This study analyzes the Pazarcik and Elbistan earthquakes, which occurred on February 6, 2023 and are among the most destructive seismic events of the 21st century. Since the greatest damage was seen in Hatay in these earthquakes centered in Kahramanmaras, the study aims to contribute to the field of earthquake engineering by evaluating the seismic data obtained from these regions. In the first part of the analysis, peak ground accelerations (PGA) recorded at the stations in Kahramanmaras and Hatay were examined and these data were compared with the DD1 (maximum considered earthquake) and DD2 (design basis earthquake) design levels of the Turkish Building Earthquake Code (TBEC 2018). In addition, the effects of ground properties and proximity of faults on seismic records obtained from various stations were evaluated by examining the PGA distribution spatially. The impacts of factors such as the near-fault effect, directivity effect, ground amplification effect and impulse-like motions were determined by examining the peak ground accelations, peak ground velocities, peak ground displacements and spectral accelerations. The study uses NGA-West2 Ground Motion Prediction Equations (GMPEs) to evaluate peak ground accelerations in stiff soil and to consider impulse and directivity effects. In addition, the applicability of USGS Vs30 maps in Turkiye is evaluated by comparing with AFAD data. These comprehensive analysis provide critical insights from a structural safety perspective on how seismic characteristics change with ground properties and proximity to earthquake sources.

The severe damage observed in the Kathmandu Basin, Nepal, during past earthquakes necessitates a thorough study of the seismic behavior of the basin sediments. As the shear-wave velocity is directly related to the elastic shear modulus of the material, it is essential to determine it to incorporate the behavior of the soil in the design of the structure. Hence, we determined average shear-wave velocity in upper 30 m (Vs30) of soil in Bhaktapur district in the eastern part of the Kathmandu Basin at 73 observation points, employing two methods involving the use of non-invasive microtremor array measurements (MAMs). These MAMs are widely used for determining subsurface soil characteristics by analyzing the ambient vibrations of the ground. The first method involves inversion using a genetic algorithm, and the second is a method for obtaining Vs30 directly from the dispersion curve. We found that Vs30 in the southeastern part of the study area was higher than that in other parts. Conversely, Vs30 in the western region was lower. The calculated Vs30 values were used to classify the sites. The elevated eastern and southeastern areas with high Vs30 were categorized as dense soil or soft rock, whereas the areas with low Vs30 that had suffered significant damage during the 2015 Gorkha earthquake were classified as soft soil sites.

The shallow seismic methods, including seismic refraction and 1D MASW, were used to investigate the shallow soil in the vicinity of five damaged building blocks in the village of El-Kalaheen. These building blocks exhibited structural problems including cracks, fissures and displacements between neighboring buildings. The results of both methods show that the shallow subsurface consists of two layers: a surface layer of loose sands, gravels, silts and clays and a compacted sandy clay layer that forms the bedrock in the area. The resulting seismic velocities were used to calculate the geotechnical parameters of the two layers, including Poisson's ratio, shear modulus, Young's modulus, material index and N-value. In addition, the shear wave velocities resulting from the 1D MASW method were used to calculate the average Vs30 in the site. The calculated values of the geotechnical parameters show a gradual increase in the competence of the upper layer from fairly competent and loose in the south of the area to competent and denser in the north. The geotechnical parameters of the bedrock also show an increase from moderately competent in the south to denser and more competent in the north. Possible zones of weakness are also observed in the southern part of the site. The calculated Vs30 indicates a site with stiff soil classification.

Local soil effect plays an essential role in estimating of earthquake damage that occurs on the existing structures and in the planning and design of the new structures. One of the most critical steps in determining the earthquake design characteristics of a region is related with determining the behavior of the layers that form the soil in that region under cyclic stresses that develop because of earthquakes. Kutahya Dumlupinar University central campus needs constant new construction as the student potential increases each year in addition to the existing building stock. For this reason, data have been collected by using microtremor at 36 points and Multichannel Analysis of Surface Waves (MASW) at 4 points to determine the mechanical and physical characteristics of soil. Data being collected by the single station microtremor method were evaluated by means of horizontal-vertical spectral ratio technique, and the dominant vibration frequency values were evaluated, and the shear wave velocities (Vs30) up to a depth of 30 m were obtained by evaluating the data collected with MASW method. By establishing the relationship of the parameters obtained from both methods with the geological units, the results about the soil characteristics of the study zone were revealed. In accordance, the middle and northwest parts of the study area were composed of rock units when compared to the southeast part, and this boundary was controlled by an antithetic fault.