Suitability of the 1d assumption for ground response analysis in the epicentral area of the 2016 mw 6.0 amatrice earthquake (central Italy)

Abstract

The 2016-2017 Central Italy seismic sequence was recorded by the 3A network deployed in theepicentral area and composed of 50 seismic stations. Taking advantage of microzonation activities, we retrieved site information for a subset of these stations, including shear-wave velocity profiles from down-hole tests down to a minimum depth of 30 m. In this paper we compared the available empirical transfer functions with the theoretical one-dimensional transfer functions calculated from site characterization information. The former were computed by weak-motions spectral ratios using either a reference site (SSR) or horizontal-to-vertical ratios (EHV); the theoretical curves were computed using the STRATA code under the linear-elastic assumption. We have applied some classification strategies to discriminate sites that can be interpreted as having a 1D site response. We observed a poor match between empirical and theoretical amplification functions, suggesting that the 1D assumption may not hold for the majority of the selected stations.