Floating Rate and Sea Surface Outlet Point of Ocean Bottom Seismometer

Ocean bottom seismometer (OBS) active and passive experiments are the most useful methods to reveal crustal and upper mantle structures under the ocean, but till now, few OBS experiments have been done in the Arctic and Antarctica, where the main challenges are finding and recovering the OBSs sheltered by the high coverage rate of floating ices. For the forthcoming OBS experiments in the polar regions, it is necessary to study the time and the location of OBS surfacing to the sea (outlet position). To reveal the process of OBS sinking and floating in the sea and to find the law of OBS's outlet position, we use the information of the up-floating rate, deployment position and recovery position of OBS during three expeditions of the 2019 South China Sea OBS observation, 2020 Western Pacific OBS experiment and 2011 the South China Sea three-dimension OBS experiment in this study. The main results are as follows: (1) The OBS shows stable up-floating rate in the vertical direction, which will be helpful to predict the moment of OBS surfacing to the sea; (2) the OBS locations on the sea bottom are randomly distributed with the offset of the drop location, which indicates that the water depth at the drop point has no obvious linear correlation with the relocation offset distance; (3) the outlet position and deployment position of OBS suggest very close distance, with a statistical estimate of < 300 meters (31%) and < 500 meters (59%).