The 2023 Turkey earthquake sequence involved unexpected ruptures across numerous fault segments. We present 3D dynamic rupture simulations to illuminate the complex dynamics of the earthquake doublet. Our models are constrained by observations available within days of the sequence and deliver timely, mechanically consistent explanations of the unforeseen rupture paths, diverse rupture speeds, multiple slip episodes, heterogeneous fault offsets, locally strong shaking, and fault system interactions. Our simulations link both earthquakes, matching geodetic and seismic observations and reconciling regional seismotectonics, rupture dynamics, and ground motions of a fault system represented by 10 curved dipping segments and embedded in a heterogeneous stress field. The Mw 7.8 earthquake features delayed backward branching from a steeply branching splay fault, not requiring supershear speeds. The asymmetrical dynamics of the distinct, bilateral Mw 7.7 earthquake are explained by heterogeneous fault strength, prestress orientation, fracture energy, and static stress changes from the previous earthquake. Our models explain the northward deviation of its eastern rupture and the minimal slip observed on the Sürgü fault. 3D dynamic rupture scenarios can elucidate unexpected observations shortly after major earthquakes, providing timely insights for data-driven analysis and hazard assessment toward a comprehensive, physically consistent understanding of the mechanics of multifault systems.
This content will become publicly available on January 4, 2026
Near-field earthquake ground motions characterized by strong velocity pulses can cause extensive damage to buildings and structures. Such pulses were identified during the Mw 7.8 and Mw 7.5 earthquake doublet of the 2023 Turkey seismic sequence, potentially contributing to the extensive damage it caused. Therefore, a better understanding and characterization of pulse properties (e.g. period and amplitude) and their underlying physical factors are crucial for earthquake-resistant design. In this study, we characterize the velocity pulses reported in observed records and synthetic waveforms generated by a three-dimensional (3D) dynamic rupture simulation of the Mw 7.8 event. We observed significant variability in the pulse properties of the observed records in near-fault regions, particularly regarding their orientations. This variability was not fully captured by the dynamic rupture simulation. Our results indicate that directivity effects are not the only factors influencing pulse characteristics in this earthquake doublet. While site effects (e.g. basin effects) may influence pulse characteristics at some stations, local heterogeneities in slip amplitude, orientations, and fault geometries can be critical in generating or influencing pulse properties in this earthquake doublet.
more » « less- PAR ID:
- 10564785
- Publisher / Repository:
- SAGE Publications
- Date Published:
- Journal Name:
- Earthquake Spectra
- ISSN:
- 8755-2930
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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