MS 6.1 EARTHQUAKE IN PAPUA NEW GUINEA MAY BREAK LOCAL SEISMIC QUIET PERIOD

SUMMARY

The largest event of the day was an Ms 6.1 off the northern Coast of
Papua New Guinea. Although seismicity along the north coast of Papua New
Guinea is fairly strong compared to many areas of the world, the
event today occurred in an area where recent activity has been fairly
light. The last earthquake of Ms>=6 within 100 km of today's event
was on Nov. 16, 1981 (Ms 6.9). It was preceded by a foreshock of
Ms 6.6 on Sept. 26, 1980. No such events occurred between 1968 and 1980.
In 1968 a series of events also occurred in the region beginning
with a Ms 6.1 on Sept. 8; a Ms 6.5 on Sept. 27 and a Ms 7.5 on
Oct 23, 1968 (44 days after the first event in the series).
There has been a tendency for events of Ms>=6 in the region to
cluster in time. From 1935-1939 - 3 events; 1940-1960 - no events;
1961-1962 - 4 events; 1962-1965- no events; 1965 - two events;
1966-1967 - no events; 1968 - 3 three events; 1969-1979 - no events;
1980 - 1981 - two events; 1982-2000 - no events. Since the last
period which was 18 or more years between events occurred in 1940-1960
and was followed by 9 events between 1961 and 1968 and ending with the
largest event ever recorded in the region (Ms 7.5 on Oct 23, 1968),
the 18-year quiet and the history of clustering in time may indicate
this is a region to watch for a high rate of activity over the next
several years.

GLOBAL

Since it is difficult to find global seismic data over weekends,
as many teleseismic networks do not report, I am attaching a listing
of events which have been reported from local and teleseismic
sources since the last report (see end of report).
The most active region was Indonesia which saw 8 earthquakes of ML>=4.9
over the past 24 hours. Four of these (Ml 5.9, 4.9, 4.9, 5.1)
occurred in the region south of Bali to Sumbawa Island. An Ms 4.7
was also recorded in Halmahera and an Ms 4.1 (SR 5.1) in the Celebes
in addition to the Papua, New Guinea earthquake (Ms 6.1).
A small earthquake (Ml 3.9) was felt in the Shillong, Assam
region of northern India yesterday.
Three earthquakes of Ml>=4 were recorded in Central America -
two in Guatemala (Ml 4.1, 4.6) and one in the Gulf of Tehuantepec (Ml
4.0). These may have been affected by the approach of Hurricane
Iris to the region.
There was also a lot of activity in the region of Greece over the
past 2 days including events in Northern Greece (Ml 4.4, 3.6, 3.6);
the Aegean Sea (ml 3.4, 3.4); Crete (Ml 3.9, 4.1); and the Ionian Sea
(Ml 3.5, 3.7, 3.5). An Ml 3.7 also occurred in the Izmir region of
Turkey.

U.S./CANADA

Most networks were down for the weekend and the coming holiday on
Monday. The largest earthquake reported today was a Ml 3.0 NW of
Paradise, CA. An Ml 2.9 was also recorded near Silver Lake, CA,
continuing the current increased activity in the L.A. region. Other
events in the L.A. region today included quakes near Newport Beach (Ml 2.2);
MacArthur Park (Ml 1.4); and Beverly Hills (Ml 2.3). It has been unusual
for 3 events of Ml>=3 to occur in the L.A. area in a given day during
2001. This occurred on only two other days this year - September 3 when
2 aftershocks of a Ml 2.9 occurred and January 14, 2001 when there was
a Ml 4.0 and Ml 4.3 in the area.
Several other areas also showed unusual activity. A line of events at
122.0 W included yesterday's Ml 3.0 at Saratoga, CA (37.2N). Other events
occurring today at 122.0W were at 39.5N (Willows, Ml 1.9); 37.6N (Union City
Ml 2.0) and at 37.9N (Pleasant Hill, Ml 1.4).
Besides the earthquake at Paradise, CA, a Ml 2.4 also occurred near
Portola and Willits (Ml 2.1) in northern California.
Central California also saw activity near San Juan Bautista (Ml 2.1, 2.1)
and the Ocotillo/Calexico region of Southern California was active with
events of Ml 2.1, 1.9, 2.0., 2.1, and 1.9. Other activity in California
occurred in the Lake Isabella region (Ml 1.9, 1.9); and Joshua Tree (Ml 2.0).

It was a comparatively active day for seismicity in the California/Nevada
region. To 19:00 UT PDT 15 events of Ml>=1.5 had been recorded in 13 different
regions. The seismicity of the region increased considerably from
September 24- October 3, coincidentally with a series of strong
geomagnetic storms. From October 4-5, as the storms dissipated,
the seismicity in the region also declined.
During the period 25 August to September 23, at at least 15
events were recorded in the region o only one day - 16 on September 2.
Starting on the 24th of September through October 3, all but one day
saw at least 15 such events in the region. The period of the geomagnetic
storminess was from 23 September through October 3. Table 1 below
compares the number of events of Ml>=1.9 in the California/Nevada
area (from web-based lists) with the geomagnetic A-index for the
past 1.5 months. I leave it to the reader to decide if the coincidence
between increased geomagnetic storminess and increased numbers of
events in the California/Nevada region is merely coincidence or
if, as we have speculated here, there is some physics relating the
two.

Table 1: Numbers of events in the California/Nevada region of Ml>=1.9
since August 25, 2001 (from on-line data):

Data source:

http://quake.usgs.gov/recenteqs/Quakes/quakes0.html
http://sec.noaa.gov/ftpdir/indices/old_indices/2001Q3_DGD.txt
http://sec.noaa.gov/ftpdir/indices/old_indices/2001Q4_DGD.txt

YEAR MO DA #E MIDLAT A-INDEX

2001/08/25 7 10
2001/08/26 7 9
2001/08/27 3 14
2001/08/28 13 6
2001/08/29 4 5
2001/08/30 6 8
2001/08/31 10 11
2001/09/01 6 4
2001/09/02 16 2
2001/09/03 7 12
2001/09/04 11 11
2001/09/05 6 6
2001/09/06 7 3
2001/09/07 13 4
2001/09/08 7 5
2001/09/09 9 7
2001/09/10 13 5
2001/09/11 10 12
2001/09/12 12 9
2001/09/13 8 11
2001/09/14 10 8
2001/09/15 5 10
2001/09/16 9 7
2001/09/17 3 6
2001/09/18 12 7
2001/09/19 11 8
2001/09/20 12 7
2001/09/21 10 3
2001/09/22 3 6
2001/09/23 5 18
2001/09/24 16 5
2001/09/25 20 17
2001/09/26 20 13
2001/09/27 18 9
2001/09/28 21 10
2001/09/29 15 19
2001/09/30 11 15
2001/10/01 22 25
2001/10/02 18 24
2001/10/03 15 26
2001/10/04 9 9
2001/10/05 2 10
2001/10/06 10 6
2001/10/07 15

No events of Ml>=3 were reported from Canada, Alaska, the east or
central U.S. or Hawaii. A Ml 2.1 occurred near the Dalles, Oregon.

Many areas of California were expected to see increased seismicity
today because they are statistically more active at the point in
the Lunar cycle (see yesterday's report). This may have had an effect
on the local seismicity today as well.

NEW ZEALAND

The on-line seismogram from IGNS shows a moderate (Ml 3.5-4.5) earthquake
in New Zealand, probably on North Island occurring about 2:00 p.m. NZDT
(about 7:00 PDT). IGNS has not reported parameters for this event
at this writing. Otherwise, traces of only a few minor events could be
found on the seismogram over the past 24 hours.

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 very quiet conditions today.
There were no X- or M- class flares observed on the sun. No
seismic watches based on geomagnetic effects are current.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20011007events.txt

TROPICAL STORMS

Iris was upgraded to Category 1 Hurricane status today. Hurricane
Iris is taking a path slightly south of that originally anticipated and
is expected to hit the eastern coastline of Guatemala and Belize
tomorrow (8-9 October) as a category 2 hurricane. Two earthquakes were
recorded in Guatemala today with Ml 4.6 and 4.1. The low atmospheric pressure
associated with the hurricane system may have allowed enough uplift of the
continental plate near Guatemala/El Salvador for these earthquakes to have been
triggered due to reduced normal stresses across the the subduction zone.
For trackline data see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200111.html

Tropical Storm Jerry is hitting the Windward/Leeward Islands in
the Caribbean today. It is expected to track northwestward south
of Puerto Rico, Hispaniola and Cuba becoming a category 1 hurricane
on Tuesday. Related seismicity is likely to be relatively minor
because the path follows directly on Hurricane Iris, and Jerry
is expected to be the weaker of the two storms.
For trackline data see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/at200112.html

TIDAL TRIGGERING (LUNAR)

Statistics have been done on many regions of the world in terms of
relationship of significant regional earthquakes with respect to lunar cycle.
Each report will summarize the most likely areas for tidal triggering
for the next day based on these statistics. It is expected
that tidal triggering will add an additional 0.5 - 1.0 units of
magnitude to events which are about to occur or will move these
events forward in time by up to seven days in the regions where
there is a statistical correlation between lunar phase and
earthquakes.

October 8 is 21 days after the previous New Moon.
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

Central California MB>=0.0 37 2.4 0.04
Central California MB>=3.0 18 2.2 0.05
Central US MB>=1.0 79 3.4 0.01
East US MB>=1.0 12 2.2 0.05
N So. America MB>=4.0 19 2.1 0.05
Rocky Mountains MB>=4.0 88 3.4 0.01
San Andreas MB>=0.0 17 2.8 0.02
San Andreas MB>=2.0 64 2.9 0.02
San Andreas MB>=3.0 38 2.7 0.02
Geysers MB>=0.0 7 2.6 0.03
Mammoth Lakes MB>=0.0 62 2.8 0.02
Utah MB>=0.0 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

China MB>=4.0 -19 -2.3 0.05
Global MB>=6.0 -11 -1.9 0.05
NW Europe MB>=4.0 -11 -2.4 0.04

EARTHQUAKE LISTING FROM WEB SOURCES FOR PAST 24 HOURS

ASIA

O: 07Oct2001 02:21:10 3.2S 143.0E MS=6.1 NEI NEAR N COAST OF NEW GUINEA
O: 07Oct2001 02:21:16 2.7S 142.5E MS=5.7 GSR NEAR N COAST OF NEW GUINEA

O: 07Oct2001 12:13:06 0.7N 124.4E MS=4.1 GSR MINAHASSA PENINSULA, SULAW

O: 07Oct2001 03:44:20 1.7S 127.5E MS=4.7 GSR HALMAHERA, INDONESIA

O: 07OCT2001 12:37:40 11.6S 115.0E SR=4.9 AEIC1 S DENPASAR, INDONESIA
O: 07OCT2001 12:11:40 11.5S 115.0E SR=4.9 AEIC1 S DENPASAR, INDONESIA

O: 07OCT2001 12:13:10 2.3S 125.0E SR=5.0 AEIC1 SE P.LELENG, INDONESIA

O: 06OCT2001 23:02:30 8.6S 116.2E SR=5.1 AEIC1 SE MATARAM, INDONESIA

O: 06OCT2001 19:53:20 8.3S 113.5E SR=5.7 AEIC1 SE LUMAJANG, INDONESIA

O: 06oct2001 19:27:?? 26.0N 091.5E ML=3.9 ASC Approx. SE of Makariagaon
Note: ASC Earthquake Report
According to reports by the Press Trust of India (PTI)
a mild earthquake was felt in Shillong (Meghalaya),
India at 00:57 IST on October 7th, 2001. The
seismological department in Shillong stated that the
quake which had a magnitude of 3.9, was centered
75 kilometers NE of Shillong in Assam, Shillong is located
at 25.6N 91.85E.

Please note that the location given in the "ASC
Recent Earthquakes" list is based on this press release
and is an estimate of where the epicentre is.

CENTRAL/SOUTH AMERICA

O: 07OCT2001 05:05:48 15.5N 95.8W ML=4.0 SSN GOLFO DE TEHUANTEPEC, MX

O: 07OCT2001 09:56:42 10.6N 86.3W MC=3.0 SIS NICARAGUA, C.A.
O: 07OCT2001 15:20:28 11.4N 87.2W MC=3.1 SIS NICARAGUA, C.A.
O: 07OCT2001 01:30:23 11.3N 86.0W MC=3.2 SIS NICARAGUA, C.A.

O: 07OCT2001 14:03:36 13.1N 89.0W MC=4.1 SIS GUATEMALA, C.A.
O: 07OCT2001 02:18:17 13.4N 89.9W MC=4.6 SIS GUATEMALA, C.A.
EUROPE

O: 08OCT2001 01:05:26 38.6N 40.5E ML=3.1 KAN GENC, TURKEY

O: 06OCT2001 04:58:26 41.6N 20.9E ML=3.2 NOA NORTHERN GREECE
O: 06OCT2001 05:07:21 41.0N 20.8E ML=3.6 NOA NORTHERN GREECE
O: 06OCT2001 07:26: 1 40.6N 21.0E ML=4.4 NOA NORTHERN GREECE
O: 06OCT2001 07:37:32 40.6N 21.1E ML=3.6 NOA NORTHERN GREECE

O: 05OCT2001 21:20: 7 39.0N 24.1E ML=3.4 NOA AEGEAN SEA, GREECE
O: 06OCT2001 06:09:20 38.9N 24.5E ML=3.4 NOA AEGEAN SEA, GREECE

O: 06OCT2001 16:14:58 36.4N 28.3E ML=3.7 NOA TURKEY

O: 06OCT2001 12:03:55 35.3N 26.8E ML=3.9 NOA CRETE AREA, GREECE
O: 06OCT2001 22:18:24 35.2N 26.7E ML=4.1 NOA CRETE AREA, GREECE

O: 05OCT2001 22:30:21 37.9N 20.9E ML=3.5 NOA IONIAN SEA
O: 06OCT2001 13:07:28 37.5N 20.9E ML=3.7 NOA IONIAN SEA
O: 06OCT2001 14:19:19 37.5N 20.7E ML=3.5 NOA IONIAN SEA
O: 07OCT2001 02:36:56 37.2N 20.6E ML=3.0 NOA IONIAN SEA
O: 07OCT2001 02:43:19 37.3N 20.5E ML=2.9 NOA IONIAN SEA
O: 07OCT2001 03:15:44 37.3N 20.8E ML=3.1 NOA IONIAN SEA

U.S/CANADA

CALIFORNIA/NEVADA

O: 06OCT2001 23:13:17 36.1N 117.9W ML=2.6 NCSN NE of Coso Junction, CA

O: 06OCT2001 22:53:02 37.0N 121.7W ML=2.0 NCSN WSW of Gilroy, CA

O: 8OCT2001 0:09:47 32.7N 115.4W ML=1.9 SCSN ENE of Calexico, CA
O: 07OCT2001 21:25:54 32.7N 115.4W ML=2.1 SCSN ENE of Calexico, CA
O: 07OCT2001 22:51:41 32.7N 115.4W ML=2.0 SCSN NE of Calexico, CA
O: 07OCT2001 16:52:00 32.7N 115.4W ML=1.9 SCSN NE of Calexico, CA

O: 8OCT2001 1:36:19 33.3N 117.6W ML=1.0 SCSN S of San Clemente, CA

O: 07OCT2001 18:58:36 33.3N 115.8W ML=1.4 SCSN W of Bombay Beach, CA

O: 07OCT2001 18:58:20 33.5N 117.9W ML=2.2 SCSN S of Newport Beach, CA
O: 7OCT2001 2:52:21 33.9N 118.1W ML=1.7 SCSN NW of Cerritos, CA

O: 07OCT2001 23:43:20 34.0N 116.3W ML=2.0 SCSN S of Joshua Tree, CA

O: 07OCT2001 17:44:12 34.0N 118.3W ML=1.4 SCSN E of Macarthur Park, CA
O: 07OCT2001 8:53:41 34.1N 118.4W ML=2.3 SCSN NE of Beverly Hills, CA
O: 07OCT2001 17:29:07 34.1N 118.3W ML=2.9 SCSN E of Silver Lake, CA

O: 7OCT2001 5:16:16 35.8N 118.4W ML=1.9 SCSN N of town of Lake Isabella, CA
O: 7OCT2001 5:24:48 35.8N 118.4W ML=1.9 SCSN N of town of Lake Isabella, CA

O: 07OCT2001 14:33:42 36.8N 121.5W ML=2.1 NCSN S of San Juan Bautista, CA
O: 8OCT2001 1:41:39 36.8N 121.5W ML=2.1 NCSN S of San Juan Bautista, CA

O: 7OCT2001 5:08:09 36.9N 121.7W ML=1.6 NCSN ENE of Watsonville, CA

O: 7OCT2001 1:21:30 37.2N 122.0W ML=1.4 NCSN SSW of Saratoga, CA

O: 07OCT2001 17:48:47 37.6N 122.0W ML=2.0 NCSN N of Union City, CA
O: 8OCT2001 0:02:43 37.9N 122.0W ML=1.3 NCSN SE of Pleasant Hill, CA

O: 07OCT2001 21:55:37 39.3N 123.4W ML=2.1 NCSN SSW of Willits, CA

O: 07OCT2001 16:22:12 39.5N 122.0W ML=1.9 NCSN ESE of Willows, CA

O: 07OCT2001 20:53:22 39.8N 120.7W ML=2.4 NCSN WSW of Portola, CA

O: 07OCT2001 21:13:32 39.8N 121.7W ML=3.0 NCSN NW of Paradise, CA

PACIFIC NORTHWEST/CANADA

O: 07OCT2001 14:52:07 45.8N 120.7W ML=2.1 PNSN NE of The Dalles, OR

O: 06OCT2001 11:04:26 48.8N 122.1W ML=1.8 PNSN E of Deming, WA
O: 06OCT2001 11:03:22 48.8N 122.1W ML=2.1 PNSN E of Deming, WA
O: 06OCT2001 10:52:09 48.8N 122.1W ML=3.0 PNSN ESE of Deming, WA
O: 06OCT2001 10:34:12 48.8N 122.1W ML=1.9 PNSN E of Deming, WA

O: 05OCT2001 21:55:58 47.8N 122.5W ML=1.2 PNSN NE of Poulsbo, WA

ROCKY MOUNTAIN AREA

O: 07OCT2001 12:47:22 45.7N 112.1W MD=0.9 MBMG HELENA AREA,MONTANA
O: 07OCT2001 12:35:27 45.7N 112.1W MD=1.9 MBMG HELENA AREA,MONTANA

O: 07OCT2001 04:39:20 44.8N 111.4W MD>1.0 MBMG HEBGEN LAKE, MONTANA

ALASKA

O: 06Oct2001 03:19:00 55.9N 154.4W MB=4.6 NEIS SOUTH OF ALASKA