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

阿什利·斯特里格博士获得了NSF EAR博士后奖学金，将在俄勒冈州立大学开展一项研究并扩大参与计划。该项目将侧重于建立卡斯卡迪亚可能因大地震而破裂的弧前断层的时间和空间目录。在大地震后的几个月和几年内，应力扰动触发的断层破裂对俯冲带沿岸地区的地震危险性具有重要意义。利用俯冲带地震的记录评估这些断层上地震的时空关系，将有助于深入了解地壳对巨型逆冲事件的响应，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范围，并建立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美国国家科学基金会资助的“增加地球科学多样性”方案的伙伴关系，向人数不足的本科生进行外联；学生将通过实地考察、辅导和作为实地助理参与进来。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与陆上古地震下沉研究直接相关，这些研究已经确定了埋藏的森林和沼泽地层，以及卡斯卡迪亚地震的近海浊流记录。该项目中的方法包括使用新的LiDAR数据来绘制和描述长期(10,000-10,000年)断层表达和使用古地震技术评估短期(1,000-10,000年)沿卡斯卡迪亚俯冲带的几个关键地壳断裂的活动性。将利用陆上地壳弧前断层的空间和时间活动信息，对大地震后的应力降进行定性比较。

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.