Ground Penetrating Radar (GPR)

GPR is a subsurface imaging technique that utilizes high frequency electromagnetic energy (typically in the 50 MHz to 2 GHz range). The EM waves are transmitted into the subsurface and a portion of them are reflected back to a receiver each time an interface between contrasting material types is encountered. The rapid acquisition and processing of GPR data makes it a popular geophysical method for shallow subsurface exploration. However, GPR signals are attenuated rapidly by soils with high clay content thus making it more popular for site with high sand content in the soil. GPR is useful for a variety of applications, including:

  • Soil stratigraphy
  • Sub-slab void delineation
  • Pavement and sub-base thickness
  • Bridge deck assessment
  • Buried object location
  • Utility location
  • Ice thickness determination
  • Bathymetry
  • Grave location
  • Karst feature mapping

The GPR data examples below illustrate both three-dimensional and two-dimensional data that were acquired from the surface of a concrete slab.

  • two-dimensional GPR data
  • three-dimensional GPR data

GPR can be integrated into both surface and borehole tools. Data may also be acquired from a watercraft or ice sled for some applications.