AVO reported that sulfur dioxide emissions were detected by local gas monitoring sensors at Cleveland starting on 21 June. The emission rate increased during 24-30 June and then declined to background levels on 1 July. Although sulfur dioxide emissions had declined, vigorous steaming and moderately elevated surface temperatures at the summit were detected in satellite images the following days. On 5 July the Volcano Alert Level was raised to Advisory (the second lowest level on a four-level scale) and the Aviation Color Code was raised to Yellow (the second lowest color on a four-color scale). During 6-8 July a few small earthquakes were detected, steaming from the summit was observed, and elevated surface temperatures were characterized as weak. On 8 July the Volcano Alert Level was lowered to Normal and the Aviation Color Code was lowered to Green.

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)