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ALASKA VOLCANO OBSERVATORY
Tuesday, January 4, 2005 2:00 PM AST (23:00 UTC)
MOUNT VENIAMINOF VOLCANO (CAVW #1102-07)
56°10'N 159°23'W, Summit Cone Elevation 7,073 ft (2,156 m)
Current Level of Concern Color Code: YELLOW
Previous Level of Concern Color Code: GREEN
Several small ash emissions have been observed coming from the intracaldera
cone of Mount Veniaminof in recent internet camera images from Perryville.
This activity is above what we consider to be normal background. Thus the
color code for Mount Veniaminof has been upgraded to YELLOW.
Ash emission were visible starting around 9:38 AST (18:38 UTC), but could
have been obscured by clouds in previous images. The discrete ash emissions
are small, rising several hundred feet above the cone which has an
elevation of 7,073 ft (2,156 m) above sea level, and dissipating as they
drift towards the east. Ash fall is likely very minor, and confined to the
Very weak seismic tremor was observed starting on January 1, and has
increased slightly over the past 2 days. The character of the signal
changed to that of numerous discrete events this morning, with events
occurring about once per minute with durations of about 10-20 seconds.
These seismic signals are similar to those recorded during steam emissions
and ash emissions from April to October, 2004. However, there are no
indications from seismic data that events significantly larger than those
observed are imminent. We expect that steam and ash emissions may continue
intermittently and could pose a hazard to people and low-flying aircraft in
the vicinity of the active cone.
Mount Veniaminof volcano is an andesitic stratovolcano with an ice-filled
10-km diameter summit caldera located on the Alaska Peninsula, 775 km (480
mi) southwest of Anchorage and 35 km (22 mi) north of Perryville.
Veniaminof is one of the largest (~ 300 km3) and most active volcanic
centers in the Aleutian Arc and has erupted at least 12 times in the past
200 years. The most recent significant eruption of the volcano occurred in
1993-95 and was a moderate Strombolian eruption from the main intracaldera
cone in the northwest sector of the caldera above Cone Glacier. The
eruption was characterized by intermittent low-level emissions of steam and
ash, and a small lava flow was extruded into the summit caldera ice field
producing an ice pit. Minor explosions producing small ash occurred in 2002
and in recent weeks. Previous historical eruptions have produced ash plumes
that reached 6,000 m (20,000 ft) above sea level and ash fallout that
blanketed areas within about 40 km (25 mi) of the volcano.
ABBREVIATED COLOR CODE KEY (contact AVO for complete description):
GREEN volcano is dormant; normal seismicity and fumarolic activity
YELLOW volcano is restless; eruption may occur
ORANGE volcano is in eruption or eruption may occur at any time
RED significant eruption is occurring or explosive eruption
expected at any time
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
Tom Murray, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Ken Dean, Acting Coordinating Scientist, UAF-GI
email@example.com (907) 474-7364
The Alaska Volcano Observatory is a cooperative program of the U.S.
Geological Survey, the University of Alaska Fairbanks Geophysical
Institute, and the Alaska Division of Geological and Geophysical Surveys.