GNGTS 2013 - Atti del 32° Convegno Nazionale

technique is the independence from the initial velocity model. The data processing can be summarized in the following steps: i) travel times are computed from a given initial velocity model, and the least-square error E i between computed and observed traveltimes is determined for each iteration i as follows: (4) where N is the number of observations, j indicates each observation, t obs and t cal are observed and calculated traveltime, respectively; ii) the velocity model is perturbed by including a random velocity constant and calculating the new least-square error E 1 ; iii) the probability P that the new model is acceptable is determined: (5) (6) Fig. 3 – Sismo-stratigraphic section. The black triangles show the distribution of the geophones; gray diamonds represent the shot points. 49 GNGTS 2013 S essione 3.1