摘要
In the paper, the distribution characteristics of strong earthquakes in Sichuan-Yunnan area and their geological tectonic background, especially the relation to Sichuan-Yunnan and Sichuan-Qinghai crustal blocks have been studied. The main results are: a) Strong earthquakes in Sichuan-Yunnan area distribute mainly in Sichuan-Yunnan and Sichuan-Qinghai crustal blocks; b) Most of strong earthquakes of the two blocks distribute mainly along their boundary faults; c) A few strong earthquakes are not obviously related to active faults. It shows that the relation between strong earthquakes and geological tectonics can be very complex; d) There is a certain correlativity for seismic activities among boundary faults of the two blocks, but they have different features; e) There are some anomalous changes of velocity structures in the deep crust of boundary faults of the two blocks. Many boundary faults, especially Longmenshan fault, cut obviously the Moho discontinuity. The Xianshuihe fault, a typical strike-slip fault, has no obvious indication of cutting the Moho discontinuity, but has distinct low-velocity zone in different depths.
In the paper, the distribution characteristics of strong earthquakes in Sichuan Yunnan area and their geological tectonic background, especially the relation to Sichuan-Yunnan and Sichuan Qinghai crustal blocks have been studied. The main results are: ① Strong earthquakes in Sichuan Yunnan area distribute mainly in Sichuan Yunnan and Sichuan Qinghai crustal blocks; ② Most of strong earthquakes of the two blocks distribute mainly along their boundary faults; ③ A few strong earthquakes are not obviously related to active faults. It shows that the relation between strong earthquakes and geological tectonics can be very complex; ④ There is a certain correlativity for seismic activities among boundary faults of the two blocks, but they have different features; ⑤ There are some anomalous changes of velocity structures in the deep crust of boundary faults of the two blocks. Many boundary faults, especially Longmenshan fault, cut obviously the Moho discontinuity. The Xianshuihe fault, a typical strike slip fault, has no obvious indication of cutting the Moho discontinuity, but has distinct low velocity zone in different depths.
出处
《地震学报》
CSCD
北大核心
2004年第2期211-222,共12页
Acta Seismologica Sinica
基金
State Key Basic Research Development and Programming Project of China (G1998040700/95-13-02-03).
