中国数字地震台网(CDSN)单台站P波偏振分析

doi:10.12196/j.issn.1000-3274.2020.04.004

摘要/Abstract

摘要： 偏振分析可以定量描述地震波的质点运动。 P波质点运动在水平方向上发生偏振, 使得传播方向会偏离台站与地震震源之间大圆弧的方向。 P波偏振分析可以用来约束地下结构以及反映地震各向异性, 提供与剪切波分裂等手段不同的证据。本文介绍并使用主成分分析(Principle Component Analysis, PCA)的方法, 计算了单一地震台的P波偏振, 同时, 利用谐和分析, 对台站下方的各向异性进行了分析。将P波偏振分析应用到中国数字地震台网(China Digital Seismograph Network, CDSN)的四个台站10年左右的数据, 筛选并分析了震相清晰、信噪比高的远震三分量初至P波的质点运动, 拟合出四个台站接收到的地震事件后方位角与P波水平偏离角度之间的三角函数曲线, 计算出拉萨台、昆明台下方上地幔各向异性的偏振方向分别为66°和57°, 大致呈现北东东方向。

关键词: P波偏振, 中国数字地震台网, 主成分分析, 各向异性

Abstract: Polarization analysis can quantitatively describe the particles motion of seismic wave. The horizontal polarization of initial P particle motion can deviate from the great circle azimuth from station to source. P wave polarization data may provide constraints on subsurface structure an anisotropy different from those travel times and shear wave splitting. We use principle component analysis method to calculate P wave polarization of a seismic station, together with a harmonic analysis for the anisotropy beneath the receiver. In the principle component analysis, we take the singular value decomposition algorithm. Four seismic stations of China Digital Seismograph Network (CDSN) are investigated by this method. We analyze particle motions of teleseismic P wave records, fitting the sine curves and estimate the fast directions of anisotropy of single station of LSA and KMI stations. The fast direction of LSA is 66°, and the fast direction of KMI is 57°.

Key words: P wave polarization, CDSN, Principal Components Analysis, Anisotropy

中图分类号:

P315.7

陈彦含, 吴庆举. 中国数字地震台网(CDSN)单台站P波偏振分析[J]. 地震, 2020, 40(4): 49-62.

CHEN Yan-han, WU Qing-ju. P Wave Polarization Analysis on Part CDSN[J]. EARTHQUAKE, 2020, 40(4): 49-62.

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