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

职业：第四纪地壳分布式变形的滑移率和地震计时，以评估太平洋西北地区顺时针旋转的结构适应性

• 批准号: 2145879
• 负责人: Ashley Streig
• 金额: $ 58.23万
• 依托单位: Portland State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2145879&HistoricalAwards=false
• 关键词: CAREER; Slip; rates; earthquake; timing

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.

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。这里的抗震工作主要集中在卡斯卡迪亚近海俯冲带及其发生 9 级 (M9) 地震的潜力。西雅图断层等陆上断层上的破坏性地震对该地区构成的威胁也知之甚少。俄勒冈州陆上几乎没有发现活动断层，但新的激光地形图像（激光雷达）揭示了分布在整个景观中的广泛且以前未知的活动断层。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移率信息，并将其纳入该团队的断层边界地壳区域模型中，该模型可适应太平洋西北地区的变形。该信息可用于更新美国地质勘探局国家地震灾害图以及断层类型和活动模型。该项目将通过地震地质学领域的研究生研究助学金和带薪本科生实习为女性和代表性不足的少数族裔研究生和本科生提供支持，从而扩大代表性不足群体对重要 STEM 学科的参与。它还为早期职业女性首席研究员提供支持。该项目将与俄勒冈州波特兰市的俄勒冈科学与工业博物馆合作，开发一个有关区域构造和地震地质学的互动演示展览。这一博物馆合作伙伴关系的主要目标是向 K-12 观众、教师和家长提供地质学、板块构造学、地震科学领域以及社区地震危害方面的教育。 胡安德富卡板块向东北方向的倾斜俯冲和内华达山脉向北的撞击驱动整个太平洋西北地区相对于稳定的北美地区积极的顺时针旋转。地理块模型将区域分解为断层边界旋转块系统，由类似全球定位系统 (GPS) 站速度的区域定义。 GPS定义的区块边界被认为是活动断层活动的焦点，但并非所有区块边界都与已知断层系统一致。拟议的项目旨在识别第四纪活动结构，表征其滑移率，并弥补大地测量确定的块模型和适应长期地壳旋转平移的地质绘图结构之间的应变预算缺口。该项目旨在通过对太平洋西北中部地区进行有针对性的构造地貌和古地震调查来增进对地壳变形的了解，该地区过去 30,000 年来断层活动的速率和时间仍然不受限制。该时间范围内的数据将弥合大地测量（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式剪切模型之间的差异。本研究收集的数据将评估根据 GPS 速度数据确定的刚性至半刚性块边界的持久性。拟议研究的结果将提高我们对全新世至晚更新世时期太平洋西北旋转的复杂地壳调节的理解。该奖项反映了 NSF 的法定使命，并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，被认为值得支持。