This work provides an overview of recent developments and calibrations of empirical ground-motion models (GMMs) for the vertical component of seismic ground motions in Italy, including both Fourier Amplitude Spectrum (FAS) and response spectral acceleration (SA) models. Special attention is given to models including near-source conditions. The motivation comes from the growing interest in using the vertical component for earthquake engineering applications, such as ground-motion simulation, source characterization, selection of multi components spectrum compatible records for dynamic analysis, where amplitude, frequency content and consistency with horizontal components are key.

The models are calibrated using the ITA18 dataset, a comprehensive and quality-checked collection of strong-motion recordings from shallow crustal events, mainly in Italy, covering a wide range of magnitudes, source-to-site distances, and site conditions (Vs30). Predictions are provided at 103 discrete frequency points, allowing detailed spectral analysis.

The functional forms include Mw, rupture distance, focal mechanism and site effects represented by VS30. A residual analysis is carried out addressing the between-event, site-to-site and event- and site- corrected components.

The proposed models contribute to a better understanding and characterization of vertical ground motions and provides a useful support for three components spectrum-compatible accelerograms selection and advanced seismic hazard analyses in the Italian context.