Gravity inversion by means of growing bodies

This paper presents a gravity inversion method for determining the volumes of bodies with pre-established density contrasts. The method works step-by- step on a prismatic partition of the subsurface volume, expanding the anoma lous bodies to fit the observed gravity values in a systematic exploration of model possibilities. The process is treated in a 3-D context; at the sam e time, it can determine a simple regional trend. Moreover, positive and ne gative density contrasts are simultaneously accepted. The solution is obtai ned by a double condition: (1) the e(2)-fitness to the observed gravity dat a (model fitness) and (2) the minimization of the total (weighted) anomalou s mass (model smoothness). A positive parameter is used to balance the two minimization terms. The method is applied to a simulated example and also t o a real example: the volcanic island of Gran Canaria (Canary Islands, Spai n). In both cases, the results obtained show the possibilities of the metho d.