Collaborative Research: Constraints on Interseismic Locking near the Trench on the Oregon Segment of the Cascadia Subduction Zone Using Seafloor Geodesy (GNSS-A)

合作研究：利用海底大地测量 (GNSS-A) 对卡斯卡迪亚俯冲带俄勒冈段海沟附近的震间锁定进行约束

• 批准号: 2126396
• 负责人: Mark Zumberge
• 金额: $ 40.13万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2126396&HistoricalAwards=false
• 关键词: Collaborative; Research; Constraints; Interseismic; Locking

This project aims to measure the relative movement between the North American and Juan de Fuca tectonic plates across the Cascadia Subduction Zone to help quantify the earthquake and tsunami hazards. The Cascadia Subduction Zone, which is represented by a major fault at the interface of two tectonic plates, is a potential source of large earthquakes and tsunamis. Recent large earthquakes, such as the 2011 Tohoku earthquake, have demonstrated that rupture can extend to surprisingly shallow depths, where large vertical displacements of the seafloor can generate a tsunami. It is important to learn if the situation is similar on the Cascadia Subduction Zone, increasing the hazard from a large tsunami along the US west coast. Determining whether the seafloor in Cascadia moves at the subducting plate rate or is slowed because the fault is locked locally is also important to the scientific understanding of the fault mechanics. The technical challenge is to make these observations on the seafloor, which is both difficult to access and corrosive to instrumentation. Thus, this effort requires specialized techniques for making the necessary observations. This project will support the training of a graduate student and postdoctoral fellow in the use of seafloor geodetic techniques, and the project will further develop the engineering human resources and infrastructure needed to advance seafloor geodesy. The time series of seafloor benchmarks at three existing sites on the accretionary prism of the Cascadia Subduction Zone offshore Oregon will be extended using the GNSS-Acoustic method. These seafloor sites were established in previous years with varying numbers of surveys on each, yielding initial estimates of tectonic plate velocities at three of four sites along the margin. Three new surveys will be performed with a GNSS-Acoustic-equipped Wave Glider during the two-year project. The Wave Glider approach greatly reduces the survey cost compared to that undertaken with a research vessel. In addition to undertaking the geodetic surveys, new algorithms will be explored that improve the data processing, including algorithms designed to mitigate biases from the acoustic velocity structure of the water column and by capitalizing on multi-GNSS data. Finally, the amount of kinematic locking at the trench will be inferred using elastic boundary element models, with the goal to identify if plate locking varies along strike and correlates with structural features in the outer accretionary prism.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.

该项目旨在衡量北美和胡安·德福卡构造板之间的相对运动，以帮助量化地震和海啸危害。 卡斯卡迪亚俯冲带在两个构造板的界面处的主要断层表示，是大地震和海啸的潜在来源。 最近的大型地震，例如2011年的Tohoku地震，证明破裂可以延伸至令人惊讶的浅层深度，那里的大型海底垂直位移可以产生海啸。 重要的是要了解卡斯卡迪亚俯冲带的情况是否相似，从而增加了美国西海岸的大海啸危险。 确定卡斯卡迪亚的海底是以俯冲板速率移动还是放慢速度，因为当地的断层锁定在当地锁定也是对断层力学的科学理解也很重要。 技术挑战是在海底上进行这些观察，这既难以进入仪器，也很难腐蚀。 因此，这项工作需要专门的技术来进行必要的观察。 该项目将支持对使用海底大地测量技术的研究生和博士后研究员的培训，该项目将进一步发展促进海底地理地板所需的工程人力资源和基础设施。俄勒冈州卡斯卡迪亚俯冲带的增生棱镜上的三个现有地点的海底基准测试时间序列将使用GNSS-Acoustic方法扩展。 这些海底地点是在前几年建立的，每个海底地区的调查数量各不相同，从而在沿边缘的四个位点中的三个地点中的三个位置进行了构造板速度的初步估计。 在为期两年的项目中，将使用配备GNSS声学的波滑翔机进行三项新的调查。 与研究船相比，波滑翔机方法大大降低了调查成本。 除了进行大地测量外，还将探索新的算法，以改善数据处理，包括旨在减轻水柱的声速结构的偏见以及通过资本化多gnss数据来减轻偏见的算法。 最后，将使用弹性边界元素模型来推断沟槽的运动锁定量，目的是确定板块锁定是否随罢工而变化，并且与外部积聚棱镜中的结构特征有所不同。该奖项反映了NSF的法定任务，并通过使用该基金会的知识优点和广泛的影响来评估NSF的法定任务。