Short period surface waves, recorded during a seismic refraction survey in the Sannio region (Southern Italy), have been modeled to infer a shallow velocity model for the area. Based on the decrease of resolution with depth, due to the bias on group velocity estimates arising from interference of the Rayleigh waves with higher modes, we carried out a procedure of fitting, with synthetic seismograms, of selected filtered traces with a gaussian filter, having a width at half height equal to 1 Hz and a central frequency lying in the range [1,4] Hz. We estimated the likelihood between synthetic and observed seismograms by measuring their semblance. In this way we were able to infer a more refined local velocity model characterized by a high Vp and Vs vertical gradient in the sedimentary cover. Two ad hoc resolution studies, based on group velocity and amplitude data respectively, indicate that the local velocity model is a good velocity model also for the entire studied area. The increase in the number of available data when using amplitude information allows us to make a more selective choice in the model parameter space (Vp and Vs of each layer) and to solve for the Vp/Vs ratio. The inferred Vp velocity in the half-space is equal to 2.8 km/s. This value is in excellent agreement with that inferred by other authors (3 km/s) by modeling P-wave travel time vs. distance. The best-fit model furnish low Vp/Vs for the sedimentary cover so indicating a high degree of the sediment�s compaction in the studied area. The inferred shallow high-velocity gradient indicates that the shallow sedimentary layer in the area could trap and focus the energy traveling into it.