ASA 125th Meeting Ottawa 1993 May

3aUW10. Detection of buried landmines by imaging with surface waves.

Peter A. Krumhansl

Bill G. Watters

David A. Sachs

BBN STC, 70 Fawcett St., Cambridge, MA 02138

A technique has been developed to search an area of soil for buried landmines from a remote position. A two-dimensional synthetic aperture array of seismic sources and receivers is laid down adjacent to the search area. Broadband seismic sources generate Rayleigh surface waves that illuminate a search area out to a radius of 6 m and a depth of about 0.5 m. An array of vertical geophones receives backscattered signals that are recorded digitally. Unconsolidated soils have high rates of attenuation so an array with up to 21-dB of gain is used. A delay-and-sum near-field beamformer computes a 60x80 pixel image of the region's scattering strength. The search area image displays the location and character of landmine echoes along with clutter. A large amount of field data has been collected at several sights. The mine echoes have been detected at ranges up to 5 m (Pd=0.8). Landmines have been distinguished from rocks and holes, and false alarms due to system artifacts are being reduced. [Work supported by U.S. Army BRDEC.]