Renewal Proposal: Investigation of Global Scale Seismic Mantle and Core Structure Using Forward and Inverse Approaches

提出的地球深部结构研究计划旨在为地幔和地核的全球地球动力学模型提供地震学约束，以帮助我们进一步了解地球深处驱动板块构造、导致地震和火山爆发的机制。由此产生的关于主要结构（如上升流和下升流）的位置、形状和强度的信息，将使更广泛的地球科学领域的非地震学家（地球动力学家、矿物物理学家和地球化学家）受益。该项目将直接资助培养6名研究生和2名博士后。我们估计这将导致至少8篇论文发表在评审期刊上。该项目旨在利用正演和反演方法，利用全球和区域数字宽带站阵列收集的地震波形来研究地球的深层结构。中心目标是实现一种基于复杂三维（3D）结构中精确地震波场计算的新方法，如高效的C-SEM（“耦合谱元方法”）所提供的，用于正问题，以及Frechet导数的近似估计用于逆问题。这种混合方法将使我们能够降低计算成本，同时通过使用完整波场显着提高分辨率。我们特别计划：+利用C-SEM建立地球上地幔的三维弹性、非弹性和各向异性结构模型+解决大尺度地幔层析模型的参数化问题，以更好地约束上地幔和下地幔主要非均质省的边界。+结合长周期波形和体波数据，绘制全球范围内岩石圈/软流圈系统的各向异性结构。+继续我们的核心敏感数据收集和解释计划+进一步研究地球低频“嗡嗡声”的产生机制

The proposed program of investigation of deep earth structure aims at providing seismological constraints on global geodynamical models of the earth's mantle as well as the core, to help further our understanding of the mechanisms, deep inside the earth, that drive plate tectonics, causing earthquakes and volcanic eruptions. The resulting information on the location, shape and strength of major structures such as upwellings and downwellings will benefit a broader community of non seismologists in geosciences (geodynamicists, mineral physicists and geochemists. This program will directly contribute to the education of 6 graduate students and 2 post-docs. We estimate that it will result in at least 8 publications in refereed journals.This program is aimed at investigating the deep structure of the earth using seismic waveforms collected at global and regional arrays of digital broadband stations using forward and inverse methodology. A central goal is to implement a novel approach based on the combination of accurate seismic wavefield computations in complex three dimensional (3D) structures, as afforded by the efficient C-SEM ("Coupled spectral element method"), for the forward problem, and approximate estimation of Frechet derivatives for the inverse problem. This hybrid approach will allow us to keep the computational costs down while significantly improving resolution through the use of the complete wavefield. We plan, in particular, to:+ Develop models of 3D elastic, anelastic and anisotropic structure of the earth's upper mantle using C-SEM+ Address the issue of parametrization of large scale tomographic models of the mantle to better constrain the boundaries of major heterogeneous provinces both in the upper and in the lower mantle.+ Combine long period waveform and body wave data to map the anisotropic structure of the lithosphere/asthenosphere system at the global scale. + Continue our program of inner core sensitive data collection and interpretation + Investigate further the mechanisms of generation of the earth's low frequency "hum"