[SSS12-P20] Tectonic features of active faults and seismicity in the Tehran basin, Iran
Keywords:Tehran, Alborz Mountains chain, Kavir Desert, geomorphic indices, index of relative active tectonics (IRAT)
In this study, we focus on the deformation features of active faults developed in the Tehran basin, based on the deformation features of active faults developed in the Tehran basin, based on the interpretations of aerial photographs, perspective view of DEM, Google Earth and satellite imageries, geomorphic indices, seismic data and field investigations. Field investigations guided by the interpreted results of images and analysis of geophysical data reveal that the active faults are mainly developed along the topographical boundary between the mountains and basin, which are characterized by the deformational feature of oblique thrusts with horizontal displacement component. The faults mainly strike E–W to ENE–WSW (?) and dip to north with varied angles between ~25° and 85°. Locally, the faults are characterized by left-lateral strike-slip topographical features, with systematic left lateral offset or deflection of valleys and streams. The faults cut the terrace risers and alluvial fans which are inferred to be formed in the late Quaternary and Holocene, indicating the current activity of these faults. Seismic data also show that the many historical earthquakes and many micro-earthquakes occurred in the study region, consistent with our results. Our results show that the active faults in the Tehran region are the potential source of large earthquakes and may require further more study for accessing the seismic hazard in the densely populated urban regions around the Tehran city, Iran.