Testing Transient Triggering of Earthquakes with Aftershock Spatial Distributions

用余震空间分布测试地震瞬态触发

• 批准号: 0001118
• 负责人: Paul Bodin
• 金额: $ 3.54万
• 依托单位: University of Memphis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-15 至 2002-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001118&HistoricalAwards=false
• 关键词: Testing; Transient; Triggering; Earthquakes; Aftershock

The objective of this proposal is to illuminate the relative importance of the transient and permanent components of stress perturbations in triggering earthquake aftershocks. The PI proposes to undertake a study of the global scale that uses existing data. The simple notion that underlies the proposed work follows previous research on triggering of aftershocks by the Landers earthquake. For earthquakes that feature unilateral rupture propagation, permanent (static) stress changes are spatially symmetric while peak transient (dynamic) stresses are asymmetric. This difference provides a means to study the relative roles of each of these components of stress perturbations. The proposed work will seek to determine whether a systematic relationship exists between the spatial symmetries of aftershock distributions and the propagation characteristics (rupture directivity) of the mainshock. The research will: 1) survey databases and the literature to determine which earthquakes have both reliable estimates of directivity effects (or their absence), and statistically reliable aftershock (and before mainshock) catalogs, and 2) devise and apply metrics that compare the spatial distribution of stress fields with aftershock occurrence patterns, focussing on spatial symmetry or asymmetry. Additional research steps will also be included, such as waveform modeling of at least some earthquakes to constrain models of dynamic stresses at seismogenic depths and numerical elastic modeling to estimate the static stress field changes.

这一提议的目的是阐明应力扰动的瞬时分量和永久分量在触发地震余震中的相对重要性。国际和平研究所建议利用现有数据对全球范围进行研究。这项拟议工作背后的简单概念是在之前关于兰德斯地震引发余震的研究之后提出的。对于以单边破裂传播为特征的地震，永久(静态)应力变化在空间上是对称的，而瞬时(动态)应力峰值是不对称的。这种差异提供了一种研究应力扰动每个分量的相对作用的方法。拟议的工作将寻求确定余震分布的空间对称性与主震的传播特征(破裂方向性)之间是否存在系统的关系。这项研究将：1)调查数据库和文献，以确定哪些地震既有可靠的方向性效应(或其缺失)估计，又有统计上可靠的余震(和主震前)目录，以及2)设计和应用将应力场的空间分布与余震发生模式进行比较的度量标准，重点是空间对称或不对称。还将包括其他研究步骤，例如至少对一些地震进行波形建模，以约束孕震深度的动应力模型，以及使用数值弹性建模来估计静态应力场的变化。