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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

INFORMATION RELEASE

Wednesday September 11, 2002 2:30 PM ADT (2230 UTC)



MT. 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



On September 10, AVO detected minute-long pulses of low-frequency tremor occurring every 2-5 minutes on several seismic stations at Mt. Veniaminof volcano. This type of seismicity is indicative of volcanic unrest. Tremor amplitudes gradually increased throughout the day, then remained constant overnight. Amplitudes have fluctuated today, but remain at levels similar to yesterday afternoon. Retrospective analysis of seismic data suggests tremor began as early as September 8th. AVO has not received any visual reports of anomalous activity at Veniaminof. Poor weather conditions have limited satellite observations.



Mt. 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. 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.



AVO has been receiving data from the Mt. Veniaminof seismic network since late June 2002. Sufficient time has passed for AVO to have a good understanding of background seismicity levels and station reliability. We are now adding Mt. Veniaminof to our seismically-monitored volcanoes and initiating it at Level of Concern Color Code YELLOW because of the anomalous seismicity. AVO will continue to monitor the situation closely and will issue further updates as information becomes available.

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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