Accession Number:

ADA503442

Title:

Analysis Using Surface Wave Methods to Detect Shallow Manmade Tunnels

Descriptive Note:

Conference paper

Corporate Author:

MISSOURI UNIV-ROLLA DEPT OF GEOLOGY

Report Date:

2008-12-01

Pagination or Media Count:

11.0

Abstract:

Multi-channel Rayleigh wave data were acquired across a 1 meter diameter spillway tunnel along three parallel traverses with surface to tunnel separations of 0.90 meters, 2.15 meters and 3.13 meters depth, respectively. These surface wave data were acquired by placing a 24- channel geophone array perpendicular to the center-line of the spillway tunnel and incrementally moving the array across the tunnel. The near source-receiver offset was 6 meters the 4.5 Hz geophones were spaced at 0.5 meters. The tunnel locations were identified visually on velocity-filtered common-shot gathered field records. Tunnel locations were also identified by analyzing common shot-gathered records using two newly-developed automated interpretation programs Spiking Filter Analysis and Attenuation Analysis of Rayleigh Waves AARW. Electrical resistivity data was acquired along each traverse for comparison purposes. The engineering geophysics community has recently focused on the use of Rayleigh surface wave methods, such as Multichannel Analysis of Surface Waves MASW and Refraction Micrometer ReMi, to detect manmade tunnels in the earths shallow subsurface. Successful tunnel-detection applications of these methods have been reported. However, further experimental and analytical investigations are required to comprehend all significant aspects of the observed surface wave data. This case study reports on three alternate surface wave methods that were used to locate a 1 meter diameter tunnel visually-identified diffractedreflected surface-wave energy the Attenuation Analysis of Rayleigh Wave AARW and Spiking Filter Analysis.

Subject Categories:

  • Geology, Geochemistry and Mineralogy
  • Miscellaneous Detection and Detectors
  • Radiofrequency Wave Propagation

Distribution Statement:

APPROVED FOR PUBLIC RELEASE