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Alaska Beat

Alaska's Cleveland Volcano downgraded after ash eruption

  • Author: Craig Medred
  • Updated: September 27, 2016
  • Published December 30, 2011

Cleveland Volcano, located in Alaska's Aleutian Island chain, has been downgraded in status following an eruption that launched an ash cloud 15,000 feet into the air, according to the Alaska Volcano Observatory.

The eruption was detected early morning Thursday, when satellite imagery revealed an ash cloud approximately 50 miles away from the volcano, the result of an earlier eruption (see the slideshow in this article for that imagery). Seismic detection equipment located at the faraway Okmok Volcano detected the distruption and pegged the eruption at about 4 a.m. Thursday.

The volcano rests 45 miles west of the small community of Nikolski, located on a separate island. Because of the volcano's remoteness, the U.S. Geological Survey has no real-time monitoring equipment on the island. The volcano has seen varying levels of activity since July.

The eruption prompted the raising of the alert level at the volcano to "watch" and the aviation warning level to "orange." On Friday, those warnings were downgraded to "advisory" and "yellow," respectively.

The decision to downgrade the volcano came around 2 p.m. Friday, when satellite imagery revealed no further activity from the peak.

"Intermittent lava eruption from late July through early October emplaced a dome at (the volcano's) summit," the AVO reported. "There is a possibility that effusion could resume and send lava over the crater rim and down the steep flanks of the volcano. Such lava flows might collapse and produce avalanches of hot debris that reach the sea and may be accompanied by small ash clouds."

The AVO warns that unexpected ash clouds of 20,000 feet or higher could still result from the volcano's continuing instability, but yesterday's eruption may have been an isolated incident. Cleveland last erupted in 2001, spitting out an ash cloud that blasted to the 39,000-foot level, well above the minimum of 20,000 feet that is generally considered dangerous to most aircraft flying over the area.

Read more and get updates at the Alaska Volcano Observatory.

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