关键词: 地壳, 上地幔, 速度构造, 深断裂

Abstract: By using seismic data obtained from six wide angle reflection and refraction profiles passing through the area,the velocity structures and tectonics of the crust and upper mantle in the Datong Yanggao seismic region and its surrounding areas have been studied in detail. The results show that the crust and upper mantle velocity structures and tectonics have obviously both longitudinal and lateral heterogeneities. A great number of basement faults exist in the shallow crust which correspond to the deep structures. According to the characteristics of wave groups,the interfaces of crust interior and the undulations of the velocity contours as well as the boundaries of the low velocity abnormal blocks,three deep crustal faults are inferred. The most obvious low velocity block in the upper crust lies in the neighbourhood of Datong Yangyuan and in its south boundary exists a deep crustal fault. The Datong Yanggao earthquake swarm is associated this low velocity abnormal block as well as the deep faults.

Key words: Crust, Upper mantle, Velocity structure, Deep seated fault