Geoelectric Investigations

The vertical electrical sounding (or VES) method is used to investigate how resistivity varies with depth. This technique involves taking a series of resistivity measurements at progressively longer distances between current electrodes (A-B) and potential electrodes (M-N), within various types of quadripolar arrangements. A mathematical model is then used to obtain true resistivity value and the actual thickness of layers of different resistivity.

Fields of application:
Geological modelling
Verification of presence or search for groundwater
Searching for water
Searching for hidden or buried cavities
Stratigraphic research

Multielectrode prospecting involves taking a number of apparent resistivity readings using quadripoles arranges along profiles, fitted with a certain number of electrodes (in general at least 48), usually equidistant along the investigation line, which can be controlled from a programmable georesistivity meter, so that operation can either take place when current is emitted (A, B) or when measuring potential (M, N).
Acquired data are processed using mathematical algorithms, to define two-dimensional electroresistive sections, in which resistivity variations can be highlighted, both vertically (as in VES) or along the investigation profile.
The use of special and complex electrode configurations installed in areas and powerful software, means that 3D resistivity models of the subsoil can be obtained.

Fields of application:
Study of landslides
Geological modelling
Verification of the presence of structural discontinuities (faults, sliding surfaces, etc.)
Verification of presence or search for groundwater
Study of pollution phenomena in the ground or beds
Searching for water
Definition of contaminated volumes
Searching for hidden or buried cavities
Stratigraphic research
Identification of underground utility leaks

Induced polarisation is a type of multielectrode prospecting that is often associated with ERT investigations, as it enables the measurement of the capacitative component of terrain (known as Induced Polarisation), following the emission of electric current into it. The physical parameter measured in the time domain is represented by apparent loadability, namely power loss along a discharge transient.

Fields of application:
Geological modelling
Study of landslides
Verification of presence or search for groundwater
Study of pollution phenomena in the ground or beds
Searching for water
Definition of contaminated volumes
Stratigraphic research

The Self-Potential method is a passive geoelectric type of investigation which involves the measurement of electric power variations in the subsoil, caused by an electrical field generated by natural sources (hydraulic, thermal and chemical), using a couple of non-polarizable electrodes. Spontaneous Potential components are mostly Electrokinetic Potential, generated by the flow of the aquifer, and Electrochemical Potential, generated by the difference of solute concentrates following redox reaction between water and rocks it comes into contact with.