Evaluation of Geophysical Surface Methods for Measuring Hydrological Variables in Fractured Rock Units.
NTIS: PB/84-158021 :146 pages
A simplified theoretical model for the use of electrical resistivity measurements to determine joint orientation and intensity was developed. A field procedure based on the theoretical model was applied to a physical model under laboratory conditions and at two field sites. The two field sites were identical geologically but differed in that one site was intensely mined while the other was unmined. In all three cases, joint strike was determined within approximately 5 degrees and the relative indications of joint intensity were correct. In addition to the electrical measurements, the anisotrophy associated with seismic velocity and attenuation was measured at each field site. The seismic measurements, in comparison with the electrical measurements, were much less informative and more difficult to interpret. A computer-automated system for the continuous monitoring of resistivity depth soundings was deployed at one of the sites. Continuous 48-h monitoring following a rainfall suggested that the downward movement of water could be detected.
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