Métodos Eléctricos de Prospección

"Probably the most widely geophysical technique used is the electrical measurement. Many types of these measurements are made at the surface of the earth to investigate subsurface conditions in an area. In the most commonly used method, an electric current is driven through the ground and the resulting potential differences are measured at the surface.
To use electrical methods is necessary a physical property contrast: the electrical resistivity. The property of the electrical resistance of a material is usually expressed in terms of its resistivity."

Prem V. Sharma