Frequency domain attenuation tomography (FDAT) (a new approach in defect mapping using GPR)

Cross-hole GPR tomography is widely used for defect mapping in civil engineering. As a departure from conventional tomography data processing, the real part of frequency spectrum of the entire data set of tomographic array was inverted to generate the attenuation tomogram at a particular representative frequency. We named this approach as Frequency Domain Attenuation Tomography (FDAT), which has a distinct advantage over conventional data processing by way of identifying even the minute details of the inherent medium defect. This paper describes the results of our experiments with FDAT with two classical cases of mapping a crack in the concrete block and a small-scale geological fault, which could not be detected in conventional attenuation or velocity tomogram. It is expected that this study will throw a new area of interpreting the cross-hole GPR tomography data in the frequency domain.