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Alaska's Cleveland Volcano downgraded after ash eruption

Alaska Dispatch
Aerial photograph of the Mt. Cleveland lava and summit crater on August 8, 2011. Mt. Cleveland is on Chuginadak Island in Alaska's Aleutian chain.
Photo by Dave Withrow/NOAA
Annotated NOAA satellite image from 5:02 AM AST on 29 December 2011 showing a drifting ash cloud from a small eruption of Cleveland Volcano.
Photo courtesy AVO/UAF-GI
Satellite radar image from the TerraSAR-X sensor, showing the summit of Cleveland Volcano on February 10, 2012. It shows the presence of a small lava dome within the summit crater.
Image courtesy of AVO/USGS
This GeoEye IKONOS image shows a faint plume issuing from Cleveland Volcano at 2:31 PM on September 14, 2010. Red in this image highlights areas of vegetation detected by the near-infrared channel.
Photo courtesy Alaska Volcano Observatory/GeoEye
A small volcanic plume rose above remote Mount Cleveland on June 1, 2010. This false-color image was acquired by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA’s Terra satellite.
Image by NASA Earth Observatory
Aerial photograph of the Mt. Cleveland lava and summit crater on August 8, 2011. Mt. Cleveland is on Chuginadak Island in Alaska's Aleutian chain.
Photo by Kym Yano/NOAA
Aerial photograph of the Mt. Cleveland lava and summit crater on August 8, 2011. Mt. Cleveland is on Chuginadak Island in Alaska's Aleutian chain.
Photo by Dave Withrow/NOAA
Worldview satellite image collected on August 9, 2011 of the summit crater of Cleveland Volcano. The irregularly shaped dark object in the center of the image is the newly erupted lava dome. It is surrounded by brightly colored mineral deposits produced by volcanic gas emissions. A thin steam cloud partially obscures the view.
Image courtesy of AVO/USGS, copyright 2011 DigitalGlobe
Ashfall on the Lady Gudny on July 21, 2008.
Photo courtesy Anne Hillman, KIAL/Unalaska Community Broadcasting
2008 aerial photograph of the Island of Four Mountains region, including Mount Cleveland.
Photo by Cyrus Read/ AVO, U.S. Geological Survey
The eruption of Cleveland Volcano on May 23, 2006, is featured in this image photographed by an Expedition 13 crewmember on the International Space Station.
Photo courtesy Image Analysis Laboratory, NASA Johnson Space Center
The island with a prominent caldera in left (west) of image is Herbert, just northeast of it is Carlisle, and Mount Cleveland lies almost directly east. The western flanks of Tana are visible in the lower right of the image. Photographed on January 1, 2001.
Photo courtesy Image Analysis Laboratory, NASA Johnson Space Center
Mount Cleveland is a 1,730-m (5,676 ft)-high stratovolcano in Alaska's Aleutian chain. Photographed on July 24, 1994.
Photo by M. Harbin/AVO, University of Alaska Fairbanks
A webcam image showing an eruption at Cleveland Volcano on June 19, 2012.
Alaska Volcano Observatory photo

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.