Gravimeter

A gravimeter is a highly sensitive instrument used to measure the local strength of the Earth's gravitational field, detecting the very small variations in gravity that occur from place to place due to differences in the density and distribution of underlying rock, and, in some applications, changes in gravity at a single location over time. Practical relative gravimeters, capable of measuring small differences in gravity between locations with useful precision, were developed from the 1930s onward, most notably through instruments designed by the American geophysicist Lucien LaCoste, whose spring-based gravimeter design became a long-standing industry standard for field gravity surveying. Gravimeters are widely used in geophysics and geology for mapping subsurface geological structures, in petroleum and mineral exploration to help locate deposits associated with density anomalies, and in geodesy, where satellite-borne gravimetric instruments now also measure gravity variations to study ice sheet mass loss, groundwater changes and the shape of the Earth itself.