Simulation of large earthquake synchronization and implications on North Anatolian fault zone

Abstract

The North Anatolian Fault (NAF) zone has consistently exhibited a sequence of westward-migrating earthquakes with magnitudes exceeding 7 ($M_w>7$) during its last three seismic cycles. To investigate the mechanisms underlying this behavior, we conducted multi-cycle simulations using a rate-and-state friction (RSF) model. The model incorporates three seismogenic asperities aligned along the fault strike, separated by barriers that inhibit rupture propagation. By simulating spontaneously occurring earthquakes, we analyzed variations in the timing of large events across the asperities. Our results indicate that both the strength and length of the barriers play a critical role in controlling the coupling between asperities, while variations in asperity length exert a relatively minor influence. Simulations with very weak barriers—permitting rupture jumps between asperities—and very strong barriers—limiting stress transfer—tended to produce synchronized earthquake cycles. In contrast, intermediate-strength barriers that allowed limited stress transfer generated more variable, non-synchronized cycles. These findings suggest that faults coupled primarily through static stress transfer are more prone to desynchronization, whereas those coupled via dynamic triggering or afterslip may maintain synchronization over multiple cycles. Although the model is simplified, it offers meaningful insights into the seismic behavior of the NAF and contributes to a deeper understanding of fault system dynamics.