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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

WEEKLY UPDATE

Friday, April 30, 2004 12:30 PM ADT (20:30 UTC)



ALASKA VOLCANOES



MOUNT VENIAMINOF VOLCANO (CAVW #1102-07)

5610'N 15923'W, Summit Cone Elevation 7,073 ft (2,156 m)

Current Level of Concern Color Code: YELLOW



Unrest continues at Mount Veniaminof volcano and is characterized by small,

intermittent ash emissions, low-level volcanic tremor, and small volcanic

earthquakes. During this past week, small ash emissions were observed

during periods of clear weather on April 25 and 28. Ash clouds rose from

1,000 to 3,000 feet above the active cone (~8,000 to 10,000 feet or ~2,400

to 3,050 m above sea level), and during times of strong winds were observed

drifting for distances of less than 10 miles (~16 km). Seismic activity has

fluctuated, but remains above background levels. However, there are no

indications that more vigorous activity is imminent or even likely.

We expect that steam and ash emissions similar to those observed this week

may continue intermittently and could 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, internet camera data 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 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 clouds very

similar to those observed this past 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

occurring

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



CONTACT INFORMATION:



Tom Murray, Scientist-in-Charge, USGS

tlmurray@usgs.gov (907) 786-7497



John Eichelberger, Coordinating Scientist, UAF-GI

eich@giseis.alaska.edu (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.

VOLCANO ALERT LEVELS
NORMAL
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
ADVISORY
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
WATCH
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway but poses limited hazards.
WARNING
Hazardous eruption is imminent, underway, or suspected.

AVIATION COLOR CODES
GREEN
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
YELLOW
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
ORANGE
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway with no or minor volcanic-ash emissions [ash-plume height specified, if possible].
RED
Eruption is imminent with significant emission of volcanic ash into the atmosphere likely OR eruption is underway or suspected with significant emission of volcanic ash into the atmosphere [ash-plume height specified, if possible].

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Page modified: May 27, 2014 10:23
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