GPR Principles and Applications
Ground-penetrating radar, also known as surface-penetrating radar, geo-radar, or more commonly by the abbreviation GPR, has seen significantly increased acceptance as a viable near-surface geophysical technique in recent years. The practice of employing radio waves to image the subsurface dates to work conducted on glaciers in the Austrian Alps in the 1920s (Stern, 1929). Research on the ice-penetrating capabilities of radio waves languished until the late 1950s, when it was noted that newly installed radar altimeters on aircraft could penetrate through the Greenland icecap and display the aircraft’s height above the underlying bedrock, which led to a number of mishaps (Waite and Schmidt, 1961). Although the ability to penetrate ice was a limitation for the reliance on radar altimetry for low-altitude flying in Polar regions, agencies such as NASA took an interest in the ability of radar to penetrate the ground in suitable environments. A rudimentary GPR system was launched onboard Apollo 17 in an attempt to determine surface conditions prior to a manned mission to the moon (Simmons et al., 1972).