Studies of Global Seismicity and Earth Structure

这项研究是在处理震源分析和地球结构的两项前拨款下进行的5年调查的延续。主题包括：1)继续进行质心矩张量（CMT）分析；2)结合波形和走时观测，改进CMT分析程序；(3)将CMT方法扩展到利用远震表面波分析较小的事件；4)利用SKKS和SKS观测资料，结合三维地幔模型，对外核结构进行约束；5)利用组合数据集获得改进的球对称参考地球模型；6)联合反演地幔P、S三维速度结构；7)开展地震与地球动力联合反演模拟实验，探索三维速度模型的地球动力学意义；8)在三维地球结构模拟实验中加入更高频率的数据，以提高径向和横向分辨率；9)开发混合区域/全球模型参数化的程序，这将允许对大尺度区域结构进行适当的反演；10)研究地幔各向异性和衰减的横向变化，以及如何在三维建模实验中解释这些现象。这些努力为世界地震学界提供的服务，特别是CMT目录，被广泛用于确定地球结构、构造和地震分析。这项研究是国家减少地震危害计划的一个组成部分。

This research is a 5-year continuation of investigations carried out under two former grants dealing with earthquake source analysis and earth structure. Topics include 1) continuation of the ongoing Centroid Moment Tensor (CMT) analysis; 2) refining the CMT analysis procedure through the combined use of waveforms and travel time observations; 3) extending the CMT procedure to the analysis of smaller events by the use of teleseismic surface waves; 4) using SKKS and SKS observations, in conjunction with 3D mantle models, to constrain outer core structure; 5) using combined data sets to obtain improved spherically symmetric reference Earth models; 6) performing joint inversions for the P and S 3D-velocity structure of the mantle; 7) performing modeling experiments based on joint inversion of seismic and geodynamic data, as well as exploring the geodynamic implications of the 3D velocity models; 8) including higher frequency data in the 3D earth structure modeling experiments in order to improve radial and lateral resolution; 9) developing procedures for hybrid region/global model parameterizations which will allow for proper inversions for large- scale regional structure; 10) investigation of mantle anisotropy and lateral variation in attenuation and how these phenomena may be accounted for in the 3D modeling experiments. The service provided by these efforts to the world seismological community, especially the CMT catalog, is widely used in determination of earth structure, tectonics, and earthquake analysis. This research is a component of the National Earthquake Hazard Reduction Program.