Influence Of Galvanic Currents On Electromagnetic Surveys

In this paper we differentiate the electromagnetic response from<br>various targets into two components. These are the vortex current<br>component, which is generated by the time-varying primary magnetic<br>field, and the galvanic current component, generated by the primary<br>electric field. Separation of the response into these two<br>components is an approximation, the accuracy of which is a function<br>of variables such as target conductivity contrast, background<br>conductivity, target size, distance from target to the transmitter,<br>transmitter type, frequency or time range of measurement, etc.<br>(McNeill, 1985). That it is an approximation, albeit useful,<br>should be kept in mind.