The AC‐geoelectrical sounding method: a combined electric/electromagnetic prospecting tool

Abstract

Christensen, Niels B0ie 1987 12 01: The AC-geoelectrical sounding method: a combined electric/ electromagnetic prospecting tool. Boreas, V~I .16, pp, 387-392.0~10. ISSN 0300-9483. BOREASSince 1979 the Laboratory of Geophysics, University of Aarhus, has been developing a new prospecting tool for obtaining information on the topmost 100 m of the earth. The method is an extension of the conventionalgeoelectricsoundingmethod, but instead ofdirect current (DC) the AC-geoelectricalsounding method uses alternating current (AC) with frequencies in the range 100 Hz to 20,000 Hz. The use of alternating current adds an inductive contribution to the ordinary galvanic electric field, thus producing two different sorts of information about the underlying earth structure. These two sets of information are, in many cases, of complementary nature, which enables determination of the ground parameters much more accurately than would otherwise be possible from ordinary DC-geoelectrical soundings. Among these cases is the high resistivity equivalence which appears so frequently in Danish Quaternary dcposits.