Alaska volcano shows signs of impending eruption

Recent satellite images of a remote Alaska volcano along a flight route for major airlines show it may be poised for its first big eruption in 10 years, scientists said. The alert level for an Alaska volcano is being raised after officials say that the persistent thermal anomalies spotted in satellite data merit attention and caution.

The Alaska Volcano Observatory has issued an eruption advisory for the
5,676 foot-tall Cleveland Volcano, located on the uninhabited island of Chuginadak in the Aleutian chain (map at right) about 940 miles southwest of Anchorage.

The advisory was based on "thermal anomalies" detected by satellite, the observatory said on Thursday. Those measurements indicate the volcano could erupt at any moment, spewing ash clouds up to 20,000 feet above sea
level with little further warning, the observatory said. (Left: satellite view of volcano @ NASA)

A major eruption could disrupt international air travel because Cleveland Volcano, like others in the Aleutians, lies directly below the commercial airline flight path between North America and Asia, said John Power, scientist-in-charge at the Alaska Volcano Observatory.

The volcano's last major eruption came in 2001, when it blasted ash
more than 5 miles into the sky and spilled lava from the summit crater.
On 19th February 2001 Cleveland volcano erupted explosively for 8
hours. An ash cloud reached an altitude of 12 km. The eruption cloud extended in two directions, 40 km northwest and 60 km southeast of the volcano. Ash drifted for 7 h before falling at the town of Nikolski, 75 km northeast of the volcano.

Mt. Cleveland erupted explosively again
on 11th March 2001. The eruption was smaller than the 19th February 2001 event, and lasted 3 hours. Ash reached an altitude of 8 km. On 13th March 2001 after 42 hours the ash cloud extended 1000 km towards Kodiak Island. The last explosive eruption occurred on 19th March 2001, and produced an ash cloud to a height of 9 km. Cleveland has experienced several smaller eruptions or suspected eruptions since then.

So far, airlines have not changed their flight patterns because of Cleveland's heat emissions, said Steve McNutt, a University of Alaska
Fairbanks scientist who works at the observatory. Data readings have indicated that the volcano may erupt at any moment. If an eruption did occur ash clouds as high as 20,000 feet (3.7 miles) above sea level would be expected, which could severely disrupt air traffic. Airlines operating through the region are aware that an eruption could happen suddenly and without further warning, and are preparing for potential travel chaos.

Scientists are not always certain about what is happening at the remote volcano, observatory officials said. The town of Nikolski, the nearest
settlement to Cleveland Volcano, is 45 miles away.

Although Cleveland is among the most active of Alaska's roughly 90 volcanoes, no seismic equipment is set up there because the costs of working in such a remote area are prohibitive, observatory officials said.

Still, Cleveland is the only Alaska volcano blamed for an eruption-caused human death in recorded history. A U.S. soldier who was stationed on Chuginadak Island during World War Two disappeared during an eruption and was presumed killed.

Without sophisticated monitors like those used to keep tabs on volcanoes closer to Anchorage and other populated areas, scientists must rely on a variety of other observations to track Cleveland's eruptions, McNutt said. Those include satellite data, eyewitness reports and video from mariners and pilots in the area.

"Cleveland is a particular bugaboo for us because it is right on the air route" with no seismic equipment, Power said.

Reuters,"Alaska volcano shows signs of impending eruption", accessed July 25, 2011
Pilot News Magazine, "Alaska volcano shows signs of impending eruption", accessed July 25, 2011
Volcano Live, "Cleveland Volcano", accessed July 25, 2011
The Watchers, "Aleutian Cleveland volcano shows signs of impending eruption", accessed July 25, 2011
The Christian Post, "Alaska Volcano May Erupt, Travel Chaos May Erupt", accessed July 25, 2011


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