Ground motion model for reference rock sites in Italy

Then, we re-calibrate the ITA10 prediction equations for horizontal peak ground acceleration at 20 spectral ordinates in the period range 0.04-2 s, accounting for sites that we identify as references rock sites. The resulting reference median values are, on average, 35-40% lower than those calculated by Bindi et al. (2011) model for rock sites. Conversely, the ground motion variability is not significantly changed, even if we introduce a new site soil category to describe the reference rock stations.