Magnetotellurical Measurements

Mapping the deep subsurface with magnetic induction

Magnetotellurical  measurements (MT) is a magnetic technique which determines the electrical conductivity of the subsurface in a non-destructive way. It can be used for the exploration of the first kilometres of the subsurface.

Measuring principle
The MT technique is based on the natural variations in the main field. These variations are caused by currents in the ionosphere which are strongly influenced by solar winds and thunderstorms. This locally generated energy propagates between the surface and the ionosphere over large distances. The MT technique induces a magnetic field into the subsurface which penetrates the subsurface vertically and is reflected by transitions in material. The reflected signal is than registered, creating an accurate model of the subsurface.

Applications
Because the MT technique has a wider depth range than most seismic reflection techniques, it is particularly useful for:
  • mapping deep geology where seismic reflection methods are insufficient
  • detection of deep oil and gas reservoirs.
  • detection of salt domes
  • detection of structures with high conductivity, such as minerals and ores