Development of a hybrid gravimeter system onboard an underwater vehicle

We are developing a hybrid gravity survey system using a gravimeter and a gravity gradiometer to survey sub-seafloor density structure. This paper describes the development of a gravimeter with forced gimbals for this purpose. The aimed precision is about 0.1 mgal, one order better than sea surface gravimetry. After a successful feasibility study by using a Scintrex CG-3M gravimeter under a condition of pitching and rolling as well as heaving, we are developing a new underwater gravimeter system with a gravity sensor by Micro-G LaCoste. The design, performance, and future tasks are described.