## 4 Site Response Analyses  
It is important to analyze the relationship between earthquakes and ground structure when improving soil conditions. For seismic analysis and design, factors such as fault type, site-specific soil characteristics, and shallow soil conditions must be considered. In earthquake-prone regions, the selection, budgeting, and design curves for seismic zones, as determined by national regulations (TEC, 2018), play a crucial role in structural planning. Another key parameter in site-specific analyses is the response spectrum. From an engineering perspective, acceleration spectra are widely accepted as parameters that characterize earthquake motions and are essential for structural design [34]. Research on evaluating seismic analysis performance in compliance with regulations is ongoing, with continuous efforts to improve methodologies [35; 36]. \begin{table}
\begin{tabular}{c c} \hline
**Soil Type** & **Definition** \\ \hline ZA & Sound, hard rocks V\({}_{\text{s(30)}}\) \(>\) 1500 \\ ZB & Slightly weathered, medium sound rocks 760\(<\) V\({}_{\text{s(30)}}\) \(<\) 1500 \\  & Very dense sand, gravel, and hard clay layers or dissociated, \\ ZC & very cracked \\  & weak rocks \\  & \(360<\) V\({}_{\text{s(30)}}\) \(<\) 760 \\ ZD & Medium dense—dense sand, gravel, or very solid clay layers \\  & \(180<\) V\({}_{\text{s(30)}}\) \(<\) 360 \\  & Loose sand, gravel, or soft—solid clay layers or profiles with a soft clay \\ ZE & layer (cu \(<\) 25 kPa) thicker than 3 m, providing PI \(>\) 20 and w \(>\) 40\% \\  & conditions V\({}_{\text{s(30)}}\) \(<\) 180 \\ ZF & Soils that require site-specific research and evaluation. \\ \hline \end{tabular}
\end{table} 
Table 2: Determine local soil classes according to TEC 2018. Figure 6: Turkey Earthquake Hazard Map [33]. To minimize structural damage and enhance earthquake-resistant construction, it is necessary to assess soil behavior under seismic loads and properly design superstructures. The design spectrum values specified in earthquake codes serve as a basis for determining ground motions. These values account for the natural vibration periods of structures and help establish the horizontal and vertical loads affecting them. The design spectra represent the maximum response of a site to various seismic forces, considering local seismic characteristics and soil conditions. The spectra defined in regulations are generated by classifying soil based on shear wave velocity (V\({}_{s(30)}\)), corrected SPT blow count (N\({}_{60(30)}\)), and undrained shear strength (cu\({}_{(30)}\)), without explicitly distinguishing between sand and clay behavior. Historical earthquake records indicate that soil amplification has significantly contributed to structural damage. Notable examples include the 1985 Mexico City earthquake, the 1999 Kocaeli earthquake, and the 1989 Loma Prieta earthquake [37,38]. Therefore, site-specific analyses are crucial in mitigating seismic damage. In the same way, the damping-unit deformation curve was obtained to define the damping of soils under dynamic loads. The damping ratio-shear strain curve of the BH-1 well is shown in Figure 7. This process was applied to other boreholes as well. In this study, [PERSON] et al. [28] performed site-specific 1D soil amplification analyses using the DeepSoil program. This software allows for both equivalent linear and nonlinear analyses (in both the frequency and time domains). Acceleration, stress, amplification, Fourier response spectra, and response spectra are obtained for each soil layer in the analyses based on the defined soil layers and acceleration records. The selection of the analysis method, calculation method, pore water confinement changes, and the unit method to be used are all chosen in the program interface. Then, the layer name, thickness, unit weight, and shear wave velocity values of the defined soil layers are entered. In the second step, the shear stress value of each layer, as well as the shear modulus-strain curve and damping curves of each layer, should be determined.