上海佘山地震台阵地壳精细结构研究

Detailed crustal structure in Shanghai Seismic Array

选取上海佘山地震台阵16个子台记录的远震波形数据,采用时间域反褶积方法计算不同频率的P波接收函数,采用H-κ叠加搜索方法获取每个子台下方地壳厚度和v_(P)/v_(S)波速比值。研究结果显示:整个台阵下方地壳厚度和波速比值存在弱横向不均一性,其中上海佘山地区平均莫霍面深度较浅,约26.9 km;v_(P)/v_(S)比值较高,约1.87。采用最小二乘法联合多频率P波接收函数和瑞利频散曲线,反演上海佘山地震台阵下方地壳S波速度结构,结果显示,中地壳存在S波低速结构,与前人研究结果相一致。

In this paper,the teleseismic waveform data recorded at 16 sub-stations of the Sheshan Seismic Array in Shanghai are selected,and the time-domain deconvolution method is used to calculate the P-wave receiver functions at different frequencies,and the H-κstacking method is used to obtain the thickness of the crust beneath each sub-station and the v_(P)/v_(S) ratio.The results show that there are weak lateral inhomogeneities in crustal thickness and v_(P)/v_(S) ratio beneath the whole array,with the average Moho surface depth in the Sheshan region of Shanghai being thin,about 26.9 km,and the v_(P)/v_(S) ratio being high,about 1.87.The inversion of the S-wave velocity structure of the crust beneath the Sheshan Seismic Array is performed by using the least-square method in combination with the multi-frequency P-wave receiver functions and Rayleigh dispersion curves,and the results show that there is an S-wave low-velocity structure in the middle crust,which is consistent with the results of previous studies.