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ARCHIVED REPORT
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ALASKA VOLCANO OBSERVATORY

INFORMATION RELEASE

Tuesday, August 20, 2002 2:30 PM ADT (2230 UTC)



SHISHALDIN VOLCANO

5445' N, 16358'W, CAVW Number 1101-36

Summit Elevation 9,373 ft (2,857 m)

Level of concern color code GREEN



On Friday evening, August 16, 2002, the Alaska Volcano Observatory received notification of a pilot report via the National Weather Service (NWS) Alaska Aviation Weather Unit (AAWU) of volcanic activity at Shishaldin Volcano. The pilot report indicated: "Shishaldin Volcano appears to be erupting. Steam and dark clouds rising to 10,500 (feet) moving NW-SE". A NWS weather observer in Cold Bay, located about 60 miles (100 km) east of the volcano, reported a steam-rich plume coming from Shishaldin Volcano. As per operating policy, the AAWU issued an "eruption SIGMET" advising the aviation community of the possibility of airborne volcanic ash.



Upon receiving the pilot report, the Alaska Volcano Observatory immediately analyzed seismic and satellite data and determined that Shishaldin was at a normal background state and had not erupted. Further discussions with the NWS weather observer in Cold Bay indicated that the observed steam plume was not uncommon at Shishaldin Volcano.



The last significant ash-producing eruptions of Shishaldin Volcano occurred in April to May 1999. Since that time, low-frequency seismic events and occasional steam plumes have characterized activity at the volcano. Shishaldin continues to be at color code GREEN.

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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URL: avo.alaska.edu/activity/avoreport_archives.php
Page modified: May 27, 2014 10:23
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