Interpretation pitfalls to avoid in void interpretation from ground-penetrating radar imaging

Abstract

Voids are features that occur commonly in near-surface geophysical imaging. They are usually readily identified in ground penetrating radar (GPR) imaging because of the strong reflection amplitudes, akin to the “bright spot” in oil and gas exploration. However, voids are often misidentified. Some voids are missed, and other anomalous features are misinterpreted as voids, when in fact they are not. We evaluate s ome examples of features will be presented from glacial imaging and engineering geophysics that were misinterpreted as voids, compare them with real voids, and we determine the differences that separate them. Another example from archaeology was identified as a void based on incomplete data, and was only coincidentally coincident with a void. In particular, in addition to strong top and bottom reflections, voids may have multiple reflections but will not have internal reflections. Voids will also tend to be limited in extent, and won’t, in general, underlie an entire GPR profile.