利用多重滤波法提取面波群速度及其高斯滤波参数取值

Measurements of surface-wave group velocity using MFT and the value of Gaussian filter parameter

介绍了多重滤波法提取瑞利面波群速度的原理和步骤,并基于不同震中距的理论瑞利面波数据和高质量的实际数据,采用4种不同的高斯滤波参数α取值方案提取群速度曲线,结果表明:当周期范围跨度较大时,高斯滤波参数α取值不仅应考虑震中距,还应考虑周期;对于不同震中距,在周期小于45 s时,高斯滤波参数α取值范围较大,但在周期大于45 s时,不同的高斯滤波参数α取值对群速度的提取影响较大,此时α的取值应谨慎;在这4种不同的α取值方案中,本文改进后的周期分段α取值方案效果最好。

Principle of multiple filter technique(MFT) was illustrated. Based upon synthetic Rayleigh waves at different epicentral distances and high-quality real data, MFT was applied to measure group velocities using four different values of Gaussian filter parameter. The results show that the value of Gaussian filter parameter should be chosen,not only for the epicentral distance, but also the period. When the period range is wide, Gaussian filter parameter has wide value range. When the period is smaller than 45 s, the value of Gaussian filter parameter should be decided carefully. When the period is longer than 45 s,the value will affect largely the group velocity measurements. The optimized values of Gaussian filter parameter proposed is the best in this paper.