A Global Study of Anisotropy and Composition in Earth's Mantle

地球地幔各向异性和组成的全球研究成像地球详细三维结构的首选方法是全球地震层析成像。到目前为止，全球地震层析成像的重点一直是在整个地幔中的地震速度的横向变化的图像，并推断其原因和地球演化的影响。这项资助的主要重点是致力于建立整个地幔各向异性的综合模型。各向异性是由各向异性晶体的排列或流场中织构的发展引起的地震波速度的方向依赖性。因此，从动力学的角度来看，各向异性至少和非均匀性一样重要，因为它使我们得以一窥地球深部的流动和变形。解决整个地幔的各向异性是一项复杂的任务，因为各向异性在地幔的不同部分具有根本不同的形式。因此，假设整个地幔具有简单的各向异性形式的反演很可能注定要失败。在这里，我们遵循一种策略，使我们能够整合许多不同的数据类型，以生成一个各向异性的模型，可以解释大部分的观察。由于我们也有兴趣发展一个各向异性的全局视图，我们还通过调整和应用一些最新的观测技术来提高分裂观测的数量和质量，（数百万）地震图，其中包括全球分布的记录以及区域阵列。这项工作的主要目标是第一次真正全球性地观察整个地幔的各向异性。这项研究的结果将通过一个网站和匿名ftp向研究界广泛传播。 该项目将创建详细的地幔结构和各向异性的全球图像，从而提高对我们星球的历史和构造的理解。最后，这笔赠款支持SIO的研究生教育。

A Global Study of Anisotropy and Composition in Earth's MantleThe method of choice for imaging the detailed 3D structure of the Earth is global seismic tomography. To date, the focus of global seismic tomography has been to image lateral variations in seismic velocities throughout the mantle and to infer their cause and implications for the evolution of the Earth. The main focus of this grant is to work towards an integrated model of anisotropy of the whole mantle. Anisotropy is the directional dependence of seismic wave speed caused by alignment of anisotropic crystals or the development of texture in a flow field. Thus, anisotropy is at least as important as heterogeneity from a dynamical point of view as it gives us a glimpse of flow and deformation in the deep Earth.Resolving anisotropy throughout the mantle is a complex task as anisotropy takes fundamentally different forms in different parts of the mantle. Thus, inversions that assume simple forms of anisotropy throughout the mantle are likely doomed to failure. Here, we follow a strategy that allows us to integrate many different data types to generate a model of anisotropy that can explain the bulk of the observations.Since we are also interested in developing a global view of anisotropy, we are also increasing the quantity and quality of splitting observations by adapting and applying some recent observational techniques to large databases of (several million) seismograms which include globally distributed recordings as well as regional arrays. The main goal of this work is a first truly global look at anisotropy throughout the mantle.Results of this research will be widely disseminated to the research community through a web site and anonymous ftp. This project will create detailed global images of mantle structure and anisotropy leading to an improved understanding of the history and tectonics of our planet. Finally, this grant supports graduate student education at SIO.