The impact of site effects on ground motion is a critical factor for earthquake disaster prevention and mitigation, as these effects can amplify ground motion and affect building fragility. On February 6, 2023, southeastern Turkey was struck by two strong earthquakes, with magnitudes of Mw7.7 and Mw7.6, followed by numerous aftershocks. These events resulted in severe casualties and substantial economic losses. Field investigations revealed severe damage to mid-rise and high-rise buildings in Kahramanmara & scedil; and Antakya. Both cities are located in valley regions, which are particularly susceptible to earthquake damage due to the amplification of ground motion caused by soft soil conditions and valley topography. In this paper, Horizontal-to-Vertical Spectral Ratio (H/V) technique is used to decipher how site effects affect ground motion and damage using the strong motion records. The analysis revealed that the predominant frequency of ground motion decreases near the valley areas and increases toward the hill slopes. These spatial variations in predominant frequency have significant implications for building safety. Structures located in areas where the predominant frequency matches their natural frequency are more prone to resonance effects, significantly increasing the risk of damage during seismic events. Additionally, the study found that the nonlinearity of the site conditions amplified the acceleration response spectrum at a period of 1 s. This amplification exceeded the local structural design capacity. The findings indicate that site effects can significantly intensify earthquake damage in Kahramanmara & scedil; and Antakya by amplifying ground motion and increasing the vulnerability of mid-rise and high-rise structures.

On February 6, 2023, T & uuml;rkiye experienced two major earthquakes centered in Kahramanmara & scedil; and felt in 11 provinces. As a result, more than 50,000 people were killed and more than 100,000 buildings collapsed or were heavily damaged. This great destruction shows again the importance of cities being resilient against disasters. This study examines earthquake damage to buildings in terms of settlement suitability and building characteristics in densely built areas of Antakya and Defne, the central districts of Hatay province where the building damage rate was the highest. The study has identified two main questions regarding whether the suitability of the ground for settlement can be differentiated in terms of earthquake damage and whether building characteristics affect earthquake damage in terms of the different suitability categories. Suitability is analyzed under three categories: critically suitable, moderately suitable, and suitable. Building characteristics involve building height, ground coverage area, number of basement floors, and total construction area. The study uses geographic information systems to determine settlement suitability and superimpose this over damage. Additionally, multinomial logistic regression is used to analyze the effect of building characteristics on earthquake damage, with the results showing earthquake damage to be higher in critically and moderately suitable areas. In terms of building characteristics, building height has the greatest effect on earthquake damage, while the presence of a basement floor reduces earthquake damage, especially in critically suitable areas. An increase in the ratio of building height to ground coverage area was also found to be a factor that increases earthquake damage.