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Archived Report
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ALASKA VOLCANO OBSERVATORY

INFORMATION RELEASE

Monday, April 19, 2004 5:30 PM ADT (01:30 UTC April 20)



MOUNT VENIAMINOF



MOUNT VENIAMINOF VOLCANO (CAVW #1102-07)

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

Previous Level of Concern Color Code: GREEN

Current Level of Concern Color Code: YELLOW



Perryville residents reported that a steam emission, possibly containing a

small amount of volcanic ash, was visible above Mount Veniaminof most of

the day on April 18, 2004. It became most vigorous at approximately 5:30 pm

ADT (01:30 UTC April 19) when it rose to 1500-2000 feet above the

intracaldera cone (8500-9000 feet above sea level). Over the past week,

there have been several episodes of low-level volcanic tremor and small

volcanic earthquakes. Seismic activity was most energetic from April 14 to

17 and then decreased notably prior to the emissions observed on April 18.

Starting at approximately 11:30 ADT today, tremor and earthquake levels

increased, albeit to lower levels than those during the previous week.



The recent activity is above what we consider to be normal background. Thus

the color code for Mount Veniaminof has been upgraded to YELLOW. Steam and

ash emissions similar to those reported on April 18 may occur. However,

there are no indications from seismic data that events significantly larger

than those observed on April 18 are imminent. AVO will continue to monitor

activity at Mount Veniaminof using seismic and satellite data, in

conjunction with 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 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,

occurred in 2002, and in February 2004. 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.



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
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