Analysis of Source and Subsurface Structure Effects on Simulated Long Period Ground Motions in the Kahramanmaraş–Hatay Region

Abstract

The 6 February 2023 Kahramanmaraş earthquake sequence demonstrated the importance of physics-based ground-motion modeling in southeastern Türkiye, where sedimentary basin structures and soil-layer velocity contrasts significantly affect seismic wave propagation. This study presents the first regional-scale three-dimensional (3D) physics-based earthquake simulation framework developed for the Southeastern Anatolia region using the 2023 aftershock sequence. In the initial stage, a high-resolution 3D structural model covering an 80 × 80 km domain beneath the Kahramanmaraş Basin was constructed to explicitly represent shallow sedimentary layers and inclined deep structural interfaces. To evaluate the influence of structural complexity on seismic wave propagation, moderate-magnitude aftershocks were simulated using a horizontally layered model that integrates shallow sedimentary layers with inclined deep interfaces. Subsequently, moderate-magnitude aftershocks (Mw 4.5, 4.6, and Mw 4.9) were simulated from different source locations to investigate spatial variability in basin wavefield evolution. The modeling framework was then expanded to a regional three-dimensional domain covering approximately 200 km × 150 km and extending to the Moho depth (~30 km), incorporating the Hatay region and multiple AFAD strong-motion stations for model validation. The simulations demonstrate that shallow low-velocity sediments and inclined basin geometry significantly modify seismic wave propagation by enhancing late-arriving phases, prolonging shaking duration, and amplifying long-period ground motions (T ≥ 2 s). Comparisons between synthetic and observed ground motions demonstrate that the developed model successfully reproduces the primary characteristics of the recorded waveforms. These findings highlight the importance of incorporating three-dimensional basin structures in regional ground-motion simulations and provide an advanced framework for improving ground-motion prediction, supporting earthquake-resilient urban planning strategies and physics-based seismic hazard assessments in southeastern Türkiye.

Keywords

• Earthquake simulation
• Long period ground motions
• Seismic wave propagation
• Kahramanmaraş earthquakes
• Finite difference method

Supporting Institution

TUBITAK 2219, Institute of Science Tokyo (formerly Tokyo Institute of Technology)

Ethical Statement

Ethics committee approval was not required for this study because of there was no study on animals or humans.

Thanks

This study was carried out during the author’s postdoctoral research period at the Tokyo Institute of Technology and was supported by the Scientific and Technological Research Council of Türkiye (TÜBİTAK) through the 2219 International Postdoctoral Research Fellowship Program. The author sincerely thanks the Disaster and Emergency Management Authority of Türkiye (AFAD) for providing the strong-motion records used in this study. All maps and spatial visualizations were generated using the Generic Mapping Tools (GMT). The three-dimensional regional velocity model and the numerical ground-motion simulations were developed and implemented by the author as part of the postdoctoral research conducted at the Tokyo Institute of Technology.

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