Seismicity of Tehran City Region and its Vicinity Based on Tehran City Seismic Network (TCSN) Data

From June 2004 to December 2008 low seismic activity was recorded near North-Tehran، Taleghan and Kahrizak faults and inside of Tehran city. In contrast، seismic activity along Mosha، Garmsar and North-Alborz faults is considerable. Generally seismic activity decreases from 51 degrees longitude to west. Two earthquakes with 15 and 17 km depth were located in the west of Tehran city. The calculated focal mechanism for one of them is pure strike-slip. High seismic activity is observed along Mosha fault close to Damavand، Boumehen cities and Lavasant-e-Bozorg region. Calculated focal mechanisms along this fault includes both strike-slip، and reverse mechanisms that implies transpression motion، dominantly left-lateral slip along this fault that continued to Lavasanat region in south of the eastern end of the North Tehran fault. Precise location of some events shows depth range of 4-32 km. Generally، calculated focal mechanisms in studied region include both strike-slip and reverse mechanisms and seems that in southern part، approaching Central Iran، reverse mechanisms are dominant. It implies slip partitioning in southern margin of Central Alborz.