Abstract
ABSTRACTThe 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.
Highlights
It is well known that interferometric synthetic aperture radar (InSAR) has been widely used for mapping the Earth’s surface deformation (Massonnet et al 1993), but it is limited to onedimensional (1D) deformation mapping in the line-of-sight (LOS) direction
While the InSAR method has been widely used for measuring surface displacements, the multiple-aperture interferometry (MAI) method was not applied in many cases because it requires the high interferometric coherence
This study shows the 3D surface displacements induced by the 2003 Bam earthquake by using coseismic ascending and descending InSAR pairs obtained from the ENVISAT ASAR sensor
Summary
It is well known that interferometric synthetic aperture radar (InSAR) has been widely used for mapping the Earth’s surface deformation (Massonnet et al 1993), but it is limited to onedimensional (1D) deformation mapping in the line-of-sight (LOS) direction. That means deformation mapping from the InSAR measurement cannot be available in the along-track direction, which in turn we cannot retrieve the precise 3D movements of the surface. For the better understanding of geological processes of natural hazards such as earthquakes and volcanic activities, three-dimensional (3D) surface deformation mapping has been becoming increasingly more essential. Even though the offset tracking method has been used for measuring along-track displacements, the accuracy of the offset-derived azimuth deformation is much lower than that of the LOS deformation by InSAR, and the north component in 3D deformation is quite noisy. Many previous studies have suggested the various scenarios of the Bam earthquake, we expect that the 3D measurements are able to provide a little different but meaningful interpretation about the fault behaviour
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