Seismic Hazard Evaluation and Strain Dynamics in the Simav Fault Zone: A Comprehensive Analysis of Earthquake Recurrence and Energy Release Patterns

This study aims to determine the earthquake hazard of the Simav Fault Zone (SFZ), one of the key tectonic features of Western Anatolia—a region that serves as a natural laboratory for geoscientists due to its complex tectonic structure and swarm-type seismic activity generated by multiple active graben systems. For this purpose, the a (6.33) and b (0.92) seismic parameters based on the Gutenberg–Richter magnitude–frequency relationship were first calculated using M ≥ 3 earthquakes that occurred between 1900 and 2024 along the SFZ. Moreover, the recurrence periods of events with magnitudes between M = 5 and M = 7.1 were determined (ranging 32 and 982 years), and the seismic hazard levels in the region were identified. The spatial density of the earthquakes and the regional distribution of the energy they released were analyzed, and the variations in seismic activity along the fault and energy flow in the region were investigated. For the evaluation of past earthquakes with the current strain field of the region, using geodetic velocity data, the strain rates of each segment of SFZ were calculated (reaching 90 ns/year) and findings related to stress accumulation processes were obtained. The findings, along with previous events, indicate that the region is susceptible to seismic hazards and that even moderate earthquakes pose a significant threat to both infrastructure and the population. This study, which seeks to enhance the understanding of seismic hazards and regional strain accumulation in the SFZ, is expected to serve as a valuable tool in seismic hazard assessments and local disaster management strategies, and to provide a critical reference for decision-makers in effective earthquake risk management.