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Archived Report
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ALASKA VOLCANO OBSERVATORY

WEEKLY UPDATE

Friday, April 16, 2004 12:15 PM ADT (20:15 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: GREEN



Several low-level episodes of volcanic tremor and volcanic earthquakes have

been recorded under Veniaminof over the past week. The tremor occurred in

pulses lasting several minutes, and the largest events were recorded on

most of the stations in the seismic network. This represents the strongest

activity since early 2003 when the volcano's color code was downgraded from

yellow to green.



No small bursts of ash from the intracaldera cone at Veniaminof have been

reported from Perryville or passing pilots, or noted in satellite data

since February of this year. No significant changes in the thermal

signature of the intracaldera cone have been noted in satellite data. The

color code for Veniaminof remains at GREEN.



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, Veniaminof, 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].
PDF version of these definitions
URL: avo.alaska.edu/activity/avoreport_archives.php
Page modified: June 11, 2012 11:50
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