Ground penetrating radar and structural geological mapping investigation of karst and tectonic features in flyschoid rocks as geological hazard for exploitation

• Karst features and sliding surfaces pose a hazard for exploitation in open pit mines.
• They were successfully investigated with a low-frequency (50 MHz) GPR method.
• Correlation with geological mapping gave insight into the structural setting.
• Cavities in flyschoid rocks develop at open joints and fractures.
• A detailed GPR survey could diminish the possibility of work accidents.

We evaluated the use of ground penetrating radar (GPR) in detecting karst cavities and discontinuities that could form potential landslide surfaces in flyschoid rocks of the Rodež open pit mine in Anhovo (W Slovenia). We recorded 21 GPR profiles in three consecutive benches with the unshielded 50 MHz rough terrain antenna (RTA) system, and correlated them with the results of detailed structural and lithological mapping of the area. We located several karst cavities and confirmed the presence of discontinuities with the interpretation of GPR profiles alone. However, their correlation with geological and structural data gave a more precise insight into the structural setting of the studied area. The different discontinuity families specified in the Rodež open pit mine are mainly the result of the strike-slip tectonics and gradual anisotropic lithology. The complexity of the intersections of structural discontinuities and the mechanical properties of rocks contribute to the formation of sliding surfaces and the developing of karst features. Cavities and phreatic channels develop in the vadose zone in calcarenites and result from complex structural deformation and karstification factors at the open joints or larger structural fractures.