In recent years, there has been an increasing emphasis in exploration placed on transient electromagnetic (TEM) measurements beneath the surface, to help improve the resolution of small conductive targets beneath complex over­burden, and to enable the detection of targets that cannot be detected with surface methods because of their intrinsic detection depth limitation. For example, in 1980, CSIRO developed a bore-hole receiver probe (Hone and Pik, 1980), which is now in routine commercial use and, in 1985, KIER investigated a new application of the TEM technique with SIROTEM in underground mine workings to detect missed targets below known bodies (Lee et al. 1986).