On February 6, 2023, two devastating seismic events, the Kahramanmaras, earthquakes, struck the Eastern Anatolian Fault Line (EAF) at 9-h intervals. The first earthquake, with a moment magnitude (Mw) of 7.7, struck the Pazarc & imath;k district, followed by a second earthquake with a moment magnitude (Mw) of 7.6 in the Elbistan district, both within the Kahramanmaras, province. These dual earthquakes directly impacted eleven provinces in Eastern and Southeastern Anatolia leading to significant loss of life and extensive damage to property and infrastructure. This study focuses on revealing the main parameters causing to the collapse of reinforced concrete (RC) buildings by examining their compliance with legislation and earthquake codes in force at the time of construction. For this purpose, detailed examinations such as field observations, collection of general information and official documents about the buildings, determination of material properties and soil characteristics, and three-dimensional finite element (FE) analysis of 400 totally collapsed RC buildings in the Kahramanmaras,, Ad & imath;yaman, Hatay, and Gaziantep provinces, which were among the cities affected by the Kahramanmaras, earthquakes were performed. The findings of this study contribute to a better understanding of the seismic deficiencies of buildings in earthquake-prone regions and provide information on which strategies to develop to increase the resilience of buildings with similar characteristics in other earthquake regions against future seismic events. Considering that the time from the beginning of the construction of the building until its completion consists of several stages, it can be seen that 43.58 % of the errors that cause damage and collapse of the buildings in this study are made in the construction stage, 25.57 % in the FE analysis stage, 24.77 % in the license stage, and 6.07 % in the after construction stage. Thanks to the development process of earthquake codes, regulations in building inspection practices and easier access to quality materials have greatly reduced the damage and collapse of buildings constructed in recent years.

T & uuml;rkiye has a history full of devastating earthquakes from past to present. The February 6, 2023, earthquakes in Kahramanmaras, Pazarc & imath;k and Elbistan, with magnitudes of Mw 7.7 and Mw 7.6, were among the most destructive in recent history, impacting 11 provinces and causing severe structural damage, especially in regions close to the fault line. Within the scope of this study, the 400 reinforced concrete buildings that collapsed due to the 2023 Kahramanmaras, earthquakes in the provinces of Kahramanmaras,, Ad & imath;yaman, Hatay, Gaziantep were examined in terms of seismic codes and soil conditions. The evolution of the Codes on Buildings to be Built in Disaster Areas (1975 and 1997-8), Code on Buildings to be Built in Earthquake Zones (2007) to which the relevant reinforced concrete buildings are subject, and T & uuml;rkiye Building Earthquake Code (2018) were discussed. The differences between the local soil conditions in these codes were revealed and it was evaluated how these local soil properties affect the seismic vulnerability of buildings. This study's findings highlight the critical role of the soil conditions on seismic vulnerability of buildings in earthquake-prone regions. They also offer valuable insights into developing strategies to enhance the structural resilience of similar buildings in other earthquake regions against future seismic events.