Cleveland (background) and Carlisle (foreground) volcanoes in Alaska seen from an Alaska Airlines 737 in May 2012. Image by Cyrus Read, courtesy of AVO/USGS.
Last night, I noted on Twitter that the Alaska Volcano Observatory had increased the alert status at Cleveland to Orange (from Yellow) – this came after a report that an explosive eruption had taken place. Thanks to Cleveland’s remote location, confirmation of the eruption is difficult, but pilot observation, shots from the Cleveland webcam and infrasound all suggests that an explosive eruption took place, with the pilot estimating the plume might have been as high as 10.6 km / 35,000 feet. The eruption appears to be fairly ephemeral (a standard behavior for Cleveland), as satellite images taken around the time that the pilot reported the ash plume show only thin ash around the volcano – this isn’t entirely surprising if the explosion was caused by a collapse of the dome at Cleveland’s summit.
This is pretty much all that is going on in the Aleutians right now – Iliamna, another volcano that showed some restlessness earlier this year, has settled in a pattern of low-level (yet above background) seismicity that leaves it at Yellow alert status. However, the Aleutian’s northern Pacific cousins in Kamchatka are definitely keeping busy, especially Shiveluch, where the volcano has been producing frequent ~6-8 km / 20,000- to 26,000-foot plumes.