Testing sedimentary basin models for ground motion simulation: the case of the Fucino intramountain basin in the Apennines (Italy)

Sedimentary basins are of great interest for ground motion simulations, because of their power to amplify seismic motion and because urban areas are often built on sediment covers. Realistic and detailed 3D basin models have shown to significantly improve the physics-based ground motion modeling in terms of fit between recorded and synthetic seismograms. However, discerning between the uncertainties due to source, path or site effects is not simple.

A good proxy of the seismic response of small- to moderate-scale sedimentary basins is their resonance frequencies, often investigated by experimental measurement of the Horizontal to Vertical spectral ratio (H/V) computed on ambient seismic vibrations or earthquake records. Since these parameters strongly depend on the geometry and mechanical properties of the sediment fill, a wavefield numerical simulation in a realistic 3D media should ideally reproduce them. The comparison of resonance frequencies obtained from real and simulated waveforms can help in discerning inconsistencies in the 3D models, and may help in evaluating the goodness of the model and highlighting areas where it may be improved

We apply this approach in the Fucino intermountain sedimentary basin (Central Apennines, Italy) for which several stratigraphic models, exploration and geophysical data are available in the literature. We critically combine the stratigraphic models of the basin with regional crustal models available in the literature and build an appropriate 3D velocity model. We then perform 3D seismic wave propagation simulations using a spectral-element code; and we compare simulated and experimental seismograms and resonance frequencies for different basin models observing similarities and discrepancies.