中国大陆及邻区SKS波分裂研究

SKS波分裂测量是研究大陆地幔的形变特征、探索大陆动力学和演化过程的重要工具. 本文对中国大陆及邻区地震台站的SKS波分裂现象进行了研究. 选用中国数字化宽频带地震台网(CB台网)和美国IRIS数据中心提供的三分量宽频带数字化地震资料，使用SC(Silver and Chan,1991)方法，得到了中国大陆及周边地区80多个台站下方上地幔各向异性参数，即快波偏振方向φ和快慢波到时差δt. 快波偏振方位在相同地块有一定的优势排列方向，大多数台站快波偏振方向都能与过去或现今大规模的构造运动得到很好的符合. 整个研究区域所得到的分裂延迟时间在0.4～2.4s之间，平均为1.2s. 根据SKS波测量得到的分裂参数，分析了该研究区域各向异性介质的特性，从而探索与岩石弹性各向异性相关的地球内部动力学过程.

A study on SKS wave splitting beneath the China mainland and adjacent regions

SKS wave splitting measurement is a powerful tool to characterize mantle deformation and study the dynamics and evolution of continents. We have made measurements of SKS wave splitting beneath the China mainland and adjacent regions. Our goal is to obtain the magnitude and orientation of upper mantle anisotropy and provide constraints for the evolution model of the crust and mantle. We use the technique of Silver and Chan to determine SKS wave splitting parameters at more than 80 three component broadband stations in China and neighboring regions, including the azimuths of fast polarization direction(φ) and delay times of split shear wave(δt). The fast wave polarization directions beneath most stations share a common preferred orientation in a same tectonic block. The fast axes show good correlation with the past and present day tectonic movement. Delay times range from 0.4s to 2.4s with an average about 1.2s. According to the splitting parameters of SKS wave, anisotropic characteristics in the study region are analyzed to investigate the dynamic process in the Earth.