Seismic Demand Amplification and Structural Vulnerabilities in the 2023 Kahramanmaraş Earthquake Sequence: Insights from Ground Motion Data and RC Building Failures

On February 6, 2023, southeastern Türkiye experienced two major earthquakes (Mw 7.8 and Mw 7.6) along the East Anatolian Fault Zone, leading to widespread structural damage and significant loss of life. This study aims to investigate the seismotectonic characteristics of the events, analyze strong ground motion recordings relative to Turkish seismic code design spectra (TBEC-2018), and assess the damage mechanisms observed in reinforced concrete structures. Ground motion data from affected provinces demonstrated peak ground accelerations exceeding code expectations by up to 5 times, particularly in areas with soft alluvial soils, amplifying seismic demands through site effects and near-fault phenomena. Structural assessments revealed that damage mechanisms were dominated by soft and weak story irregularities, short column shear failures, strong beam-weak column behavior, pounding effects between adjacent buildings, and inadequate transverse reinforcement, especially at beam-column joints. These vulnerabilities, combined with amplified seismic demands, resulted in catastrophic failures even in structures nominally designed under modern codes. The findings emphasize the urgent need for integrating performance-based seismic design, site-specific hazard assessment, and stricter construction quality controls. This study offers critical recommendations for improving seismic resilience in Türkiye and other tectonically active regions.