REFERENCE ROCK SITES VERSUS EC8-A SITES

Abstract

Although rock sites are generally classified as A, according to the Eurocode 8, they can be affected by site-effects, caused by particular stratigraphic and/or morphological features. A common, and sometimes critical, assumption is to consider class EC8-A as representative of reference rock sites; for example, typically waveforms recorded by stations classified as EC8-A are used to calibrate the soil amplifications of the Ground Motion Prediction Equations. We propose six proxies based on geological, topographical and geophysical data to discriminate reference rock sites. We applied these proxies to reclassify the EC8-A stations of the data-set used to calibrate the more recent Italian ground motion predictions equation (Bindi et al., 2011). Furthermore, we recalibrated a new set of predictive equations for reference sites, testing their performance against those obtained by Bindi et al. (2011) for the EC8-A sites.