## 2 Materials and Methods  
The study area, Duzce Basin, is an intermountain basin located in the Western Black Sea Region. Duzce Province is located between 40\({}^{\circ}\)37\({}^{\prime}\) and 41\({}^{\circ}\)07\({}^{\prime}\) north latitudes and 30\({}^{\circ}\)49\({}^{\prime}\) and 31\({}^{\circ}\)50\({}^{\prime}\) east longitudes, as seen in Figure 1, and covers an area of approximately 2593 km\({}^{2}\). The southern border of the basin is determined by the Duzce Fault, with Efteni Lake in the west and Bolu Mountain in the east. While the northern part of the study area is characterized by a sloping terrain structure, the plain has a generally flat topography. Geological studies including drilling studies, geophysical data and field observations show that the plain is mainly composed of Pliocene-Quaternary alluvial fan deposits (Qal). The oldest geological unit in the region is the Precambrian Meta granitoids (PEy) located in the southwest of the Duzce plain [51]. The Duzce Fault forms the boundary between these old units and the Quaternary sediments consisting of clastic materials such as gravel, sand, silt, and clay [49; 52]. The thickness of these sediments, which mostly accumulate in alluvial and lacustrine environments, was determined by drilling and geophysical data [53; 54]. The sedimentary sequence varies between clay, silt, sand, and gravel, reflecting the presence of ancient river beds or lake beds. The northern and north-western parts of the study area, where the slopes are steeper, belong to the Caycuma Formation (Tec), which consists of limestone, agglomerate, tuffite, marl-level sandstone, siltstone, and claystone alternations [55]. The alluvial structure of the plain, shallow groundwater levels (ranging between 0.10-2.6 m), and associated geotechnical challenges such as liquefaction, subsidence, and  
Figure 1: Geology of the Dúzce–Bolu Region, Active Faults and Destructive Earthquakes [50]. limited bearing capacity highlight significant constraints for construction. The Duzce and Bolu regions are seismically highly active because they are located within the North Anatolian Fault Zone (NAFZ), a major strike-slip fault system separating the Eurasian and Anatolian plates [56]. Extending approximately 1200 km, the NAFZ is one of the most critical tectonic structures in Turkiye [57; 58]. Numerous historical and instrumental earthquakes have occurred 100 km east and west of Duzce city centre [59]. The closest faults to the Duzce basin are the Duzce Fault, the Hendek Fault, and the Cilimli Fault, and the Duzce and Hendek faults are classified as active, while the Cilimli Fault is considered potentially active [60]. For this study, data obtained from 27 boreholes opened in the Danca and Azmimilli neighbourhoods of the Duzce city centre were analysed. A map of Turkiye is presented in Figure 2, showing the location of Duzce province and the locations of Danca and Azmimilli neighbourhoods where the drillings were opened. The drillings are located in two separate neighbourhoods, in different locations. The neighbourhoods where the drillings were opened and the approximate drilling areas are shown in Figure 2. However, for more detailed information, the link is provided \"[[https://www.harita.gen.tr/81-duzce-haritasi/](https://www.harita.gen.tr/81-duzce-haritasi/)]([https://www.harita.gen.tr/81-duzce-haritasi/](https://www.harita.gen.tr/81-duzce-haritasi/)) (accessed on 23 April 2025)\" [61]. In this study, soil samples obtained from 27 boreholes opened in Danca and Azmimilli neighbourhoods in Duzce city centre were analysed. The stratigraphy generally shows light  
Figure 2: Location of the work area. sandy silty clay, silty clayy sand, silty coarse sandy clay, gravel and coarse sand-gravel sequences from top to bottom. A cross-sectional representation of the study area is given in Figure 3.  
In cohesive soils, the settlement is largely time-dependent. Since the permeability of fine-grained soils is very low, water is released from the loaded soil very slowly and a time-dependent settlement occurs.