The application of EM-34 aims to obtain data of apparent electrical conductivity of the subsurface through the electromagnetic induction technique as an alternative to electrical surveys that employ galvanic technique to measure apparent electrical resistivity.
In the application of the EM method, a low-frequency alternating electric current passes through the transmitting coil, which creates a primary magnetic field in the vicinity of the coil, inducing the flow of secondary currents (eddy currents or eddy-induced eddy currents) in any conductor present underground (McNEILL, 1980a).
These secondary currents, in turn, produce a secondary magnetic field, which carries information from the subsurface conductors. The resulting total field is detected by the receiving coil and is used to generate estimates of the electrical conductivity of the subsurface.
