EAGER: Quantification of Ocean Water Column Contributions to Bottom Pressure offshore Cascadia using Current and Pressure Recording Inverted Echo Sounders

EAGER：使用电流和压力记录倒置回声测深仪量化海水柱对卡斯卡迪亚近海底部压力的贡献

• 批准号: 1728060
• 负责人: Meng Wei
• 金额: $ 10万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-03-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1728060&HistoricalAwards=false
• 关键词: EAGER; Quantification; Ocean; Water; Column

Large earthquakes occur at subduction zones where one tectonic plate plunges underneath another. Some of these earthquakes generate large tsunamis. Our ability to understand which earthquakes produce tsunamis is limited by the lack of information about how the seafloor is moving offshore. To address this, continuously recording bottom pressure recorders have been deployed over the subduction zone off the coast of Oregon to estimate long-term vertical deformation. Seafloor pressure measurements combine both seafloor movement and a contribution from the overlying ocean water column. Present efforts to estimate water-column contributions to the measurement use a regional oceanographic model. This model, however, has difficulty estimating pressure variations from eddies and currents near the seafloor, which may be significant. During the project, special instruments will be placed near to the ocean bottom pressure recorders. These instruments will be able to measure the changing pressures from the overlying water column, allowing for a more accurate measure of the tectonic deformation that is occurring offshore. The project supports an early career faculty member from an under-represented group.This project will quantify the water-column contributions to the signal from ocean bottom pressure recorders using in situ observations. Specifically, four Current and Pressure Recording Inverted Echo Sounder (CPIES) will be deployed offshore Oregon near existing ocean bottom pressure recorder benchmarks. CPIES are unique because they simultaneously measure bottom pressure, current, and round-trip acoustic travel time from the sea floor to the sea surface and back. By combining these measurements, the water signal can be separated from the measured bottom pressure signal. These measurements complement existing measurements and provide critical information to distinguish water column signal from tectonic signal for both long-term and transient signals. Methodology developed from previous physical oceanographic process studies will be applied and this effort will demonstrate the application for geophysical studies.

大地震发生在一个构造板块俯冲到另一个构造板块之下的俯冲带。其中一些地震会引发大海啸。 由于缺乏有关海底如何向近海移动的信息，我们了解哪些地震会产生海啸的能力受到限制。为了解决这个问题，连续记录的底部压力记录仪已被部署在俄勒冈州海岸的俯冲带，以估计长期的垂直变形。海底压力测量联合收割机将海底运动和上覆海洋水柱的作用结合起来。目前的努力，估计水柱的测量使用区域海洋学模型的贡献。 然而，这个模型很难估计海底附近涡流和海流的压力变化，这可能很重要。在该项目期间，将在海底压力记录仪附近放置特殊仪器。这些仪器将能够测量上覆水柱的压力变化，从而更准确地测量近海发生的构造变形。该项目支持一名来自代表性不足群体的早期职业教师。该项目将使用现场观测来量化水柱对海底压力记录仪信号的贡献。具体而言，四个海流和压力记录倒置回声测深仪（CPIES）将部署在俄勒冈州近海现有海底压力记录仪基准附近。CPIES是独一无二的，因为它们同时测量海底压力，海流和从海底到海面和返回的往返声传播时间。通过组合这些测量，可以将水信号与测量的底部压力信号分离。这些测量补充了现有的测量，并提供了关键的信息，以区分水柱信号从构造信号的长期和瞬态信号。将应用从以前的物理海洋学过程研究中发展出来的方法，这一努力将证明其在地球物理研究中的应用。