Simultaneous determination of location of ocean-bottom criistal-deformatioil stations and 3D acoustic velocity profile improvements in marine geodesy

我们研制了一套测量海底地壳变形的观测系统。它是一个复合系统，使用了用于定位机载换能器的运动学GPS技术和用于在机载和海底换能器之间测距的声学技术。我们在Surtiga湾的700-1004米深度的三个地点共七个海底站完成了重复测量。在第一个地点，我们在2002年的两个月里测量了五次，定位了两个海底应答器。我们获得了每个海底传感器在水平和垂直位置的单次测定的标准误差分别为4-9 cm和4-13cm，对于重复测定的水平和垂直分量的标准误差分别为16-20 cm和31-44 cm。在2002年和2003年，我们每年两次在第二个和第三个地点安装了两个海底传感器。单年内单次和重复测定的误差与第一次测点的误差非常相似，但2002年至2003年间海底传感器位置的差异比上述结果大3至10倍，这表明测量中涉及一些未知但简单的误差。我们相信这可以在2004年进行的下一次测量中得到解决。因此，本研究开发的系统可以在允许的允许水平上应用于海底地壳变形观测

We have developed a observation system to measure seafloor crustal deformation. It is a composite system using a kinematic GPS technique for positioning an onboard transducer and an acoustic technique for ranging between the onboard and seafloor transducers. We accomplished repeated measurements at three sites with a total of seven seafloor stations at depths 700-1004 m in the Surtiga Bay. At the first site, we measured to locate two seafloor transponders five times for two month in 2002. We obtained for the single determination of each seafloor transducer the standard errors of 4-9 cm and 4-13cm for horizontal and vertical locations, respectively, and for the repeated, determination the standard errors of 16-20 cm and 31-44 cm for the horizontal and vertical component, respectively. At each of the second and third sites we located two seafloor transducers two times in each year of 2002 and 2003. The errors in the single and repeated determinations within single years are quite similar to those of the first site, but the differences in location of seafloor transducers between 2002 and 2003 are 3 to 10 times larger than the above results, suggesting that some unknown but simple errors are involved in the measurements. We believe that this can be solved in next measurements carried out in 2004. It is thus concludes that the system developed in this study can be applied to observations of seafloor crustal deformation with a tolerable allowance level