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ALASKA VOLCANO OBSERVATORY
Friday, May 14, 2004 10:30 AM ADT (18:30 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
Unrest continues at Mount Veniaminof volcano, characterized by
intermittent, low-level volcanic tremor, and small volcanic earthquakes. We
have no evidence of ash emissions during the past week. Cloudy conditions
have obscured observation of Veniaminof by satellite, and the internet
camera system in Perryville is still down for repair. Over the past week,
seismic activity was more intermittent and lower in amplitude than it was
in previous weeks; however, seismicity suggests that ash burst activity may
occasionally occur. There are no indications that more vigorous activity is
imminent or even likely. However activity at Veniaminof could increase
rapidly, and steam and ash emissions may pose a hazard to people and
low-flying aircraft in the vicinity of the active cone.
AVO will continue to monitor activity at Mount Veniaminof using seismic
data, satellite images, and observer reports. AVO has increased the
frequency of seismic data analysis to provide early warning of increased
activity, should it occur. Public access to archived internet camera images
(collected at Perryville) can be found at www.avo.alaska.edu.
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.
SHISHALDIN VOLCANO (CAVW #1101-36)
54°45'N 163°58'W, Summit Cone Elevation 9,373 ft (2,857 m)
Current Level of Concern Color Code: YELLOW
Seismic unrest continues at Shishaldin volcano, characterized by sequences
of volcanic earthquakes, small explosions, and seismic tremor. A weak
thermal anomaly was observed at Shishaldin's summit on May 11. This thermal
anomaly was similar to those observed occasionally since January 2004. We
see nothing at this time to indicate that an eruption is imminent.
However, activity at Shishaldin could increase rapidly and ash and gas
emissions could occur at any time. AVO will continue to monitor activity
using seismic data, satellite images, and observer reports.
Shishaldin volcano, located near the center of Unimak Island in the eastern
Aleutian Islands, is a spectacular symmetric cone with base diameter of
approximately 10 miles (16 km). A small summit crater typically emits a
noticeable steam plume with occasional small amounts of ash. Shishaldin is
one of the most active volcanoes in the Aleutian volcanic arc, erupting at
least 28 times since 1775. Most of Shishaldin's eruptions have consisted
of small ash and steam plumes, although the most recent eruption in
April-May 1999 produced an ash column that reached a height of 45,000 ft
above sea level.
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,
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
firstname.lastname@example.org (907) 786-7497
Steve McNutt, Acting 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.