Page 493 - Moving the Earth_ The Workbook of Excavation

BLASTING AND TUNNELING

BLASTING AND TUNNELING 9.93

depth of bedrock. It is also used to determine leaking running water in earth dams, evidence of
life in blocked tunnels and earthquake rubble, stability of overhanging cliffs, large ice masses,
concrete structures during quiet periods of construction, underground foundations while under-
pinning is being replaced, communication through rock or pipe, robbing pillars of mineral-bearing
ore, and so forth.
With the Seismitron, timbers about to break sound just as one would expect wood to sound
under these conditions. Rock about to fall sounds like rock about to fall. Earth about to slide
sounds just like earth about to slide. In other words, just like the subject of physics; natural and
normal.