The refraction seismic method is aimed at the direct determination along the vertical scanner of the speed of propagation of seismic waves, with continuity, within the medium examined. From the analysis of the speed values, it is possible to reconstruct the subsurface geometries and obtain information about the mechanical condition of the crossed materials (thickening, stiffness, state of fracturing, alteration, etc.). The methodology considers the phenomenon of refraction of elastic waves, artificially generated on the surface, in correspondence of interfaces that separate soils at different conditions of density, assuming that the ground explored has the behavior of a linear elastic stress-strain.