Mantle Structure from Joint Inversions of Seismic and Geodynamic Data

该项目的目标是建立一个更好的地震剪切速度在地幔中的三维变化模型，并探索地震模型对地幔流动的影响。通过使用半自动方法测量所有S波和多次反弹S波以及sc波和所有多次反弹sc波的延迟时间，将改进地震模型。也将使用SKS和SKKS波。工作的第二个方面将是对通过上地幔传播的地震数据使用非线性波形反演，以提取对上地幔敏感的数据在地幔中的传播时间延迟和路径。研究人员还将对地震数据和地球动力学数据（重力场和地形）进行联合反演，以测试地幔内流动状况的不同假设。地震速度与可观测到的地球动力学数据（如地球重力场）之间的联系取决于地幔的粘度、密度与速度的比例，以及地幔中任何流动障碍的性质。我们将对一系列模型进行联合反演，看看哪种类型的模型与观测到的地震数据最一致，而不是非唯一的地震模型。这项工作将对涉及地球物理和化学性质和演化的所有地球科学领域产生广泛的影响，包括矿物物理学、地球动力学和地球化学。该项目还将支持两名学生的研究生教育。

GrandEAR-0309189The goal of the project is to develop a better model of the three-dimensional variations in seismic shear velocity in Earth's mantle as well as to explore the implications of the seismic model for flow in the mantle. The seismic model will be improved by use of a semi-automatic approach to measuring delay times of all S and multi-bounce S waves as well as ScS and all multi-bounce ScS waves. SKS and SKKS waves will also be used. A second aspect of the work will be to use a nonlinear waveform inversion on seismic data that propagate through the upper mantle to extract travel time delays and paths through the mantle for data sensitive to the upper mantle. The investigators will also conduct joint inversions of the seismic data and geodynamic data (gravity field and topography) to test different hypotheses for the flow regime within the mantle. The connection between seismic velocity and observable geodynamic data, such as the Earth's gravity field, depends on the viscosity of the mantle, the density to velocity scaling, as well as the nature of any flow barriers in the mantle. We will run joint inversions for a range of models to see what types of models are most consistent with the observed seismic data as opposed to non-unique seismic models. This work will have a broad impact on all areas of earth science concerned with the physical and chemical nature and evolution of Earth including mineral physics, geodynamics, and geochemistry. The project will also support the graduate education of two students.