Destructive impact of successive high magnitude earthquakes occurred in Türkiye's Kahramanmaraş on February 6, 2023

Two successive earthquakes with moment magnitudes of Mw = 7.7 (focal depth = 8.6 km) and Mw = 7.6 (focal depth = 7 km) occurred approximately within 9 h on February 6, 2023, in Turkiye, respectively. The epicenters were the Pazarcik and Elbistan districts of Kahramanmaras. Both earthquakes occurred in the East Anatolian Fault Zone, one of Turkiye's two major active fault systems. Between these two severe earthquakes, there was one more big aftershock with a moment magnitude of 6.6, the epicenter of which was in the Nurdagi District of Gaziantep. Then, on February 20, 2023, another aftershock earthquake with a magnitude of Mw = 6.4 occurred in Yayladagi district of Hatay. As a result of the earthquakes, severe damage occurred in several provinces and districts with a population of around 15 million, and more than 50,000 people have lost their lives. This study presents on-site geotechnical and structural investigations by a team of researchers after the Kahramanmaras earthquakes. It summarizes the performance of the building environments as a result of on-site assessments, taking into account observed structural damage, local site conditions, and strong ground motion data. The possible causes of the observed damage are addressed in detail. These earthquakes once again revealed the common deficiencies of existing reinforced concrete structures in Turkiye, such as poor material quality, poor workmanship, unsuitability of reinforcement detailing, and inadequate earthquake-resistant construction techniques. Precast concrete and masonry structures in the region were also severely damaged during the earthquakes due to insufficient engineering service, poor materials, deficiencies during construction, etc.