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ALASKA VOLCANO OBSERVATORY
Monday, April 19, 2004 5:30 PM ADT (01:30 UTC April 20)
MOUNT VENIAMINOF VOLCANO (CAVW #1102-07)
56°10'N 159°23'W, Summit Cone Elevation 7,073 ft (2,156 m)
Previous Level of Concern Color Code: GREEN
Current Level of Concern Color Code: YELLOW
Perryville residents reported that a steam emission, possibly containing a
small amount of volcanic ash, was visible above Mount Veniaminof most of
the day on April 18, 2004. It became most vigorous at approximately 5:30 pm
ADT (01:30 UTC April 19) when it rose to 1500-2000 feet above the
intracaldera cone (8500-9000 feet above sea level). Over the past week,
there have been several episodes of low-level volcanic tremor and small
volcanic earthquakes. Seismic activity was most energetic from April 14 to
17 and then decreased notably prior to the emissions observed on April 18.
Starting at approximately 11:30 ADT today, tremor and earthquake levels
increased, albeit to lower levels than those during the previous week.
The recent activity is above what we consider to be normal background. Thus
the color code for Mount Veniaminof has been upgraded to YELLOW. Steam and
ash emissions similar to those reported on April 18 may occur. However,
there are no indications from seismic data that events significantly larger
than those observed on April 18 are imminent. AVO will continue to monitor
activity at Mount Veniaminof using seismic and satellite data, in
conjunction with visual reports.
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 clouds,
occurred in 2002, and in February 2004. 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
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
John Eichelberger, Coordinating Scientist, UAF-GI
email@example.com (907) 474-5530
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.