Method for Rapidly Detecting Subterranean Tunnels by Detecting a Non-Null Value of a Resultant Horizontal Magnetic Field Component.
DEPARTMENT OF THE NAVY WASHINGTON DC
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This invention provides for the detection and location of subterranean tunnels, voids and other anomalies. Two magnetic fields are established by passing current in two parallel wires laid out horizontally on the earths surface in the general area in which an anomaly is known or suspected to be. Magnetic field null measurements are made along a center line between the parallel wires. The presence of a tunnel warps or distorts the magnetic fields and causes the signal level to increase when the measurement is made over the tunnel or void beneath. Author
- Civil Engineering
- Magnetic and Electric Field Detection and Detectors