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U.S. Geological Survey Crustal Studies Technical Letter Number 17

In cooperation with the Defense Advanced Research Projects Agency

Preliminary Report on Some Factors Affecting Shotpoint Efficiency

By W.H. Jackson and J.H. Healy


Thumbnail of and link to report PDF (9.9 MB)Abstract

A study of first-arrival amplitudes from 6 water shotpoints and 7 drill-hole shotpoints in parts of central and western United States indicate a variation of over 100 to 1 between the best and poorest shotpoints.

Water shotpoints are, in general, superior to drill-hole shotpoints; however, one drill-hole shotpoint produced higher signal amplitudes than more than half of the water shotpoints. Signal amplitudes from drill-hole shotpoints varied by a factor of over 20. Saturated clay shooting medium appears to be the best shooting medium. Amplitudes from water shotpoints varied by a factor of about 10. Signal amplitude increases, in general, with water depth for bottom shots.

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For additional information:
Contact Information, Earthquake Science Center, Menlo Park Science Center
U.S. Geological Survey
345 Middlefield Road, MS 977
Menlo Park, California 94025

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Suggested citation:

Jackson W.H., and Healy, J.H., 1964, Preliminary report on some factors affecting shotpoint efficiency: U.S. Geological Survey Crustal Studies Technical Letter Number 17, 23 p. (Available at




Field Measurements

Shotpoint Evaluation



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