GPR is a non-invasive, non-destructive geophysical method that uses reflected and backscattered electromagnetic waves to image, locate and quantitatively identify changes in electrical properties in the subsurface. Its primary feature is a very short electromagnetic pulse, which allows a vertical resolution ranging from centimeters to a few meters, depending on bandwidth. In general, GPR surveys can generate large quantities of field data and, under the right conditions, can provide detailed subsurface information of a scope that is superior to that obtained from single-point sources such as drill holes. However, when available, confirming data from drill holes should always be used as a means of verifying the conclusions drawn from the radar records.
A GPR system generates an electromagnetic pulse that is transmitted into the ground with an antenna that is moved along the surface, which moves at a uniform speed and direction. Whenever there is a change in the dielectric constant of the subsurface material, a portion of the pulse energy is reflected back to the surface and is detected by the receiving antenna. This reflected pulse provides information on the attenuation characteristics (signal strength) associated with the subsurface material and the two-way travel time is recorded. A computer, with appropriate software, will then record the strength and time taken for the reflection of signals and through extensive processing demonstrates the depth at which rock configuration alters.
GPR is extensively practical in civil engineering (road construction, buried pipe leak detection), agriculture (soil survey), environmental protection, archeology, mining, geology, and detection of buried ordnance & mines.
