Rupture process of the July 11, 2004, Tibet (M_w 6.2) earthquake

The source rupture process of the July 11, 2004, Tibet (M_w 6.2) earthquake is investigated by a finite fault model using far field broadband body wave records. The results show that it is a shallow dip-slipping predominant normal-fault earthquake, and the hypocentral depth is about 12.5km. The fault plane has a strike of 152° and a dip of 44°, and the average slip angle is - 117°. The rupture nucleates near the hypocenter, then propagates to the two ends of the fault with an average velocity of 2.8km/s, and the slip reaches to its maximum value of 43cm at about 5km northeast of the epicenter. The main principal T axis of the fault plane solution shows roughly EW extension, which is controlled by a local rift belt in NNW-SSE or nearly NS direction, and the thrust motion of the southern Tibetan plateau towards north is the main mechanical reason of this earthquake.