STRONG EVENTS IN UTAH - Ml 3.5, GULF OF CALIFORNIA (Mb 4.7), NO CALIFORNIA Ml 4.6

SUMMARY

Significant regional events occurred in a number of areas of
the western North America today. These ranged from a Ml 3.5 late
tonight near Coalville, Utah, the largest event in Utah since
November, 2001 to a Ml 4.6 off the Coast of Northern California
to an Mb 4.7 in the northern Gulf of California area just south
of the California border with Mexico. It seems quite possible that
this flurry of large to moderate events in the region was related
to the strong geomagnetic storm of March 24.
The last previous event in Utah of Ml>=3.5 occurred in close
connection with the last major geomagnetic storm which also occurred
in late November, 2001.

GREAT GOOD FRIDAY EARTHQUAKE OF 1964 - OCCURRED ABOUT THIS TIME 38 YEARS AGO

The largest earthquake ever recorded in the region of North America
occurred late on the evening of March 27 (Alaska time) in 1964. This
Mw 9.6+ earthquake has been the subject of extensive analysis and
study over the years. Nearly 100 years earlier one of the largest
events to be recorded on Hawaii occurred in 1868 (Mw 7.0) but
was followed by the largest a week later (Mw 7.9) on April 4, 1868.
Further details of these two events are sampled in the
"Tomorrow in earthquake History section below".
The Alaska earthquake occurred at about 7:36 p.m. PST, the Hawaii
earthquake occurred near mid-day. Both triggered occasionally
large tsunamis.

GLOBAL

Seismicity around the world today was uneventful except for a
Ms 5.7 this evening in the region of Halmahera, south of the
Philippines. This is probably a regional aftershock of the
Mw 7.5 Mindanao earthquake earlier this month.
Since the strong geomagnetic storm on March 24, the world's
ocean rift systems have become active. After two weeks during
which no mid-ocean events were recorded during mid-March, in
the past three days earthquake have abounded in the mid-Ocean
rift areas. These have included events today in the ridge
near Easter Island (Mb 4.6); and yesterday to the east of
this location (Mb 4.9). Both of these are southeast of Easter
Island. Mid-Oceans or ocean rift events have also occurred
in the Gulf of California (Mb 4.4, 4.7); at Hawaii (Mb 3.5);
at Revillo Gigedo Islands west of Mexico (Mb 4.2); in the Northern
Mid-Atlantic Ridge (Mb 4.4, 5.2) and on the West Chile Rise (Mb 5.1).
An earthquake in Nevada in a similarly high heat flow area registered
Ml 4.4. It is quite common to see this type of explosion of
seismicity in high-heat flow regions following strong geomagnetic
storms. Volcanism is also commonly associated with these storms.
It is unfortunate that there are currently no sites available
on the web where current volcanic eruptions are listed as they
occur - a situation very different from that of earthquake activity.
Volcanism usually increases about 4-6 days after strong geomagnetic
storms (apparently there is a preparation time for heated
magma to result in an eruption). This would mean that volcanism
should increase over the Easter holiday weekend - i.e. the
next three days and should be strongest along the western
Pacific region.
Other earthquakes listed today occurred off the Coast of
Northern California (Mb 4 to 4.6); in the Kermadec Islands
area (Mb 4.2) in the Kuril Islands (Mb 5.1) and as aftershocks
in the region of the Hindu Kush Mb's 6.1. Tonight four earthquakes
occurred off the east coast of Honshu, Japan in the Mj 4-5 range,
the first strong grouping in this area in several weeks.
This area had been expected to see FFA from the Ryukyu Islands
earthquake as noted in the FFA forecast:

"17-19 degrees: Central east coast Japan,..."

and

"The most likely events of Mw>=5 in the next 10 days appear to be:

... off East Coast of Honshu, Japan"

U.S./CANADA

The largest events in the U.S./Canada region today were at
opposite ends of the state of California and included a Mb 4.7
in the northern Gulf of California and a Mb 4.6 off the coast
of Northern California. The Gulf has seen three moderate earthquakes
in the past two days of Mb 4.5 and 4.4, this is the largest thus
far. The area is 103 degrees from the Ryukyu earthquake - an area
near the core-mantle shadow zone boundary where strong FFA activity
is expected as noted in the FFA forecast:

"...the core-mantle shadow zone boundary does pass from the Gulf of
California up through the SW to Missouri and into southern Canada. These
areas are areas of generally low seismicity anyway, but small FFA are
possible here."

and

"103-107 degrees***: Gulf of California ..."

Also occurring at 103-107 degrees from Ryukyu has been a series of
light shocks off the coast of Spain and Portugal over the past
several days.
The strongest activity outside of these two zones in the U.S.
occurred in the central California area near San Ramon where a
series of light Ml 2.1, 1.9 .. shocks preceded a Ml 2.9 this
afternoon. Earthquakes of Ml>=2 also occurred in Central and
Northern California near the Geysers (Ml 2.0), Bishop (Ml 2.0)
and San Juan Bautista (Ml 2.3). In southern California activity
was concentrated in the Joshua Tree (Ml 3.0, 2.1) and Calexico
zones (Ml 2.9, 2.9, 2.4).
The strongest earthquake outside of the California area was
a Ml 3.5 about an hour ago this evening in the Coalville, Utah
area. This is the strongest earthquake in the region of Utah since
November 19, 2001 when a Ml 3.7 hit the area near Sevier, Utah.
This region is also part of the high heat-flow Basin and Range
province and could be reactive to strong geomagnetis storms.
One earthquake of Ml 3.6 was reported in the Cook Inlet region
of Alaska this morning as were two others of Ml about 3.
An event of Ml 2.2 was also reported by GSC in southern Ontario
this afternoon. This was also an area at the C-M shadow zone
boundary and an area where FFA were expected.

NEW ZEALAND

Two moderate earthquakes have been listed in the region of
New Zealand since the last daily report. These were in the
Kermadec Islands - Mb 4.2 and as a Ml 3.8 south of Blenheim
on South Island this morning. New Zealand falls within 30 degrees
longitude of the sub-solar longitude as the geomagnetic storm
began and was under seismic watch conditions at this time.

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 quiet today. There were no
solar flares of M- or X-class observed. Larger earthquakes
associated with strong geomagnetic storms often occur 4-5 days
after those storms commence.

Flare # START MAX END CLASS

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20020327events.txt

TIDAL EFFECTS

March 30 is the seventeenth 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

Kermadec MB>=4.0 13 1.9 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

Arctic MB>=4.0 -30 -1.9 0.05
Greece MB>=4.0 -9 -2.3 0.05
N Indonesia MB>=4.0 -35 -1.9 0.05
Utah MB>=0.0 -10 -2.0 0.05
Caribbean MB>=4.0 -22 -2.5 0.04

TOMORROW IN EARTHQUAKE HISTORY

GLOBAL:

Two of the largest events in the U.S. occurred on this date.
A Ms 7.0 in Hawaii in 1968 on March 28 was one of only 4 shocks
that size to be located in that state. It was a foreshock to
a M2 7.9 on April 3. The other great quake in the U.S. occurred
on this date (Good Friday) in Alaska in 1964. This is believed
to be the largest earthquake ever recorded in North America.
The strongest earthquake ever recorded in Nebraska followed
the Good Friday Alaska event by several hours and was probably
aided by that earthquake. Also on this date the strongest
event in the southern Idaho region occurred in 1975.
Disastrous earthquakes also killed thousands in Chile and
Turkey on this date. In 1963, 1964 and 1965 March 28 was
marked by uniquely strong and damaging earthquake in
Iceland, Alaska and Chile respectively.

The following events of Mw>=7 have occurred on this date in
recorded history:

MO DA HR MN SC YEAR LATIT LONGIT DEP MW LOCATION

3 28 23 28 0 1868 19.400 -155.300 5 7.0 Hawaii
This was a foreshock to the April 3 event. At Kahuku, a
stone house was destroyed, the chimney of the Mission house
was also destroyed and the walls of the stone church
were cracked. AT Kona stone walls were thrown down, masses of
rock were thrown off the cliff at the bay, stone buildings were
damaged and teh cisterns of the Kona Plantation were cracked.
At Waiohinu, walls were shaken down and the stone church was
cracked from top to bottom. Also felt at Hilo.

3 28 7 49 22 1921 12.500 -87.500 0 7.4 Nicaragua
3 28 3 57 54 1922 -21.000 -68.000 90 7.2 Argentina
3 28 12 38 37 1931 -7.000 129.500 80 7.3 Banda Sea
3 28 12 6 24 1958 36.510 70.980 188 7.0 Hindu Kush/Pakistan
3 28 9 36 5 1961 0.000 124.000 150 7.4 Mindanao, Philippines
3 28 0 15 46 1963 66.290 -19.860 0 7.1 Iceland area
This was one of the largest earthquakes in Iceland in modern times.
Several were injured and there was slight damage in northern
Iceland.

3 28 3 36 14 1964 61.050 -147.480 23 8.5 Central Alaska
See note under U.S./CANADA

3 28 16 33 15 1965 -32.420 -71.100 68 7.4 Central Chile
About 400 persons were killed or missing, 350 others were injured.
and extensive property damage was reported throughout Central Chile.
The mining village of El Cobre completely disappeearted after the
shock shattered a 230-foot dam, cascading two million tons of water
and mud into the town. There was extensive damage to bridges, roads,
and public utilities, and structural damage to thousands of buildings i
in Santiago and Valparaiso. At Llay-Llay, almost every building was
heavily damaged by the earthquake an ensuing fire. Several other
towns north of Santiago also reported extensive damage.

3 28 21 2 23 1970 39.210 29.510 18 7.3 Turkey
1086 killed, 1174 injured, 8,229 buildings destroyed , 5,586
buildings damaged at Gediz Turkey and surrounding areas by this
earthquake and major aftershocks. Felt throughout Anatolia at
Istanbul and on Chios and Lesbos Islands.

3 28 11 0 22 2000 22.338 143.730 127 7.6 Volcano Islands
One of the largest event to occur in this region in recent
history. No reports of damage.

U.S./CANADA

3 28 21 50 0 1913 36.200 -83.700 0 5.3 Kentucky/Tennessee/NC
Near Knoxville, Tenn. Two shocks were felt over an area 70 by 40
miles, with noticeable rise and fall of gournd in some places.
Fire alarms were set off. Knox County Courthouse, a massive structure
trembled for two minutes. Movable objects were overthrown and
bricks fell from chimneys. Nausea was reported by some.

3 28 4 20 26 1933 58.200 -149.000 0 5.6 Southern Alaska
3 28 19 43 16 1949 42.000 -126.000 0 5.8 Off Coast of Oregon
3 28 12 29 15 1961 51.900 -176.150 62 6.2 Andreanoff Islands, Aleutians
3 28 3 10 0 1964 47.900 -113.800 0 5.0 Montana/Idaho
Near Ennis Montana, At Ennis well water was muddied and a large
insulator broke. This was one of several events in the U.S. which
preceded the great Alaska earthquake.

3 28 3 36 14 1964 61.040 -147.730 33 9.3 Central Alaska
This has been called the largest earthquake ever recorded in
the U.S. or Canada at Mw 9.3. It was felt over approximately
700,000 square miles of Alaska, the Yukon and British Colombia,
Canada. This was one of the most violent every recorded and
vertical displacements were found over and area of 200,000 square
miles. On the southeast end of Montague Island vertical
displacement was up to 50 feet.
While uplift was great so was subsidence. The zone of subsidence
covered and area of about 110,000 square miles and included the
western portion sof Prince William Sound and nearly all of Kodiak
Island.
The earthquake generated many tsunamis either directly or through
landsliding. These devastated towsn along the Gulf of Alaska and
in Hawaii and California.
The low population of the area and the time of occurrence when
schools and businesses were closed or uncrowded and low tides conspired
to keep the death at about 131. The greatest damage occurred in
Anchorage 80 miles from the epicenter where there were rock and mud-
slides, slumping, water spouts, liquifaction and sand boils.
There were thousands of felt aftershocks in the months to come
and total cost was estimated at $400 to $500 million.

3 28 10 8 43 1964 43.000 -101.600 16 5.0 Wyoming/Dakotas
A foreshock occurred on March 27. Furniture vibrated and moved at
Van Tassell. Also felt in Nebraska and South Dakota.
This event was felt over a large area of Nebraska, South Dakota,
and border areas of Montana and Wyoming. It was th most widely
felt shock since that of November 15, 1877 and was the first to
center in Nebraska since March 1, 1935. At Alliance, part of a
Chimney cap fell on one residence. A highway about 10 miles
south of Merriamn sustained about 75 cracks and steep banks
reportedly fell into the Niobrara River. Plaster fell, walls
cracked and several dises brodk. Slight damage was also obtained
in Martin and Deadwood, So. Dakota. The logical conclusion is that
this event and the others in the western U.S. on this and the
previous date were in some way related to the great Alaska
earthquake.

3 28 10 10 0 1964 48.000 -113.800 0 5.0 Montana/Idaho
3 28 15 19 40 1969 31.500 -114.300 33 5.0 SW U.S.A
3 28 2 39 58 1973 44.479 -110.359 8 5.0 Yellowstone/Wyoming
3 28 2 31 6 1975 42.061 -112.548 5 6.2 Montana/Idaho
In the Ridgdale area of teh sparsely populated Pocatello
Valley, this earthquake shifted several ranch houses on their
foundations and toppled many chimneys. At Malad City, 20 km
northeast of this epicenter about 40 percent of Chimneys
were toppled. Total property damage was estimated at $1 million.
Ground fractures were contained in a zone about 0.6 km long by
5 cm wide. The shock triggered many snow avalanches northeast
of the valley. The largest earthquake ever located in this
region.

3 28 6 55 15 1976 52.701 -167.153 36 5.2 Fox Islands, Aleutians
3 28 5 26 50 1987 52.000 -173.000 0 5.3 Andreanoff Islands, Aleutians
3 28 1 48 23 1996 52.318 -168.668 33 5.4 Fox Islands, Aleutians
3 28 12 3 2 1996 51.000 -169.000 0 5.0 Fox Islands, Aleutians
3 28 19 50 51 1996 50.000 -170.000 0 5.7 Fox Islands, Aleutians
3 28 22 23 42 1999 51.720 -177.339 67 5.2 Andreanoff Islands, Aleutians