Geometrical Form of Fault Zones in the Crustal Interior in Xichang Region Determined by Seismic Travel-time Tomography

The geometry of the fault and spatial relations between faults are the basis for studying the crustal deformation,dynamics,their surface response,and for modeling the relations between fault movement and strong earthquake.To fully understand the relation between strong earthquake and deep crustal faults,Anninghe fault,Zemuhe fault and Jinhe fault,we apply the algorithms on seismic ray tracing and travel-time modeling to first arrival Pg wave and reflection wave from the fault for Yanyuan-Xichang-Leibo high-resolution seismic profile,and the direct information on the velocity and fault from three faults mentioned above has been obtained.The results show that: Anninghe fault and Zemuhe fault incline towards east with dip of 32~35 degree,and their velocity structures present low velocity zone of tongue-like shape;those two faults extend downwards to the crystalline basement at large scale and control most strong earthquake activities in this region.Jinhe fault inclines towards east with dip of 30 degree,and extends downwards at least 5 km.