Detection of Shallow Subsurface Cavities Associated with Old Abandoned Coal Mines of Raniganj Coalfiled to Avoid Possible Inundation in Mines

Old abandoned coal mines of Raniganj Coalfield pose a major problem of inundation. These abandoned old workings are inaccessible in most of the cases. Most of these old workings are shallow in nature. Usually, Abandoned Mine Plan (AMP) of these workings are not available. If available, these may not be reliable. In the absence of any plan, it is not possible to delineate the old workings either by surveying or drilling. In order to locate these cavities, High Resolution Shallow Seismic (HRSS) survey is necessary. Before undertaking such a survey, modelling study is essential in understanding the seismic signature over the subsurface cavities in a variety of geological settings for proper interpretation of cavity anomalies. Seismic response over one dry and one water-filled cavities have been presented here. The time sections (unmigrated) could detect the subsurface voids with high frequency source for dry cavities. In addition, the migrated time sections clearly detected and delineated galleries filled with air. Similar studies have been extended for water-filled cavities. However, the water-filled cavities can partly be delineated by using the approach described in this paper. This study of void delineation can help planning and design processes to avoid possible inundation from nearby water bodies, surface and ground water.