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ALASKA VOLCANO OBSERVATORY
Friday, April 22, 2004 11:30 AM ADT (19:30 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
Following several episodes of low-level volcanic tremor last week, and
reports of increased steam emission that possibly contained some ash, AVO
raised the Concern Color Code to YELLOW on Monday, April 19. During
subsequent days this week there has been a marked decrease in the episodes
of low-level volcanic tremor and small volcanic earthquakes. Seismic
activity was most energetic from April 14-17 and then decreased notably
prior to the emissions observed on April 18. No emissions were reported
AVO will continue to monitor activity at Mount Veniaminof using data from
the seismic network and satellites in addition to 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 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 very similar to those
reported last week occurred in 2002. 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.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 25 volcanoes in Alaska.
Satellite images of all Alaskan volcanoes are analyzed daily for evidence
of ash plumes and elevated surface temperatures. Some volcanoes may
currently display anomalous behavior but are not considered to be at a
dangerous level of unrest.
Wrangell, Spurr, Redoubt, Iliamna, Augustine, Snowy, Griggs, Katmai,
Novarupta, Trident, Mageik, Martin, Aniakchak, Pavlof, Dutton, Isanotski,
Shishaldin, Fisher, Westdahl, Akutan, Makushin, Okmok, Great Sitkin, and
Kanaga volcanoes are in color code GREEN. All are at or near normal levels
of background seismicity. AVO did not detect ash plumes or significant
elevated surface temperatures in the vicinity of any 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
email@example.com (907) 786-7497
John Eichelberger, Coordinating Scientist, UAF-GI
firstname.lastname@example.org (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.