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Geoelectrics

Geoelectric methods are used to determine the electric resistivity of the subsurface. The common measurement procedure is 2D-Geoelectrics. Geoelectric sounding, mapping and IP-measurements are applied as well.

Sample applications:

  • Exploration of geology, faults, and fracture zones
  • Embankment inspection
  • Boundaries of moist areas
  • Detection of cavities and tunnels
  • Land development
  • Landfill investigation
  • Reservoir exploration (mass deposits)
  • Corrodibility of buried cables and pipes

Penetration depths of about 10-100 m

Chain of measuring electrodes

Chain of measuring electrodes

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.


Geoelektric profile with interpretation

Geoelectric profile with interpretation

The result of geoelectric profiling is a depth slice of the electrical resistivity distribution in subsoil. Through combination of parallel profiles a spatial model in the form of a block diagram becomes possible. geoFact is also capable to perform real 3D-measurements and interpretation.


Measuring principle

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).

(from KNOEDEL, KRUMMEL, LANGE (1997):”Handbuch
zur Erkundung des Untergrundes von Deponien und
Altlasten, Vol. 3: Geophysik”, Springer-Verl. Berlin)

Here you can find an example of a geoelectric application.