Updated hazard and risk assessment for middle-southern Turkiye by PSHA methods after two damaged earthquakes in 2023

This study reassesses the seismic hazard and economic risks in southeastern Turkiye, particularly around the East Anatolian Fault Zone (EAFZ), following the 2023 M_w7.8 and M_w7.6 earthquakes. Using probabilistic seismic hazard analysis (PSHA) with Monte Carlo simulations, we compiled data from 5775 earthquake events occurring between 1990 and 2023. The results reveal significantly higher seismic hazard levels than previous models estimated. The average Peak Ground Acceleration (PGA) along major fault zones reaches 0.564 g, with values up to 0.802 g at the intersection of the EAFZ and the Narlidag Fault Zone (NFZ). Spectral accelerations (SA) for short periods (0.2 s) reached 1.865 g, and SA for longer periods (1.0 s) ranged from 0.388 g to 0.641 g. Site effects were incorporated, with PGA amplification factors exceeding 1.6 in soft soil areas, reflecting the variability of ground motion. Comparisons with previous seismic models, such as the Middle East Earthquake Model (EMME14) and the European Seismic Hazard Model (ESHM20), revealed that seismic hazard in the region had been underestimated. To validate the model, we compared the predicted values with recorded ground motions from the 2023 earthquakes. The results showed a good match, confirming the reliability of the hazard model. Economic risk analysis highlighted high potential losses in provinces such as Hatay, Kahramanmaras, Gaziantep, and Adiyaman. Unreinforced masonry buildings and industrial buildings are at significant risk of damage. The findings emphasize the urgent need for improved building safety, enhanced disaster preparedness, and targeted risk reduction strategies in high-risk areas.