Seismic imaging: Conclusions

After careful processing, using special software tools to remove near-surface delay-time effects, the seismic reflection method was used to map subsurface mines. Two criteria were employed to map the void structures: a decrease in reflection amplitude and the presence of diffractive reflection energy. The interpretation was improved by the use of electric logs, even though a down hole velocity calculation was not possible and no VSP was available. The data quality would have improved if the shot spacing were decreased from 20 ft (6 m) to 10 ft (3 m) so that the CMP fold were increased from 12 to 24. However, despite the choice of this wide shot interval, we were able to confirm the presence or absence of undermined areas.