Measuring Sea Floor Motion: New Technology for Continental Margin Geodesy

测量海底运动：大陆边缘大地测量新技术

• 批准号: 1538179
• 负责人: Timothy Dixon
• 金额: $ 82.21万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1538179&HistoricalAwards=false
• 关键词: Measuring; Sea; Floor; Motion; New

The giant earthquakes and tsunamis of 2004 (Sumatra) and 2011 (Japan) were wake up calls that our ability to estimate future earthquake magnitude and tsunami potential is weak. The difficulty of measuring offshore strain accumulation in this challenging environment is a contributing factor. The proposed research will lead to new technology for measurement of sea floor motion and deformation in the shallow continental shelf environment, including strain accumulation and release in the critical shallow offshore region of subduction zones. If successful, the proposed technology could augment current on-land monitoring in the Cascadia subduction zone in the Pacific Northwest, a key US priority because of the likelihood of a major earthquake and tsunami here in the future. Existing technology for sea floor geodesy has limitations in terms of sensitivity, drift, and cost, limiting precise, long term, continuous, and spatially dense observations. This is especially true in the shallow continental shelf environment, where salinity and temperature variations in the ocean mean that the speed of sound in water is highly variable, challenging acoustic ranging techniques, and where oceanographic transients can confuse interpretation of sea floor pressure records. We propose to develop a new type of sea floor geodetic system, suitable for the shallow (less than 200 m) continental shelf environment. Our concept is based on a successful Italian design that uses high precision GPS mounted on a semi-rigid structure, moored to the sea floor. The system has been tested at 100 meters water depth on the flank of an active volcano. A network of such instruments would be economically feasible (ship operations are only required for initial installation and periodic maintenance, not data retrieval) and promises precise, accurate, continuous, real time deformation measurements, with fidelity nearly equivalent to land-based GPS networks. This research will develop and demonstrate such a system.

2004年（苏门答腊）和2011年（日本）的大地震和海啸敲响了警钟，我们估计未来地震震级和海啸潜力的能力很弱。 在这种具有挑战性的环境中测量近海应变积累的困难是一个促成因素。 拟议的研究将产生新的技术，用于测量浅大陆架环境中的海底运动和变形，包括俯冲带关键浅海区的应变积累和释放。如果成功，拟议的技术可以增强目前在太平洋西北部卡斯卡迪亚俯冲带的陆地监测，这是美国的一个关键优先事项，因为未来这里可能发生大地震和海啸。现有的海底大地测量技术在灵敏度、漂移和成本方面存在局限性，限制了精确、长期、连续和空间密集的观测。在浅大陆架环境中尤其如此，海洋中的盐度和温度变化意味着水中的声速变化很大，这对声学测距技术提出了挑战，海洋学瞬变可能混淆对海底压力记录的解释。 我们建议开发一种新型的海底大地测量系统，适用于浅（小于200米）的大陆架环境。 我们的概念是基于一个成功的意大利设计，使用高精度GPS安装在一个半刚性结构，停泊在海底。该系统已在活火山侧面100米水深处进行了测试。 这类仪器的网络在经济上是可行的（只需要船舶操作进行初始安装和定期维护，而不需要数据检索），并保证精确、准确、连续、真实的时间变形测量，其保真度几乎相当于陆基全球定位系统网络。 这项研究将开发和演示这样一个系统。