InSAR surface displacement field and fault modelling for the 2003 Bam earthquake (southeastern Iran)

Abstract

Descending and ascending track satellite images of the new European C-band Envisat Advanced Synthetic Aperture Radar have been used to detect the surface displacement field during the 26 December 2003, Mw 6.5, Bam earthquake in southeastern Iran and to determine the fault parameters. In this work, displacement field maps have been realized from interferograms for both tracks. The surface displacement pattern from InSAR revealed that slip occurred along an unknown fault. Based on modelling (Okada, 1985), fault parameters with variable slip distribution (geometric and kinematic) have been considered to better reproduce the InSAR pattern. These parameters have been also constrained by the available seismological data. The modelled interferogram versus the unwrapped interferogram shows low residual values for a fault 18 km long, 12 km wide and with a top of the fault plane at 0.5 km from the surface. The best fitting strike, dip and rake are 177◦, 88◦ and 166◦, respectively.