Dynamics of episodic supershear in the 2023 M7.8 Kahramanmaraş/Pazarcik earthquake, revealed by near-field records and computational modeling

The 2023 M7.8 Kahramanmaras/Pazarcik earthquake was larger and more destructive than what had been expected. Here we analyzed nearfield seismic records and developed a dynamic rupture model that reconciles different currently conflicting inversion results and reveals spatially non-uniform propagation speeds in this earthquake, with predominantly supershear speeds observed along the Narli fault and at the southwest (SW) end of the East Anatolian Fault (EAF). The model highlights the critical role of geometric complexity and heterogeneous frictional conditions in facilitating continued propagation and influencing rupture speed. We also constrained the conditions that allowed for the rupture to jump from the Narli fault to EAF and to generate the delayed backpropagating rupture towards the SW. Our findings have important implications for understanding earthquake hazards and guiding future response efforts and demonstrate the value of physics based dynamic modeling fused with near-field data in enhancing our understanding of earthquake mechanisms and improving risk assessment. The 2023 Mw 7.8 Pazarcik earthquake, Turkiye was characterized by spatially non-uniform rupture propagation that included transient episodes of supershear rupture, according to a 2D model informed by nearby seismic records.

Automated summary

This study analyzed the 2023 M7.8 Kahramanmaras/Pazarcik earthquake in Turkey and developed a dynamic rupture model to reveal the spatially non-uniform propagation speeds and conditions for rupture jump and delayed backpropagation. These findings have important implications for earthquake hazards and future response efforts.