Site effects observed in Antakya after the Mw 7.7 Pazarcik and Mw 7.6 Elbistan Earthquakes on the 6th February 2023 (Türkiye)

On February 6, 2023 Eastern Türkiye was shaken by two consecutive catastrophic earthquakes of moment magnitudes 7.7. and 7.6, induced by a left-lateral strike-slip fault in Eastern Anatolian Fault Zone. The first earthquake with a moment magnitude 7.6 was felt at 4:17 local time in the morning, while, approximately nine hours later, the second earthquake with a moment magnitude 7.7 increased the massive damage that occurred in eleven provinces of Türkiye including Hatay, Kahramanmaraş, Adıyaman, Malatya, Osmaniye, Gaziantep, Kilis, Şanlıurfa, Diyarbakır, Adana and Elazığ. In this paper, a specific focus is devoted to show the site effects observed in Antakya after the strong shakings as revealed by an extensive analysis of the collected ground motion records and geological and geotechnical data. It is shown that basin effects are associated with a higher level of damage compared to areas with the same level of ground shaking but without detrimental conditions of the local soils. The lessons learned from this seismic event highlight the key role played by the seismic response analysis and related tools of microzonation studies for the mitigation of the seismic risk.