Interplay between ground deformation and seismicity during the 2005–2025 unrest at Campi Flegrei

We investigate the relationship between the cumulative number of earthquakes and ground uplift at the Campi Flegrei caldera (South Italy) during the ongoing unrest (2005-present). While previous studies have explored this correlation, we propose a nonlinear epidemic model that captures new features of the caldera system. Our model describes earthquakes' occurrence as a cascading process driven by ground deformation. The nonlinearity reflects the reduced efficiency of the triggering mechanism, which contributes to the short duration of seismic swarms. This mechanism may represent a general framework for understanding the occurrence of volcanic earthquakes worldwide.