The SanBa Project (Santos Basin- Seismic Research experiment) is part of more general investigations conducted by our teams on processes of thinning of the continental crust which built passive margins and intra-continental basins. The project will allow a comparison between the deep structure of the wide Santos margin (with its conjugate, the narrow Namibe margin) and the adjacent Espirito Santo-Angolan system on which the team has already done extensive studies (Moulin 2003; Moulin et al., 2005; Aslanian et al., 2009; Moulin et al., 2010a, 2010b). The Sanba Project will be a new part of the ongoing typology for a general characterization of different margin types that we are building, taking into account the margins tectonic history, the general and regional geodynamics and the influence of the mantle segmentation (Moulin et al., 2006; Aslanian et al., 2009). Its aim is to test existing models and/or propose a new model for the history of the margin that takes account of all the geophysical, geodynamical and geological observations.