Earth Planets Space, Vol. 60 (No. 5), pp. 447-452, 2008
Chang-Wook Lee1,3, Zhong Lu2, Oh-Ig Kwoun3, and Joong-Sun Won1
1Department of Earth System Sciences, Yonsei University, 134 Sinchon-dong, Seodaemun-gu, Seoul 120-749, Korea
2U.S. Geological Survey, U.S.A.
3SAIC, U.S. Geological Survey Center for Earth Resources Observation and Science, Sioux Falls, SD, U.S.A.
(Received October 14, 2006; Revised March 12, 2007; Accepted September 7, 2007; Online published May 16, 2008)
The Augustine Volcano is a conical-shaped, active stratovolcano located on an island of the same name in Cook Inlet, about 290 km southwest of Anchorage, Alaska. Augustine has experienced seven significant explosive eruptionsin 1812, 1883, 1908, 1935, 1963, 1976, 1986, and in January 2006. To measure the ground surface deformation of the Augustine Volcano before the 2006 eruption, we applied satellite radar interferometry using Synthetic Aperture Radar (SAR) images from three descending and three ascending satellite tracks acquired by European Remote Sensing Satellite (ERS) 1 and 2 and the Environment Satellite (ENVISAT). Multiple interferograms were stacked to reduce artifacts caused by atmospheric conditions, and we used a singular value decomposition method to retrieve the temporal deformation history from several points on the island. Interferograms during 1992 and 2005 show a subsidence of about 1-3 cm/year, caused by the contraction of pyroclastic flow deposits from the 1986 eruption. Subsidence has decreased exponentially with time. Multiple interferograms between 1992 and 2005 show no significant inflation around the volcano before the 2006 eruption. The lack of a pre-eruption deformation signal suggests that the deformation signal from 1992 to August 2005 must have been very small and may have been obscured by atmospheric delay artifacts.
Key words: Surface deformation, atmospheric effects, interferograms, pyroclastic flow deposits, subsidence.