The ground penetration radar (GPR) technique is compared with two seismic methods, the spectral-analysis-of-surface-waves (SASW) and the crosshole, for detection of buried objects. Tests were performed in a 7 m diameter by 2 m deep sand bin in the G. G. Brown Lab of the University of Michigan. The bin is filled with uniform silica sand compacted to a uniform density of about 16 kN/m3 . During the filling process, a three-cell void was buried at a depth of 305 mm to the top in the center of the bin. GPR, SASW and crosshole tests were performed with all three cells empty, one cell (center cell) empty, and all cells full of sand. The three experimental techniques are being compared with each otherfor efficacy of void detection.