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TitleDetection of tunnels and boulders using shallow SH-SH reflected seismic waves
AuthorPugin, A J -M; Brewer, K; Cartwright, T; Sargent, S L
SourceThe Leading Edge vol. 38, no. 6, 2019 p. 436-441,
Alt SeriesNatural Resources Canada, Contribution Series 20180347
PublisherSociety of Exploration Geophysicists
Mediapaper; on-line; digital
File formatpdf (Adobe® Reader®); html
Subjectsgeophysics; surficial geology/geomorphology; engineering geology; Economics and Industry; seismic methods; seismic surveys; seismic waves; s waves; glacial deposits; lag deposits; boulders; subsurface waste disposal; mines; coal mining; in-field instrumentation; field methods; Methodology; Tunnels
Illustrationsphotographs; spectra; seismic sections
ProgramGroundwater Geoscience Aquifer Assessment & support to mapping
Released2019 06 01
AbstractWe present three case studies on detecting buried glacial boulders, a sewage tunnel, and abandoned coal mine tunnels using shear-wave reflection methods. The seismic signature of such subsurface features is in the form of an isolated diffraction, distinctly recognized on seismic sections obtained from shallow seismic surveys using a transverse horizontal (H2) source and a multichannel landstreamer that consists of H2 geophones. We used H2 impulsive and vibrator sources with varying bandwidth. Based on field experiments with multicomponent recordings, we determined that the H2-H2 source-receiver configuration is the most optimal to generate downgoing horizontally polarized shear (SH) waves and upcoming SH reflected and diffracted waves. A shallow SH-SH image using a microvibe high-frequency sweep exhibits a wavelength between 1 and 2 m, which is comparable to that of a ground-penetrating radar image with the additional advantage of deeper penetration.
Summary(Plain Language Summary, not published)
We present the results of three surveys to demonstrate that shear wave seismic reflection (Sh) with impacting and vibrating sources and receivers in perpendicular transverse (H2) direction from the line acquisition direction can image diffractions induced by burried boulders, abandoned coalmine shafts and sewage tunnels. Similar high quality diffractions features as such seen with Ground Penetrating Radars are observed using Sh, shear wave seismic reflection method are best imaged using transverse horizontal sources and recording capacities (H2,H2). These data sets were acquired using a narrower band frequency vibrating (Minivib 1TM), a broadband high frequency in-house developed vibrating (Microvibe) or an impulsive hammer source, coupled with a multichannel landstreamer. The high coherency of the Sh-wave technique can be compared with an electromagnetic Ground Penetration Radar but with a much better penetration.

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