The effects of 3D normal fault interactions in seismic cycles

Numerical earthquake simulators are valuable tools for investigating the causal dynamics between seismic events and improving our understanding of seismic sequences. This approach has been widely applied to single strike-slip faults, but physics-based simulations of earthquake cycles for normal fault(s) and networks are still limited. This is partly due to the focus on studying the California fault system and the computational cost of modelling dip-slip faults, which involve additional computations related to normal stress changes during the earthquake cycle. We aim to address this gap by focusing on the effect of normal fault interaction in the generation of complex seismic sequences. Using the open-source boundary-element method QDYN, we model two 3D normal faults incorporating rate-and-state friction and elastic interactions. We examine the impact of variable spatial offsets between the faults on different properties of the earthquake cycle, including slip, slip rate, magnitude distribution, and recurrence intervals within and between faults. By doing so, we aim to provide a physical explanation for the spatial and temporal variability observed in the geological record of natural normal fault networks, such as those found in the Central and Southern Apennines in Italy. Our results will shed light on the behaviour of normal fault networks and contribute to a more comprehensive understanding of earthquake cycles in these systems.