Bouguer anomaly

Bouguer anomaly  (b-zhâr)

The difference between the expected value of gravity at a given location (taking into account factors such as latitude, longitude, altitude, and the rotation of the Earth) and its actual value. Bouguer anomalies suggest the existence of locally dense or light regions of the Earth, where a large meteorite or an oil field might be buried beneath the surface. Bouguer anomalies can be measured in several ways depending on whether the density and shape of the terrain between the measuring point and sea level is calculated, estimated, or ignored.