Community Seafloor Geodetic Infrastructure for the Measurement of Deformation

用于测量变形的社区海底大地测量基础设施

• 批准号: 1935996
• 负责人: Mark Zumberge
• 金额: $ 546.75万
• 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: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1935996&HistoricalAwards=false
• 关键词: Community; Seafloor; Geodetic; Infrastructure; Measurement

Subduction zones are geologic faults that begin offshore where one tectonic plate slides beneath another. Because of friction, some of the motion of the lower plate is transferred to and builds up in the upper plate. The abrupt release of the built-up strain caused by this energy transfer causes the strongest earthquakes on earth. These great earthquakes cause widespread damage from ground shaking and from flooding of coastal areas from resulting tsunami waves. Recent events have occurred in Sumatra in 2004, Chile in 2010, and Japan in 2011. Subduction zones also lie offshore the U.S. coasts along Northern California, Oregon and Washington State and another along Alaska and the Aleutian Islands. Both of these subduction zones have experienced great earthquakes in the past -- Alaska had a great earthquake in 1964 and Oregon and Washington State in 1700 -- and both will do so again in the future. A goal of the scientific community is to better understand the geophysical processes at work at these subduction zones in order to improve assessment of potential earthquake hazards. Land-based high-precision measurements with the Global Navigation Satellite System (GNSS) can measure the slow build-up of strain locally, but even the coastal sites are too far from the submerged shelf to provide reliable estimates far offshore, where the fault zone reaches the seafloor and where most tsunamis are generated. The GNSS-Acoustic technique, which combines GNSS with acoustic ranging from a small robotic platform on the sea surface to sensors (transponders) on the sea floor, allows measurement of centimeter-scale horizontal motion of the seafloor. This can be combined with measurements of ambient pressure at the sea floor to detect vertical as well as horizontal motions. To date only one prototype vehicle and approximately a dozen seafloor transponder have been available for the scientific community. This project will add three new robotic platforms and forty-eight additional seafloor transponders and for the first time incorporate pressure sensors directly in several of the transponders. This project will approximately quintuple the equipment available to the research community to make these important measurements.This one-year project will procure and commission geodetic instrumentation to measure seafloor deformation. Several recent and prominent workshop reports and vision documents by the earth science community have identified a need for growing seafloor geodetic capabilities to answer pressing questions about earthquake, tsunami, and volcanic processes. The infrastructure will provide accurate horizontal and vertical positioning of the seafloor through two reliable and proven techniques with published scientific results: GNSS-Acoustics and sea water pressure. Data from both systems will be acquired using wave gliders, which are remotely operated wave- and solar-powered sea surface platforms. This award does not fund operation, maintenance, nor deployment of this infrastructure for science. Seafloor geodesy is poised to be transformative. It will allow for a broad community of existing and next-generation earth scientists to study active deformation on the seafloor. Improved access to these instruments will foster and communicate knowledge of the new methods and science outside of the current and very small marine community, to a much larger scientific community primarily consisting of highly-skilled land-based geodesists, and an inclusive next-generation scientific workforce.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.

俯冲带是一种地质断层，从一个构造板块滑到另一个板块下面的地方开始。由于摩擦，下板块的一些运动被转移到上板块并在上面板块积累起来。这种能量转移引起的累积应变的突然释放导致了地球上最强烈的地震。这些大地震会造成大范围的破坏，包括地面震动以及由此产生的海啸引发的沿海地区洪水。最近的地震分别发生在2004年的苏门答腊、2010年的智利和2011年的日本。俯冲带还位于美国海岸附近的北加州、俄勒冈州和华盛顿州，以及阿拉斯加和阿留申群岛沿岸。这两个俯冲带过去都经历过大地震——阿拉斯加在1964年发生过一次大地震，俄勒冈州和华盛顿州在1700年发生过一次大地震——而且未来都将再次发生大地震。科学界的一个目标是更好地了解在这些俯冲带工作的地球物理过程，以便改进对潜在地震危险的评估。使用全球导航卫星系统（GNSS）的陆基高精度测量可以测量局部应变的缓慢积累，但即使是沿海站点也距离水下大陆架太远，无法提供可靠的离岸估计，那里的断裂带到达海底，也是大多数海啸产生的地方。GNSS-声学技术将GNSS与从海面上的小型机器人平台到海底传感器（应答器）的声学范围相结合，可以测量厘米级的海底水平运动。这可以与海底环境压力测量相结合，以检测垂直和水平运动。迄今为止，只有一个原型车和大约十二个海底应答器可供科学界使用。该项目将增加三个新的机器人平台和48个额外的海底应答器，并首次将压力传感器直接集成到几个应答器中。这个项目将使研究团体能够获得的进行这些重要测量的设备增加大约五倍。这个为期一年的项目将采购和启用测量海底变形的大地测量仪器。最近一些著名的研讨会报告和地球科学界的远景文件已经确定需要增加海底大地测量能力，以回答有关地震、海啸和火山过程的紧迫问题。该基础设施将通过两种可靠且经过验证的技术（gnss声学和海水压力）提供准确的海底水平和垂直定位，并发表科学成果。两个系统的数据将通过波浪滑翔机获取，这是一种远程操作的海浪和太阳能海面平台。该奖项不资助该科学基础设施的运营、维护或部署。海底大地测量学即将发生变革。它将允许现有和下一代地球科学家的广泛社区研究海底的活动变形。改善对这些仪器的获取，将促进新方法和科学知识的传播，使其不局限于目前规模很小的海洋社区，而扩展到一个更大的科学社区，主要由高技能的陆地测地线师和包容性的下一代科学工作者组成。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Shallow Water Seafloor Geodesy With Wave Glider‐Based GNSS‐Acoustic Surveying of a Single Transponder

• DOI: 10.1029/2023ea003043
• 发表时间: 2023-10
• 期刊: Earth and Space Science
• 影响因子: 3.1
• 作者: Surui Xie;M. Zumberge;Glenn Sasagawa;D. Voytenko