A System for Continuous Measurement of Horizontal and Vertical Crustal Deformation of the Seafloor

[00:84968 . chadwell]该项目研究测量洋中脊附近海底地壳现今变形的技术。通过直接测量安装在胡安·德·富卡海岭上的海底传感器之间的声波范围，可以精确地测量出地壳板块在很长一段时间内移动的速度。为了继续正在进行的平板监测工作，现有装置将在2002年之前被更换，届时电池可能会耗尽到无法进行应答器内部测距的水平。该项目允许建造第二代仪器，以解决现有设备的缺点，同时保持1994年至2001年至2006年地壳运动测量的不间断时间序列。拟议的设计将是一种新型的海底仪器，可以配置为将时间和空间采样扩展到每小时/每天测量10公里的尺度距离。新的设计将把水平和垂直地壳变形测量结合到一个智能控制器中，该控制器将响应温度、压力、倾斜和移动时间等背景测量值的变化，因为持续偏离背景测量值可能表明构造活动的开始。新系统的多传感器和扩展的空间覆盖范围将适用于其他山脊或其他海底断层，例如在俯冲带的大陆架上。在第一年，这些仪器将在圣地亚哥近海进行为期一个月的部署和测试。在第二年，这些仪器将被部署在胡安德富卡山脊的南裂缝段的轴向裂缝上。

0084968ChadwellThis project addresses techniques to measure present-day deformation of seafloor crust in the vicinity of mid-ocean ridges. By measuring the acoustic range directly between seafloor mounted transducers on the Juan de Fuca Ridge, the rate at which crustal plates move over long time periods can be precisely measured. To continue an ongoing plate monitoring effort, the existing installation will be replaced prior to 2002 at which time the batteries will likely be depleted to a level that will not permit intra-transponder ranging. This project allows construction of a second generation instrument that will address shortcomings in the existing installation while maintaining an unbroken time series of crustal motion measurements from 1994 through 2001 to 2006. The proposed design will be a new type of seafloor instrument that can be configured to extend the temporal and spatial sampling to hourly/daily measurements over 10-km scale distances. The new design will incorporate both horizontal and vertical crustal deformation measurements in an intelligent controller that will respond to changes in background measurements of temperature, pressure, tilt and travel times as sustained deviations from background measurements may indicate the onset of tectonic activity. The multiple sensors and extended spatial coverage of the new system will be applicable to other ridges or across other seafloor faults e.g., on continental shelves at subduction zones. In year one, the instruments will be constructed and tested during a month-long deployment in waters off-shore San Diego. In year two, the instruments will be deployed across axial Cleft of the South Cleft Segment on the Juan de Fuca Ridge.