TOMÁŠ PÁNEK, JAN HRADECKÝ, KAREL ŠILHÁN APPLICATION OF ELECTRICAL RESISTIVITY TOMOGRAPHY (ERT) IN THE STUDY OF VARIOUS TYPES OF SLOPE DEFORMATIONS IN ANISOTROPIC BEDROCK: CASE STUDIES FROM THE FLYSCH CARPATHIANS

Electrical Resistivity Tomography (ERT) has become one of the most applied and user-favourable geophysical technique in geomorphological research. Multiple character of the technology using various electrode arrays significantly reduces measurement time and is suitable for applications even in hardly accessible mountain areas. ERT can be used for various problems concerning slope deformations and accompanying landform assemblages. Our study shows that the best results are obtained in sites with high resistivity contrasts in subsurface environment associated with e.g. changes of lithology or ground water conditions. Good results, which significantly extrapolate geomorphic and speleological investigations, were obtained in elevated gravitationally spread ridges with the presence of crevice-type caves. Resistivity soundings in such settings bring a new insight into the internal structure of deeply disrupted mountain ridges. Very promising seems to be also delimitation of bodies of active, water-saturated landslides or lacustrine deposits behind landslide dams. On the other hand, some problems with the interpretation of ERT record are associated with the study of internal structure and depth of old inactive landslides situated in relatively homogenous flysch layers. Although ERT sounding results must be interpreted critically, they always shed some light on the internal characteristics of slope deformations and in combination with other methods they create a reliable base for the analysis of so far unrecognized features of slope deformations.