【摘要】 基于中国国家和区域数字地震台网记录,采用CAP方法反演了2012年9月7日云南彝良5.7、5.6级地震的震源机制解和震源深度,并利用IRIS提供的远震记录深度震相(P、PP、SP)进一步确定了震源深度,最后结合地震序列分布、地震烈度分布和区域地质背景讨论了发震构造.结果显示彝良5.7级地震的震源机制解为节面I走向243°、倾角62°、滑动角149°,节面Ⅱ走向349°、倾角63°、滑动角32°;5.6级地震的震源机制解为节面I走向241°、倾角37°、滑动角162°,节面Ⅱ走向346°、倾角79°、滑动角54°,这两次地震的发震构造均为NE走向的石门断裂,震源矩心深度均为6km左右,表明地震的能量释放主要发生在地壳浅部,这也是导致震区严重灾害的一个重要原因.更多还原

【Abstract】 Based on the records of CSN and regional digital seismic networks,we obtained the focal depth and focal mechanism of the Ms5.7 and Ms5.6 Yiliang earthquakes of Sep.7,2012 with the "Cut and Paste"(CAP) method,and used the teleseismic depth phases like P,PP,and SP from IRIS records to determine the focal depth.Further,we analyzed the rupture characteristics and seismogenic structures of the Yiliang earthquakes combining with the earthquake epicenters,seismic intensity,and geologic settings in the region.Our result shows that the best double couple solution of the Ms5.7 event is 243°,62°,and 149° for strike,dip,and rake angles respectively,the other nodal plane is 349°,63°,and 32°;for the Ms5.6 event the solution is 241°,37°,162° with the other nodal plane of 346°,79°and 54°.We infer that both of the Ms5.7 and Ms5.6 earthquakes occurred on the NE striking Shimen fault and the focal depths of the events are about 6 km,the released seismic energy was concentrated in shallower crust which is an important reason for the serious seismic damage in the region.更多还原