S-wave velocity and radial anisotropy structure of the Southern Italy from probabilistic tomography inversion

Southern Italy is a tectonically active region presenting a high seismic risk. The convergence between the African and European plates has produced intense crustal deformation, widespread active faulting zones, and a highly complex tectonic architecture. Developing 3-D seismic tomography models in such a setting is essential for improving our understanding of the crustal heterogeneity and its impact on seismic hazard. Here we measure the dispersion properties of cross-correlation functions obtained from ambient noise interferometry for 69 broadband stations for the period between 2020 to 2024. To improve the azimuthal coverage and address data gaps, we extract group velocities of surface waves from 28 regional earthquakes (M>5). We jointly invert the earthquake and ambient noise dispersion data to obtain Rayleigh and Love wave group velocity maps at periods ranging from 5 to 23 s in a probabilistic framework. We then perform 1-D depth inversions of both surface wave types to retrieve depth-dependent isotropic Voigt velocity (V_Voigt) and radial anisotropy models. The resulting surface-wave group velocity distributions, together with the 3D V_Voigt and shear-wave radial anisotropy models, reveal pronounced seismic signatures associated with the Lagonegro Basin unit, located between the Apennine chain and the Apulian carbonate platforms. These findings provide new constraints on the crustal structure of Southern Italy and contribute to a more refined understanding of its tectonic and seismic behavior.