Gravimeter

A gravimeter measures gravitational acceleration, the local value of g near 9.81 m/s squared, and in marine geophysics maps small spatial variations that reveal subsurface density. A shipborne gravimeter on a stabilized platform records gravity along survey lines while corrections remove the Eotvos effect of the moving vessel, the latitude variation, and free-air and Bouguer terms. The resulting anomalies trace sediment basins, salt bodies, ridges, and trenches because denser rock raises gravity. Marine gravity also defines the geoid and supports altimeter-derived bathymetry. Relative gravimeters read differences to microGal precision; absolute instruments measure g directly.