Seismological Investigations of Earthquakes and Deep Earth Structure

全球地震台站网络现在记录了大量的数据，其中有关于地震和地球深部结构的丰富信息。 然而，对这些数据的分析已经滞后，因为传统方法是时间密集型的，并且没有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。 这个卧底圣地亚哥项目开发并应用这些新方法来研究各种主题。 其中包括：（1）利用散射的地震波了解地球深处小规模结构的频率和强度，（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，以测试大地震是否在根本上不同于小地震，（4）利用地震波在上地幔尖锐界面上的反射研究这些界面。这项研究可能会导致改进地球结构和地震破裂过程的模型，全球地震网络提供的大量高质量数字记录的增加，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的全球地震数据。圣地亚哥考察各种地球物理问题。 其中包括：（1）对主要体波地震相位之间的散射能量进行观测和建模，以在短于地震层析成像所能分辨的尺度长度上限制地幔不均匀性的统计特性，（2）探索反投影与有限断层和多CMT方法相比在分辨复杂破裂方面的分辨率极限，并系统地应用反投影研究最近的大地震，（3）分析地震P波频谱，以估计大地震的应力降和辐射能量，并解决地震标度问题。（4）叠加全球和美国阵列地震图，利用顶部反射解决上地幔不连续性。 该项目支持U.C.的教育计划。圣地亚哥通过为研究生和博士后学生提供资金。 这项研究可能会导致改进地球结构和地震破裂过程的模型，这将是感兴趣的构造，地球动力学和矿物物理学界。一些结果可能有助于为未来大地震的地震风险估计提供信息和做出贡献。结果将通过出版物、会议介绍和提供给SIO的材料广泛传播。的教育和推广计划。

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.