An approximative method to obtain inner mass distributions starting only from gravimetric data and topographic chart digitalization is described. Roughly, the sensitive subsoil volume is divided into a suitable cell partition of equally determinable regular blocks. Then, the gravimetric effect for unit density for each cell on each surface point is determined. A global least-squares adjustment for every cell and every regular gravimetric point is carried out in order to derive the anomalous density values for each block, and, finally, by using local polynomial approximation, a continuous structural model from the discrete "cubist" solution is performed. A volcanic caldera structure, the known caldera of Las Canadas, has been gravimetrically observed. In this paper we present the methodology we have developed to analyze the measured gravimetric data and show the results corresponding to the inner mass density distribution for this volcanic structure.
