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ALASKA VOLCANO OBSERVATORY
Friday, July 9, 2004 10:25 AM ADT (1825 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
Short intervals of low-level volcanic tremor continue intermittently at
Mount Veniaminof. The episodes of tremor likely indicate small, low level,
ash and steam emissions. Though satellites had clear views of the volcano
most the week, no volcanic activity was observed in their data. Web camera
views have been clear since Monday and have shown intermittent puffing of
what appears to be mixed ash and steam. Tremor bursts correlate with these
puffing events. Pilot reports supported by web camera images indicate ash
clouds approaching 10,000 ft ASL on Thursday. Conditions at Veniaminof
could change rapidly and activity could become more vigorous without
warning. Steam and ash emissions could pose a hazard to people and
low-flying aircraft in the vicinity of the caldera. AVO will continue to
monitor activity at Mount Veniaminof using seismic data, satellite images,
internet camera data and observer 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 emissions
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. The unrest is characterized
by weak seismic tremor and occasional discrete low-frequency earthquakes.
This level of activity is similar to that observed over the past several
weeks. Clear satellite views of the volcano since Tuesday showed no
volcanic activity although thermal data on Wednesday indicates that the
crater is warmer than background. We see nothing at this time to indicate
that more vigorous activity is imminent. However, activity at Shishaldin
could increase rapidly and ash and gas emissions may pose a hazard to
people and low-flying aircraft in the vicinity of the summit.
AVO will continue to monitor activity at Shishaldin Volcano 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
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 27 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, Kanaga, Tanaga,
and Gareloi 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
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
Chris Nye, Acting Coordinating Scientist, UAF-GI
email@example.com (907) 474-7430
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.