GPS/acoustic seafloor geodetic observation: method of data analysis and its application
GPS/acoustic seafloor geodetic observation: method of data analysis and its application
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DOI：
10.1186/bf03351923
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发表时间：
2006-01-01
影响因子：
3
通讯作者：
Colombo, OL
中科院分区：
文献类型：
--
作者：
Fujita, M;Ishikawa, T;Colombo, OL
我们一直在开发一个系统，通过结合动态全球定位系统和声学测距技术来探测海底地壳运动。采用线性反演方法，由移动测量船的坐标和测量的声波在海水中的走时确定海底站的位置。通过估计声速结构的时间变化，定位精度大大提高。我们将我们的方法应用于在海底参考点，MYGI，位于日本东北部的宫城县，预计在不久的将来会发生一场巨大的地震的测距数据。从2002-2005年期间的7个运动观测获得的MYGI的水平坐标的时间序列表现出线性趋势，散射均方根约为2厘米。线性拟合的时间序列给出了板内地壳速度超过几厘米，每年向西北，这意味着强烈的板间耦合在这个地区。在南海海槽沿着的MYGI和其他海底参考点，通过比较活动中独立的一天子集解，对每个活动解的精度进行了检查。由此产生的重复性看起来是很好的相关性的时间和空间的稳定性，在海水中的声速结构取决于石油的区域以及季节。
We have been developing a system for detecting seafloor crustal movement by combining kinematic GPS and acoustic ranging techniques. A linear inversion method is adopted to determine the position of seafloor stations from coordinates of a moving survey vessel and measured travel times of acoustic waves in seawater. The positioning accuracy is substantially improved by estimating the temporal variation of the acoustic velocity structure. We apply our method to the ranging data acquired at the seafloor reference point, MYGI, located off Miyagi Prefecture, in northeast Japan, where a huge earthquake is expected to occur in the near future. A time series of horizontal coordinates of MYGI obtained from seven campaign observations for the period 2002-2005 exhibits a linear trend with a scattering rms of about 2 cm. A linear fit to the time series gives an intraplate crustal velocity of more than several centimeters per year towards the WNW, which implies strong interplate Coupling around this region. The precision of each campaign solution was examined at MYGI and other seafloor reference points along the Nankai Trough through comparison of independent one-day subset solutions within the campaign. The resultant repeatability looks to be well-correlated with the temporal and spatial stability of the acoustic velocity structure in the seawater depending oil the region as well as the season.