## 2 Characteristics of the Research Area  
The city of Wroclaw is situated in southwest Poland (Figure 1) on the Silesian Lowlands and covers an area of 293 km\({}^{2}\). The Oda River flows through the centre of the analyzed area. The Oda river valley is parallel to the main tectonic dislocations in Lower Silesia, i.e., the Sudetic Marginal Fault, the main dislocation zone of the middle Oda and the Hamburg-Krakow fault (Figure 2). In the southern part of the Wroclaw area, in the sub-Cenozoic bedrock, the main fault of the middle Oda runs in the NW-SE direction [29]. The drop of metamorphic rocks on this fault exceeds 1500 m. It is assumed that in the Neogene the amplitude of downthrow exceeded 150 m [30]. Metamorphic rocks on the Fore-Sudetic block belong to several units: Middle Oda Complex, Kamieniec Zabkowicki Unit, and Sleza Ophiolite Complex [29]. The boundaries between these metamorphic complexes are generally in the direction of NNE-SSW. In the western part of Wroclaw, the Lower Permian sandstones and siltstones are exposed in the sub-Cenozoic bedrock. Sandstones of lower and middle (unseparated) triassic age occur also in the eastern part up to the Fore-Sudetic Block. They dip towards the north at an angle of 5 degrees. Triassic rocks are strongly dislocated, creating small tectonic horts and grabens. Elevation differences of these structures exceed 50 m. In the SE part, beyond the boundaries of Wroclaw, Upper Cretaceous formations occur in a tectonic graben. In the area of Brzeg, under the Cenozoic deposits, there is a horst made of Triassic sediments. In the Neogene, the area of Wroclaw was in the axis of the Central European Subsidence Zone [31]. Inferring from the difference in the thickness of the Neogene deposits lying on the Fore-Sudetic Block and on the Fore-Sudetic Homocline, it can be concluded that vertical movements in the Middle Oda Fault Zone had an amplitude of 50 to 180 m. These movements had greater amplitude in the eastern part, and smaller in the western. Figure 1: Location of the research area. Figure 2: Sub-Quaternary topography with location of faults determined by [PERSON] [29] and modified by [PERSON] et al. [30]. In the Tertiary sediments, a pentagon-shaped graben with a 40 to 60 m thick glacial deposits is clearly marked (Figure 2). It partially coincides with the structure named by [32] the Wroclaw Through. On the basis of a small number of boreholes, [PERSON] [32] placed this structure only in its SE part. The genesis of this structure, which looks like a tectonic graben, is not unequivocally explained. Undoubtedly, the unit's SW frames are closely related to the Middle Oda Fault, whereas, its northern end is located in the zone of the presumed fault of Trzebnica [33]. The eastern boundaries of the Wroclaw basin reach the Mosina-Olesnica-Brzeg fault, which to the north of Trzebnickie Hills, is already a narrow tectonic fault. There is a subglacial gutter (Olesnica tunnel) up to 160 m deep in the zone of this fault. In the western part of Wroclaw, the boundary of the sub-quaternary basin does not coincide with known faults. It cannot be ruled out that this is because of interpretation based only on differences in height of stratigraphically different Triassic sediments with sub-quaternary morphology. Indirect hydrographic evidence confirms the possibility of increased subsidence in Wroclaw. These include the so-called Wroclaw water node, where four tributaries flow into the Oda River on a small stretch. Another indication is a strong tendency of the Oda River to create many channels indicating the anastomosing character of this river in Wroclaw, an increased subsidence rate related to the exploitation of underground waters has been demonstrated in [34]. Research carried out later showed that, after changes in industrial processes that reduced demand for water, the rate of subsidence caused by the depression cone decreased [35]. The southeastern part of Poland is an aseismic region with vertical ground surface displacements in the range of a few  millimeters per year.