Routine seafloor geodetic observation around Japan

Institute of Industrial Science, University of Tokyo and the Hydrographic and Oceanographic Department, Japan Coast Guard have been jointly developing the seafloor geodetic observation network around Japan. The seafloor reference points have been distributed along the major trenches, such as the Japan trench and the Nankai trough. A total of 16 seafloor geodetic reference points have been deployed by the end of 2003. We have visited the seafloor reference points repeatedly in order to make measurements. Although we reached certain level with the already existing system, we come up with the possible improvements of the system as we accumulate the experience of the observations using the system. Trials to improve the system are always done in order to achieve a full centimeter level geodesy on the seafloor.