The application of the 2D/3D electrical resistivity tomography (ERT) method in investigating the carbonate karst of the Zakrzówek Horst

Abstract

A characteristic features of the geological structure of the Krakow area are tectonic horsts and grabens. The Zakrzówek Horst is one of the seven horst structures within the Krakow area, located in the south-western part of the area. It is built of Upper Jurassic limestones, where numerous karst caves have been developed. The caves of the Zakrzówek Horst probably form a system of interconnected caves. This hypothesis has been tested in the western region of the Zakrzówek Horst using the electrical resistivity tomography (ERT) method. The investigations were conducted in the parallel profile configuration as well as with the data processing procedure based on the 2D and 3D inversion. The results of these studies are an attempt to locate additional voids as well as fractured zones in the carbonate rock mass. The studies confirmed the hypothesis that the Jasna Cave is probably only a fragment of a vast cave system developed within the Zakrzówek Horst. As a result of the research carried out with the ERT method, the most prospective directions for future speleological research have been determined.

Evaluation of rock mass units using a non-invasive geophysical approach

“…ERT is a commonly used geophysical practice that can investigate the heterogeneous subsurface with high-resolution lateral and vertical imaging of resistivity 1 , 17 , 18 , 27 , 28 , 32 , 39 . Electrical resistivity measured in ERT surveys is controlled by different factors, including subsurface rock/lithology type, mineralogy, weathering degree, clay, fractures and faults, porosity, rock association, temperature, water content, pores electrical connectivity, salinity, permeability and rock alteration 15 , 32 .…”

“…Many geophysical methods, namely electrical resistivity tomography (ERT), ground penetrating radar (GPR), induced polarization (IP), controlled source audio frequency magnetotelluric (CSAMT), seismic refraction tomography (SRT), self-potential (SP), magnetic and gravity are widely carried out in geotechnical, environmental and groundwater studies 1 , 6 , 15 , 17 , 18 , 23 – 37 . Compared to the borehole approaches, geophysical methods offer volumetric measurements of the subsurface 28 , 38 . Furthermore, such methods are non-destructive, non-invasive, relatively faster, economical and comparatively user-friendly 25 , 39 .…”

“…Marescot et al 61 solved the uncertainty in water-clay evaluation for slope instability investigation by combining ERT with IP in the Swiss Alps. ERT is progressively being used in geotechnical engineering to achieve 2D/3D detailed mapping of the subsurface 1 , 15 , 18 , 27 , 28 , 32 . However, ERT can only assess the subsurface at shallow depths 32 , 62 .…”