ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, October 7, 2011, 11:02 AM AKDT (Friday, October 7, 2011, 19:02 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
The eruption of a lava dome in the summit crater of Cleveland Volcano continues. Satellite observations over the past week show that the edge of the dome is now at the level of the crater rim on the southwest and east-northeast sides, and may soon overflow the crater rim on these flanks. At present, most of the lava dome volume is contained within the summit crater, and thus not prone to gravitational collapse. No ash emissions have been detected during the current eruption which began in July, 2011, and AVO has received no other reports of activity at this volcano.
If the lava dome continues to grow in the summit crater, the possibility of an explosive event increases. With continued lava dome growth, lava may eventually overflow the crater rim to produce a lava flow and/or collapse to produce pyroclastic flows. Sudden collapse of the effusing lava could result in the generation of a volcanic ash cloud. However, lava may continue to erupt without an explosive event. It is possible that explosions from the summit crater vent could produce ash clouds that may exceed 20,000 ft above sea level. These events can occur without warning and may go undetected in satellite imagery for hours. However, lightning associated with significant ash-producing events may be detected within minutes using an automated alarm system.
AVO does not have a real-time seismic network on the volcano and thus we are unable to track local earthquake activity related to volcanic unrest, provide forecasts of eruptive activity, or rapid confirmation of explosive, ash-producing events. In the event of a large explosive eruption like that in 2001, it is possible that seismic signals may be recorded on AVO seismic networks at nearby volcanoes. 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.
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, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Korovin, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Redoubt, Shishaldin, Snowy, Spurr, Tanaga, Trident, 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.
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
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.