Abstract
An ocean bottom gravimeter system was newly developed to carry out seafloor gravimetry in the same way as on land. The objectives are 1) development of gravity bench marks on the seafloor to monitor deformation of the seafloor and 2) dense seafloor gravimetry to obtain fine density structure beneath the seafloor. The gravimeter adopts a Scintrex CG-3M/SB gravimeter suspended by gimbals to keep the sensor vertical. The other components are tilt meters, a depth sensor, a data logger/controller, and a set of Ni-Cd battery cells. These are set into 2 pressure spheres, one made of titanium alloy and the other made of glass so that the system can be used up to 6,500 m in depth. Trial experiments at shallow sea floor have shown the performance as was expected.
