## 2 Materials and Methods  
### Study Area and Its Geological Background  
The study area is situated in Konya, in central Anatolia. The high-speed rail line spans 218 km and is designed for a maximum operating speed of 300 km/h or 190 mph, commencing its service on 23 August 2011 [32]. The study area with the datasets consisting of radar images is approximately 800 km\({}^{2}\), and the length of the line passing through this area is 30 km. A section of the high-speed railway line connecting Ankara and Konya is shown in Figure 1.  
As seen from Figure 1 and the map in Appendix A, most of this railway line passes through rural/agricultural areas. One of the most important problems in the region is the continuously increasing number of sinkholes. Karstification has caused sinkhole evolution to be recognized as a dynamic and natural process in Konya [33]. Additionally, groundwater has been decreasing as a result of artesian wells drilled inside the city. As an outcome, the area exhibits a linear deformation [34] and a fine-grained sediment soil structure, particularly in regions with dense agricultural land near the Konya plain. This phenomenon results in sinkholes and land subsidence because the sediments settle in response to groundwater withdrawal that occurs quickly [35]. Sinkhole is a detailed research subject, and since it is not the main research subject of briefly described here in order to get to know the region in more detail but will not go into more depth. Through the analysis of measurements from the diagnostic train and reports obtained from the maintenance department, three distinct areas were identified along a 30 km extension of the track. The first area, referred to as the unstable area, exhibited instability. The second region, known as the stable area, showed no signs of instability. The third location, a station area, could not be evaluated due to the absence of data from the diagnostic train, but it was analyzed using the InSAR technique. The first section spans approximately 6 km and is situated between the rural regions of Asagipinarbasi and Yukaripinarbasi. The second test area is situated in the Selcuklu district of Konya, and it encompasses a 3.5 km length of the railway line that runs through the inner city. This part is primarily characterized by residential and industrial areas. Finally, the third analyzed segment pertains to the central train station in Konya City Centre (Appendix A). An analysis of the geological conditions in the region was conducted in order to provide a comprehensive understanding of the subsidence situation. Geological maps show that the railway line passes through alluvial sediments, made up of mainly clay and silt, interbedded with sandstone and gravel in the Konya Basin (Figure 2a,b). Such clay and silt units are characterized by high compressibility, playing as a predisposing factor in the processes of subsidence induced by groundwater extraction. Figure 2a represents the geological structure of the first study area as 'Qa', and Figure 2b represents the geological structure of the second study area as 'Qa' and 'Qae'. In the Turkish State of Railways report, the geological structure of the third study area, which is the range of Km: 181 + 190-212 + 555, is mostly covered by old alluvium 'Qae'. Since the location of the relevant region corresponds to approximately km: 210+000, the definition of this km interval also includes the third study area. Moreover, old alluvium 'Qae' is generally composed of gravelly sand, clay and silt. The report also states that setting the railway on a weak substructure represented by the clayey levels in the alluvium should be considered as a potential subsidence problem. These clay units are characterized by their great compressibility, which makes them important factors in the consolidation and subsidence processes caused by groundwater extraction [36]. Figure 1: Photograph depicting a section of the Ankara–Konya High-Speed Railways provided by the Gokhan Kizilirmak.