面波群速度测量误差分析

An error analysis of surface wave group velocity measurement

通过一系列的理论实验和实际数据处理,分析采用单台多重滤波法和双台互相关法提取面波群速度的误差.结果表明,面波群速度测量误差随震中距和周期的变化而变化.为了减少频散测量误差,需要选择合适的高斯滤波参数.高斯滤波参数应随周期的增大而减少,并随震中距的增大而增大.结合前人工作,本文提出了一个高斯滤波参数的经验选择公式.研究也表明,采用双台互相关法测量面波群速度,由于面波振幅谱变化更剧烈,测量中会产生更大的系统性误差,这时有必要利用瞬时周期修正提取的面波群速度频散.

Multiple filter technique and correlation method were used to analysis the error in surface wave group velocity measurement.The result shows that the error correlates with the period and epicentral distance.In order to minimize the error,we shall choose suitable Gaussian filter parameter.The filter parameter should decrease with the increasing period and increase with the increasing epicentral distance.On the basis of previous studies,we give a simple empirical formula of the choosing of the Gaussian filter parameter,in which both the period and epicentral distance are included. When the correlation method is used to measure the group velocity,the spectral amplitude of surface wave changes rapidly with the period and a greater systematic error is produced compared to the one station method,so the instantaneous period correction is more desired to modify the measured dispersion curve.