Development of a Geoelectric Device of Capacitive Contact for Studying Archaeological Targets in Very Resistive Zones

In studies of highly resistive subsoils, geoelectric method with galvanic contact is not effective due to the difficulty to obtain a good contact and therefore a good current flow. The potential differences generated are very small, of similar magnitude to the noise level. The aim of this work is to develop a technique in order to facilitate the electric contact in such cases. In order to do more efficient the electrical contact, we designed and developed a low power geoelectric equipment using alternating injection current and capacitive coupling which can be used in highly resistive mediums and also on hard surfaces like asphalt or concrete. We have studied the processing and interpretation of data obtained with this equipment. It was studied the conditions under which the equipment can operate similarly to geoelectric galvanic contact so that data can be interpreted under the same patterns of interpretation. The studies made on scale models with the capacitive equipment on simulated soils with very high resistivity media, agree with the results obtained with the usual galvanic contact.