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U.S. Geological Survey
Tuesday, May 5, 2009, 1:49 PM AKDT (Tuesday, May 5, 2009, 21:49 UTC)

60°29'7" N 152°44'38" W, Summit Elevation 10197 ft (3108 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Current activity at Redoubt volcano suggests that a significant explosive event is likely, though not certain, in the coming days. The level of seismicity, rate of dome growth, and gas output indicate that an explosive event could occur at any time with little or no warning. Since about May 2, shallow earthquake activity beneath the actively growing lava dome has been slowly increasing. Recent observations indicate that small, ash-producing rockfalls from the dome's north side are becoming more frequent.

The seismic activity consists primarily of repetitive events occurring several times per minute as well as more continuous volcanic tremor. Similar seismicity was observed prior to several explosions earlier in the 2009 eruptive sequence and many of the explosive events during the 1989-90 eruption. The lava dome that has grown in the summit crater is now roughly equal in size to the largest dome that was emplaced during the 1989-90 eruption. As the dome grows larger it becomes increasingly unstable and is more and more likely to experience a complete or partial dome failure. A dome failure event could produce voluminous block and ash flows down Drift glacier and could generate significant amounts of meltwater.

Should a significant explosion, dome collapse, or both occur, the event will likely produce high altitude (>30,000 ft ASL) ash plumes, trace to minor ash fall in parts of south-central Alaska, lahars and flooding in the Drift River valley, and pyroclastic flows in the immediate vicinity of the volcano. The effects of the next explosive event or events could be similar to what has been observed so far during the 2009 eruption.

AVO is monitoring the situation closely and the observatory is staffed 24/7. AVO will provide frequent updates of the volcano's status and the earliest possible warning of significant explosive activity and other hazardous phenomena. The next AVO visit to the volcano is planned for May 7, weather permitting.

VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu



Tom Murray, Scientist-in-Charge, USGS
tlmurray@usgs.gov (907) 786-7497

Mike West, Acting Coordinating Scientist, UAF
west@gi.alaska.edu (907) 474-6977

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.
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