Revised seismic classification of the ITACA stations, according to the EC8 and the Italian norms site classes

Abstract

The activities carried out within Task 2 aim to collect, organize and synthesize geological, geomorphological, geotechnical and geophysical data for the location site of the Accelerometric National Network (RAN) stations in Italy, managed by the Department of Civil Protection, to improve the knowledge about the subsoil (see Delverable D05) and to permit a subsoil and topographic site classification based on EC8 categories. At the end of the project the subsoil of 695 stations have been classified using an hybrid approch, based on surface geology, spectral classification and Vs profils from different recording tecniques (DH, CH, MASW, ESAC). These activities have been useful to link the ITACA database with the software REXEL to select natural accelerograms, compatible with Norme Tecniche per le Costruzioni (NTC2008) and EUROCODE 8 (EC8) spectra, which may also reflect characteristics of the source in terms of magnitude and epicentral distance. For 688 station sites have been provided also a topographic classification using a GIS based semiautomatic method with “by-hand” corrections using topographic maps and/or Google Earth software. A Microsoft Excel Database which also allows to track all changes that have been made since the beginning of the project related to the site classification has been developed.