Exploring Fault Behaviour and Seismic Hazard in the Central Apennines through Earthquake Simulations

The Central Apennines (Italy) are characterized by moderate seismicity and active fault systems capable of generating damaging earthquakes. However, the limited duration of historical and paleoseismic records restrict our understanding of long-term fault behaviour. In this study, we use the Multi-Cycle Earthquake Rupture Simulator (MCQsim) to construct a 3D model of 42 active normal faults and to generate multiple 100,000-year-long synthetic earthquake catalogues. We systematically vary key model parameters, including dynamic friction and fault strength heterogeneity, to assess their influence on earthquake occurrence rates, magnitudefrequency distributions, and rupture scaling.

The simulations reproduce the regional Gutenberg–Richter trend and show magnitude–average slip and magnitude–rupture area relationships consistent with empirical scaling laws and the available historical catalogue. Seismic productivity and rupture characteristics are most sensitive to variations in dynamic friction and fault heterogeneity. Although uncertainties arise from simplified fault geometries and assumptions about seismogenic depth, the overall agreement between synthetic and observed seismicity suggests that MCQsim effectively captures key aspects of long-term fault-system behaviour. These results indicate that physics-based synthetic earthquake catalogues can improve constraints on earthquake recurrence and rupture scenarios, providing valuable input for probabilistic seismic hazard assessment in regions characterized by moderate seismicity, complex active fault systems, and sparse observational data.