Collaborative Research: Understanding the Connections Between Strain Transients and Earthquake Swarms

合作研究：了解应变瞬变与地震群之间的联系

• 批准号: 0952249
• 负责人: Eliza Richardson
• 金额: $ 11.87万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-15 至 2014-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0952249&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Connections; Between

The Plate Boundary Observatory instruments were installed to detect time periods when the deformation of the Earth's crust speeds up or slows down. These transient, predominately aseismic deformation episodes have now been recognized worldwide using geodetic datasets from subduction zone thrust faults, volcanic normal faults, and major strike slip faults. Recent studies have documented that these strain transients often trigger swarms of small to moderate earthquakes. So far, the small number of examples with truly high-quality constraints on the space-time distribution of both the seismic and aseismic fault slip limits the mechanical understanding of earthquake triggering by strain transients. This study combines geodetic inversions and earthquake triggering studies to improve the mechanical models that connect strain transients with increases in earthquake rate. Previous work shows that current mechanical models do not quantitatively predict the stochastic properties of earthquake swarms during transients. A GPS network filtering approach is being employed to detect new strain transients in the Salton Trough in southern California, the Cascadia subduction zone in Oregon and Washington, and the Alaskan subduction zone. The seismicity associated with any detected transients is then analyzed using a combination of stochastic and mechanical models of earthquake triggering to estimate the temporal history of rate-changes associated with individual transients. As the precision of these tests of mechanical triggering models increases, so does our understanding of how earthquake triggering works in different tectonic environments. When teachers become involved in scientific research, they are better able to model the process of science for their own students; the excitement of playing a role in scientific discovery translates directly to enthusiasm in the classroom. Three teachers per year recruited from Penn State's Master of Education in Earth Sciences program (https://earth.e-education.psu.edu/) participate in a 10-week research effort in which they are trained to analyze catalogs of earthquake swarms that are temporally and spatially correlated to geodetically-detected strain transients. This research effort and related instruction serves as the "capstone" for their master's degree. They are working in teams to analyze swarms related to strain transients as well as to develop teaching plans for disseminating the results of their work to secondary students in their own schools. In addition, they are creating learning objects from this work that will be made publicly available as part of Penn State's Open Educational Resources initiative. Therefore, the results of this project have the unprecedented potential to create both a new science product of interest to EarthScope scientists, and new teaching and learning objects for immediate use by secondary school teachers worldwide.

安装板块边界观测仪器是为了探测地壳变形加速或减慢的时间段。这些瞬态的、主要是抗震的变形事件现已在世界范围内通过俯冲带逆冲断层、火山正断层和主要走滑断层的大地测量数据集得到认可。最近的研究表明，这些瞬变应变经常引发群小到中度地震。到目前为止，对地震和地震断层滑移的时空分布具有真正高质量约束的例子很少，限制了对应变瞬变触发地震的机械理解。这项研究结合了大地测量反演和地震触发研究，以改进将应变瞬变与地震速率增加联系起来的力学模型。先前的工作表明，当前的力学模型不能定量预测瞬态期间地震群的随机特性。 GPS网络过滤方法被用来检测南加州索尔顿海槽、俄勒冈州和华盛顿州卡斯卡迪亚俯冲带以及阿拉斯加俯冲带的新应变瞬变。然后使用地震触发的随机模型和机械模型的组合来分析与任何检测到的瞬变相关的地震活动，以估计与单个瞬变相关的速率变化的时间历史。随着机械触发模型测试精度的提高，我们对地震触发在不同构造环境中如何工作的理解也随之增加。当教师参与科学研究时，他们能够更好地为自己的学生模拟科学过程；在科学发现中发挥作用的兴奋感直接转化为课堂上的热情。每年从宾夕法尼亚州立大学地球科学教育硕士项目 (https://earth.e-education.psu.edu/) 招募的三名教师参加为期 10 周的研究工作，他们接受培训以分析与大地测量检测到的应变瞬变在时间和空间上相关的地震群目录。这项研究工作和相关指导是他们硕士学位的“顶点”。他们正在团队合作分析与应变瞬变相关的群体，并制定教学计划以将他们的工作成果传播给自己学校的中学生。此外，他们正在从这项工作中创建学习对象，这些对象将作为宾夕法尼亚州立大学开放教育资源计划的一部分公开发布。因此，该项目的成果具有前所未有的潜力，既可以创造出 EarthScope 科学家感兴趣的新科学产品，也可以创造出可供全世界中学教师立即使用的新教学对象。