从远震P波的尾波里分离高信噪比的S波

Isolating the high signal-noise ratio S-wave from teleseismic P-wave coda

随着全球宽频地震台的迅速增加,P波接收函数技术已经成为探测地壳上地幔结构的标准工具之一,其基本原理就是从远震记录波形上分离出台站下方的间断面上产生的P_S转换相,从而确定间断面的深度和特性.文章介绍了三分量记录的远震资料经过坐标旋转、反褶积运算后从P波的尾波里分离出S波(P_S转换波)的P波接收函数技术.然而,近地表存在低速沉积层时,可能在接收函数波形里引起强烈的多次振荡相,为此引入了滤波技术消除这些振荡相对来自地壳上地幔速度间断面所产生的P_S转换波及其多次反射波P_pP_S,P_pS_S+P_SP_S的影响.另外,由于来自地壳上地幔速度间断面上产生的P_S转换波及其多次反射波P_pP_S,P_pS_S+P_SP_S是弱信号,文章还引入了相位权重叠加技术以增强P波接收函数的信噪比.

With the rapid increase of the broadband seismic stations on the world,P receiver functions technique with teleseismic events is very suitable for studying the crust and uppermantle structure beneath stations,thus becoming one of the standard tools for such study.The principle of P receiver functions is to separate the converted P_S phases generated at the discontinuities beneath stations and to determine the depth of the discontinuities with the converted P_S phases.In the study,we have introduced the P receiver functions technique which isolates the S wave（ P_S conversion phase） from P wave coda by rotating and deconvolving 3-conponent recordings.However,the presence of lower-velocity sediment may give rise to strong reverberations in P receiver functions. We have applied the filtering technique to remove the effect of the strong reverberations on the P_S phase,P_pP_S and P_pS_S＋P_SP_S phases generated at the discontinuities in crust and upper mantle. On the other hand,since the P_S phase,P_pP_S and P_pS_S＋P_SP_S phases generated at the discontinuities in crust and upper mantle are very weak,so we have applied phase-weighted stacking technique to improve the signal-to-noise ratios in P receiver functions.