Cross-borehole seismic probing to locate high-contrast anomalies

Technical Report · Fri Feb 19 04:00:00 EST 1982

OSTI ID:5170983

Lytle, R J; Portnoff, M R

Seismic probing between boreholes is useful for locating high-contrast geophysical anomalies such as an abandoned tunnel. Theoretical studies of continuous-wave components of a swept-frequency or pulse seismic wave interaction with a tunnel show that both the signal minima and the phase structure of the received signal can be used for locating the anomaly. The theoretical studies show that as the source and receiver are lowered in separate boreholes straddling the anomaly, the signal minima and the phase structure can be easily interpreted to yield both the lateral and vertical positions of the anomaly. Plane waves of compressional, horizontally polarized shear, and vertically polarized shear wave types incident on a cylindrical horizontal anomaly have been considered. All components of the total seismic field have been calculated using an exact formulation. The variation of the response is studied as a function of the ratio of anomaly diameter to wavelength. The resulting fields in the receiver borehole are an effective diagnostic when a wavelength in the surrounding medium is less than or equal to the diameter of the anomaly. These results are analogous to the corresponding electromagnetic case which has been studied previously.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5170983
• Report Number(s): UCID-19247; ON: DE82016038
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580203* -- Geophysics-- Geophysical Survey Methods-- (1980-1989)
BOREHOLES
CAVITIES
GEOPHYSICAL SURVEYS
SEISMIC SURVEYS
SUBSURFACE STRUCTURES
SURVEYS
TUNNELS
UNDERGROUND FACILITIES