As previously reported (BGVN 33:11) , the Alaska Volcano Observatory (AVO) had raised the aviation color code for Cleveland on 24 December 2008 to Yellow and the alert level to Advisory, following a thermal anomaly near the summit that was present for two days. The anomaly was occasionally observed into early January 2009. On 2 January, a short-lived ash explosion produced an ash plume that rose ~ 6 km and drifted ~ 240 km ESE before dissipating.

A small explosive eruption on 25 June 2009 sent an ash cloud rose to an estimated altitude of 4.6 km, which quickly detached from the volcano and drifted S. Another small and brief explosive eruption occurred on 2 October. A small detached ash cloud rose to maximum altitudes of 4.6-6.1 km and drifted ~ 600 km NE, dispersing over the Bering Sea. No further activity was detected through 19 October, so the Alert Levels were lowered to "Unassigned." Cleveland is not monitored by a real-time seismic network, thus the levels "Green" or "Normal" do not apply because background activity is not defined.

Geological Summary. The beautifully symmetrical Mount Cleveland stratovolcano is situated at the western end of the uninhabited Chuginadak Island. It lies SE across Carlisle Pass strait from Carlisle volcano and NE across Chuginadak Pass strait from Herbert volcano. Joined to the rest of Chuginadak Island by a low isthmus, Cleveland is the highest of the Islands of the Four Mountains group and is one of the most active of the Aleutian Islands. The native name, Chuginadak, refers to the Aleut goddess of fire, who was thought to reside on the volcano. Numerous large lava flows descend the steep-sided flanks. It is possible that some 18th-to-19th century eruptions attributed to Carlisle should be ascribed to Cleveland (Miller et al., 1998). In 1944 it produced the only known fatality from an Aleutian eruption. Recent eruptions have been characterized by short-lived explosive ash emissions, at times accompanied by lava fountaining and lava flows down the flanks.

Information Contacts: Alaska Volcano Observatory (AVO), a cooperative program of the U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508-4667, USA (URL: http://www.avo.alaska.edu/), the Geophysical Institute, University of Alaska, P.O. Box 757320, Fairbanks, AK 99775-7320, USA, and the Alaska Division of Geological and Geophysical Surveys, 794 University Ave., Suite 200, Fairbanks, AK 99709, USA.