Seismological Investigations of Deep Earth Structure

全球地震台网提供的大量高质量数字记录的不断增加，使得研究地球深部地震结构的各种新方法成为可能。 通过分析成千上万的地震图，往往可以解决数据中的新特征，或者对以前在较小尺度上解决的问题进行更全面的分析。该项目建议继续并扩大对全球地震数据集的分析，以解决地球深部结构的细节。 拟议的研究包括：1）上地幔不连续面分析（410-和660-间断）振幅变化使用PP和SS前兆，2）使用反投影和偏移方法更好地成像地幔间断结构（应用于SS前兆和接收器函数），3）PKP和PP前兆的建模和反演，以映射地幔中小尺度非均匀性的散射强度，4）P波频谱分析，解决地幔衰减的频率依赖性和横向变化; 5）系统分析S-to-P转换相位，识别与化学不均匀性有关的中地幔假设不连续性。

EAR-9909267ShearerThe increasing availability of large numbers of high-quality digitalrecords from the global seismic networks has made possible a variety of new ways to study deep Earth seismic structure. By analyzinghundreds or thousands of seismograms, it is often possible to resolvenew features in the data, or to perform more comprehensive analyses ofproblems that were previously addressed on smaller scales.This project proposes to continue and extend analyses of global seismic datasets to resolve details of deep Earth structure. Proposed studies include: 1) analysis of upper-mantle discontinuity (410- and 660-discontinuities) amplitude variations using PP and SS precursors, 2) the use of back-projection and migration methods to better image mantle discontinuity structure (applied to SS precursors and receiver functions), 3) modeling and inversion of PKP and PP precursors to map the intensity of scattering from small-scale heterogeneity in the mantle, 4) analyses of P-wave spectra to resolve the frequency dependence and lateral variability in mantle attenuation, and 5) systematic analysis of S-to-P converted phases to identify hypothesized discontinuities in the mid-mantle related to chemical heterogeneity.