CAREER: Slip rates and earthquake timing of distributed Quaternary crustal deformation to evaluate structural accommodation of clockwise rotation of the Pacific Northwest

历史上，美国西北太平洋地区很少发生破坏性地震，尽管该地区位于地震活跃的卡斯卡迪亚俯冲带之上。这里的地震恢复工作主要集中在近海卡斯卡迪亚俯冲带及其发生9级（M9）地震的可能性。陆上断层上的破坏性地震，如西雅图断层，也是该地区所知甚少的威胁。在俄勒冈州的陆地上几乎没有发现活动断层，但新的激光地形图像（激光雷达）显示了广泛的、以前未知的活动断层分布在整个景观中。该项目的目的是为这些新发现的断层建立古地震时间和断层滑动率信息，并将其纳入该小组的区域模型，该模型涉及太平洋西北部变形的断层边界地壳块。这些信息可用于更新美国地质勘探局国家地震危险图和断层类型和活动模型。该项目将扩大代表性不足的群体对一个重要的STEM学科的参与，通过研究生研究助学金和地震地质学领域的带薪本科生实习，为女性和代表性不足的少数民族研究生和本科生提供支持。它还为一名早期职业女性首席调查员提供支助。该项目将与位于俄勒冈州波特兰的俄勒冈州科学与工业博物馆合作，开发一个关于区域构造和地震地质的互动演示展览。这个博物馆合作伙伴关系的主要目标是教育K-12观众，教师和家长关于地质学，板块构造，地震科学领域和地震灾害在他们的社区。 胡安·德富卡板块的斜向东北俯冲和塞拉内华达州地块的向北撞击驱动了整个太平洋西北地区相对于稳定的北美的积极顺时针旋转。地质块体模型将该区域分解为一个由断层限制的旋转块体组成的系统，这些块体由具有相似全球定位系统（GPS）台站速度的区域定义。GPS定义的块体边界被认为是活动断层的焦点，但并非所有块体边界都与已知的断层系统一致。拟议的项目旨在确定第四纪活动结构，确定其滑动速率的特征，并弥补大地测量确定的块体模型和地质测绘结构之间的应变平衡不足，以适应长期地壳旋转的平移。该项目旨在通过对太平洋西北部中部的有针对性的构造地貌和古地震调查，提高对地壳变形的认识，在过去30 000年中，该地区的断层活动速率和时间仍然不受限制。这一时间范围内的数据将弥补大地测量（短期）和基岩（长期）旋转观测之间的观测差距，并将解决块体模型和分布剪切模型之间的差异。在这项研究中收集的数据将评估从GPS速度数据确定的刚性到半刚性块体边界的持久性。拟议的研究结果将提高我们的理解复杂的地壳适应太平洋西北旋转在全新世晚更新世time.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Historically, few damaging earthquakes have occurred in the Pacific Northwest region of the United States, although the region overlies the seismically active Cascadia Subduction Zone. Earthquake resilience efforts here have largely focused on the offshore Cascadia Subduction Zone and its potential for magnitude-9 (M9) earthquakes. Damaging earthquakes on onshore faults, such as the Seattle fault, are also a poorly understood threat to the region. Few active faults have been identified onshore in Oregon, but new laser terrain imagery (lidar) has revealed widespread and previously unknown active faults distributed across the landscape. The purpose of this project is to establish paleo-earthquake timing and fault slip rate information for these newly discovered faults and to incorporate them into the team's regional model of fault bounded crustal blocks that accommodate deformation in the Pacific Northwest. This information can be used to update the USGS National Seismic Hazard Map and models of fault style and activity. This project will add to the broadening of participation of under-represented groups in an important STEM discipline, by providing support for female and underrepresented minority graduate and undergraduate students through graduate student research assistantships and paid undergraduate internships in the field of earthquake geology. It also provides for support an early career female principal investigator. The project will collaborate with the Oregon Museum of Science and Industry in Portland, OR, to develop an interactive demo exhibit on regional tectonics and earthquake geology. The primary goal of this museum partnership is to educate K-12 audiences, teachers, and parents about geology, plate tectonics, the field of earthquake science, and earthquake hazards in their community. Oblique northeast-directed subduction of the Juan de Fuca plate and northward impingement of the Sierra Nevada block drive active clockwise rotation of the entire Pacific Northwest region relative to stable North America. Geo block models break the region into a system of fault-bounded rotating blocks, defined by regions of similar global positions system (GPS) station velocities. GPS-defined block boundaries are thought to be the focus of active faulting, but not all block boundaries coincide with a known fault system. The proposed project seeks to identify Quaternary active structures, characterize their slip rates, and to close the strain budget shortfall between geodetically determined block models and geologically mapped structures accommodating translation from long-term crustal rotation. This project is designed to improve understanding of crustal deformation through targeted tectonic-geomorphic and paleoseismic investigations in the central Pacific Northwest where the rates and timing of faulting during the past 30,000 years remain unconstrained. Data in this time range would bridge the observational gap between geodetic (short-term) and bedrock (long-term) observations of rotation and would resolve discrepancies between block models and models of distributed shear. Data collected in this study will evaluate the persistence of rigid to semi-rigid block boundaries determined from GPS velocity data. Results of the proposed study will improve our understanding of complex crustal accommodation of Pacific Northwest rotation in Holocene to late-Pleistocene time.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.