Investigation of soil behaviors under the effect of earthquake: Diyarbakir and its surroundings

Earthquakes constitute the primary factor in the assessment of site response. The soil exhibits dynamic behavior depending on the level of ground acceleration induced by seismic events. The recording of these acceleration values during earthquakes is performed by strong-motion accelerograph stations. In this thesis study, the site response characteristics of the existing strong-motion stations located in the province of Diyarbakır were investigated. Microtremor measurements were conducted at the eight operational stations, and the shear-wave velocity profiles, Vs30 values, soil classifications, amplification factors, and predominant site period/frequency values were determined. Based on these data, bedrock depth and the vulnerability index were estimated through empirical approaches. Furthermore, ten earthquake records with magnitudes of Mw ≥ 4.0 obtained at each station were analyzed to determine site amplification and predominant site frequency. By comparing the strong-motion recordings with the microtremor-based estimates, possible variations in ground-motion characteristics during wave propagation to the stations were evaluated. Additionally, the Sivrice, Pazarcık, and Elbistan earthquakes—which significantly influenced the seismicity of Diyarbakır—were examined to characterize seismic impacts within the study area. Finally, structural analyses were performed using the PGA values prescribed by the two most recent seismic codes, together with those recorded at the stations, enabling a comparative assessment of the influence of ground acceleration on structural performance. The findings of the study indicate that the destructive effects of earthquakes observed in Diyarbakır were not attributable to the soil conditions at the strong-motion stations. It was concluded that, had the existing seismic code provisions been adequately implemented, the level of structural damage would not have been as extensive.