Brantax - engineering survey

underwater, underground
and surface investigation

Electromagnetic investigations

Electromagnetic methods detect anomalies in the inductive proprieties of the earth’s subsurface rocks. An alternating voltage is introduced into the earth by induction from transmitting coils either on the surface or in the air, and the amplitude and phase shift of the induced potential generated in the subsurface are measured by detecting coils and recorded.


Electromagnetic (EM) surveys provide an accurate and cost effective means of characterizing subsurface conditions at a site. A number of EM methods are available for use, each with its own advantages and limitations.

In electromagnetic (EM) surveying, the electrical conductivity of the ground is measured as a function of depth and/or horizontal distance. Different rocks, buried structures and objects exhibit different values of electrical conductivity. Mapping variations in electrical conductivity can identify anomalous areas worthy of further geophysical or intrusive investigation.

Applications of electromagnetic investigations:

  • Bedrock depth
  • Measuring the thickness of permafrost
  • Soil / Layers unconsolidated
  • Groundwater Contamination
  • Detection of septic systems
  • Detection of buried tanks
  • Characterization of buried waste
  • Detection of unexploded bombs (UXO)
  • Delimitation of disposition pits / trenches
  • Buried fuel tanks
  • Concrete study
  • The size and limits of buried deposits
  • Evaluation of buried  paved roads
  • Detection of cables and pipelines
  • Maps of groundwater contamination
  • Identification of household objects buried
  • Detection of voids and cavities
  • Cemeteries
  • Historic structures

Other methods used in geophysical investigations: