Site characterization of Italian accelerometric stations

The last release of the strong-motion database ITACA (ITalian ACelerometric Archive v 2.1, http://itaca.mi.ingv.it) includes, to date, about 25,222 three-component accelerometric waveforms generated by 1365 earthquakes with magnitude between 3.0 and 6.9 and recorded by 1210 stations in the time frame 1972–2015. One of the main goals of ITACA is to improve the characterization of the recording sites from the geological and geophysical point of view and to provide seismic classification according to Italian seismic code. To this aim, metadata of recording stations are stored in three main thematic levels (topographic features, geological features and geophysical measurements) useful for a large variety of applications in engineering seismology or earthquake engineering. In particular, 206 recording stations have been characterized by quantitative measurements of velocity profiles, conducted through different techniques (active and/or passive), and the VS,30 values are available in ITACA 2.1. Moreover, 357 horizontal to vertical spectral ratios of Fourier spectra of ambient noise and the value of the fundamental frequency are also accessible. All details about the stations contained in the ITACA database are described in specific reports.