GNGTS 2017 - 36° Convegno Nazionale

404 GNGTS 2017 S essione 2.2 The plot on the right in Fig. 2c shows the comparison of the surface station UMSG (thin lines) and the borehole station UMBG (thick lines). These stations show two main differences: in the range 0.8 – 2 Hz the amplitude of the H/V ratios of UMSG is almost the double of the H/V ratios of UMBG. This could be explained by the presence of the overlying layers. At frequencies higher than 10 Hz the amplitude of the H/V ratios of UMBG is around 1 while the Fig. 3 - Joint inversion of the average correlation coefficients and the mean H/V ratio obtained on coda waves for the station CELG. a) The black dots and the relative error bars are the autocorrelation coefficients, computed for each Ring, as a function of the frequency. The red line is the minimum misfit model among all the models investigated (grey band). b) H/V ratio (black dots) and relative error bars, the red line is the ellipticity function for the fundamental mode of Rayleigh waves for the minimum cost model. c) Minimum misfit S-wave velocity model (red line) and space of explored models (grey band).