Geophysical Application of Power Lines EM Fields

As it has been shown by using numerical forward modelling and experimental field measurements, the electromagnetic fields due to power lines can give geological information even in the vicinity of powerlines. For the localisation of relatively near-surface lateral inhomogeneities, we recommend to construct a map about the ratio of electric field components measured in two neighbouring sites, along profiles parallel to the power line. Such a survey can be carried out easily, quickly and cheaply, and by means of a very simple instrumentation. This method may become a useful complementary tool of traditional geoelectric soundings. The stratigraphic identification and the depth position of the inhomogeneities are given from related traditional measurements. It is possible to obtain a vertical resolution from several upper harmonics of the fifty hertz, too. For such a frequency-sounding a simultaneous measurement of the electric and magnetic field components is suggested, which requires multichannel, frequency-selective voltmeters of higher sensitivity -possibly with digital recording - as well as additional theoretical and field examinations.