Gradiometry

Gradiometry is a geodetic technique that measures spatial variations or gradients of the Earth’s gravity field rather than absolute gravity. By detecting differences in gravity over short distances, gradiometers provide high-resolution information about subsurface mass distribution. In geodesy, gradiometry is used for detailed mapping of geological structures, studying the Earth’s crust, monitoring water and ice mass changes, and supporting satellite missions that refine the global gravity field.

More Info: https://geodesy.science/item/satellite-gravimetry/