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GEO-ELECTRIC
EXPLORATIONS
› S.E.V. (Vertical electric explorations)
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.