A pilot report, web camera image, and infrasound data indicated that an ash producing explosion occurred at Cleveland Volcano on Tuesday, June 19, around 22:05 UTC (14:05 AKDT). The pilot report suggests the volcanic cloud height is 10 km (35,000 feet) above sea level. Infrasound data indicated the eruption was short in duration.
Cleveland is now on Aviation Color Code: ORANGE/Alert Level: WATCH.
Latest report from AVO said additional sudden explosions of blocks and ash are still possible with little warning. It is possible for associated ash clouds to exceed 20,000 feet above sea level. If a large ash-producing event occurs, seismic, infrasound, or volcanic lightning networks should detect the event and alert AVO staff. There is no real-time seismic monitoring network on Mount Cleveland so AVO is unable to track activity in real time.
Satellite imagery shows only a weak ash signal, suggesting a thin cloud that dissipated quickly. It was just one explosion, which was very typical of the thing Cleveland has been doing in the last year. It is possible that the cloud rose to less than 35,000 feet, as the height was just one pilot's estimate - Stephanie Prejean, a U.S. Geological Survey seismologist at the observatory in Anchorage.
Pilots have been advised of potential risks from Cleveland, which might explode again, it could do that any time.
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 December 2011.
Scheveluch and Karymsky
Also on Aviation Color Code ORANGE as of June 19, 2012 are Kamchatkan volcanoes Scheveluch and Karymsky. Report.
Sources: AVO, kscnet.ru