Interpreting the Direction of the Gravity Gradient Tensor Eigenvectors: The Main Tidal Force and its Relation to the Curvature Parameters of the Equipotential Surface

Abstract

Rotating the gravity gradient tensor about a vertical axis by an appropriate angle allows one to express its components as functions of the curvatures of the equipotential surface. The description permits the identification of the gravity gradient tensor as the Newtonian tidal tensor and part of the tidal potential. The identification improves the understanding and interpretation of gravity gradient data. With the use of the plunge of the eigenvector associated with the largest eigenvalue or plunge of the main tidal force, it is possible to estimate the location and depth of buried gravity sources; this is illustrated in model data and applied to FALCON airborne gravity gradiometer data from the Canning Basin, Australia.