# A Case Study of the Radon Hazard at the Boundary of a Coal Minefield
## 2 Materials and Methods  
### Study Location  
The study area was located in the Kuznetsk coal basin, in the territory of the Salair-Altai-Irtysh fold. The soils within this site are characterized by leached chernozem. The variation in altitude relief is 40 m, with the average height above sea level being 240 m.  
Figure 1 illustrates the study area, pinpointing the sites of observation, as well as the areas affected by both old and new coal mining activities. Figure 1 also features the tectonic fault location and its associated disturbance zone. Kuzbass is known for its shift in the stress-strain condition of the lithosphere, which results in technogenic seismic activities [28]. This situation can lead to a remarkable variation in radon fields, particularly in areas with tectonic disturbances due to their activation. Figure 1: Study area. The study area comprises two tectonic blocks divided by the Zhurinsky Fault and its disturbance zone. These blocks comprise rocks from the Upper Permian System and are included in the Ukstat and Kazankovo-Markinsky formations. These formations are characterized by a rhythmic sequence of sandstones, siltstones, and coals with subordinate mudstones. The Paleozoic rocks have been subject to compression in the form of brachyysmal folds. Anticlinal folds are of little significance as large interblock faults are typically located along their cores, such as the Zhurinsky and Kilchigizsky Faults, among others. Anticlinal folds are folds in which the rock layers have a convex shape, and the layers dip outward from the axial part toward the periphery. The Zhurinsky Fault formed as blocks converged and can be associated with strike-slip movements, as well as thrusting in certain areas. This fault corresponds to a significant zone of rock deformation. It is characterized by a change in the displacement incidence angle. The crushing zone thickness, established during prospecting activities, spans up to 300 m [29]. There is an assumption that this disturbance was activated in the Neogene-Quaternary Periods [30]. Permanian sediments are overlain by friable deposits of Cretaceous-Paleogene weathering crust and Cenozoic N-Q sediments. The thickness of Quaternary sediments varies between 10 and 60 m and tends to be greater toward watersheds. The following is a description of the most thorough section near the research site. The Miret formation, located at the lowest section, belongs to the Miocene zone of the Neogene Period. Its composition is dense, mottled, montmorillonite-kaolinite clay, with rubble, gravel, and carbonate concretions, and with a total thickness of about 7 m. It is overlain by the Mokhov formation belonging to the Pliocene Period of the Neogene System. The thickness of this formation is about 10 m. Its composition is clay with pebbles and gravel, with red-colored fossil soils. Above, the Upper Eopleistocene-Lower Pleistocene deposits are related by genesis to the diluvial-proluvial deposits. This stratum has a thickness of approximately 17.5 m and is primarily made up of clay. Next is the Bachat formation, which belongs to the upper part of the Middle Pleistocene and the lower part of the Upper Pleistocene. The sediment composition genetically refers to the diluvial-proluvial sediments in the form of loans with a total thickness of about 10 m. The alluvial deposits of the second supra-flood terrace (the Krasnobrodskaya formation), located above, belong to the upper section of the Upper Pleistocene. The sediment composition mainly consists of loans with a total thickness of around 24 m. The upper section comprises Upper Pleistocene subaerial deposits, specifically loess-like loans [31]. We evaluated the area around two mines. One mine, designated as \"young\", began coal mining in 2018 and is currently active. The second mine in the vicinity of our study area had ceased operations. The effect of distance from these mines on radon content in soil air and its emission was considered separately, as the dynamic processes occurring above these mines may differ in intensity.