Towards True Amplitude Tomography

9814570Nolet这项研究涉及地震层析成像基础研究计划的继续。散射波信息将被纳入正在进行的西太平洋上地幔结构的调查。 波散射对长周期S波走时全球反演的影响将使用以前开发的算法进行研究。 可靠的估计层析图像的分辨率和协方差将开发使用近似广义逆的基础上反投影。 这些估计将被纳入计划重新参数化，最大限度地减少断层图像中的分辨率异质性的文物。 体波走时中的有限频率效应将被扩展到包括“首波”Pn和Sn，最终目标是将Pn和Sn走时与上地幔结构的波形约束联合收割机结合起来。 新算法将在玻恩近似（目前使用的方案）之外进行测试，以模拟更复杂的振幅异常，例如由强聚焦和衍射引起的异常。目标是通过更好地量化成像误差的统计特性，以及通过更正确地解释波形振幅来提高分辨率，从而在短波长和中波长下对结构非均匀性成像进行重大改进。

9814570Nolet This research involves the continuation of a fundamental research program in seismic tomography. Scattered wave information will be incorporated into ongoing investigations of upper mantle structure in the western Pacific. The effects of wave scattering on global inversions of long period S wave travel times will be investigated using previously developed algorithms. Reliable estimators for the resolution and covariance of tomographic images will be developed using approximate generalized inverses based on back-projection. These estimators will be incorporated into schemes for reparametrization that minimize the artifacts of resolution heterogeneity in tomographic images. Finite frequency effects in body wave travel times will be extended to include the "headwaves" Pn and Sn, with the ultimate aim to combine Pn and Sn travel times with waveform constraints on upper mantle structure. New algorithms will be tested beyond the Born approximation (currently the scheme used) in modeling more complicated amplitude anomalies, such as caused by strong focusing and diffraction. The goals are to make significant improvements in the imaging of structural heterogeneity at short and intermediate wavelengths, both through a better quantification of the statistical properties of imaging errors, and by increasing the resolving power through a more correct interpretation of waveform amplitudes.