Şükrü Onur Karaca

Numerous significant earthquakes have occurred along the North Anatolian Fault Zone (NAFZ), Türkiye’s most important fault zone. An earthquake with magnitude of Mw 6.0 occurred near the Gölyaka District of Düzce Province at 04:08 local time on November 23, 2022. According to the moment tensor solutions published by national and international seismology centers, the earthquake occurred at the northeast end of the Karadere segment within the NAFZ and was caused by a right-lateral strike-slip fault in the NW-SE direction. In this study, the differential interferometric synthetic aperture radar (InSAR) method was employed to analyze the deformation. Four Sentinel-1A complex datasets were used, two of which were ascending (2022/11/15 and 2022/11/27) and two of which were descending (2022/11/14 and 2022/11/26) pre- and postearthquake, to determine the deformation that occurred after the earthquake. In addition, surface deformation movements in both the east-west and vertical directions were calculated using these two data sets. Elastic dislocation modeling was performed by applying linear and nonlinear inversion to determine slip distribution related to the fault structure, using the displacement amount obtained from DInSAR results and data obtained from the Global Centroid Moment Tensor (GCMT) catalog. Based on the findings from the DInSAR analysis, subsidence of approximately 5 cm and eastward movement of 8 cm were detected on the northern block of the Düzce segment. This right-lateral movement corresponds to an area of approximately 105 km2 northwest of the Düzce segment. On the southern block of the Düzce segment, elevation of about 3 cm and westward movement of about 3 cm were observed. Elastic dislocation modeling shows that the observed deformation model can be explained by slip on a single planar fault for the Gölyaka-Düzce earthquake. A right-lateral strike-slip fault with northwest dip was observed, extending down to a slip-centroid depth approximately 9.2 km within the upper crust region. The elastic slip modeling in this half-space resulted in a slip of 0.35 m, Mw of 6.1, strike of 264°, dip of 66°, and rake of –165°. This study reveals that the Düzce segment was the location where the earthquake occurred, but it is also believed that the Karadere segment was impacted by this seismic event. Overall, the study provides information about the occurrence of the Gölyaka-Düzce earthquake, subsequent deformation, and the elastic fault model in half-space.

The surface deformation caused by tectonic activities and anthropogenic factors poses a great threat to cities worldwide. The investigation and monitoring of these deformations are crucial in order to create risk analysis for the future. The problem in this case is to investigate the surface deformations and their negative effects caused by groundwater use and to identify possible landslide areas. In this study, the surface deformations in Hatay province were analyzed using SBAS-InSAR. The results from these analyses were evaluated by field observations. Sentinel-1 descending (183 datasets) and ascending (147 datasets) track geometries were selected to determine the surface deformation and its temporal evolution. Both east-west and vertical surface deformations were calculated, and the surface deformation profiles, surface 3D models and time series were created. These time series were associated with monthly precipitation data. The deformation area was interpreted with regard to available well-log data and geological setting of the study area. As a result of the study, a surface deformation resembling a bowl like structure was observed in the industrial zone located in the city center of Hatay-Güzelburç. The deformation rates are approximately 22.3 cm/year in the form of subsidence, 3.6 cm/year in the form of eastern movement and 10.1 cm/year in the form of western movement. The deformation of this bowl-like structure decelerated in the winter and accelerated in the summer due to excessive water use. The average monthly precipitation dataset supports these results. The stratigraphic data from water wells and the presence of limestone outside the eastern boundary of the deformation area show a thick clay layer in the eastern block of the bowl-shaped deformation structure. The difference between these two units, which causes a sharp anomaly at the eastern border of the deformation area, is interpreted as a probable normal fault. The second study area where surface deformations are observed is the landslide zone. The deformation was found to be 7.5 cm/year in a westward direction and 1.5 cm/year as subsidence.

One of Turkey's most important neotectonic structures East Anatolian Fault Zone (EAFZ), has occurred many earthquakes. One of these earthquakes, the 6.8 Mw Sivrice-Elazig earthquake dated January 24, 2020, was felt in various provinces, especially in Elazig and Malatya, and caused the death of 44 people. It is critical to investigate this earthquake, which caused significant economic damage, and to identify possible hazards on the EAFZ. One of the remote sensing methods DInSAR was used in this study. By choosing two Sentinel 1A (Single Look Complex) descending datasets, dated 16/01/2020/01 and 28/01/2020/01 respectively (pre and post earthquake), the surface deformation and time series were determined. In addition, using the data obtained from the DInSAR results, Elastic Dislocation Modelling has been performed by applying linear and nonlinear inverse solutions to determine the slip amount of the fault structure, the fault surface slip distribution, and determine the strain area. According to the DInSAR results, while there is an offset of approximately 26 cm (away from the satellite direction) on the left block of the EAF, 19 cm offset (towards the satellite direction) are observed in the right block, respectively. Elastic Dislocation Modelling shows that the observed deformation pattern can be explained by the slip on a single plane fault of the Elazig earthquake. This fault plane was identified as a southwest strike-slip fault segment, which lies within the upper crustal region and extends to a depth of approximately 10 km. According to the results obtained by elastic modelling; slip amount (slip) was calculated as 1.95 m, Mw 6.75, rupture length 34.78 km, focal depth 10 km, width 7.4 km, strike 240.27°, slope 69.19°, rake 0.19°. Overall, the study reveals the strike-slip of the Sivrice-Elazığ earthquake, shows the deformation after the earthquake, and the elastic half-space fault model.

The Suleiman Fold-Thrust Belt represents an active deformational front at the western margin of the Indian plate and has been a locus of major earthquakes. This study focuses on the western part of the Suleiman Fold-Thrust Belt that comprises two parallel NW–SE oriented faults: Harnai Fault and Karahi Fault. These faults have known thrust components; however, there remains uncertainty about the lateral component of motion. This work presents the new observation of surface deformation using the Small Baseline Subset (SBAS), Interferometric Synthetic Aperture Radar (InSAR) technique on Sentinel-1A datasets to decompose displacement into the vertical and horizontal components employing ascending and descending track geometries. The subsurface structural geometry of this area was assessed using 2D seismic and well data. In addition, geomorphic indices were calculated to assess the relative tectonic activity of the area. InSAR results show that the Karahi Fault has a ~15 mm right-lateral movement for descending and ~10 mm/for ascending path geometries. The Harnai Fault does not show any lateral movement. Seismic data are in agreement with the InSAR results suggesting that the Harnai Fault is a blind thrust. This work indicates that the block between these two faults displays a clockwise rotation that creates the “bookshelf model”.