eEarth www.electronic-earth.net 1815-381X 1815-3828 2 1 2007 10.5194/ee-2-17-2007 http://www.electronic-earth.net/2/17/2007/ http://www.electronic-earth.net/2/17/2007/ee-2-17-2007.html http://www.electronic-earth.net/2/17/2007/ee-2-17-2007.pdf 17 25 2007-02-02 Inflation of the Aira Caldera (Japan) detected over Kokubu urban area using SAR interferometry ERS data D. Remy remy@dgf.uchile.cl S. Bonvalot M. Murakami P. Briole S. Okuyama Institut de Recherche pour le Développement (IRD), UR154, France Institut de Physique du Globe de Paris, 4 Place Jussieu, 75005 Paris, France Geographical Survey Institute, Mizusawa Geodetic Observatory, Japan Kyoto University, Dept. of Geophysics, Kyoto, 606-8502, Japan presently at: Dept. of Geophysics, University of Chile, Santiago, Chile Nine ERS-1 and ERS-2 descending orbit data acquired over Aira Caldera between June 1995 and November 1998 were used to create 36 differential interferograms. Although the interferograms exhibit a relatively low level of coherence, even for couples sampling short time intervals (6 months), Synthetique Aperture Radar (SAR) observations reveal a distinct range change pattern over Kokubu urban area whose amplitude increases with the time separation between SAR images. The analysis of the ground deformation time series relative to the earliest ERS images showed a maximum uplift of about 20 mm between the north and the south of the urban area during the period covered by our satellite observations. Taking the reduced surface of the coherent area into account, we performed a simple modeling of the deformation field assuming an inflating spherical source within an elastic half-space medium located beneath the centre of the Aira Caldera. 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