甘东南地区地壳介质各向异性特征

Seismic Anisotropy in the Crust in Southeastern Area of Gansu Province

利用甘肃数字地震台网(2001-2008年)的观测资料,采用SAM分析方法进行剪切波分裂,获得了甘东南地区7个台站319条剪切波分裂参数。结果表明甘东南地区快剪切波平均偏振方向与该区域最大主压应力方向一致,是区域应力环境的较好描述;位于活动断裂上或几条活动断裂交汇部位的台站的快剪切波偏振优势方向大多数与对控震的活动断裂走向一致;复杂的局部构造会影响剪切波分裂结果,造成偏振优势方向与主要活动断裂走向不一致,或与区域主压应力相差较大的现象。

Based on the observation data recorded by Gansu Seismological Network（2001-2008）,using the SAM technique for S wave splitting analysis,the 319 shear-wave splitting parameters at 7 stations are obtained in southeastern area of Gansu province.It is shown that the average polarization of fast shear-wave is consistent with the regional maximum horizontal compressional stress,it is an efficient tool to depict regional stress field.The dominant polarization direction at stations which located on active fault or cross point of some active faults is consistent with the strike of main earthquake-controlling fault.However,for some stations the fast S wave polarization directions are not consistent with the fault strikes and the direction of regional maximum horizontal compresstional stress,probably owing to the influence of local complicated crustal structure.