Geotechnical aspects and site investigations on Kahramanmaras earthquakes, February 06, 2023

On 6 February 2023, two major earthquakes centered in Kahramanmaraş, occurring nine hours apart, caused significant damage in eleven cities in the south and southeast of Turkey. A seven-day on-site assessment following the main shocks revealed infrastructural and structural damages in the region; the driving mechanism of damages caused by the earthquake from structural and geotechnical perspectives is evaluated. This paper initially compares the seismic characteristics of the measured earthquake records using the well-known ground motion prediction equations that form the essence of Turkey's earthquake hazard map. Later, the measurements of the structural damage resulting from the observed ground deformations are presented. Emphasis was placed on the determination of free field liquefaction and ejecta, as well as the lateral spreading events on the site where evidence of such cases is discussed. Damages to other engineering structures such as roads and retaining walls are also inspected. The results of a preliminary site investigation are presented for a site from Adıyaman/Gölbaşı where severe liquefaction was observed. Finally, the assessment of hazard levels and structural devastation in the impacted area is outlined, with a discussion on underlying causes.