Using surface geophysical methods to detect voids in the near-surface zone

This study investigates the properties of rock formations using seismic down/up-hole measurements and electrical resistivity methods to identify structural anomalies such as voids. Surveys were conducted in four test wells in southern Poland and the analysis emphasizes the practical applications of mentioned geophysical techniques in subsurface imaging. The seismic method measured wave propagation, while electrical resistivity assessed rock resistance variability, aiding subsurface zoning. The methodology involved designing resistivity maps as depth cuts, based on seismic results. Presented velocity profiles identified weak zones, and was establishing critical geomechanical boundaries in depth, which was a basis for further resistivity geometry projecting. Resistivity measurements were conducted radially around wells, highlighting resistivity anomalies that signify risks related to subsurface void migration and changes in geomechanical properties. The analysis confirmed a general trend of increasing seismic velocity with depth, with significant deviations suggesting differences in rock quality. The resistivity method at the selected depth-cuts, mapped zones with high resistance, which was a direct indicator of the presence of changes in the rock mass. These findings are crucial for planning safe earthworks, soil stabilization, and environmental monitoring, particularly in subsidence-prone areas. Future research may enhance anomaly detection and monitor changes in rock mass properties over time. Combining seismic velocity profiling and resistivity measurements proves effective in identifying subsurface structures, which is vital for risk mitigation in engineering and environmental projects.

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Opracowanie rekordu ze środków MNiSW, umowa nr SONP/SP/546092/2022 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2024)