Radially Anisotropic 3D Velocity Model of the Central Apennines Lithosphere: The CI23 Model

Abstract

We present the first application of Full-Waveform Inversion (FWI) for a radially anisotropic 3D velocity model of the lithosphere beneath central Italy. The retrieved model (Formula presented.) constrains P-wave ((Formula presented.), (Formula presented.)) and S-wave velocities ((Formula presented.), (Formula presented.)) in the period range 8–50 s. (Formula presented.) model correlates well with regional lithological formations and highlights a negative radial anisotropy anomaly (Formula presented.) localized beneath the epicentral region of the 2016–2017 Amatrice-Visso-Norcia (AVN) seismic sequence. An opposite trend (positive radial anisotropy anomaly, i.e. (Formula presented.)) is observed in the area affected by the 2009 L’Aquila (AQ) seismic sequence. We interpret the velocity anomalies in terms of local tectonic structures, particularly the Olevano-Antrodoco-Sibillini (OAS) thrust—Gran Sasso Thrust (GST) systems, while also considering possible evidence of overpressured fluids and fluid migration. Additionally, the observed anomalies may reflect transient velocity variations induced by the ANV and AQ seismic sequences.