Synthetic normal faulting of the 9 January 2008 Nima (Tibet) earthquake from conventional and along‐track SAR interferometry

Abstract

We use Synthetic Aperture Radar Interferometry (InSAR) to derive the coseismic deformation field of the 9 January 2008 Nima (Tibet) earthquake. The results show an asymmetric deformation pattern, consistent with normal faulting on a NW‐dipping fault plane. The complex line‐of‐sight (LOS) fringe pattern suggests that a second, synthetic fault in the hanging wall of the mainshock rupture slipped during the event, most likely during the largest aftershock. We use conventional and along‐track InSAR data to invert for the geometry and the slip‐distribution on the two fault planes. The focal mechanisms of the mainshock and its largest aftershock show normal faulting with a small left‐lateral strike‐slip component near the NE‐trending Riganpei Cuo fault, which is consistent with our InSAR observation and inversion result. This event suggests that normal faulting in addition to previously established conjugate strike‐slip deformation in the region contributes to the internal deformation of central Tibet.