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AVO VOLCANO ACTIVITY NOTIFICATION

ALASKA VOLCANO OBSERVATORY STATUS REPORT
U.S. Geological Survey
Monday, December 12, 2011, 12:32 PM AKST (Monday, December 12, 2011, 21:32 UTC)


CLEVELAND VOLCANO (VNUM #311240)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

No unusual activity was observed in partly cloudy satellite views of Cleveland today. AVO has received no reports of activity.

The new lava dome began growing at Cleveland in late July 2011 and eventually reached about 10 m (33 feet) below the crater rim. Last observed dome growth occurred in early October, and recent views of the summit show gradual subsidence and disintegration of the summit dome. 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 prior to deflation was about one million cubic meters (1.3 million cubic yards).

Whether the eruption is over or has merely paused is not certain. Effusion could resume at any time 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.

Sudden explosions and ash emission could also 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:
http://www.avo.alaska.edu/activity/Cleveland.php

Please see http://www.avo.alaska.edu/color_codes.php for complete definitions of Aviation color codes and Volcano alert levels.





CONTACT INFORMATION:

Michelle Coombs, Acting Scientist-in-Charge, USGS
mcoombs@usgs.gov (907) 786-7497

Jon Dehn, Acting Coordinating Scientist, UAF
jdehn@gi.alaska.edu (907) 474-6499

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.
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URL: avo.alaska.edu/activity/report.php
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