基于背景噪声初步研究河北及邻区的剪切波速度结构

摘要/Abstract

摘要： 本文根据2010年1～12月河北及邻区的83个宽频地震仪12个月连续噪声记录, 分析了河北及邻区瑞利面波的群速度频散曲线并反演了主要分区内的典型路径剪切波速度结构。首先采用多重滤波方法提取了台站对5～50 s的面波群速度频散曲线, 然后用Herrmann线性反演方法反演了剪切波速度结构。结果表明, 群速度频散曲线及剪切波速度分布特征与地表地质和构造特征表现出较好的相关性, 清晰地揭示了地壳内部的横向速度变化。在短周期(8～20 s), 拥有较厚的沉积层的平原地区表现为明显的低速特征, 而隆起地区则表现为较高的群速度分布特征: 随着周期的增加(>20 s)速度的特征有所改变, 30 s之后由于受地壳厚度的影响, 两者的速度差异逐渐缩小, 在中下地壳波速度随深度增加而增大。同时, 研究发现在研究区域内西南方向的噪声源占主导作用。

关键词: 面波: 频散曲线: 剪切波: 速度结构: 噪声源

Abstract: We present the surface wave dispersion results of the application of the ambient noise method to broad-band data recorded at 83 stations from digital seismic networks of the Hebei and surrounding areas. Firstly we used the multiple-filter analysis method to extract surface wave group velocity dispersion curves from inter-station paths at periods from 5 to 50 s. Then using linear inversion method to obtain shear wave velocity distribution. The results of group and shear wave velocity distribution maps generally demonstrate good correlations with surface geological and tectonic features. The results of the group velocity tomography show that at short periods (8~20 s), basin areas are clearly resolved with low group velocity due to its thick sedimentary layer, and the uplift areas show relative higher group velocity distribution. With the increase of period (>20 s) the group velocity distribution changed, and velocity gap between the basin and uplift areas had reduced after the 30 s period, due to the thickness of the Earth's crust, and beneath the middle-lower the shear wave velocity increase with depth. Our results alsoshow that in this study the dominated noise sources come from the north-west.

Key words: Surface wave, Group velocity dispersion, Velocity structure, Noise source

中图分类号:

P315.7

刘丽, 宫猛, 胡斌, 曾祥方, 罗艳. 基于背景噪声初步研究河北及邻区的剪切波速度结构[J]. 地震, 2012, 32(4): 103-112.

LIU Li, GONG Meng, HU Bing, ZENG Zhi-fang, LUO Yan. Preliminary Study of Shear Wave Velocity Structure of Hebei and Surrounding Areas from Ambient Seismic Noise[J]. EARTHQUAKE, 2012, 32(4): 103-112.

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