INDUCED INTERFACIAL POLARIZATION AND ITS MANIFESTATION IN ELECTRICAL AND ELECTROMAGNETIC PROSPECTING METHODS

The article, by the example of a layered material which can be reduced to a two-layer equivalent illustrates the differences in the frequency and transient responses of interfacial polarization depending on which source – current or voltage – is used to excite the ground in electrical and EM geophysical prospecting methods. In material science, a voltage source is usually used to study interfacial polarization. In this case, the manifestations of interfacial polarization are known as the Maxwell-Wagner effect. As for the geophysical induced polarization method, it uses a current source to energize the ground, which causes frequency and transient responses of the interfacial polarization to differ from those predicted by the Maxwell-Wagner theory. In principle, using the interfacial polarization frequency or transient responses measured with both current and voltage sources, one can find all properties of the equivalent two-layered model. In practice, however, polarization of grounding electrodes complicates the in-situ studies of the Maxwell-Wagner effect using a grounded source. There is no such a problem in the time domain electromagnetic prospecting method: when the current in the transmitter loop is switched off, a vortex electric field is induced in the ground, which – in terms of the circuit theory – is equivalent to using the voltage source.