 Gravity gradiometry is used by oil and mineral prospectors to measure the density of the subsurface, effectively by measuring the rate of change of gravitational acceleration due to underlying rock properties.From this information it is possible to build a picture of subsurface anomalies which can then be used to more accurately target oil, gas and mineral deposits.It is also used to image water column density, when locating submerged objects, or determining water depth (bathymetry).