How we apply electrical resistivity tomography and vertical electrical sounding methods to multiple applications for the best outcomes

RSK Geosciences has extensive experience in applying vertical electrical sounding (VES) and electrical resistivity tomography (ERT) methods to multiple applications, including geological investigation, landfill mapping and sinkhole detection. The electrical properties of the subsurface vary with the soil material, the presence and saturation level of fluids and the presence of buried objects. By employing different electrode configurations, it is possible to determine the apparent resistivity at various locations and depths. Comparison with computer models makes it possible to identify any anomalous areas or features. As different strata, objects and saturating fluids exhibit different values of electrical resistivity, it is possible to map their distribution.

Vertical electrical sounding

The most basic of these methods to determine the electrical resistivity of the ground versus depth is vertical 1D electrical sounding. This is undertaken with the use of a pair of current electrodes and measuring the potential gradient within the subsurface. By increasing the spacing of the electrodes, the depth of the investigation below the centre point is increased.

Electrical resistivity tomography

Where information on the lateral variation of the ground materials is required to produce 2D profiles, the electrical resistivity imaging or ERT technique is used. The introduction of multi-electrode and computer-controlled systems enables semi-automated surveys, allowing large data sets to be collected more quickly and at reduced cost. Three-dimensional surveys, which are invaluable when surveying complex geological or man-made features, are now a practical and cost-effective tool. RSK Geophysics routinely employs state-of-the-art processing software that allows forward modelling and inversions of resistivity data using complex mathematical algorithms.

Self potential imaging

Self potentials are measurements of the difference in natural ground electrical potential between two points on the ground surface. They can be generated by a number of different sources, including groundwater flow, mineral deposits and chemical diffusion. Read more…

Self potentials measurements can vary from less than a millivolt to over one volt, and the sign (+/-) of the potential is a diagnostic factor in the interpretation of self potential anomalies. Although there are many sources of self potentials, the common factor among them is groundwater. The potentials are generated by the flow of water and by water acting as an electrolyte and as a solvent of different minerals and compounds.

Induced polarisation

Induced polarisation (IP) imaging is a complementary technique to electrical resistivity imaging and is concerned with the capacitance (how much energy is stored) of the subsurface. In conjunction with resistivity, IP imaging can provide additional delineation of subsurface materials. Read more…

  • Hydrogeological investigations (e.g., groundwater flow determination and contaminant transportation)
  • Landfill delineation
  • Leak detection in reservoirs and dams
RSK Geosciences Projects - Sparrow Lodge Farm - featured

Featured case study
Solar PV farm geotechnical assessment – Sparrow Lodge Farm

RSK was engagedto undertake a geoenvironmental assessment of a proposed 30 mV solar PV site in Buckinghamshire. The geoenvironmental survey included several phases such as desk studies, intrusive investigations, in situ and ex situ geotechnical testing, electrical and thermal resistivity surveys, topographic surveys, dynamic cone penetration testing, soakaway testing and factual and interpretive reporting.

Find out more about the project

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RSK Geosciences is part of the RSK group of companies

The RSK group is a leading integrated environmental, engineering and technical services business offering bespoke end-to-end solutions to a variety of sectors. Headquartered in the UK but with an established presence throughout Europe, Africa, the Middle East, Asia and Australia, RSK helps organisations around the world achieve their business aspirations in a sustainable and efficient manner.