Community Seafloor Geodetic Infrastructure for the Measurement of Deformation

俯冲带是地质断层，开始离岸，一个构造板块滑到另一个下面。由于摩擦力的作用，下板块的一些运动被传递到上板块并在上板块中积累起来。 由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。这些大地震造成了广泛的破坏，从地面震动和沿海地区的洪水从由此产生的海啸波。最近的事件发生在2004年的苏门答腊，2010年的智利和2011年的日本。 俯冲带也位于沿着北方加州、俄勒冈州和华盛顿州的美国海岸近海，另一个位于沿着阿拉斯加和阿留申群岛。这两个俯冲带在过去都经历过大地震--阿拉斯加在1964年发生过大地震，俄勒冈州和华盛顿州在1700年发生过大地震--这两个俯冲带在未来都会再次发生。科学界的一个目标是更好地了解这些俯冲带的地球物理过程，以改善对潜在地震危险的评估。利用全球导航卫星系统进行的陆基高精度测量可以在当地测量应变的缓慢积累，但即使是沿海地点距离水下大陆架也太远，无法提供可靠的估计，因为离岸很远，断层带就在那里到达海底，海啸也大多发生在那里。全球导航卫星系统声学技术将全球导航卫星系统与从海面上的小型机器人平台到海底传感器（转发器）的声学测距相结合，能够测量海底厘米级的水平运动。这可以与海底环境压力的测量相结合，以探测垂直和水平运动。 迄今为止，科学界只得到了一个原型飞行器和大约12个海底转发器。 该项目将增加三个新的机器人平台和48个额外的海底转发器，并首次将压力传感器直接纳入几个转发器。 该项目将使研究界可用于进行这些重要测量的设备增加约五倍，该项目为期一年，将采购和委托使用大地测量仪器来测量海底变形。地球科学界最近的几份重要研讨会报告和愿景文件已经确定，需要提高海底大地测量能力，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和经过验证的技术（全球导航卫星系统声学和海水压力）提供海底的精确水平和垂直定位，并已公布科学成果。这两个系统的数据将使用波浪滑翔机获取，波浪滑翔机是远程操作的波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。它将使现有和下一代地球科学家的广泛社区能够研究海底的主动变形。更好地获得这些仪器将促进和传播新方法和科学的知识，而不是在现有的非常小的海洋社区之外，传播给主要由高技能的陆地大地测量学家组成的更大的科学界，一个包容性的下一个-该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准。

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.