Collaborative Research: Continental Shelf Geodesy: Continued Development of a Low Cost Sea Floor Geodetic System Based on GPS

合作研究：大陆架大地测量：持续开发基于 GPS 的低成本海底大地测量系统

• 批准号: 2023633
• 负责人: Timothy Dixon
• 金额: $ 110.52万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023633&HistoricalAwards=false
• 关键词: Collaborative; Research; Continental; Shelf; Geodesy

Existing technology for sea floor geodesy (measuring small motions of the sea floor) has limitations in terms precision and cost. This is especially true in the shallow continental shelf environment, where highly variable salinity, temperature and density of the ocean cause problems for acoustic ranging and sea floor pressure techniques. Potential applications of the proposed system include monitoring of underwater volcanoes, offshore oil and gas fields, and the shallow offshore portion of subduction zones. Measuring strain accumulation and release processes in the shallow offshore region of subduction zones is especially important because it has the potential to improve our understanding of giant subduction zone earthquakes and tsunamis, as well as improve our ability to forecast these catastrophic events.The proposed design is based on a successful Italian concept that uses high precision GPS mounted on a semi-rigid structure and moored to the sea floor. That system has been successfully tested up to 140 meters water depth on the flanks of an active volcano, but only acquired vertical component data. The Italian design has been modified to reduce costs and enable measurement of the full three-dimensional displacement vector. Initial tests have demonstrated that a simple rigid spar design is suitable for water depths up to 40 meters. A steel spar is attached by shackle to a heavy seafloor anchor and is kept near vertical by a near-surface float. GPS on top of the buoy measures instantaneous position, while tilt and heading sensors allow correction for buoy motion, enabling daily estimates of the position of the sea floor anchor precise to 1-2 cm. The new research proposed here aims to develop and demonstrate a deeper water version, suitable for water depths up to 150 meters, by adding a cable with orientation sensors to the buoy.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.

现有的海底大地测量技术（测量海底的微小运动）在精度和成本方面存在局限性。在浅层大陆架环境中尤其如此，海洋的盐度、温度和密度变化很大，给声学测距和海底压力技术带来了问题。该系统的潜在应用包括监测水下火山、海上油气田以及俯冲带的浅海部分。 测量俯冲带近海区域的应变积累和释放过程尤为重要，因为它有可能提高我们对俯冲带巨型地震和海啸的认识，并提高我们预测这些灾难性事件的能力。所提出的设计是基于成功的意大利概念，该概念使用安装在半刚性结构上并停泊在海底的高精度 GPS。该系统已在活火山侧面 140 米水深处成功进行了测试，但仅获取了垂直分量数据。 意大利的设计经过修改，以降低成本并能够测量完整的三维位移矢量。初步测试表明，简单的刚性翼梁设计适用于深达 40 米的水深。钢梁通过卸扣连接到重型海底锚上，并通过近海面浮子保持接近垂直状态。浮标顶部的 GPS 可以测量瞬时位置，而倾斜和航向传感器可以校正浮标运动，从而能够每天对海底锚的位置进行精确到 1-2 厘米的估计。这里提出的新研究旨在通过在浮标上添加带有方向传感器的电缆来开发和演示更深水版本，适用于水深达 150 米。该奖项反映了 NSF 的法定使命，并通过评估被认为值得支持利用基金会的智力优势和更广泛的影响审查标准。