The 2023 Turkey–Syria Earthquake Sequence: Ground-Motion and Local Site-Effect Analyses for Kahramanmaras City

Abstract

This study investigates the ground-motion analysis and local site effects in Kahramanmaras city during the 6 Feb 2023 Turkey–Syria earthquake sequence. The damage distribution was non-uniform, concentrated in an area with 8–10-story buildings on alluvial soil. Comparison between the recorded data and several ground-motion models examined in this study indicates that ground-motion models predict the spectral accelerations around 3 times less than what observed during the first event. Site response analyses are carried out for three sequential earthquakes with magnitudes greater than 6.5 occurred on 6th of February 2023. Deconvolution analysis shows that the peak ground acceleration of bedrock motions correlates with distance: 0.1 g farthest, 0.3 g nearest, and ~ 0.2 g intermediary stations in Kahramanmaras city. The results of convolution analysis indicate that the ground surface spectral acceleration of the first event is the dominant spectra compared to the second and third events for periods less than 4 s. The results of site response analysis show that the 10-story buildings tolerated a spectral acceleration upto 0.85 g which is ~ 1.8 times greater than what is recommended by the available national design spectrum (i.e., the 2007 Turkey seismic design code). This means that the recorded motions in Kahramanmaras city have return periods larger than the 475 years of the Turkish seismic design code.