The depths to the reflecting interfaces are calculated from the arrival times in the GPR data if the EM propagation velocity in the subsurface can be estimated or measured.ġ.1.2 GPR measurements as described in this guide are used in geologic, engineering, hydrologic, and environmental applications. The receiving GPR antenna records the reflected waves over a selectable time range.

The transmitting antenna radiates EM waves that propagate in the subsurface and reflect from boundaries at which there are EM property contrasts. Data are normally acquired using antennas placed on the ground surface or in boreholes. GPR detects changes in EM properties (dielectric permittivity, conductivity, and magnetic permeability), that in a geologic setting, are a function of soil and rock material, water content, and bulk density. GPR is most often employed as a technique that uses high-frequency electromagnetic (EM) waves (from 10 to 7000 MHz) to acquire subsurface information.

1.1.1 This guide covers the equipment, field procedures, and interpretation methods for the assessment of subsurface materials using the Ground Penetrating Radar (GPR) Method.

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