Homer, Alaska - News - Redoubt advisory issued 11/12/08

Story last updated at 9:39 PM on Wednesday, November 12, 2008

Redoubt advisory issued

BY MICHAEL ARMSTRONG
STAFF WRITER

The Alaska Volcano Observatory last week changed the volcano alert level for Redoubt Volcano to advisory, with an aviation code level of yellow. In a notice issued Nov. 5, AVO said it changed the alert level due to changes in gas emission and heat output from the volcano about 82 miles west of Kenai in Lake Clark National Park on the west side of Cook Inlet. "There is no indication that an eruption is imminent or even certain," AVO said in a press release.

Photo by Game McGimsey

This Nov. 2 photo shows features observed on Redoubt Volcano.

Starting in July, field crews working near the volcano summit smelled hydrogen sulfide gas. In September, a pilot flying nearby also reported smelling hydrogen sulfide, as did workers at the Drift River Oil Terminal 22 miles downstream from Redoubt. The gas smells might indicate new magma entering chambers under Redoubt, AVO said in its alert.

Satellite images taken on Oct. 13 showed increased warming. Observers on flights over Redoubt also reported seeing bare, steaming rock, including a 150-foot wide melt hole on the Drift Glacier.

Seismographs on Redoubt have shown a modest increase in low-frequency earthquakes, suggesting that if new magma has entered the volcanic system, it is still deep. The main hazards at this time are from steam explosions on the summit, noxious gas plumes, ice- and ice-rock-water avalanches on Drift Glacier, and increased water flow on Drift River.

Redoubt last erupted in the winter of 1989-90. Based on measurements then, AVO said it would expect a dramatic increase in seismicity before another explosive eruption. AVO crews are monitoring Redoubt closely. Seismicity remains low compared to levels observed before the last eruption. Last week, crews also installed more geophysical equipment and a Web camera.

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute and the Alaska Department of Geological and Geophysical Surveys. For more information, visit www.avo.alaska.edu. Phone recordings on the status of Redoubt and other volcanoes is at (907) 786-7478.

Michael Armstrong can be reached at michael.armstrong@homernews.com.

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