Use of Two-dimensional Direct-current-resistivity Profiling to Detect Fracture Zones in a Crystalline Rock Aquifer near Lawrenceville, Georgia
Williams, Lester J.
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Two-dimensional direct-current resistivity (2D dc-resistivity) profiling was used to detect fracture zones in a crystalline-rock aquifer near Lawrenceville, Georgia. This work—which is a component of a ground-water resource investigation—was conducted by the U.S. Geological Survey in cooperation with the City of Lawrenceville. Profiling using 2D dc-resistivity methods is conducted by laying out an array of electrodes along a straight line and measuring an apparent resistivity. Electrical current is injected into the ground through two current electrodes and the voltage difference is measured at two potential electrodes. A multi-electrode system was used to collect apparent resistivity readings along the linear arrays. A commercially available switching unit was used to atomatically select four electrodes along the array; this allowed the collection of several hundred to several thousand measurements along a single profile, depending on the configuration of the array and the number of electrodes used.