Gravity inversion by means of growing bodies
Speaker: Wu-Cyun Sun
Abstract
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 anomalous 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 same time, it can determine a simple regional trend. Moreover, positive and negative density contrasts are simultaneously accepted.
The solution is obtained by a double condition: (1) the l2-fitness to the observed gravity data (model fitness) and (2) the minimization of the total (weighted) anomalous mass (model smoothness). A positive parameter is used to balance the two minimization terms.
In this way, we have designed an efficient inversion gravity method, confirmed by a real data set from the island of Fuerteventura. The results show a clear correlation between the sources of gravity field in the model and the three volcanic complexes recognized in Fuerteventura by other geological studies.
Reference
Camacho, A.G., Montesinos, F.G., Vieira, R., 2000, Gravity inversion by means of growing bodies. Geophysics 65(1):95–101
Montesinos, F.G., Arnoso, J., Vieira, R., 2005, Using a genetic algorithm for 3-D inversion of gravity data in Fuerteventura (Canary Islands). Int J Earth Sci (GeolRundsch) 94: 301–316