High-resolution seismic reflection survey at Dover AFB: A comparison of three seismic sources
- Hanscom AFB, MA (United States)
- Kansas Geological Survey, Lawrence, KS (United States)
- Elohi Geophysics, Inc., Meadows, TX (United States)
In June of 1995, the Earth Sciences Division of the Air Force Phillips Lab, with survey equipment from the University of Delaware and assisted by the Kansas Geological Survey and Elohi Geophysics, conducted a geophysical site characterization of the SERDP-funded Groundwater Remediation Field Lab (GRFL) located at Dover AFB, Delaware and administered by Applied Research Associates for USAF Armstrong Lab. Seismic data were collected in order to (1) compare the results using three different compressional sources and (2) cover the field site well enough to characterize the seismic response of the shallow subsurface. This paper will focus primarily on the first of these two goals. Seismic data were collected along three north-south profiles set 10 meters apart, each profile with a different compressional source: a 5.5kg sledgehammer, a 12-gauge firing rod from Betsy Seisgun Inc. shooting 150 grain blanks, and a portable piezoelectrically driven vibrator, developed by Elohi Geophysics, operating with a 90Hz-450Hz sweep. An east-west cross line was collected using the sledgehammer source in order to tie the three profiles together. A laser theodolite provided station location and elevation control. The primary targets were the water table (that had been marked on maps at a depth of about 3 meters) and a sand-clay interface at about 15 meters depth. We collected 24-channel CMP data using a half meter spacing of both source and 100Hz geophones. Field C after initial walkaway noise testing with each source did not show any one source to be outstanding A practical early result of the seismic survey showed the water table to be at just over 10 meters. We have associated the strongest reflection event with the water-table interface. Seismic data comparison in this study is based on spectral content, total energy and signal-to-noise ratios, as well as a discussion of coherency of the primary reflection event at the water table.
- OSTI ID:
- 381478
- Report Number(s):
- CONF-960477-; TRN: 96:004278-0012
- Resource Relation:
- Conference: 9. annual symposium on the application of geophysics to engineering and environmental problems, Denver, CO (United States), 15 Apr - 1 May 1996; Other Information: PBD: 1996; Related Information: Is Part Of SAGEEP `96: Proceedings of the symposium on the application of geophysics to engineering and environmental problems; Bell, R.S.; Cramer, M.H. [comps.]; PB: 1353 p.
- Country of Publication:
- United States
- Language:
- English
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