Kahramanmaras, and its surroundings were devastated with major earthquake doublets of Mw = 7.8 Pazarc & imath;k and Mw = 7.6 Elbistan/Ekinoz & uuml; on February 6th, 2023. While a wide scatter of reinforced concrete (RC) structures experienced damage, mid-rise residential buildings constitute a large bulk with heavy damage or total collapse. Among many reasons, poor concrete strength and brittle fracture of rebars along with liquefaction-caused soil deformations contributed to building damage. This paper investigates structural, geotechnical, and architectural conditions of mid-rise RC residential buildings with heavy damage. The geotechnical component includes the investigation of liquefaction-caused settlement and subsidence of loose foundation soils. Architectural reconnaissance suggests that commonly encountered design mistakes observed in past earthquakes were repeated. Field investigation concludes that loose saturated silty and sandy soils exhibit liquefaction leading to permanent damage on the mid-rise buildings while tunnel-form code-designed RC buildings with seven-to-ten stories performed well.

This study investigates the effects of the February 6, 2023, earthquakes in T & uuml;rkiye, measuring 7.8 and 7.6 magnitudes (Mercalli intensities XI and X). It comprehensively assesses their impact, along with the subsequent Hatay earthquake (Mw 6.4), on various structures, including residential RC buildings, commercial, industrial, and strengthened structures, as well as critical lifeline components such as roads, bridges, power, and telecommunication systems, and areas affected by soil failures. Immediate field observations were conducted to assess changes and gather insights. The findings will contribute to the development of recommendations for future seismic damage prevention and mitigation strategies.

In response to the significant earthquakes that struck Turkey and Syria on February 6, 2023, a collaborative reconnaissance team, consisting of researchers and engineers from Japan and Turkey, was formed by the Japan Association for Earthquake Engineering, the Architectural Institute of Japan, the Japan Society of Civil Engineers, and the Japanese Geotechnical Society. This coalition conducted an in-depth on-site investigation from March 28 to April 2, two months after the catastrophic seismic events. In Islahiye, a landslide resulted in the formation of a landslide dam. Another landslide occurred in Tepehan on a relatively gentle slope formed of limestone, with possible correlations to fault movements. Iskenderun encountered not just building collapses on soft ground, but also instances of the tilting of buildings and ground subsidence attributed to the liquefaction of reclaimed coastal soil. Golbasi witnessed significant liquefaction-induced damage to structures with shallow foundations on soft ground, involving tilting and settling. However, a more comprehensive investigation is required to accurately map the extent of the liquefied soil layers. Antakya and Kahramanmaras emerged as regions where building damage coincided with surface ground vibrations. Despite severe building collapses, Antakya's relatively stable ground showed an average S-wave velocity exceeding AVS30 400 m/s. This suggests potential wave amplification due to underlying geological structures. Kahramanmaras displayed notable building damage concentrated in alluvial fan formations. (c) 2023 Production and hosting by Elsevier B.V. on behalf of The Japanese Geotechnical Society. This is an open access article under the CC BYNC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).