Multimethod geophysical investigation in karst areas: case studies from Silesia, Poland

Carbonate rocks are particularly susceptible to karstification, resulting in the formation of structures, such as enlarged fissures, caverns, and sinkholes. These structures pose direct risk to construction and human safety, especially in urbanised areas. In this study, we demonstrate the application of multimethod geophysical reconnaissance, combining electrical resistivity tomography (ERT), induced polarisation (ERT-IP), seismic refraction tomography (SRT), and multichannel analysis of surface waves (MASW), to identify the subsurface karst structures at two sites in the Silesian District, Poland. This methodology allowed the identification of the geological structure to a depth of up to 40 m, which exceeds the requirements for geotechnical reconnaissance. At site 1, Niedzieliska, a 30-m-wide and 20-m-deep structure, filled with younger sediments, was interpreted as a karst sinkhole. At site 2, Tucznawa, a 180-m-wide fault zone overlain with suffusion-susceptible sediments was identified. The multimethod geophysical approach presented here can be applied to locate and interpret subsurface karst forms in similar karst terrains worldwide.