Banana-Doughnut Traveltime Tomography

基本上所有现今的走时层析反演都忽略了衍射波前愈合，并且未能考虑有限频率地震波从未扰动的球形地球射线中“感觉”3D结构的能力。 我们使用NSF Grant的支持来开发3D香蕉甜甜圈走时灵敏度内核，该内核正确地解释了所有这些有限频率效应。 我们打算继续这些研究在格兰特-0105387下，扩展理论来处理近掠和近临界波，这些波没有被本公式充分建模，并使用我们的3D灵敏度内核来反演Guy Masters教授和他的合作者在斯克里普斯海洋学研究所过去十年收集的广泛的全球互相关走时数据集。 我们还将开发和应用相速度的2D变化、表示测得的体波走时对核幔边界或410 km或660 km不连续面上地形的灵敏度的2D内核、使用地震阵列进行差分走时测量的3D灵敏度内核以及其他地震观测值的2D和3D灵敏度内核，包括体波和表面波的到达角和振幅。 最后，我们将进行一系列广泛的数值验证和合成反演研究，在伪随机介质和现实的全地幔模型，以确定地幔粗糙度需要引起显着的衍射效应后，长周期地震走时。

Essentially all present-day traveltime tomographic inversions ignore diffractive wavefront healing, and fail to account for the ability of a finite-frequency seismic wave to "feel" 3D structure off of the unperturbed spherical-earth ray. We used the support of NSF Grant EAR-9725496 to develop 3D banana-doughnut traveltime sensitivity kernels, which correctly account for all such finite frequency effects. We intend to continue these investigations under Grant EAR-0105387, extending the theory to treat near-grazing and near-critical waves that are not adequately modeled by the present formulation, and using our 3D sensitivity kernels to invert the extensive global cross correlation traveltime dataset collected over the past decade by Professor Guy Masters and his collaborators at the Scripps Institution of Oceanography. We shall also develop and apply 2D variations in the phase velocity, 2D kernels that express the sensitivity of a measured body-wave traveltime to topography on the core-mantle boundary or the 410 km or 660 km discontinuities, 3D sensitivity kernels for differential traveltime measurements made using seismic arrays, and 2D and 3D sensitivity kernels for other seismic observables, including arrival angles and amplitudes of both body and surface waves. Finally, we shall conduct an extensive series of numerical validation and synthetic inversion studies, in both pseudo-random media and realistic whole-mantle models, in order to ascertain the degree of mantle roughness needed to give rise to significant diffraction effects upon long-period seismic traveltimes.