SUBSIDENCE OF THE COLLAPSED CALDERA OF MIYAKEJIMA, 2006-2011

摘要

Ground deformation of Miyakejima, Japan, between 2006 and 2011 was investigated from Synthetic Aperture Radar images to gain insights into the mechanics of postcaldera deformation associated with the 2000 eruption. 70 and 69 interferograms were created from 22 ascending and 21 descending images, respectively, of PALSAR boarded on the ALOS satelitte. Our result reveals a localized vertical subsidence of up to 150 mm/yr around the collapsed summit. The observed displacement field is well modeled by a closing sill at 0.5 km below the surface. The compaction volume is too small to be consistent with the amount of sulfur dioxide emission. The modeled sill would thus represent the compaction of the conduit column associated with the summit collapse, rather than the gas emission.