(2) Issued:(20111230/2257Z)
(3) Volcano:Cleveland (CAVW# 1101-24-)
(4) Current Color Code:YELLOW
(5) Previous Color Code:orange
(6) Source:Alaska Volcano Observatory
(7) Notice Number:2011/A8
(8) Volcano Location:N 52 deg 49 min W 169 deg 56 min
(9) Area:Aleutians Alaska
(10) Summit Elevation:5676 ft (1730 m)
(11) Volcanic Activity Summary:Cleveland Volcano is has been lowered to aviation color code YELLOW and alert level ADVISORY. No new explosive activity has been observed at the volcano since yesterday morning.

A detached drifting ash cloud from the volcano was detected early yesterday morning in satellite imagery. Ground coupled air waves from the explosion were detected at a distant seismic network located on Okmok Volcano that place the time of the explosion from Cleveland at 13:12 UTC, Dec. 29.

Intermittent lava eruption from late July through early October emplaced a dome at the summit. 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.

More sudden explosions producing ash or ejecting blocks could also occur with plumes exceeding 20,000 feet above sea level. 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 at Cleveland.

Additional information on Cleveland Volcano and the current activity may be found at this link:

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

(12) Volcanic cloud height:Unknown
(13) Other volcanic cloud information:Unknown
(14) Remarks: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.
(15) Contacts:John Power, Scientist-in-Charge, USGS
jpower@usgs.gov (907) 786-7497

Chris Nye, Acting Coordinating Scientist
cnye@giseis.alaska.edu (907) 474-7430
(16) Next Notice:A new VONA will be issued if conditions change significantly or alert levels are modified. While a VONA is in effect, regularly scheduled updates are posted at