Along measurement profiles electrodes (metal sticks) are plunged into the ground. Control electronics manage in selected patterns two electrodes for electrical current input and two other to measure the potential field. geoFact has available modern multi electrode equipment with up to 255 electrodes.
For the measurement a direct current (DC) is injected into the subsurface by two grounded current electrodes. A spatial potential field with equipotential lines perpendicular to the current flow is generated in the subsoil. At geological boundaries and areas with conductivity disparities a refraction of the flow-lines appears. The surveying of the potential fields allows a deduction of a resistivity distribution in the subsurface. The resistivity depends on the material properties (e. g. porosity, water saturation, and the amount of electrolytes in the pore water).
Here you can find an example of a geoelectric application.