【摘要】 利用最小特征值法,分析了喜马拉雅地区56个台站的地震记录,其中有39个台站能观察到S波分裂,其平均分裂时间在0.8 s左右.沿台站GAIG-T0040连线的东西两侧各向异性参数呈现明显的差别:其以西地区,约有一半的台站没有观测到S波分裂,快波方向主要为NW和NWW方向;以东地区台站的快波方向在MBT(主边界断裂)以南为NNE向,平均分裂时间为1.05 s;低喜马拉雅地区为NE和NEE向,平均分裂时间为0.72 s;而在特提斯喜马拉雅地区为N-S和NNE向,平均分裂时间为0.68 s.综合其他研究结果,认为东西向各向异性参数的差异是由于印度块体向北推进时的横向不均匀性造成的,而南北向的变化与该地区构造单元的分布一致.更多还原

【Abstract】 The records of 56 stations in Himalaya area were analyzed by using the method of minimizing the eigenvalue.Shear wave splitting was observed in thirty-nine stations of them.The average splitting time is about 0.8s.The parameters of splitting are not only different from south to north,but also different either side of the line joining the stations GAIG and T0040(AA′).To the west of the line,FPD(fast polarization direction) is mainly in the NWW or NW direction.To the east of it,FPD is in NNE to the south of MBT.FPD is NE or NEE in Lesser Himalaya and it becomes N-S or NEE in Tethys Himalaya.Comparing with other studies,we argue that the difference of splitting parameters between east and west is produced by lateral heterogeneous collision between Indian plate and Eurasia plate.The variation from south to north to the east of AA′ is produced by the complicated structure in this area.更多还原