V.E.S. / S.E.O.
Instrumentation for geognostic investigation
This type of survey is carried out with the purpose to reconstruct an electro-tomography 1D for a measurement point. The geo-electric method consists in the experimental determination of the resistivity distribution characterising the electric structure of a medium. In the SEV method, the distance between the electrodes is increased progressively and the ratio between d.d.p. and the current intensity is measured from time to time. The resistivity values thus obtained are influenced by the characteristics of the materials at increasingly greater depths. In view of this second effect, a geometric correction must be made and therefore factors that depend on distances MN (measurement electrodes) and AB (input electrodes) must be introduced in the calculation of the resistivity. According to the variations of the electrodes positions along the geo-electric area, different quadrupole systems are identified: Wenner and Schlumberger. A profile 1D of the ground resistivity is obtained below one point.