Permalink : http://hdl.handle.net/2115/38164

JaLCDOI : 10.14943/gbhu.72.353

On July 12 (UTC), 2008, Okmok volcano in the Aleutian Islands began to erupt after a lapse of 11 years. Okmok volcano is located on Umnak Island in the Aleutian volcanic chain, and has erupted from an active vent located in the southwest part of the caldera floor more than 10 times since 19th century. Although there are few habitants around Okmok volcano, ash from the eruption could lead to catastrophic airplane accidents because of the heavy air traffic over the Aleutian Islands. In the 2008 event, ash plumes were emitted up to 15,000m above sea level from the new vent located close to the caldera center, not the active vent. JAXA carried out several observations using ALOS/PALSR before and after the eruption. PALSAR can observe the volcano surface even if it is emitting a great deal of smoke. Comparing images acquired before and after the eruption, we detected surface changes on and around the Okmok caldera and could locate new vents in the area close to the caldera center. Using DInSAR technique of PALSAR data acquired after the eruption, we detected a deflation of the volcanic edifice for the period at least one and a half months after the beginning of the eruption.