Do forearc crustal faults rupture in response to stress changes from megathrust earthquakes?

弧前地壳断层是否因特大逆冲地震的应力变化而破裂？

• 批准号: 1349577
• 负责人: Ashley Streig
• 金额: $ 8.7万
• 依托单位: Streig Ashley R
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349577&HistoricalAwards=false
• 关键词: Do; forearc; crustal; faults; rupture

Dr. Ashley Streig has been awarded an NSF EAR Postdoctoral fellowship to carry out a research and broadening participation plan at Oregon State University. The project will focus on establishing a temporal and spatial catalog of forearc faults in Cascadia that may have ruptured as a consequence of megathrust earthquakes. Triggered fault rupture from stress perturbations in the months, and years following a megathrust earthquake has great implications for seismic hazard for coastal regions along subduction zones. Evaluating the spatial and temporal relationship of earthquakes on these faults with the record of subduction zone earthquakes will provide insight on the crustal response to megathrust events and will allow geologists to more carefully consider the broader range of potentially active seismic sources in Cascadia, as well as develop more holistic models of crustal structural dynamics. Integration of the proposed research on crustal fault activity will involve outreach to underrepresented undergraduate students through partnership with NSF funded "Increasing Diversity in Earth Sciences" program; students will be engaged through field trips, and mentoring, and as field assistants. Geomorphic and paleoseismic studies of this project will allow the investigator to directly evaluate the slip history of surface rupturing earthquakes on these faults. The timing of these events will be directly correlated with onshore paleoseismic subsidence studies that have dated buried forests and marsh stratigraphy, and the offshore turbidite record for Cascadia earthquakes. The methodology in this project includes using new LiDAR data to map and characterize the long-term (10,000 -100,000 yr.) fault expression and using paleoseismic techniques to evaluate the shorter term (1,000-10,000 yr.) activity of several key crustal faults along the Cascadia subduction zone. Information on spatial and temporal activity of onshore crustal forearc faults will be used to make a qualitative comparison of stress drops post megathrust earthquakes.

阿什利斯特雷格博士已被授予美国国家科学基金会博士后奖学金，在俄勒冈州州立大学开展研究和扩大参与计划。该项目将侧重于建立卡斯卡迪亚弧前断层的时间和空间目录，这些断层可能因大逆冲断层地震而破裂。 由应力扰动引发的断层破裂在一次特大逆冲断层地震后的几个月和几年内对沿着俯冲带的沿海地区的地震危险性有很大的影响。评估这些断层上的地震与俯冲带地震记录的时空关系，将提供有关地壳对巨型逆冲事件的反应的见解，并将使地质学家能够更仔细地考虑卡斯卡迪亚更广泛的潜在活跃震源，以及开发更全面的地壳结构动力学模型。整合拟议的地壳断层活动研究将涉及通过与NSF资助的“增加地球科学多样性”计划合作，向代表性不足的本科生进行宣传;学生将通过实地考察，指导和现场助理参与。该项目的地貌和古地震研究将使研究人员能够直接评估这些断层上地表破裂地震的滑动历史。这些事件的发生时间将直接与陆上古地震沉降研究，已确定了埋藏的森林和沼泽地层，以及卡斯卡迪亚地震的海上浊流记录。该项目的方法包括使用新的LiDAR数据来绘制和表征长期（10，000 - 100，000年）。断层表达和使用古地震技术来评估短期（1000 - 10000年）。沿着卡斯卡迪亚俯冲带的几个关键地壳断层的活动。关于陆上地壳弧前断层的空间和时间活动的信息将用于对大逆冲地震后的应力下降进行定性比较。