Integration of MASW and ERT methods for site characterisation: a case study from Czernichów (Southern Poland)

Abstract

The paper presents an integrated use of multichannel analysis of surface waves (MASW) and electrical resistivity tomography (ERT) to characterise the physical properties of near-surface materials, identify subsurface structures, and estimate the depth to bedrock in a planned construction area near Czernichów, close to Krakow (southern Poland). The study shows that integrating MASW and ERT provides a cost-effective and complementary approach to subsurface characterisation, delivering more reliable and less ambiguous interpretations than when the methods are applied independently, thereby reducing the need for expensive and invasive in situ geotechnical investigations. Particular emphasis is also placed on the methodological aspects of both methods. The study site is located on an alluvial plain composed of alluvial soils, sands, sand–gravel mixtures, and silty clays overlying limestone bedrock. Geophysical data were collected along five profiles. The resulting shear wave velocity models and the inverse model resistivity sections show good agreement with borehole data. The study area is characterised by a wide range of physical parameters derived from both methods. The MASW survey enabled recognition of the subsurface down to the bedrock, revealing four seismic layers differing in S-wave velocity. Nevertheless, the MASW inversion did not provide reliable estimates of the limestone S-wave velocity, although it successfully delineated its depth and morphology. The ERT survey identified three geoelectrical layers and proved to be more effective in resolving shallow geological structure, particularly in identifying the boundaries between alluvial soils and sand–gravel mixtures, whereas the depth and morphology of the limestone bedrock were constrained primarily by MASW.