The Down-Hole investigation has the aim, to determine the velocity profile of the shear waves. The combined use of the compression andshear waves allows to characterize dynamically, through the calculation of the propagation velocity of compressional waves (P) and cutting (SH), the lithologies present in the area of ​​investigation. The use of the SH shear wave velocity values ​​allows to obtain the shear wave speed parameters averaged over the first 30 m (VS30), as requested by D.M. 14/01/2008.

The combined use of the speed of the P and SH waves allows, in association with the geotechnical data, to provide a characterization of the site / land in question in terms of deformability of the materials. The propagation velocity of the compression and shear waves are related to the density ρ and and to the pairs of elastic moduli E and ν or λ and μ. Known density, by measuring the speed goes back to the “dynamic” value of the modules of a material. The dynamic values can provide useful information to verify loads and thrusts by artifacts on the foundation soil.