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Revealing the Dynamics and Episodic Supershear in the Feb 6th 2023 M7.8 Kahramanmaraş/Pazarcik Earthquake: near-field records and dynamic rupture modeling

Mohamed Abdelmeguid, Chunhui Zhao, Esref Yalcinkaya, George Gazetas, Ahmed E. Elbanna, & Ares J. Rosakis

Submitted September 10, 2023, SCEC Contribution #13273, 2023 SCEC Annual Meeting Poster #034

The 2023 M7.8 Kahramanmaraş/Pazarcik earthquake was unfortunately larger and more destructive than what had been expected. Thanks to a dense array of instrumentation from AFAD, we have a unique dataset for that earthquake that is available for various analysis approaches. This have led to a various competing point of views regarding the dynamics of rupture propagation during this devastating event. Each individual group whether relying on kinematic source inversion, or dynamic rupture present a different interpretations primarily regarding the rupture propagation speed. These varying interpretations are expected due (1) the complex multi-segmented nature of this earthquake, (2) the huge influx of near-source ground motion data that can be analyzed differently.

Here we present our version of analysis that focused on near-field seismic records and signatures observed within those records that can provide insight on the dynamics of the Mw7.8 earthquake. We use our analysis to inform and develop a dynamic rupture model that reconciles different some of the conflicting inversion results. Our results reveal a spatially non-uniform propagation speed 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 locations of supershear are identified through unique near-fault ground motion signatures that vary with rupture propagation speeds. Within the ground motion records, we also observe field observational evidence showing the mechanism of sub-Rayleigh to supershear transition. Furthermore, our numerical model highlights the important role of geometric complexity and varying frictional conditions in facilitating continued propagation and influencing and varying the rupture speed. Our results demonstrate the value of physics-based dynamic modeling fused with near-field data in enhancing our understanding of earthquake mechanisms and improving risk assessment.

Abdelmeguid, M., Zhao, C., Yalcinkaya, E., Gazetas, G., Elbanna, A. E., & Rosakis, A. J. (2023, 09). Revealing the Dynamics and Episodic Supershear in the Feb 6th 2023 M7.8 Kahramanmaraş/Pazarcik Earthquake: near-field records and dynamic rupture modeling. Poster Presentation at 2023 SCEC Annual Meeting.

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