利用多频率远震体波振幅比约束浅层地壳速度和泊松比结构的方法研究与应用

地壳浅层速度结构是地震灾害预防、矿产资源勘查和浅表地质过程研究的基础，地震波速度与泊松比结合能更好地推断地下岩石岩性和组分，为认识浅层地壳物质属性和结构变形机制提供重要依据。传统的基于体波走时和面波频散数据的成像方法受地震和台站分布影响严重，本项目提出利用多频段远震P波H/V振幅比和远震S波V/H振幅比联合反演单个台站下方浅层地壳速度和泊松比结构。这种方法适用于单个台站或少区域地震地区，而且因体波比面波频率更高所以具有更高的垂向分辨率。进一步将新方法应用至伊朗高原宽频带地震台阵记录的远震数据获取10公里以浅地壳S波速度和泊松比结构，并将其作为接收函数H-k叠加扫描的先验信息约束结晶地壳泊松比。基于研究区地壳不同深度层次的速度和泊松比结构，结合浅表地质、地表形变和深部结构图像等，研究不同构造单元岩石组分和结构特征差异，为理解伊朗高原浅层地壳变形机制及其与深部过程耦合关系提供地震学依据。

Seismic velocity structures of the shallow crust are the basis for the earthquake disaster prevention, mineral resources exploration and the understanding of related geological processes. Combination of seismic velocity and Poisson's ratio can better infer the lithology and components of the rocks, which also provides an important basis for the comprehensive understanding of the rock properties and the structural deformation mechanisms in the shallow crust. Considering that traditional imaging methods based on travel time and surface wave dispersion data are seriously affected by the distribution of receivers and/or earthquakes, this study intends to combine two teleseismic datasets at multiple frequencies, i.e., P-wave H/V and S-wave V/H amplitude ratios, to inverse for velocity and Poisson's ratio structures of the shallow crust beneath one single station. The method is suitable for the case of a single station and/or areas where earthquakes rarely occur, and has a much higher resolution in depth than the surface wave imaging methods owe to the relatively high frequency components of body waves to those of surface waves. The new method will be applied to obtain the shallow crustal velocity and Poisson's ratio structures beneath the Iranian Plateau, based on the teleseismic data recorded by the dense broadband seismic stations. The H-k technique will be improved to obtain the Poisson's ratio of the crystalline crust through removing the effect of shallow crustal structures. Combined with the pre-existing surface geological and deformation(GPS) observations and deep structural images, the newly obtained velocity and Poisson's ratio structures at different depths of the crust will provide more information on the determination of the crustal components and tectonics and their differences among different blocks, and meanwhile provide the seismological constraints for understanding the deformation mechanism of the shallow crust and its coupling relationship with the deep processes beneath the Iranian Plateau.