Electrical methods

The electrical properties of the sub-surface can be explored either electrically or electromagnetically. The two electrical methods to be discussed in this chapter are: (a) self-potential (SP) and (b) earth resistivity (ER). The induced polarization (IP) method, although it can be classified as an electrical method from the field-operational point of view, is discussed separately in the next chapter. The SP method was used by Fox as early as 1830 on the sulphide veins in a Cornish mine but the systematic use of the SP and ER methods dates from about 1920.