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

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。 由于沿断层沿着的摩擦力，一些下行板块的运动缓慢地传递到上板块，上板块弯曲收缩，储存了运动。 有时，这种累积的运动会迅速释放为地震，并使海底移位，引起海啸。 北方加州、俄勒冈州和华盛顿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，今后也会如此。 测量这种缓慢积累发生的位置和速度可以提高对潜在危险的理解。 这需要近海海底传感器来收集数据，而在过去，船舶需要访问这些数据。 在这个项目中，将开发和测试新的方法，使用更少的仪器和遥控的、自动力的海面车辆，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，将数据从海底声学上传到波浪和太阳能海面车辆，并测试一种新的低成本方法，即使用单个海底转发器在浅水（200米）中收集GPS声学数据。 机载计算机将被编程以控制声学测距系统在调制解调器模式下操作。 将在海上SIO部署一个嵌入转发器的压力传感器，以测试不同范围和深度的上传能力。 此外，将在SIO近海部署一个转发器，并远程操作海面车辆，以环绕转发器长达两周，收集GPS声学数据。 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声学方法相当，其中数据是从由三个或更多个转发器组成的阵列的中心收集的。

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.