A dc resistivity survey is an inexpensive and widely used technique for investigation of near surface resistivity anomalies. It recently has become popular for the investigation of subsurface pollution problems (NRC, 2000). In principle, it measures the electric potential field generated by a transmission of dc electric current between electrodes implanted at the ground surface. Then, an apparent (bulk or effective) electrical resistivity for a particular set of measurement electrodes is calculated using formulas that assume homogeneous earth. Many pairs of current transmission and electric potential measurements are used to "map" subsurface electrical resistivity anomalies.
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