Saturday, July 11, 2009

Alaska: Redoubt volcano's alert was downgraded

The Alaska Volcano Observatory yesterday downgraded the aviation warning code for Mount Redoubt from orange to yellow and the alert level from Watch to Advisory. Alert levels had been high since Mount Redoubt’s most recent rumblings starting March 15. The most dramatic eruptions happened between March 22 and April 4 when the volcano spewed ash, gas and steam up to 65,000 feet high. High level winds carried ash to Talkeetna, Skwentna and Trapper Creek while air traffic came to a halt for a few days.

After April 4, Redoubt continued to erupt, creating a lava dome in the summit crater. A lava flow now extends nearly 0.6 mile down the north flank of the volcano.

AVO reports that observations from overflights, webcam and satellite imagery have not been able to detect changes caused by dome growth for the past three weeks. However, the dome is unstable and AVO scientists warn that a collapse could be accompanied by the production of a large ash plume in the Drift River valley.

Lava flow has slowed significantly and may even have stopped, prompting AVO to downgrade the aviation color code to yellow and the alert level to advisory. Advisory means that volcanic activity has decreased but continues to be closely monitored for possible renewed increase. Seismic activity slowed down as well, but is still higher than normal. AVO had staff monitoring Redoubt around the clock, but now transitions employees off the 24/7 shifts.

Story by Diana Haecker

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