## 4 Results
Figure 6: Land subsidence evolution of an area located east of the Karapinar, as observed by COSMO SkyMed Interferograms. (**a**) Orthophoto image showing the location of the subsiding area. (**b**) Zoom-in image of the subsiding area with sinkhole locations. (**c**,**d**) Three-month interferogram showing no subsidence. (**e**) Four-month interferogram showing the beginning of the subsidence. (**f**) Six-month interferogram showing 1–2 fringes of subsidence. (**g**) Seven-month interferogram showing 2–3 subsidence fringes. (**h**) Nine-month interferogram showing 3–4 subsidence fringes, mostly in the east part of the subsiding area. of subsidence, one in the southern part of the area and the second in the northern part (Figure 5a). The maximum subsidence in this 6 month period is \(\sim\)40 mm (2 fringes); each X-band LOS fringe translates to \(\sim\)20 mm in vertical using Equation (1) with an incidence angle of 37.30\({}^{\circ}\) and LOS displacements of 15.5 mm, with an X-band of one fringe cycle. The deformation evolution indicates increased subsidence mostly in the southern section of the study area, in which maximum subsidence reached 40-50 mm (2-3 fringes; Figure 5b) after 7 months and 60-70 mm (3-4 fringes; Figure 5c) after 9 months. This example indicates that subsidence varies both spatially and temporally. The subsidence pattern shows an overall increase in accumulated subsidence mainly in the southern part of the study area. The subsidence evolution also indicates an increased number of localized subsidence (closed fringes) from two locations after 6 months (Figure 5a) to four and possibly five locations after 9 months (Figure 5c). The subsidence rate also varies with time. The first two fringes (\(\sim\)40 mm) were developed during a 6 month period (February to August, 2016; Figure 5a), whereas the additional two fringes, from two to four fringes in Figure 5c, occurred within a 3 month period (August to November, 2016). The subsidence evolution in the bare area located in the southern part of the Karapinar-Konya highway was studied using six interferograms spanning over a period of 3-9 months. As in the previous example, all interferograms share the same starting acquisition of 20160216. Initial subsidence of \(\
icefrac{{1}}{{2}}\) fringe (\(\sim\)10 mm) can be detected after 3 months in the eastern side of the area (Figure 6d). The subsidence evolved in both eastern and western parts of the study area. The subsidence rate also varied with time. The subsidence during the first three months (February to May, 2016; Figure 6c,d) reached only \(\
icefrac{{1}}{{2}}\) a fringe. However, the accumulated subsidence increased from \(\
icefrac{{1}}{{2}}\) a fringe to 2 fringes (Figure 6f) within the next 3 months (June to August, 2016), and to 4 fringes (Figure 6h) after additional 6 months (June to November, 2016). This observed rate change suggests a seasonal subsidence pattern of limited subsidence in the spring (February to May) and fast subsidence in the summer and fall (June to November). High temporal resolution observations were obtained from the KAPN GNSS station and groundwater level measurements acquired in well number 52258. The GNSS station is located in the western outskirts of Karapinar, and the well is located 3 km west of the GNSS station in an open agricultural area (Figures 1 and 4). The GNSS observations were compared with InSAR time series derived from the Sentinel-1 and COSMOS-SkyMed, which were projected from LOS to vertical. Time series of the vertical GNSS daily solutions for the same observation period of the Sentinel-1 data (May 2014-May 2018) revealed an accumulated subsidence of 100 mm, suggesting an average subsidence rate of 25 mm/yr. However, the time series also shows a seasonal subsidence pattern, in which the seasonal component varies from one year to another (Figure 7). The highest seasonal subsidence occurred in 2016-2017, whereas the lowest seasonal changes occurred at the beginning of the observation period, in 2014-2016.