ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, November 25, 2011, 11:54 AM AKST (Friday, November 25, 2011, 20:54 UTC)
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW
The lava dome in Cleveland's summit crater has not changed significantly during the past two weeks, according to satellite images. Elevated surface temperatures and a minor steam plume have been observed during periods of clear weather. This is to be expected due to the mass of hot lava that now fills the roughly 200-m-wide (660 feet) summit crater.
The new lava dome began growing at Cleveland in late July 2011 and eventually reached about 10 m (33 feet) below the crater rim. Throughout this period of unrest and eruption, AVO has not observed deposits or features indicative of explosions or ash emission. Cleveland's activity from late July to present can be characterized as an effusive lava eruption. The volume of the lava dome is about one million cubic meters (1.3 million cubic yards).
We are uncertain if the eruption is over or has merely paused. It is possible for effusion to resume at any time which could send lava over the crater rim and down the steep flanks of the volcano. Such lava flows could collapse and produce avalanches of hot debris that reach the sea and may be accompanied by small ash clouds.
It also remains possible for sudden explosions and ash emission to occur, and ash clouds exceeding 20,000 feet above sea level may develop. Such explosions and their associated ash clouds may 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. If a large explosive event occurs, seismic signals may be recorded on AVO seismic networks at nearby volcanoes. There is no real-time seismic monitoring network on Mt. Cleveland.
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-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.