A density model of the Euro-Mediterranean mantle by Integrated Inversion of GRACE gravity data

We present preliminary results about the density structure of the mantle below the Euro-Mediterranean area, down to 1000 km depth. The velocity variations of the P-wave tomography of the Alpine-Mediterranean area (PM0.5, Piromallo and Morelli, 2003), together with the Bouguer anomalies of the satellite-derived GGM02C (Tapley et al., 2005) high-resolution global gravity model, are inverted with the method of sequential integrated inversion (Tondi and de Franco, 2006). The approach uses a probability density function, where the information given by the seismic model and the information on the physical correlation among density and velocity parameters limit the model space within which the inversion of gravity data can operate. The density model parametrization, which uses polyhedral bodies, whose density is linearly dependent on the three coordinates (Pohànka, 1998), leads to a perfect match between the density and the velocity models, and takes into account the presence of structures characterized by a gradual increase in density with depth. Considering the gravity data resolution, we define the cell model with a horizontal regular spacing of 1° x 1°. The model horizontal dimensions are approximately 6600 km in E-W direction, and 3900 km in N-S direction. The vertical spacing is 50 km. The results, compared to existing 3D density models of the area derived from ship-borne and on land data (e.g. Makris et al., 1998) provide an indication of the extent to which GRACE data can resolve specific deep lithospheric and mantle structures.