Advances in Seafloor Geodesy: Expanded Applications of Wave and Solar Powered Surface Vehicles

俯冲带是一种地质断层，起源于近海，在那里一个构造板块滑到另一个板块下面。由于沿断层的摩擦，一些下行板块的运动被缓慢地转移到上部板块，上部板块弯曲和收缩储存运动。偶尔，这种积聚的运动以地震的形式迅速释放出来，并使海底移位，引发海啸。加利福尼亚北部、俄勒冈州和华盛顿州近海的卡斯卡迪亚俯冲带和阿拉斯加近海的阿留申俯冲带过去曾产生过大地震和海啸，而且还将再次发生。测量这种缓慢积聚发生的地点和速度可以提高对潜在危害的理解。这需要近海海底传感器来收集数据，而在过去，船只可以访问这些数据。在该项目中，将开发和测试新方法，使用更少的仪器和遥控、自供电的海面车辆，而不是船只，以降低数据收集的成本。这是一个为期一年的项目，旨在将海底的声波数据上传到海浪和太阳能海面车辆上，并测试一种新的低成本方法，即使用单个海底应答器在浅水（200米）收集gps声波数据。机载计算机将被编程控制声学测距系统在调制解调器模式下工作。SIO将在海上部署一个内置应答器的压力传感器，以测试在不同范围和深度下的上传能力。此外，一个应答器将部署在海上SIO，海面车辆将远程操作，围绕应答器收集gps -声学数据长达两周。然后，我们将评估在浅水中定位的可重复性是否与现有的gps -声学方法相媲美，后者从由三个或更多应答器组成的阵列中心收集数据。

Subduction Zones are geologic faults that begin offshore where one tectonic plate slides beneath another. Due to friction along the fault some of the down-going plate motion is slowly transferred to the upper plate which bends and contracts storing the motion. Occasionally, this built-up motion is rapidly released as an earthquake and displaces the sea floor causing a tsunami. The Cascadia subduction zone offshore northern California, Oregon and Washington and the Aleutian subduction zone offshore Alaska have generated large earthquakes and tsunami in the past and will do so again. Measuring where and how fast this slow build-up occurs can improve understanding of the potential hazard. This requires offshore seafloor sensors to collect data, and in the past, ships to access this data. In this project, new methods will be develop and tested that use fewer instruments and remotely-piloted, self-powered sea surface vehicles, rather than ships, to lower the cost of data collection.This is a one-year project to implement acoustic upload of data from the sea floor to a wave- and solar-powered sea surface vehicle, and test a new lower cost method of collecting GPS-Acoustic data in shallow water ( 200 m) using a single seafloor transponder. An onboard computer will be programed to control the acoustic ranging system to operate in modem mode. A pressure sensor embedded with a transponder will be deployed offshore SIO to test the upload capability at varying ranges and depths. In addition, a transponder will be deployed offshore SIO and the sea surface vehicle will be operated remotely to circle the transponder for up to two weeks collecting GPS-Acoustic data. We will then evaluate if repeatability of positioning in shallow water is comparable to the existing GPS-Acoustic approach where data are collected from the center of an array comprised of three or more transponders.