【作者】 刘希强； 周蕙兰； 郑治真；

【Author】 Liu Xiqiang Zhou Huilan and Zheng Zhizhen1) Post graduated School, Science and Technology of China, Beijing 100039, China2) National Centre for Seismic Data and Information, China Seismological Bureau, Beijing 100045, China

【机构】 中国科学技术大学研究生院； 中国地震局地震数据信息中心；

【摘要】 对已有分裂剪切波识别方法的原理进行了阐述。讨论了各种剪切波分裂识别方法之间的共性和差异特征、存在的缺陷。提出了定量估计剪切波分裂参数及其误差的理论和方法。 应用包含在小波变换系数中的信号偏振信息,本文提出了一种确定单台三分向记录图中P波和S波震相的小波变换方法。上要的思路是寻找地震信号在不同尺度下小波变换系数的显著特性,通过对小波变换系数的主成分分析得到不同尺度下的P和S波识别因子,进而形成确定P和S波初至的定位函数。通过对模拟资料和实际地震资料的分析,认为由小波变换方法形成的定位函数具有一定的抗噪声能力,在精确识别P波和S波初至方面是非常有效的。主要对ScS波分裂特性进行了研究。精选了99个地震事件,从每个台站中选出了210个可以较清楚识别出ScS(地震震中距大多数小于40°)和SKS(震中距大于80°)震相的记录用于分析。这210个记录取自中国CDSN台网和新疆台网的乌什台站。震相初至识别方法主要基于小波变换、主成分分析方法,分裂参数识别主要基于改进后的SC方法。给出了各台记录的地震震源参数和ScS或SKS波分裂的详细结果和各台剪切波分裂的平均计算结果和误差估计。对一些特殊剪切波传播方向上ScS或SKS波分裂的结果进行了讨论。为了验证识别方法的有效性,考虑不同震中距、不同的传播方向和不同的信噪比水平几个因素给出了对7次地震资料的方法处理结果。根据中国大陆所处的新构造环境,将观测结果与中国大陆各亚板块运动方向及相关研究结果进行了对比分析。最后对观测结果的起源进行了分析和讨论。更多还原

【Abstract】 We mainly study the characteristics of ScS (epicenter distance is less than 40 degree) and SKS waves (epicenter distance is more than 85 degree). Picked 210 ScS wave phases are studied among 99 earthquakes. These records come from CDSN Network and Wushi station of Xinjiang Network. In order to separate, accurately identify wanted seismic phases and test the validity of new methods, this paper adopts the idea that combining new methods with corrected old methods, theory seismic phase onsets with actual observed onsets. Then we present each earthquake basic parameters, results of ScS and SKS waves splitting and corresponding error estimation, and average shear wave splitting parameters and corresponding error estimation by analyses and processing of data decompression, information login , pretreatment, splitting parameters determination, results output. Based on actual recorded data, we present the processed results of 7 earthquakes to different epicenter distance, propagation direction and signal-noise ratio level. Based on theory studied results, we discuss the characteristics of ScS or SKS wave splitting parameters in all propagation directions, some propagation directions parallel or vertical fast shear wave polarization direction included and compare observation results with the motion direction of each sub-plate on the basis of new structure circumstance and other relative studied results. Studied results reveal that characteristics of anisotropic medium do not obvious chang with depth, do not exist two anisotropic medium layers, distribution range of the thickness of anisotropic layer is from 80 to 220 kilometers which locates lithostrome and asthenosphere. Observed results are caused by fossil anisotropy and asthenosphere anisotropy.更多还原