TWO MODERATE EARTHQUAKES (ML 5.0, 4.9) HIT OPPOSITE ENDS OF NEW ZEALAND

SUMMARY

Two moderate earthquakes hit on the north and south ends of the
North and South Islands respectively this morning (NZST). These were
about 80 km west of Te Anau, South Island (Ml 4.9) and on North
Island about 30 km NW of Taupo. New Zealand often shows strong
increases in seismic activity following strong geomagnetic storms.
These two events are part of a regional activation of New Zealand
which began after the Guam event on October 12 and have included
earthquakes of Mw 6.8 off the northeast coast, 5.9 near Hastings,
North Island, a swarm near Seddon, South Island yesterday and
a Ml 4.8 on South Island several days ago. Both events today
could be considered either regional aftershocks or far-field
aftershocks from Guam and the Banda Sea.

GLOBAL

Global activity was moderately high today with earthquakes of
MB>=5 occurring in New Ireland (Mb 5.2); the Mariana Islands (Mb 5.1);
the Talaud Islands (Mb 5.3); and the Bali Sea (Mb 5.4 or 5.0).
Since last report, earthquakes of Mb>=4 also occurred in New
Zealand (Ml 4.9, 5.0); the Fiji Islands (Mb 4.1); Solomon
Islands (Mb 4.5); Tonga (Mb 4.6); Irian Jaya (Mb 4.3), off Eastern
Honshu, Japan (Mb 4.3), in the Komandorsky Islands (Mb 4.4) and
Taiwan (Ml 4.1).
In the western hemisphere a Mb 4.6 occurred in the central
Aleutian Islands and a Ml 4.3 in the southern Mid-Atlantic Ridge.
Most of these events could be considered far-field aftershocks
because of their distance and placement with respect to New
Zealand, Guam and the Banda Sea.

U.S./CANADA

Activity since the proton storm began has been relatively quiet
in the U.S./Canada region. The strongest earthquake recorded occurred as
a Mb 4.6 in the Central Aleutian (Andreanoff) Islands.
In the California/Nevada region only two earthquakes of Ml>=2
have occurred since the last report - these were in the Bishop
CA area southeast of Mammoth Lakes (Ml 2.5) and in Portola Valley
south of San Francisco (Ml 2.6).
No other areas of the U.S. or Canada reported events of Ml>=2
today.

NEW ZEALAND

As reported in the summary (above), seismic activity in the
New Zealand area remained at high levels with two new epicenters
experiencing earthquakes of Ml 4.9 (Te Anau, South Island) and
Ml 5.0 (Taupo area, North Island). Yesterday two earthquakes
were also recorded in the region - a Ml 5.0 in the aftershock
zone of the August 22 mainshock and a Ml 4.2 further north near
the southern end of the Kermadec Islands.
The on-line seismogram showed the large events today well. Several
minor events (probably aftershocks of the events off the northeast
coast) could also be seen on today's record.

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

GEOMAGNETIC/SOLAR FIELDS

The strong geomagnetic storm which began at 16:48UT on October 21
has now faded to quiet geomagnetic conditions. This level of
geomagnetic activity is expected to continue for the next day
by SEC to be followed by the arrival of a new CME from the X-flare
which occurred yesterday. Seismic activity is expected to be
low in North America at least through tomorrow when the new CME
hits. After that, provided no new proton storms begin, electron
currents in the ionopshere will have a chance to organize and
strong increases in seismicity may occur including at least one event of
Mb>6.
There were two M-Class flares observed on the sun today with
the following parameters:

Flare # START MAX END CLASS

5650 + 0013 0023 0035 M1.3
5690 + 0211 0223 0234 M6.5

The first was immediately followed by the largest earthquake of the
day (Mb 5.3 at 00:40 UT) in the Talaud Islands, Indonesia and by earthquakes
near Holliser (Ml 1.3 at 00:47) and Arvin (Ml 1.6 at 00:42UT) in California.
No seismic activity has been reported associated with the second flare.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20011023events.txt

TROPICAL STORMS

Tropical Storm Narda continues moving directly towards Hawaii in the
Central Pacific. It looks like it might be a direct hit on about
Thusrsday. An increased rate of associated seismicity in Hawaii is
expected. Narda is currently about 15N 140W.

For tracking details see:
http://www.wunderground.com/auto/HurricaneSite/tropical/tracking/ep200121.html

Typhoon Podul is located WSW of Wake Island and is tracking
WNW. Current position is about 15N 157E about 1000 km east of
Guam.

For additional information see:
http://www.wunderground.com/auto/HurricaneSite/tropical/wp200101.public.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 24 is eight days after the beginning the 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

Pacific-Antarctic Ridge MB>=4.0 58 2.0 0.05
Central So America MB>=4.0 23 2.3 0.04
Mt ST. Helens MB>=0.0 40 3.0 0.01

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

Siberia MB>=4.0 -37 -2.0 0.05

EARTHQUAKE LISTINGS

GLOBAL

NEW ZEALAND

O: 23Oct2001 15:37 45.2S 166.8E ML=4.9 IGNS W of Te Anau, N.Z.
O: 23Oct2001 19:40 45.1S 166.9E ML=4.3 IGNS W. of Te Anau, N.Z.
Note: (IGNS) Likely to have been felt in Fiordland.
Note: (ED) This can be considered a far-field aftershock from
Guam (it lies 61 degrees from that event) and from the N.Z. North
Island event of October 21. The New Zealand far-field forecasat
had specifically located this event as:

"9-10 degrees: Milford Sound area, N.Z"

O: 23Oct2001 19:38 38.6S 175.8E ML=5.0 IGNS NW of Taupo, N.Z.
Note: (IGNS) May have been felt along the east coast of the North Island.
Note: (ED) This can be considered a regional aftershock from the
event off the NE coast of New Zealand (Ms 6.8) or a far field
aftershock from both Guam and Banda lying 58-59 degrees from these
two mainshocks and 3 degrees from the N.Z. shock. The far-field forecast
had stated:

From New Zealand:

"0-5 degrees: Classical and locally triggered aftershocks. Earthquakes in this
region are commonly followed by numerous aftershocks within 5 degrees.
It is likely that several of these will be Mw>5.0 and at least
one of MW>=5.5"

From Guam:

"New Zealand - North Island 37S 177E
Earthquakes of Mw>=6.5 have occurred within 2 weeks in New
Zealand after each earthquake in Guam since 1930 (with the

one exception of 1975). The probability of such an earthquake
in the next week to 10 days is considered very high. Local
personnel should be on watch, especially on North Island."

and from the Banda Sea:

"59-61 degrees: ...New Zealand (esp. of E. Coast of No. Island)"

Forecast magnitude bands have been adjusted for far-field effects.

O: 22Oct2001 02:46:27 35.8S 179.6W MB=4.2 NEIS EAST OF NORTH ISLAND, N.Z.

O: 22Oct2001 01:28:57 37.1S 179.3E MB=5.0 NEIS OFF E. COAST N. ISL, N.Z.

SOUTH PACIFIC ISLANDS

O: 23Oct2001 07:26:28 16.8S 178.7W MB=4.1 NEIS FIJI ISLANDS REGION

O: 23Oct2001 03:46:32 4.8S 153.6E MB=5.2 NEIS NEW IRELAND REGION, P.N.G.

O: 22Oct2001 23:25:22 6.6S 155.0E MB=4.5 NEIS SOLOMON ISLANDS

O: 22Oct2001 22:10:37 15.9S 173.9W MB=4.6 NEIS TONGA ISLANDS

ASIA

O: 23Oct2001 12:04:52 14.3N 145.2E MB=5.1 NEIS MARIANA ISLANDS

O: 22Oct2001 22:49:47 4.4S 139.0E MB=4.3 NEIS IRIAN JAYA, INDONESIA

O: 23Oct2001 00:40:35 3.7N 126.6E MB=5.3 NEIS TALAUD ISLANDS, INDONESIA
O: 22Oct2001 19:58:21 1.7N 126.3E MB=4.8 NEIS NORTHERN MOLUCCA SEA

O: 22Oct2001 19:44:55 37.1N 144.2E MB=4.3 NEIS OFF E COAST HONSHU, JAPAN

O: 22Oct2001 00:49:54 3.1S 103.1E MB=4.0 NEIS S SUMATERA, INDONESIA

O: 23Oct2001 11:34:08 53.1N 159.8E mb=4.0 GSR NEAR EAST COAST OF KAMCHAT

O: 23Oct2001 16:21:40 8.9S 117.0E mb=5.4 GSR SUMBAWA REGION, INDONESIA
O: 23Oct2001 16:21:40 7.6S 117.2E mb=5.0 NEIS Bali Sea, INDONESIA

O: 22Oct2001 20:54:56 53.7N 168.4E MB=4.4 NEIS KOMANDORSKY ISLANDS REGION

O: 24OCT2001 01:47:41 23.5N 120.3E ML=4.1 CWB Chiayi, Taiwan

CENTRAL/SOUTH AMERICA

O: 22OCT2001 19:40:01 7.2N 82.6W MC=4.2 CASC South of Panama, C.A.

O: 23OCT2001 06:39:29 11.5N 85.6W MC=3.1 CASC Nicarauga, C.A.

O: 23OCT2001 13:31:53 9.2N 84.0W MC=3.2 CASC Costa Rica, C.A.

O: 22Oct2001 11:09:27 13.0N 87.8W MB=3.7 NEIS NEAR COAST OF NICARAGUA

O: 22Oct2001 05:55:00 21.0S 68.0W MB=4.4 NEIS CHILE-BOLIVIA BORDER REG
O: 22Oct2001 03:36:34 22.0S 68.4W MB=4.2 NEIS NORTHERN CHILE

O: 19OCT2001 01:34:53 6.8N 73.1W Mc=3.7 ULA Dpto. Santander, Colombia.

EUROPE

O: 22OCT2001 15:16:48 51.7N 3.3W ML=1.6 BGS BARGOED,MID, ENGLAND

O: 22OCT2001 19:15:15 38.3N 27.2E ML=3.6 NOA GREECE

O: 18OCT2001 19:51 42.4N 8.1W MB=3.0 IGN N. of LEIRO GRANDE, Spain

O: 22OCT2001 20:24:32 43.1N 1.1W ML=2.0 STR SE SAINT-JEAN-PIED-DE-POR, FRAN

O: 22OCT2001 12:16:01 47.4N 6.8E ML=2.2 STR SE BELFORT, FRANCE

O: 21OCT2001 19:59:56 62.1N 25.4W ML=3.2 ISO Iceland

O: 21OCT2001 10:02:44 66.2N 16.7W ML=2.1 ISO Iceland
O: 19OCT2001 18:55:51 66.3N 16.7W ML=2.6 ISO Iceland
O: 19OCT2001 19:03:38 66.2N 16.7W ML=2.8 ISO Iceland

O: 18OCT2001 21:42:42 69.2N 14.8W ML=3.1 ISO Iceland

OCEANIA

O: 23Oct2001 03:44:29 19.9S 11.7W MB=4.3 NEIS S MID-ATLANTIC RIDGE

U.S/CANADA

CALIFORNIA/NEVADA

O: 23OCT2001 20:01:42 37.5N 118.4W ML=2.5 NCSN N of Bishop, CA

O: 23OCT2001 19:50:49 37.3N 122.2W ML=2.6 NCSN S of Portola Valley, CA

O: 23OCT2001 19:31:33 36.1N 115.4W ML=1.4 NCSN NE of Mountain Springs, NV

O: 23OCT2001 19:31:19 33.1N 117.2W ML=1.3 SCSN SSE of Vista, CA

O: 23OCT2001 19:20:27 38.7N 117.2W ML=1.7 NCSN S of Washington, NV

O: 23OCT2001 17:39:11 34.0N 116.9W ML=1.9 SCSN N of Banning, CA

O: 23OCT2001 10:35:44 37.9N 122.3W ML=1.0 NCSN N of Berkeley, CA

O: 23OCT2001 13:43:43 38.8N 122.7W ML=1.7 NCSN ESE of The Geysers, CA
O: 23OCT2001 6:41:24 38.8N 122.8W ML=2.0 NCSN NE of The Geysers, CA

O: 23OCT2001 12:17:01 38.9N 116.3W ML=1.9 NCSN NW of Pritchards Station, NV

PACIFIC NORTHWEST/CANADA

O: 22OCT2001 22:41:07 47.5N 120.7W ML=1.4 PNSN W of Wenatchee, Wa

O: 22OCT2001 15:59:07 52.6N 131.9W ML=2.3 PGC S Sandspit BC

ALASKA

O: 23Oct2001 06:05:38 51.2N 175.4W MB=4.6 NEIS ANDREANOF ISL, ALEUTIAN
O: 23Oct2001 06:05:35 51.0N 175.3W MS=4.0 GSR ANDREANOF ISLANDS, ALEUTIA