If you're a miner trapped underground by a mining accident, you might use a new technique tested in an abandoned copper mine near Tucson, Arizona, to help rescuers find you.
A report in the new issue of SEG's The Leading Edge describes a system of installing simple metal plates in multiple locations along mine walls and keeping sledge hammers adjacent to them.
Trapped miners would bang on the plates with the sledges, sending out seismic signals that can be picked up by geophones on the surface. The authors of the study report 100% success in locating test locations accurately underground.
[top, diagram shows how geophones are lined up on the ground surface above a mine tunnel. Each red star within the tunnel represents a "base station" comprised of a sledgehammer and an iron plate bolted to the mine wall. In the event of a mine collapse, the miners try to reach the nearest base station, where they use the sledgehammer to bang on the iron plate. The pattern of seismic waves "heard" by the geophones is analyzed in a computer to pinpoint the miners' location. Credit, Univ. of Utah]
[bottom, University of Utah graduate student Shengdong Liu uses a sledgehammer to whack the wall of an abandoned copper mine in Arizona during a test of a new system that could locate miners trapped by a mine collapse. Credit, Univ. of Utah]