USGS Groundwater Information: Hydrogeophysics Branch
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John H. Williams, U.S. Geological Survey, 425 Jordan Road, Troy, NY, 12180, USA
Carole D. Johnson, U.S. Geological Survey, 11 Sherman Place, Storrs, CT, 06269 USA
Imaging with acoustic and optical televiewers results in continuous and oriented 360-degree views of the borehole wall from which the character, relation, and orientation of lithologic and structural planar features can be defined for studies of fracturedrock aquifers. Fractures are more clearly defined under a wider range of conditions on acoustic images than on optical images including dark-colored rocks, cloudy borehole water, and coated borehole walls. However, optical images allow for the direct viewing of the character of and relation between lithology, fractures, foliation, and bedding. The most powerful approach is the combined application of acoustic and optical imaging with integrated interpretation. Imaging of the borehole wall provides information useful for the collection and interpretation of flowmeter and other geophysical logs, core samples, and hydraulic and water-quality data from packer testing and monitoring.
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Final copy as submitted to Journal of Applied Geophysics for publication as: Williams, J.H., and Johnson, C.D., 2004, Acoustic and optical borehole-wall imaging for fractured-rock aquifer studies: Journal of Applied Geophysics, vol. 55, Issue 1-2, p. 151-159.