Locating an Abandoned Mine Tunnel by MASW – a Feasibility Study with a Noisy Dataset

An entrance to an old coal mine was found in a residential development site. Using this site, an experimental MASW survey was carried out. Because of the unfavourable environment, the data quality was poor and dispersion analyses for the fundamental mode Rayleigh waves were very difficult among the noise and higher mode features. To deal with this difficult situation, depth-velocity models with and without a mine tunnel void are made based on the first-pass velocity analysis. Then dispersion curves were calculated for these models. The modeled dispersion curves showed that a presence of tunnel causes a “down-to-the -left” trend in the frequency-velocity space. Using this information, the data were re-analysed for dispersion curves. The inversion reached S-wave velocity sections with low-velocity features where the tunnel is present.