Monday, March 26, 2012

AVO Lowers Alert For Cleveland Volcano To "Yellow"

The slowly erupting stratovolcano in Alaska, Mt. Cleveland, has been lowered to level "Yellow/Advisory" with AVO geologists stating "No further explosions have been detected at Cleveland since March 13, and we have no evidence that lava-dome growth has renewed since then. Therefore, we are lowering the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY."

Mt. Cleveland had been experiencing slow lava dome growth for the better part of a year, with a couple of collapses and small explosions, but nothing in the range of some of its past activities. Cleveland volcano has in the past erupted quite violently creating large plumes of ash some 30,000 feet high, but this episode was slow, effusive, and really not a huge deal.

The island itself is uninhabited, and far from any populated areas. It is however the only volcano of the Aleutian arc with a fatality (one) on its record, from an eruption in 1944. Mostly the volcano has annoyingly deposited ash  on nearby towns during large eruptions, or caused air traffic diversions.

The other volcano showing signs of unrest in Alaska is Mt. Iliamna which has undergone a series of magmatic quakes, thought to be related to dike intrusion. A recent expedition by AVO scientists to this volcano has revealed an increase in gas emissions (SO2, and CO2), and vigorous steaming/fumerole action. AVOstates that this does not mean an eruption is imminent and they saw no signs of rockfall, or avalanches in the area. However, they did seem to note some slight deformation in a glacier, but they were unable to attribute that solely to the volcano.

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