Validation of a 3-D Basin Velocity Model for Physics-Based Seismic Hazard Assessment: The Sulmona Basin, Central Italy

Reliable physics-based seismic hazard assessment (PB-SHA) requires basin velocity models that accurately reproduce key characteristics of observed seismic wave propagation, which is critical for predicting ground-motion scenarios in complex sedimentary basins. We present a validation study of a three-dimensional basin model with depth-dependent P- and S-wave velocity profiles of the Sulmona Basin (central Italy), developed to represent basin-scale structures relevant for physics-based ground-motion simulations.

The model is implemented in the spectral-element code SPECFEM3D and evaluated through direct comparison of observed and synthetic seismograms at the available stations within the basin. Simulations are performed for selected regional earthquakes, with synthetic waveforms filtered to match the target frequency range of the model. Waveform misfit is quantified using the Pyflex framework, allowing an objective assessment of phase arrival times, waveform similarity, and amplitude differences across multiple stations.

The results show that the model reproduces basin-controlled wave-propagation characteristics, including waveform duration and spatial variability of ground-motion amplitudes. Amplitude variability and waveform agreement primarily reflect the depth-dependent velocity structure and 3D basin geometry, while localized misfits reflect unresolved features and the limited number and spatial coverage of recording sites.

Overall, this validation provides a first quantitative assessment of the Sulmona Basin velocity model, forming a foundation for subsequent work towards physics-based seismic hazard assessment and scenario modelling.