GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione 2.1 285 Fig. 2 – Mean residuals of the best PHV predictor excluding site effect terms, when applied to the validation dataset. Residuals were averaged over a range of recording distances (top) or source magnitudes (bottom) from minimum to increasing upper bounds (to the left) or from increasing lower bounds and maximum (to the right). Different symbols are used for residuals relative to recordings acquired under different site conditions (class B, C and D), according to the legend. Fig. 3 – Logarithmic errors affecting the estimates of PHA (to the left) and PHV (to the right) of the validation subset, provided by the best equations obtained in this study (black dots) and by Akkar and Bommer (2007a, 2007b) (open circles). Errors are plotted as function of the peak ground motion actually observed. and over-estimates for smaller peak values (Fig. 3). Such effect can be in general due to the weakness of constraints provided by the regression data characterized by very strong ground motion (being very few the recordings acquired very close to larger magnitude events). The best predictive performance of the equations obtained in this study appears mainly related to