Seismic amplification in presence of topography and their consequences for ground motion predictions and seismic code for building: the case of Italy

Abstract

This work talks about the relevance of topographic effects in local site response evaluations. In this way some Italian test sites, characterized by the presence of a seismic station installed at the top of a steep topography, were investigated. The influence of the morphology was evaluated, at first, by performing rotational spectral ratio analyses, both in term of single station measurements (i.e. horizontal to vertical spectral ratio, HVSR) and, if possible, also considering reference sites (i.e.standard spectral ratio, SSR) and, at second, evaluating the residuals (logarithmic difference between observed and predicted data) estimated in term of acceleration response spectra for period up to 2.0 s. In this way, the ground motion prediction equations calibrated for Italy by Bindi et al., 2010 were considered. Finally, in correspondence of two selected topographies with seismic stations installed both at the top and at the base, the design elastic acceleration response spectra as proposed by the Italian seismic regulations (NTC, 2008) were evaluated in terms of shape and amplitude.