利用层析成像方法研究日本俯冲带地区的速度和各向异性结构

俯冲带是地球内部物质(例如水)循环的重要组成部分，俯冲过程与地震、火山及岩石的变质改造密切相关。因此，对俯冲带的研究是认识地球内部演化及其动力系统的有效途径。地球介质的各向异性能提供构造块体现今及构造历史时期地球动力学过程的重要信息，但仅用剪切波分裂研究获得的各向异性结构存在着垂向分辨率较差的问题，不能分辨出地幔楔及俯冲板块各部分各向异性结构特征。因此本项目将进一步完善先前的各向异性层析成像程序, 利用Hi-net提供的近震初至P波到时资料， 并利用台站间波形相关 获取F-net远震波形数据的P波相对到时残差, 近震远震联合反演, 对日本俯冲带进行高分辨的P波各向异性层析成像研究, 获取有深度分辨率的俯冲带各向异性结构信息，结合剪切波分裂观测结果进行综合分析，加深人们对日本俯冲带的地下速度横向变化及各部分各向异性结构的了解, 为俯冲带的岩石学及动力学研究工作提供新的地学证据。

Subduction zones are regions of the oceanic slab including volatile compounds such as water recycling back into the mantle. The subduction process is proved to be closely related to seismogenesis, magma generation and metamorphic transformations.Thus, studying the seismic heterogeneity and anisotropy in subduction zones is of great importance in understanding the evolution and dynamic process within the Earth. Seismic anisotropy provides the important information of the present or past tectonic deformation inside the Earth. However,it is difficult to figure out exactly where and how the anisotropy originates by the shear-wave splitting measurements alone because of its poor resolution in depth.In this study, we will apply the P-wave anisotropic tomography to the crust and upper mantle in subduction zones beneath Japan as derived from local and teleseismic events.The used P-wave travel times of local envents are recorded by Hi-net. And we will get the travel time residuals using multi-channel cross-correlation from the teleseismic seismograms recorded by F-net.The obtained anisotropic tomographic images with high-resolution in depth will be in comparison with the previous tomographyic results,the shear-wave splitting measurements and the geologic structure beneath Japan. The work will improve the understanding of seismic velocity heterogeneity and anisotropy in subduction zones beneath Japan. And the work will provide new seismological evidence to the numerical simulation and metamorphicpetrology in subduction zones.