# A New Ground-Motion Prediction Model for Shallow Crustal Earthquakes in Turkiye
## 2 Database and Selection Criteria
The source-to-site metrics are limited to a maximum of 350 km according to the \(R_{JB}\) criterion. The histogram distribution of selected strong-motion records according to distance (\(R_{JB}\)) intervals is shown in Figure 5.  
The data used to develop our GMPEs consist of 20,173 records from 1565 shallow crustal earthquakes and 957 stations. The dependent variables include the horizontal component PGA, and PGV and PSA values with 5% damping for 36 different periods ranging from 0.01 to 10.0 s, converted to RotD50 [31]. The \(M_{W}\)-\(R_{JB}\) distribution of the data used in study, categorized by fault types, is shown in Figure 6. The 17 station data points located at a distance of zero (\(R_{JB}\) 0.0 km) on the surface rupture of the Kahramanmaras earthquake (\(M_{W}\) 7.8) have been shown with negligible values assigned between 0.11 and 0.27 km (with a 0.01 increment) to make them visible on the logarithmic plot without overlapping. As seen in the data, the magnitude range is broadest for \(SS\) and \(NS\) events and narrowest for \(RS\) earthquakes. Figure 4: Histogram of the number of records used to develop GMPEs, categorized by fault types. Figure 3: The cumulative number of records used in this study between 1976 and 2023. The governing variable for the site term is \(V_{S30}\), which is the average shear-wave velocity of a site in the uppermost 30 m. This parameter was also adopted for soil category assignment in the Turkish Building Earthquake Code (TBEC-2018) [32], National Earthquake Hazards Reduction Program (NEHRP; Building Seismic Safety Council [BSSC],  
Figure 5: Histogram of the number of records by distance (\(R_{\rm JB}\)) intervals. Figure 1.0 Magnitude (\(M_{\rm W}\))-distance (\(R_{\rm JB}\)) distribution of observed records used to develop the GMPMs, categorized by focal mechanism (\(SS\), \(NS\), and \(RS\) are strike-slip, normal-slip, and reverse-slip events, respectively). 2009) [33], and European Seismic Code [34]. The site term in GMPMs expresses the effect of shallow site conditions on ground-motion intensity measurements (GMIMs) as a function of \(V_{S30}\). The data used in the study were obtained from accelerometer stations with \(V_{S30}\) values ranging from 131 to 1862 m/s. The soil classification of about 905 stations belonging to AFAD was determined through in situ geophysical measurements. Active MASW (multi-channel analysis of surface waves) and passive REMI field test techniques were used in the measurements undertaken for various projects [35; 36]. Additionally, field characterization studies were carried out with active seismic measurements performed by AFAD's own engineering team using seismic equipment at the station sites, and soil information for the stations was obtained. According to the \(V_{S30}\) information of the TR-NSMN stations, the strong-motion data are classified based on the site categories defined in NEHRP-2009 and TBEC-2018 as follows: Class A: \(V_{S30}\)\(\geq\) 1500 m/s, Class B: \(V_{S30}\) = 760-1500 m/s, Class C: \(V_{S30}\) = 360-760 m/s, Class D: \(V_{S30}\) = 180-360 m/s, and Class E: \(V_{S30}\) < 180 m/s. However, for approximately 52 stations without direct \(V_{S30}\) data based on geophysical measurements, site classifications were determined using the accepted methods reported in the literature (dominant period, spectral shapes, slope, field observations, etc.). The histogram of the strong-motion data used in the study categorized by site classes is shown in Figure 1.1 Most of the data correspond to soil and soft rock sites (NEHRP and TBEC categories C and D). Figure 8 shows GMIMs with a distance (\(R_{\rm{JB}}\)) of PGA, PGV, and 5% damped response spectra (PSA) for four periods (\(T\) = 0.2, 1.0, 3.0, 6.0 s) and color-coded magnitude ranges (\(4.0\leq M_{\rm{W}}<5.0\), \(5.0\leq M_{\rm{W}}<6.0\), \(6.0\leq M_{\rm{W}}<7.0\), and \(7.0\leq M_{\rm{W}}<8.0\)). These plots show the decrease in motion (ordinate values) with distance, as well as the dependence of the distance decay on magnitude.