Complex multi-fault rupture and triggering during the 2023 earthquake doublet in southeastern Türkiye

Two major earthquakes (MW 7.8 and MW 7.7) ruptured left-lateral strike-slip faults of the East Anatolian Fault Zone (EAFZ) on February 6, 2023, causing >59,000 fatalities and ~$119B in damage in southeastern Türkiye and northwestern Syria. Here we derived kinematic rupture models for the two events by inverting extensive seismic and geodetic observations using complex 5-6 segment fault models constrained by satellite observations and relocated aftershocks. The larger event nucleated on a splay fault, and then propagated bilaterally ~350 km along the main EAFZ strand. The rupture speed varied from 2.5-4.5 km/s, and peak slip was ~8.1 m. 9-h later, the second event ruptured ~160 km along the curved northern EAFZ strand, with early bilateral supershear rupture velocity (>4 km/s) followed by a slower rupture speed (~3 km/s). Coulomb Failure stress increase imparted by the first event indicates plausible triggering of the doublet aftershock, along with loading of neighboring faults.

Liu, C., Lay, T., Wang, R., Taymaz, T., Xie, Z., Xiong, X., Irmak, T. S., Kahraman, M., & Erman, C. (2023). Complex multi-fault rupture and triggering during the 2023 earthquake doublet in southeastern Türkiye. Nature Communications, 14(1).

The authors thank Prof. Chen Ji at the University of California, Santa Barbara, for helpful discussions. The authors thank Prof. P. Martin Mai, Dr. Jihong Liu, and Prof. Sigurjón Jónsson at King Abdullah University of Science and Technology for sharing horizontal displacements derived from pixel-tracking offsets of Sentinel-1 satellite radar images. The authors also thank Jianbao Sun and Zhaoyang Zhang at Institute of Geology, China Earthquake Administration for sharing geodetic observatons of the 2023 Türkiye earthquake doublet. C. Liu was supported by the National Science Foundation of China (No. 42222403, 42230309). T. Lay’s earthquake research is supported by US National Science Foundation (Grant EAR1802364). Tuncay Taymaz acknowledges the Istanbul Technical University Research Fund (ITU-BAP) and the Alexander von Humboldt Foundation Research Fellowship Award for providing computing facilities through the Humboldt-Stiftung Follow-Up Program to support his earthquake research.

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