The determination and application of vector gravity anomalies

Abstract

Conventional gravity measurements are only of the maximum magnitude of the gravity acceleration vector. This is because the gravimeter is aligned with the gravity vector and not in a self-consistent reference frame. However, when a high-resolution geoid model is available, vector gravity data can be computed. The geoid model is used to compute the deflections of the gravity vector from the ellipsoidal normal, thus providing direction to the measured magnitude of gravity acceleration. This allows the components of the gravity vector to be computed from the gravity measurements. Since the geoid is mostly generated by deeper Earth structure, the components of the vector gravity anomaly enhance the information on deeper mass variations above that contained in the conventional gravity anomaly. This approach has been applied to the Australian gravity database and shows a number of linear features not clearly evident in conventional Bouguer gravity anomaly maps.