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

摘要： 利用通过本区6条宽角反射/折射剖面资料对大同-阳高震区及邻区地壳上地幔速度结构与构造进行了详细的研究。结果表明,地壳上地幔速度结构与构造在纵向和横向上具有明显的不均一性。浅部基底断裂发育,而在其深部,根据波组特征、壳内界面及速度等值线起伏变化和低速异常体的边界等推测有3处地壳深断裂带。本区最明显的上地壳低速体位于大同-阳原附近,其南界存在地壳深断裂,大同-阳高地震群与该低速异常体和深断裂有关。

关键词: 地壳, 上地幔, 速度构造, 深断裂