ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, October 28, 2011, 1:30 PM AKDT (Friday, October 28, 2011, 21:30 UTC)
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
AVO is unable to confirm continuing eruptive activity at Cleveland. An October 23 TerraSAR-X satellite radar image of the new lava dome indicates no discernable growth over the past several weeks. The image also shows deflation or collapse of the dome surface which is consistent with a pause in eruption of lava.
Effusion of lava may resume at any time. This could result in lava overtopping the crater rim and flowing down the flank of the volcano. Portions of this lava flow could collapse and produce avalanches of hot debris that reach the sea accompanied by small ash clouds. A sudden explosion and ash cloud exceeding 20,000 ft above sea level could also occur. Such explosions could go undetected in satellite imagery for hours. However, in cooperation with the University of Washington, AVO has implemented a lightning alarm system that may detect significant ash-producing events within minutes of onset. In the event of a large ash explosion, seismic signals may be recorded on AVO seismic networks at nearby volcanoes; there is no real-time seismic network on Cleveland.
AVO will continue to monitor the volcano using multiple sources of satellite, lightning detection, and distant seismic data.
Cleveland volcano forms the western half of Chuginadak Island, a remote and uninhabited island in the east central Aleutians. It is located about 75 km (45 mi.) west of the community of Nikolski, and 1500 km (940 mi.) southwest of Anchorage. The volcano's most recent significant eruption began in February, 2001 and it produced 3 explosive events that produced ash clouds as high as 12 km (39,000 ft) above sea level. The 2001 eruption also produced a rubbly lava flow and hot avalanche that reached the sea. The most recent minor ash emissions were observed in January and June 2009.
Additional information on Cleveland volcano and the current activity may be found at this link:
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 30 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Akutan, Aniakchak, Augustine, Dutton, Fisher, Fourpeaked, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Redoubt, Shishaldin, Snowy, Spurr, Tanaga, Trident, Ugashik-Ugashik-Peulik, Ukinrek Maars, Veniaminof, Westdahl, and Wrangell volcanoes are in color code GREEN and volcano alert level Normal. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any of these volcanoes.
Please see http://www.avo.alaska.edu/color_codes.php for complete definitions of Aviation color codes and Volcano alert levels.
John Power, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Steve McNutt, Coordinating Scientist, UAF
email@example.com (907) 474-7131
The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.