Volcano Activity Notifications

AVO/USGS Volcanic Activity Notice

Volcano: Redoubt (CAVW #1103-03-)

Current Volcano Alert Level: WATCH (WATCH)

Current Aviation Color Code: ORANGE (ORANGE)

Issued: Tuesday, May 5, 2009, 6:59 AM AKDT (20090505/1459Z)
Source: Alaska Volcano Observatory
Notice Number: 2009/A36
Location: N 60 deg 29 min W 152 deg 44 min
Elevation: 10197 ft (3108 m)
Area: Cook Inlet-South Central Alaska

Volcanic Activity Summary: Current activity at Redoubt volcano suggests that a significant explosive event is likely, though not certain, in the coming days. This event could occur at any time with little or no warning. Since about May 2 shallow earthquake activity beneath the actively growing lava dome of Redoubt volcano has been slowly increasing. The growing lava dome is becoming increasingly unstable.

Should a significant explosion 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 in the Drift River Valley, and pyroclastic flows in the immediate vicinity of the volcano.

AVO continues 24/7 operations and is monitoring the situation closely. AVO will provide frequent updates of the volcano's status and the earliest possible warning of significant explosive activity and other hazardous phenomena.

Recent Observations:
[Volcanic cloud height] Unknown
[Other volcanic cloud information] Unknown

Remarks: The seismic activity is primarily characterized by repetitive events occurring several times per minute as well as more continuous volcanic tremor. Similar seismicity has been 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 Redoubt's 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 is increasingly unstable with a growing likelihood of a complete or partial dome failure. Recent observations indicate that small, ash-producing rockfalls from the dome's north side are becoming more frequent.

Contacts: 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

Next Notice: A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu

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.