Investigating the 2023 Mw 7.8 Kahramanmaraş Earthquake Ground Motion Through 3D Physics-Based Numerical Simulations

This study presents and validates the 3D physics-based numerical simulation of the 2023 Mw 7.8 Kahramanmaraş earthquake, which caused widespread damage and thousands of fatalities across a vast region spanning Türkiye and Syria. A 325 × 355 km numerical domain was set up to include models of the causative fault of the Mw 7.8 event and a crustal velocity profile of the area. Different published kinematic rupture models were tested, with the final selection based on the evaluation of the model performance to fit the recorded ground motions. Results of the numerical simulations, performed through the spectral element code SPectral Elements in Elastodynamics with Discontinuous Galerkin (SPEED) up to a maximum frequency of 1 Hz, are enriched in the high-frequency range employing a technique based on artificial neural networks (ANN2BB) to produce broadband ground motions of practical interest for engineering applications. Simulated ground motions were validated in time and frequency domains, and across multiple intensity measures (IMs) using various techniques. The performance of simulated ground motions is tested against specific complex phenomena of the event, including directivity, directionality, and basin effects. Although some discrepancies remain due to model simplifications and uncertainties, results show good agreement with recordings, most IMs achieving “good to excellent” fit, as measured using quantitative goodness-of-fit criteria, and median normalized residuals generally below ±0.30. The study demonstrates that a 3D physics-based simulation framework can effectively characterize the main properties of ground shaking in large magnitude events with major uncertainties, which is particularly important in regions with sparse seismic instrumentation. However, this exercise has proven that a full reproduction of complex characteristics of large-magnitude events using a simplified and computationally feasible model poses various challenges.