It has been a up and down past year for Cleveland volcano in the Aleutians. The alert status for the volcano has bounced back and forth from Yellow/Advisory to Orange/Watch multiple times due to the growth of a dome of lava in the summit crater area. This dome has the potential to "plug" the conduit, causing the pressure behind the dome to rise until an explosive eruption occurs. This is exactly what happened on December 25 and 29 of 2011 when Cleveland had one of its first major explosive eruptions in years and the dome that grew in the crater over much of 2011 was destroyed. Things quieted down at Cleveland after that explosion, but new satellite imagery has shown that a new dome is already growing inside the summit crater - and now it is already 40 meters in diameters. This new dome growth has prompted the Alaska Volcano Observatory to raise the alert status for Cleveland back to Orange/Watch from Yellow/Advisory because if the volcano decides to have another explosive eruption, the hundreds of flights that come over the Aleutians will need to be alerted and/or rerouted to avoid the volcano ash. Cleveland is an especially tricky volcano to monitor as satellite imagery and first hand observations from people on the ground or in aircraft are really the only ways AVO has to keep track of what is going on - there are no seismometers near the volcano. A webcam is pointed towards the volcano, but in the Aleutians, getting a clear view can be very difficult.
Image: The summit dome at Cleveland seen on August 8, 2011. Image by Dave Winthrow, NOAA, courtesy of AVO.
