Abstract:

On April 14, 2010, a M_s7.1 earthquake struck the Yushu County, Qinghai Province, China. The authors observed the co-seismic deformation of Yushu M_s7.1 scale earthquake, on July, 14, 2010, using two periods PALSAR by Interferometric Synthetic Aperture Radar (InSAR) technology, and yielding a clearly wrapped InSAR image and solving a absolutely deformation map covering most earthquake impact region. Furthermore, referencing to the amount, region, direction and gradient of InSAR co-seismic deformation, as well as combining with tectonic setting and mechanics of strike-slip fault, this paper infers its tectonic activity features: 1)Yushu earthquake triggered a NWW extend, sinistral step, “S” shape strike-slip fault deformation belt, which contains 5 sub-sections, average slip dislocation ranging from 10.2 cm to 133.2 cm, maximum  up to 195 cm, and two of them near Jiegu Town and Longbao Town presented clear surface ruptures. 2)The difference of two walls’ movement in direction and amount shows that the seisgenic fault is a sinistral strike-slip and SW wall is an initiative wall. 3)The macro-epicenter can be located on mutation belt of NW 16 km of Yushu County; 4)The deformation amount, surface track and rupture amplitude of seisgenic fault indicate that the aftershocks will migrate towards NW alone fault. 5)This earthquake is the results of Qiangtang Block's activity and does not directly related with Wenchuan Earthquake induced by Bayan Har Block.

Key words: earthquakes, Yushu earthquake, geoseismic fault movement, InSAR, aftershocks migration