Seismological Investigations of Earthquakes and Deep Earth Structure

全球地震台站的网络现在记录了大量的数据，这些数据包含了关于地震和地球深部结构的丰富信息。然而，对这些数据的分析滞后，因为传统的方法是费时的，不能充分利用现代计算机的能力。通过将自动化方法应用于数百或数千个地震图，通常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。这个加州大学圣地亚哥分校的项目开发并应用这些新方法来研究各种主题。其中包括：(1)利用散射地震波了解地球深部小型结构的频率和强度；(2)比较和测试不同的方法来成像大地震破裂；(3)检查地震波的频率内容以测试大地震与小地震是否在基本方面有所不同；(4)利用地震波在这些边界外的反射来研究地球上地幔的尖锐界面。这项研究可能会导致地球结构和地震破裂过程模型的改进。来自全球地震台网的大量高质量数字记录的日益可用性，使得研究地震和地球深部结构的各种新方法成为可能。通过分析成百上千的地震图，通常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。该项目将继续分析加州大学圣地亚哥分校的全球地震数据，以研究各种地球物理问题。这些包括:(1)主要体波地震相之间的散射能量观测和模拟，以约束短于地震层析成像所能解决的尺度上地幔非均质性的统计性质；(2)与有限断层和多重cmt方法相比，探索反投影在解决复杂破裂方面的分辨率极限，并系统地应用反投影研究近年来的大地震。(3)分析远震p波谱，估算大地震的应力降和辐射能量，解决地震标度问题；(4)叠加全球和USArray地震记录，利用上部反射来解决上地幔不连续问题。该项目通过为研究生和博士后提供资金来支持加州大学圣地亚哥分校的教育项目。这项研究可能会导致地球结构和地震破裂过程模型的改进，这将对构造学，地球动力学和矿物物理学界感兴趣。其中一些结果可能有助于为将来估计大地震的地震风险提供信息和贡献。研究结果将通过出版物、会议报告和提供给SIO的材料广泛传播。美国的教育和推广项目。

Networks of global seismic stations now record vast amounts of data, which have a wealth of information about both earthquakes and deep Earth structure. However, analysis of these data has lagged because traditional methods are time-intensive and do not fully exploit the capabilities of modern computers. By applying automated methods to hundreds or thousands of seismograms, it is often possible to resolve new features in the data, or to perform more comprehensive analyses of problems that were previously addressed on smaller scales. This U.C. San Diego project develops and applies these new methods to examine a variety of topics. These include: (1) Using scattered seismic waves to understand the frequency and strength of small-scale structures in the deep Earth, (2) Comparing and testing different methods to image large earthquake ruptures, (3) Examining the frequency content of seismic waves to test whether large earthquakes differ in fundamental ways from smaller earthquakes, and (4) Studying sharp interfaces in the Earth's upper mantle using reflections of seismic waves off these boundaries. This research is likely to lead to improved models of Earth structure and earthquake rupture processes.The increasing availability of large numbers of high-quality digital records from the global seismic networks has made possible a variety of new ways to study earthquakes and deep Earth structure. By analyzing hundreds or thousands of seismograms, it is often possible to resolve new features in the data, or to perform more comprehensive analyses of problems that were previously addressed on smaller scales. This project will continue analyses of global seismic data at U.C. San Diego to examine a variety of geophysical issues. These include: (1) Observation and modeling of scattered energy between major body-wave seismic phases to constrain the statistical properties of mantle heterogeneity at scale lengths shorter than can be resolved using seismic tomography, (2) Exploration of the resolution limits of back-projection compared to finite-fault and multiple-CMT approaches for resolving complex ruptures, and systematic application of back-projection to study recent large earthquakes, (3) Analysis of teleseismic P-wave spectra to estimate stress drops and radiated energy from large earthquakes and address earthquake scaling issues, (4) Stacking global and USArray seismograms to resolve upper-mantle discontinuities using topside reflections. This project supports the educational program at U.C. San Diego by providing funds for graduate and postdoctoral students. This research is likely to lead to improved models of Earth structure and earthquake rupture processes, which will be of interest to the tectonics, geodynamics and mineral physics communities. Some of the results may help inform and contribute to future estimates of seismic risk from large earthquakes. Results will be widely disseminated through publications, conference presentations, and material provided to SIO?s education and outreach programs.