Historical following quakes after large events in the Mindanao,
Philippines region: MAIN AUG 15 1918 5.5N 123.0E 60 8.5 AFTEREVENTS Aug 21 43N 71W Ml 5.7 Southern Maine
This was one of the strongest earthquakes ever recorded
in the state of Maine, toppling chimneys and lowering the level
of Lake Sebago NW of Portland by about 10 cm.
Sep 7 46N 152E Ms 8.3 Northern Kurils
Sep 10 35N 98W Ml 3.5 Oklahoma MAIN MAR 2 1923 6.5N 124.0E 60 7.2 AFTEREVENTS Mar 15 43N 17W Ml 6.2 Austria
Mar 16 7N 127W Mw 7.0 Mindanao
Mar 24 31N 101W Mw 7.3 So. China MAIN DEC 19 1928 7.0N 124,0E 60 7.3 AFTEREVENTS Dec 19 21N 143E Ms 6.0 Northern Mariana Isl
Dec 26 6N 99W Ms 6.0 North of Galapagos Isl.
Dec 27 61S 55W Ms 6.1 Falkland Islands
Dec 28 7N 123E Ms 6.9 Mindanao
Jan 08 34S 57E Ms 6.3 So. Indian Ocean
Jan 13 50N 155E Ms 7.9 Northern Kuril Islands
Jan 17 10N 65W Ms 6.9 North of Venezuela MAIN JUN 4 1929 6.5N 124.5E 380 7.0 AFTEREVENTS Jun 6 1S 14W Ms 6.5 Central Mid-Atlantic Ocean
Jun 6 34S 57E Ms 6.0 South Indian Ocean
Jun 9 46N 152E Ms 6.9 Central Kuril Islands
Jun 10 71N 10E Ms 6.3 Barrents Sea/Arctic
Jun 12 4S 145E Ms 6.8 Papua, New Guinea
Jun 13 46S 151E Ms 7.3 Central Kuril Islands
Jun 13 8N 127E Ms 7.2 Mindanao
Jun 16 41S 172E Ms 7.6 Wellington, New Zealand area
Jun 20 8S 112E Ms 6.3 South of Bali, Indonesia
Jun 27 54S 30W Ms 8.3 South Sandwich Islands MAIN APR 30 1949 6.5N 125.0E 130 7.4 AFTEREVENTS May 02 34N 116E Ms 6,0 Twenty-nine Palms, California (+ aftershocks)
May 03 48N 153E Ms 7.0 Northern Kuril Islands
May 08 21S 69W Ms 6.8 Northern Chile
May 10 19N 109W MS 6.8 Jalisco, Mexico
May 23 30S 178W Ms 6.5 Kermadec Islands, N.Z.
May 24 18N 105W Ms 6.5 Jalisco, Mexico MAIN AUG 16 1976 6.3N 124.0E 33 8.0
MAIN AUG 17 1976 7.2N 122.9E 33 7.2 AFTEREVENTS Aug 17 7N 123E Ms 7.2 Mindanao
Aug 17 10N 126E Ms 6.0 Leyte, Philippines
Aug 17 42S 120E Mb 4.6 South of Australia
Although this was not a large earthquake, it was the first ever
located in this region.
Aug 20 20S 70W Ms 6.0 Northern Chile
Aug 20 38N 122W M 4.0 San Francisco, CA
Aug 21 32N 104E Ms 6.4 Szechwan, China (aftershock 6.7 on Aug 23)
Sep 8 47N 123E Mb 4.6 Tacoma, Washington
Sep 14 46N 13E Mb 6.1 Austria
Sep 16 9S 148E Mb 6.0 Papua, New Guinea
MAIN DEC 12 1978 7.3N 123.5E 33 7.3
AFTEREVENTS Dec 14 32N 50E Ms 6.2 Western Iran
Dec 15 52N 175E Mb 5.6 Rat Islands
Dec 18 54S 2E Ms 6.5 Bouvet Island, So. Atlantic
Dec 23 23N 122E Ms 7.0 Taiwan
Dec 25 10N 103W Ms 6.5 South of Mexico
Dec 31 47N 122W Ml 4.0 Washington
MAIN NOV 20 1984 5.4N 125.4E 140 7.3
AFTEREVENTS Nov 23 7S 102E Ms 6.7 South of Sumatera
Nov 23 14S 171E Ms 6.7 Vanuatu Islands region
Nov 23 37N 119W Ms 6.1 Mammoth Lakes, California
Nov 23 7S 102E Ms 6.7 South of Sumatera
Dec 03 44N 148E Ms 6.5 Central Kuril Islands (Aft. 6.0 on Dec. 17) Summary of far-field events following Hindu Kush mainshocks: In general, the events of Mb>=5 tend to fall in the areas
described by the listing of far-field events expected above
from distance considerations. The most likely events of Mw>=6 in the next 10 days appear to be:
(Number in paranthesis indicated number of times and event of M>=6
has followed a Hindu Kush mainshock within 2-3 weeks). Northern Kuril Islands (5)
Two great (Mw>8) shocks appear to have occurred in the central
and northern Kurils after large Mindanao events. Several other
large events have also been associated within several weeks. Mindanao aftershocks (5)
It is common for strong aftershock to occur within 300 km in this
region usually to the northeast and within 2 weeks. The most likely events of M>=5 in the next 10 days on the
basis of history and far-field triggering theory appear to be: Papua New Guinea (2)
Jalisco, Mexico (3)
Northern Chile (2)
South Indian Ocean (34S 57E) (2)
No. Italy/Austria (2) 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 Sandwich Islands (1)
South Atlantic Ocean (2)
Rat/Near Islands (2)
Western Iran (1)
Southern China (2)
Taiwan (1) Areas of U.S. and Canada where triggering may occur (Ml>=3.5) Near/Rat Islands , Andreanoff Islands
Southern/Central California - between 33 and 38N 114-122W
There have been 3 large or moderate events in this area following
strong earthquake in Mindanao - the Ms 6.1 at Mammoth Lakes,
a Ml 6.0 at Twenty-nine Palms and a Ml 4.0 near San Francisco.
This area is near the core-mantle shadow zone boundary from both
Hindu Kush and Mindanao, an area where seismic energy is concentrated
after large events. A moderate event is certainly possible in the
next 10 days.
Northeast - Maine
The largest event in Main occurred several days after a strong
Mindanao earthquake in 1918. Could be an area to watch.
Pacific Northwest - Two mild to moderate events have occurred
in the Tacoma/Seattle area of Washington in temporal association
with Mindanao earthquake. Another area where a mild earthquake is
potentially capable of happening at this time. SUMMARY: 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.
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