ITACAext 2.0: A High-Quality Parametric Table of Strong-to-Weak Motion Recordings for Seismological and Engineering Research in Italy

Abstract In the most recent release of the ITalian ACcelerometric Archive (ITACA) portal (v. 4.0; Felicetta et al., 2023), a parametric table (intensity measures and associated metadata) of seismic records of interest for the characterization of seismic motion in Italy was made public. This flatfile is called ITACAext and includes accelerometer and velocimeter recordings of Mw≥3.0 earthquakes and seismic networks in Italy and neighboring countries. The dataset contains parameters of recordings manually processed by experts from 1972 to 2022, with a total of 52,706 observations from 2,338 events and 2,294 stations. This dataset provides the most up-to-date overview of strong motion recordings available for Italy, including the strongest earthquake recordings of all Italian seismic sequences over the last 50 yr (1976 Friuli, 1980 Irpinia, 1997 Umbria–Marche, 2009 L’Aquila, 2012 Emilia, and 2016–2017 central Italy). It also includes a significant number of near-source records of earthquakes in volcanic and subduction areas. The flatfile contains not only the peak amplitudes (peak ground acceleration, peak ground velocity, and peak ground displacement), energy parameters (cumulative absolute velocity, Arias and Housner intensity), and ordinates of the acceleration response spectrum (damping 5%, period interval 0.01–10 s), but also the ordinates of the Fourier spectrum (f = 0.04–50 Hz), calculated for the entire signal as well as for the S phase. ITACAext also includes several metadata, all conveniently referenced, including those most relevant to the calibration and testing of ground-motion models (GMMs), such as various magnitude estimates, different distance metrics, focal mechanisms and site characterization parameters such as VS,30. To support the analysis of ground motion of tectonic origin at the national scale, a selection of shallow active crustal recordings was performed. In addition, an analysis of the quality of the dataset was carried out via residual analysis in two stages. These checks also consisted of comparing the seismic responses of collocated sensors and support the inclusion of velocimetric recordings in ground-motion analyses. In the end, we flagged 42,877 records from 2,045 events that can be confidently used to calibrate and test active shallow crustal GMMs at the Italian scale.