How earthquakes reshape carbonate aquifers: Modelling groundwater redistribution in Central Italy after the October 2016, Mw 6.5 Norcia earthquake

The carbonate hydrostructures of the Italian Apennines host major aquifers that serve as a critical groundwater resource. In tectonically active settings, such as the Sibillini Mountains, structural discontinuities and deformation features exert a dominant control on the hydraulic conductivity and storage properties of aquifers, thereby modulating groundwater flow regimes. The M w 6.5 Norcia earthquake of October 30th 2016, part of the 2016 Central Italy seismic sequence, caused extensive ground deformation and surface faulting, triggering significant and long-lasting hydrogeological changes across the Sibillini Mountains carbonate aquifer. In this study, we develop a regional-scale conceptual hydrogeological model and implement it in steady-state numerical simulations. Our modelling reproduces pre- and post-seismic groundwater flow conditions and highlights the role of major active faults in governing aquifer hydrodynamics. Simulations demonstrate that the earthquake-induced fault rupture, modelled as a binary (on-off) feature, facilitated cross-fault groundwater transfer, leading to a persistent depletion of the eastern aquifer sector and enhanced discharge in the central and western sectors. These findings provide evidence of how seismic events can reconfigure groundwater flow patterns in fractured carbonate systems, highlighting the critical role of tectonic structures in controlling their hydrodynamic balance. • Norcia 2016 earthquake triggered major aquifer redistribution in the Sibillini Mts. • Conceptual modelling guided the development of regional steady-state simulations. • Steady-state models simulated pre- and post-seismic groundwater flow regimes. • Groundwater head changed after barrier removal, reshaping flow paths and discharge. • Fault rupture enabled cross-fault flow, dropping eastern spring discharge by 73 %.