Seafloor Geodesy Using Sidescan Sonar: Analysis of the NGDC Archive

使用侧扫声纳进行海底大地测量：NGDC 档案分析

• 批准号: 1536386
• 负责人: David Sandwell
• 金额: $ 20.02万
• 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: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1536386&HistoricalAwards=false
• 关键词: Seafloor; Geodesy; Using; Sidescan; Sonar

The main objective of the project is to develop a method to use existing multibeam sonars, available on NSF-sponsored research vessels, to measure small displacements of the seafloor associated with rapid events such as earthquakes and landslides. The seafloor displacements are measured by comparing the location of a patch of seafloor surveyed at two times spanning an event. The published accuracy of this approach is currently tens of meters which severely limits the utility of the method. The planned work would greatly improve the accuracy to better than 1 m by collecting data at a slow ship speed and navigating the repeat track to closely follow the reference track. This order of magnitude improvement in displacement accuracy would provide a valuable tool for assessing and understanding large and sometimes-destructive seafloor events. Broader impacts include improvements to the system software that will be freely available to others. Funding includes the training of a graduate student in the methods of high-resolution sonar and seafloor geodesy.The project will develop a method to use existing multibeam sonars, available on NSF-sponsored research vessels, to measure small displacements of the seafloor associated with rapid events such as earthquakes and landslides. The seafloor displacements are measured by differencing the location of a patch of seafloor surveyed at two times spanning an event. The published accuracy of this approach is currently tens of meters which severely limits the utility of the method. This work would greatly improve the accuracy to better than 1 m by collecting data at a slow ship speed and navigating the repeat track to closely follow the reference track. This order of magnitude improvement in displacement accuracy would provide a valuable tool for assessing and understanding large and sometimes-destructive seafloor events. The proposal addresses one of the eight high-level science questions posed in the recent National Research Cpuncil Decadal Report (NRC, 2015), i.e., how can risk be better characterized and the ability to forecast geohazards like mega-earthquakes, tsunamis, undersea landslides, and volcanic eruptions be improved? The tools of GPS and InSAR are used to monitor the crustal deformation onshore of the Cascadia Subduction Zone but most of the locked part of the megathrust interface lies offshore. While the PI?s method does not have sufficient accuracy to monitor interseismic motions, it can serve as a pre-event survey of the surface trace similar to the San Andreas Fault B-4 lidar survey.

该项目的主要目标是开发一种方法，利用美国国家科学基金会赞助的研究船上现有的多波束声纳来测量与地震和山体滑坡等快速事件相关的海底小位移。海底位移是通过比较一次事件中两次测量的海底区域的位置来测量的。目前该方法已公布的精度为数十米，这严重限制了该方法的实用性。计划中的工作将通过以低速船速收集数据并导航重复航迹以紧密遵循参考航迹，将精度大大提高到超过 1 m。位移精度的这种数量级改进将为评估和理解大型且有时具有破坏性的海底事件提供有价值的工具。更广泛的影响包括对系统软件的改进，这些软件将免费提供给其他人。资金包括对研究生进行高分辨率声纳和海底大地测量方法的培训。该项目将开发一种方法，使用现有的多波束声纳（可在 NSF 资助的研究船上使用）来测量与快速海底位移相关的小位移。地震和山体滑坡等事件。海底位移是通过在一次事件中两次测量的海底区域的位置差异来测量的。目前该方法已公布的精度为数十米，这严重限制了该方法的实用性。这项工作通过以低速船速收集数据并导航重复航迹以紧密跟随参考航迹，将大大提高精度，优于 1 m。位移精度的这种数量级改进将为评估和理解大型且有时具有破坏性的海底事件提供有价值的工具。该提案解决了最近的国家研究中心十年报告（NRC，2015）中提出的八个高级科学问题之一，即如何更好地描述风险以及预测特大地震、海啸、海底滑坡等地质灾害的能力和火山喷发是否得到改善？ GPS和InSAR工具用于监测卡斯卡迪亚俯冲带陆上地壳变形，但巨型逆冲断层界面的锁定部分大部分位于近海。虽然 PI 方法没有足够的精度来监测震间运动，但它可以作为事件前的地表痕迹勘测，类似于圣安德烈亚斯断层 B-4 激光雷达勘测。