Intensity Characteristics of Seismograms Recorded During the February 6, 2023, M7.8 Türkiye Kahramanmaraş Pazarcik Earthquake

The strong ground motion intensity levels recorded during the February 6, 2023, Türkiye-Kahramanmaraş-Pazarcık earthquake (M7.8) were compared with the ones predicted by the four ground motion models of 2014 NGA WEST-2 Ground Motion Prediction Equations (GMPEs), and by the Turkish earthquake design code (TEC, 2018). These comparisons revealed that Adana, Malatya, and Gaziantep cities were shaken by PGA levels less intense than the ones predicted by GMPEs. Contrary to these cities, ordered from the highest to lowest positive residuals, Şanlıurfa, Hatay, Kahramanmaraş, and Elazığ cities were shaken by higher levels of PGA than those predicted by the GMPEs. The TEC DD-1 and DD-2 seismic scenario PGA levels were exceeded at 5 and 22 out of 71 stations, respectively. The residuals for the stations on the Anatolian plate side exhibited a more correlated residual trend with the recorded PGA levels. The stations of exceeded seismic PGA demands are site class ZC or softer. PGA levels for DD-1 were exceeded at stations in the city of Hatay. The highest positive residual is also estimated for the Defne-Hatay station #3135, where the most structural damage was concentrated. The spectral acceleration residuals were also assessed. The spectral acceleration levels in all period ranges were higher than those predicted by Abrahamson, Silva and Kamai (2014), Campbell and Bozorgnia (2014) GMPE models. For spectral periods longer than 0.06 and 0.3 seconds, respectively, Chiou and Youngs (2014), and Boore, Stewart, Seyhan and Atkinson (2014) medial predictions were exceeded. Additionally, the structures with spectral periods of 0.7 seconds and longer were estimated to be subjected to approximately 20 to 30 % higher seismic demands, as defined by TEC for DD-2 design basis scenario. This is listed as one of the factors among many, contributing to the concentrated damage observed in residential buildings with number of stories higher than 5 to 7.