Advances in three-dimensional deformation mapping from satellite radar observations: application to the 2003 Bam earthquake

The advance of the surface deformation measurement from synthetic aperture radar interferometry (InSAR) provides an opportunity of reinterpretation for the past controversial event in the geoscience community. According to the development of the multiple-aperture interferometry (MAI) method, three-dimensional (3D) surface displacements can be estimated with few centimetres accuracy by integrating InSAR and MAI observations. In this study, we provided a renewed fault model of the 2003 Bam earthquake using the advanced method. The 3D deformation map showed the clear distribution pattern of the right-lateral strike-slip fault as well as the additional information of an asymmetry of the surface deformation. To determine the optimal model parameters, we employed a two-segment fault model considering the multiple segments. As a result, two sub-parallel fault segments showing N-S trend were obtained. The model parameters of the second segment have relatively large uncertainties though, the first segment which is presumed as the causative fault of the Bam event has been well-modelled with precise model parameters. The more constrained fault model based on the 3D deformation field enabled us to suggest a possibility of a new interpretation and the better understanding of the fault behaviour.