Analyzing Neotectonic in Central Alborz: Preliminary results

Central Alborz corresponds to the E-W trending mountain range bounding the Oceanic Caspian domain to the South. It connects to the Talesh and the Lesser Caucasus structures to the West and the Eastern Alborz structures to the East. Central Alborz contains different geological units from Precambrian to Quaternary ages. These units, assembled in complex systems of thrusts and folds,deformed during several orogenesis related to the closure of Tethyan basins (Proto Tethys, Paleo Tethys and Neo Tethys). Since Neogene, Iran is undergoing the N-S collisionnal process between Arabian and Eurasian plates and the lateral push of the northwards converging Indian plate along its eastern border. Old structures are uplifted and reactivated, especially along the ancient margins. In Central Alborz, the recent activity is controlled by the E-W trending structures such as the North Tehran fault, the Musha fault in the South and the north Alborz fault and the Khazar fault in the North. Several large historical earthquakes occurred along these inherited structures, which represent a high seismic potential. In order to go further in assessment of seismic hazards in Central Alborz, we started a morphotectonic analysis combining remote sensing analysis (satellite imagery,air photographs, digital elevation model) and field study. Its aim is, at first, to identify and map precisely the geometry and the kinematics of the faults, and secondly, to estimate their slip rates and earthquakes return periods.