Seismological Investigations of Earthquakes and Deep Earth Structure

地震和地球深层结构的地震学研究

• 批准号: 1620251
• 负责人: Peter Shearer
• 金额: $ 60.4万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1620251&HistoricalAwards=false
• 关键词: Seismological; Investigations; Earthquakes; Deep; Earth

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.

全球地震台网现在记录了大量数据，其中包含有关地震和地球深层结构的大量信息。 然而，对这些数据的分析已经滞后，因为传统方法非常耗时并且没有充分利用现代计算机的功能。 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，或者对以前在较小规模上解决的问题进行更全面的分析。 这个加州大学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) 使用散射地震波了解地球深处小型结构的频率和强度，(2) 比较和测试不同方法对大型地震破裂进行成像，(3) 检查地震波的频率内容测试大地震与小地震是否在根本上有所不同，以及（4）利用地震波离开这些边界的反射来研究地球上地幔的尖锐界面。这项研究可能会改进地球结构和地震破裂过程的模型。全球地震网络中大量高质量数字记录的可用性不断增加，使得研究地震和地球深层结构的各种新方法成为可能。 通过分析数百或数千个地震图，通常可以解决数据中的新特征，或者对以前在较小规模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伯克利分校的全球地震数据。圣地亚哥检查各种地球物理问题。 这些包括：（1）对主要体波地震阶段之间的散射能量进行观测和建模，以限制地幔非均质性的统计特性，其尺度长度短于地震层析成像所能解析的长度，（2）探索反演的分辨率极限投影与有限断层和多重 CMT 方法解决复杂破裂的比较，以及系统应用反投影来研究最近的大地震，(3) 分析远震 P 波谱以估计应力降和来自大地震的辐射能量并解决地震尺度问题，(4) 叠加全球和 USArray 地震图，利用上部反射解决上地幔不连续性问题。 该项目支持加州大学伯克利分校的教育计划圣地亚哥为研究生和博士后学生提供资金。 这项研究可能会改进地球结构和地震破裂过程的模型，这将引起构造学、地球动力学和矿物物理学界的兴趣。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并做出贡献。研究结果将通过出版物、会议演示以及向 SIO 的教育和推广计划提供的材料进行广泛传播。