Formulas in wenner and schlumberger configurations in ers?

Answer 1

In Electrical Resistivity Surveying (ERS), the Wenner and Schlumberger configurations are commonly used for measuring subsurface resistivity.

For the Wenner configuration, the apparent resistivity (( \rho_a )) is calculated using the formula: [ \rho_a = 2\pi a V/I ] where ( a ) is the electrode spacing, ( V ) is the measured potential difference, and ( I ) is the current applied.

In the Schlumberger configuration, the formula is similar but accounts for the larger distance between the outer electrodes: [ \rho_a = \frac{2\pi (AB)^2}{(AB - a)V/I} ] where ( AB ) is the distance between the outer electrodes and ( a ) is the distance between the inner electrodes. Both configurations help in interpreting subsurface resistivity variations.