利用深反射地震数据构建的多阶面波频散曲线反演近地表横波速度结构——以跨班公湖—怒江缝合带深反射地震资料为例

深反射地震剖面法为了获取深部结构特征常常采取大的偏移距采集数据.目前公开发表的相关资料中，鲜有利用深反射地震炮集数据获取近地表的结构特征.为此，本文通过正演测试了相关数据处理流程，即利用有限差分正演了起伏地表模型的大偏移距地震单炮弹性波场特征，通过共检波点域面波信号F-K频谱叠加构建新方法，从深反射地震数据集中提取了高品质的多阶面波频散曲线，再利用多阶面波联合反演获得了近地表的结构特征.在前述正演流程基础上，利用跨越班公湖—怒江缝合带的SinoProbe深反射地震剖面中的实际炮集数据，求取了基阶和一阶瑞利波频散曲线，联合反演后得到近地表横波速度结构.该结果与初至波走时反演获取的纵波速度结构具有较好的一致性，且在近地表的浅层分辨率较纵波速度结构特征更高，而更与已有地质认识相吻合.本文提供的相关数据处理流程表明利用深反射地震炮集数据，也能够获取近地表浅层的横波速度结构.

Near surface shear wave velocity structure inversion using multi-order surface wave dispersion curves constructed from deep seismic reflection data: a real case of deep seismic reflection profile across Bangong-Nujiang suture zone

In order to obtain the deep structure characteristics, deep seismic reflection profile method usually adopts large offset acquisition. At present, there are few publications using large offset deep seismic reflection shot gather data to obtain near surface structural characteristics. Therefore, this paper tests the relevant data processing flow through forward modeling data: a layered model with an irregular topography was built and 2D elastic finite difference modeling was executed to generate long offset synthetic seismic shot gathers, the method of superposition of surface waves' F-K spectrums in common receiver domain was adopted to analyze shot records, which enabled us to obtain both fundamental-mode and higher-mode dispersion curves in irregular topography, multi-mode surface waves joint inversion was performed to generate near surface structure. Based on above processing flow, fundamental and 1^st mode dispersion curves were obtained from the SinoProbe deep seismic reflection field data in Bangong-Nujiang suture zone, a shallow shear velocity model was generated using multi-mode joint inversion. Comparing with a near-surface P-wave velocity model derived by first arrivals travel time tomography, it is shown that there is an excellent correlation between P- and S-wave velocities, and the shear wave velocity structure has a higher resolution in the shallow part, the result is consistent with current geological cognition. The processing procedure provided in this article show that the use of deep seismic reflection shot data can also obtain near-surface S-wave velocity structure.