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.

The February 6, 2023 Kahramanmaras,-T & uuml;rkiye ,-T & uuml;rkiye earthquakes with moment magnitudes 7.7 and 7.6 resulted in substantial casualties, injuries and extensive infrastructure devastation. Soil liquefaction was identified as one of the contributing factors to the damages. In this study, a data-driven approach to assess liquefaction-prone areas within an artificial neural network (MultiLayer Perceptron- MLP) was proposed. The study area, selected to cover a region with the size of 11,500 km2 2 containing Amik and Kahramanmaras, , Plains, is governed mainly by active tectonism of the East Anatolian Fault Zone. The earthquakes were considered to be responsible for numerous liquefaction occurrences in both plains. Here, a comprehensive inventory of liquefied regions was compiled from aerial photogrammetric images taken in the days following the earthquakes. Considering the availability of suitable geospatial datasets, the key factors for liquefaction modeling were selected as distance to streams, land use and land cover, slope, and topographic wetness index, and normalized difference water index (NDWI) and normalized difference vegetation index (NDVI) derived from satellite images taken a few days before the earthquakes. The Holocene unit was used as a mask to perform modeling and prediction within this litho- logical type. The F1-score and overall accuracy values obtained from the MLP on a test dataset were 80% and 82%, respectively. The study showed that geospatial databases including airborne and satellite image products have great potential for assessing liquefaction hazard at regional scale, which can be used as base data for planning and conducting further field and laboratory studies to improve the accuracy in predictions.

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.

On February 6, 2023, two significant earthquakes with magnitudes (Mw) of 7.7 and 7.6 struck Turkey, occurring nine hours apart. In addition to the tragic loss of over 50,000 lives in the earthquakes centered in Kahramanmaras,, hundreds of thousands of engineering structures, such as residences, schools, hospitals, historical landmarks, highways, and more, were severely damaged. This study assesses the damages and risk scenario following the Kahramanmaras, earthquakes concerning Siverek Castle. In addition, remediation and strengthening proposals, required to eliminate the damage and the possible risk, have been developed. The initial stage involved observational damage assessments on the castle and surrounding slopes as part of field studies, identifying five different types of damage and potential risks. Subsequently, a precise 3D digital model of the damaged castle and its slopes was generated using the digital photogrammetry method. Additionally, geological and geophysical studies were conducted in the field to determine the characteristics of the mound structure, historical castle walls, soil and rock on the slope. Non-destructive, geophysical methods consisting Vertical Electrical Sounding (VES), Seismic Refraction Method (SRM) and Multichannel Analysis of Surface Waves (MASW) measurements were specifically employed in the area with historical remnants. To verify the obtained data, five boreholes were drilled in the lower parts of the slope, and experimental studies were conducted to determine the soil and rock material properties of the slope. In the numerical studies, a total of 54 2D stability analyses were performed under static, long-term static, and dynamic conditions. Additionally, 1000 different probabilistic rockfall analyses were conducted, both in 2D and 3D, to calculate the run-out distance, bounce height, velocity, and kinetic energies of the blocks that fell or were about to fall during the earthquake. In the final stage of the study, remediation and strengthening recommendations were prepared for the strengthening of the fortification walls and slopes where failures occurred, and stability analyses were conducted. Consequently, a design proposal recommending five distinct approaches to remediate and strengthen the castle and slopes impacted by the Kahramanmaras, earthquakes was endorsed by the relevant authorities, and construction has commenced. When the remediation and strengthening works are completed, the security of the cultural heritage will be ensured, and it is planned to be opened to visitors.