Locating trapped miners using super-stacking and super-resolution properties of time reversal mirrors

We present a Time Reversal Mirror (TRM) approach for locating trapped miners inside a collapsed mine. Two steps are used to locate the trapped miners: first record a natural seismic band-limited Green's function prior to the collapse, where source points are located inside the mine at specified communication stations and the wavefields are recorded along a line of receivers on the overlying ground surface. The second step is, after a collapse occurs, the trapped miners go to the nearest communication station and hammer an SOS signal against the mine wall. The vibrations are recorded by the receivers on the ground surface, and using the previously recorded band-limited Green's functions for comparison, the location of the trapped miners can be identified. The outstanding feature of this TRM approach is its resilience to a very low signal-to-noise ratio in the recorded SOS data and its tolerance for limited aperture widths in the recording array, successfully. This method is tested using two field data sets.