Dynamic rupture process of the Mw 7.8 Kahramanmaraş earthquake (SE Türkiye): Variable rupture speed and implications for seismic hazard

Abstract

We considered various non-uniformities such as branch faults, rotation of stress field directions, and changes in tectonic environments to simulate the dynamic rupture process of the 6th February 2023 Mw 7.8 Kahramanmaraş earthquake in SE Türkiye. We utilized near-fault waveform data, GNSS static displacements, and surface rupture to constrain the dynamic model. The results indicate that the high initial stress accumulated in the seismic gap leads to the successful triggering of the East Anatolian Fault (EAF) and the supershear rupture in the northeast segment. Due to the complexity of fault geometry, the rupture speed along the southeastern segment of the EAF varied repeatedly between supershear and subshear, which contributed to the unexpectedly strong ground motion. Furthermore, the triggering of the EAF reminds us to be aware of the risk of seismic gaps on major faults being triggered by secondary faults, which is crucial to prevent significant disasters.

The overall-subshear and multi-segment rupture of the 2023 Mw7.8 Kahramanmaraş, Turkey earthquake in millennia supercycle

“…Okuwaki et al 23 perform a potency-density tensor inversion and find a 5-6 km/s speed for the southwest branch of the rupture. Wang et al 24 simulate the dynamic rupture process of the mainshock, and report that V NE is supershear while V SW varies repeatedly between supershear and subshear. Abdelmeguid et al 25 report the occurrence of supershear ruptures at the end of the southwest segment and the northeast segment of the EAF based on their observation of larger fault-parallel amplitudes compared to faultnormal amplitudes in near-field seismic recordings.…”