Recognition of fault causes in 9th March 2008 earthquake AryaShahr area by aftershocks analysis

In 9 March 2008 an earthquake with ML=5.1 ouccered in the west of Aryan-Shahr city, southeast of Iran. Many villages destroyed by this earthquake. Primarily, the Sedeh fault with N76 trend was nominated as source of this earthquake. But the distribution of aftershock dispersals has been occurred in an ellipsoid district which is not superimposed on Sedeh Fault. The long axis of distribution ellipsoid of aftershocks (N120) is nearly perpendicular to the Sedeh Fault trend. The seismic network, installed by Institute of Geophysics (university of Tehran), recorded more than 100 aftershocks during 3 monthes. All data of 3 stations were processed, common aftershocks were separate, their parameters were determine and were drawn on fault map. Therefore distribution of aftershocks location and main shock geometry of causing fault is known. Based on investigation of aftershock epicenter dispersal and the interpretation of aeromagnetic data reveal the presence a blind fault (Ghesar fault) parallel to long axis of distributionellipsoid of aftershocks.