Alexandrovsky ancient settlement is situated in the Kaluga region near the river Voria and Alexandrovka village. Self potential (SP) measurements with new non-polarizing electrodes of the second generation instead of traditional copper-copper sulfate electrodes were performed in 2013 and increased the quality of measurements. SP data were analyzed together with electrical resistivity tomography (ERT). The authors found filtration SP anomalies and proved that the main SP anomaly has diffusion-adsorption origin, determined that the Alexandrovsky site of the ancient settlement has decreased SP values.

Difference in apparent resistivity values determined in galvanic and inductive electrical and electromagnetic methods depends on macroanisotropy of layered cross-section and decreased penetration depth of galvanic methods without changing penetration depth of inductive methods. Joint influence of these two factors in case of high contrast of layers' resistivities results in difference in several tens of apparent resistivity values.