STUDY OF STRIKE SLIP FAULTS IN SUB-HIMALAYAN THRUST BELT USING REMOTE SENSING AND SEISMIC DATA

Indo-Asia collision built the spectacular Himalayas. There are several models that explain the crustal shortening of Himalayan orogen. Thin viscous model emphasizes the strata thickening and forward thrusting, and extrusion tectonics model considers primarily the escape along strike slip faults. But the strike slip faults in the sub-Himalayan thrust belt are poorly documented because the configurations of the structures have not been recognized or adequately mapped. The focus of this study is to estimate the rate of displacement along the major strike slip faults in sub-Himalayan thrust belt of Pakistan and to evaluate their overall tectonic significance in accommodating the shortening in this region. Remote sensing techniques provide an effective and economic approach to obtain geological information. The fault patterns and structural framework are extracted from ASTER data. The geomorphic features shaped by the active tectonics are acquired from ASTER derived 15m DEM. Interferograms in which continuous surface displacement along faults is shown at centimeter scale are produced using Interferometric Synthetic Aperture Radar (InSAR) technique. In addition, several seismic profiles are being processed to obtain the subsurface characteristics of these faults. The surface displacement, structural framework and subsurface characteristics of these faults indicate that crustal shortening and forward thrusting dominate the sub-Himalayas and accommodate most of the N-S shortening, the strike slip faults which divide the thrust wedges into small sheets also play important roles in accommodation of the deformation, especially the differentiated shortening between two adjacent structural units.