Investigation of the hydrogeologic role of faults in the downgoing plate through comparison of Central America, Cascadia, Nankai, and Alaska subduction zones

该奖项将资助一名在德克萨斯大学地球物理研究所（UTIG）进行两年培训的GeoPRISMS博士后奖学金。拟议的工作旨在定量确定在俯冲板块的选定段内断层的结构和含水量。这样就可以评估俯冲水对俯冲带过程的影响。该研究将使用来自中美洲、卡斯卡迪亚、南开和阿拉斯加俯冲带的现有2D和3D多通道地震数据。研究结果将有助于更好地了解俯冲带的地质灾害潜力，这对太平洋西北地区尤其重要，因为该地区在近代史上曾发生过卡斯卡迪亚巨型逆冲断层上的大地震。这位博士后是一位刚出道不久的女科学家。研究结果将在研讨会和会议上发表，并将为UTIG的高中课程开发计划做出贡献。第二部分资助1名博士后在尼加拉瓜、卡斯卡迪亚、南开和阿拉斯加俯冲带进行保幅地震叠前深度偏移、断平面反射二维波形建模和二维多道地震数据流体流动建模，探索海沟向海洋板块断裂带的含水率极限。根据这些结果，她将开始定量地评估在不同俯冲带进入板块的水化状态。南开和哥斯达黎加三维数据集对滑脱体、近基底沉积物和基底地壳岩石的地震属性分析，以及斜坡下下行板块断层的波形建模，将有助于评估上下板块水文系统之间的流体交换。该博士后研究员将在向下板块的断层上识别水向上迁移到上板块时的排水现象。这项研究的结果将有助于回答地球地质系统俯冲旋回和变形科学计划中的两个关键问题：“挥发物、流体和熔体是如何通过俯冲系统储存、转移和释放的？”以及“挥发物的释放和转移如何影响板块界面的流变学和动力学，从进入的板块和海沟到弧和弧后？”更广泛的影响：拟议的工作将更好地了解俯冲带的地质灾害潜力，这与太平洋西北地区特别相关，该地区在近代史上卡斯卡迪亚巨型逆冲断层上发生了大地震。该项目将支持一名早期职业女性科学家的博士后培训。研究结果将在研讨会和会议上发表，并将为UTIG的高中课程开发计划做出贡献。

Part 1The award will fund a GeoPRISMS postdoctoral Fellowship for two years of training at the University of Texas, Institute for Geophysics (UTIG). The proposed work seeks to quantitatively determine the structure and water content in the faults within the select segments of the subducting plates. This will allow the assessment of the effects of subducting water on subduction zone processes. The study will use existing 2D and 3D multichannel seismic data from Central America, Cascadia, Nankai, and Alaska subduction zones. The results will provide a better understanding of the geohazard potential in subduction zones, which is particularly relevant for the Pacific Northwest region where large magnitude earthquakes have occurred on the Cascadia megathrust in recent history. The postdoctoral fellow is an early-career female scientist. The results of the study will be presented at workshops and conferences and will contribute to the high school curriculum development program at UTIG. Part 2Funds are provided for a postdoctoral fellow to conduct amplitude preserved seismic prestack depth migration, 2D waveform modeling of fault plane reflections, and fluid flow modeling of the 2D multichannel seismic data at Nicaragua, Cascadia, Nankai, and Alaska subduction zones to explore the limits on the water content of the fault zones in the oceanic plate seaward of the trench. From these results she will begin to quantitatively assess the hydration state of incoming plate at different subduction zones. The seismic attribute analysis of decollement, near-basement sediment, and basement crustal rocks, and the waveform modeling of the faults in the down-going plate beneath the slope in Nankai and Costa Rica 3D datasets will allow the assessment of fluid exchange between the hydrologic systems of upper and lower plate. The post-doctoral fellow will identify water expulsion along faults in the down- going plate as it migrates upward into the upper plate. The results from this study will contribute to answer the two key questions in the GeoPRISMS Subduction Cycles and Deformation science plan: "How are volatiles, fluids, and melts stored, transferred, and released through the subduction system?" and "How do volatile release and transfer affect the rheology and dynamics of the plate interface, from the incoming plate and trench through to the arc and backarc?"Broader Impacts: The proposed work will provide a better understanding of the geohazard potential in subduction zones, which is particularly relevant for the Pacific Northwest region where large magnitude earthquakes have occurred on the Cascadia megathrust in recent history. The project will support the postdoctoral training of an early-career female scientist. The results of the study will be presented at workshops and conferences and will contribute to the high school curriculum development program at UTIG.