Electromagnetic Techniques
Time Domain Electromagnetic Profiling
Outline
This active method involves inducing eddy currents within subsurface conductors using pulsed electromagnetic (EM) energy transmitted from a square loop of wire located on the ground. The decaying secondary EM signal induced by these eddy currents is measured over a series of time windows immediately after the transmitted signal is shut-off using the transmitter loop, or more commonly, a smaller second receiver coil located at the centre or to the side of the transmitter loop. TDEM soundings are capable of providing information on the conductivity of different layers within the subsurface to depths of between 3-1000m.
