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InSAR Study of earthquakes of the Southern Tibet

S.P. Satyabala(1)

(1) National Geophysical Research Institute, Uppal Road, HYDERABAD - 500 007, India

Abstract

Active deformation in Tibet is characterized by approximately north-south striking normal faults and kinematically linked strike-slip faults. Much of the Tibetan plateau is currently extending in an east-west direction along N-S striking normal faults and the extension is manifested in a series of N-S and NE-SW trending grabens in central and southern Tibet. Constraints on the causes of Tibetan extension are necessary to determine whether the date of its initiation may be used as proxy for when Tibet achieved its maximum elevation as well as understanding processes of syncollisional extension in general.

Faulting associated with earthquakes provides one direct measure of the style of active deformation. Fault plane solutions of earthquakes within and on the margins of the Tibetan Plateau show different styles of faulting and deformation, with thrust faulting and crustal shortening normal to the margins of the plateau and with normal and strike-slip faulting resulting in roughly east-west extension within the plateau. Normal faulting plays a major role in the active tectonics of the Tibetan plateau.

We use the technique of SAR Interferometry to study the normal faulting earthquakes in the region of southern Tibet and corroborate/refine the strain field of Tibet inferred from other studies. Earthquake fault geometry, slip vectors and slip distribution are obtained by inverting the ground deformation maps obtained from SAR Interferometry using elastic dislocation models. Recent GPS studies show that deformation occurs within Tibet throughout the plateau interior by ESE-WNW extension and is spatially variable across the whole of southern Tibet. The goal is to examine whether the deformation signatures obtainable by InSAR can help in understanding aspects of the extensional stress regime along this region of south Tibet.

 

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry