RECOGNIZING SURFACE SCATTERING IN GROUND-PENETRATING RADAR DATA

Ground-penetrating radar (GPR) data may show strong noise events as a result of scattering by surface objects on the ground or above the survey line. The relative strength of these events can be large in comparison to reflections from geologic features, because radar signals in the ground attenuate exponentially whereas signals that travel in the air attenuate geometrically. Migration of GPR field data from elastic and carbonate sequences in central Oklahoma distinguishes between scattered events and geologic events because the former are focused at the air-wave velocity, while the latter are focused at the ground-wave velocity. Forward modeling using locations of scatterers derived from migration confirms the presence of scattered events, and common midpoint (CMP) gathers are helpful in identifying surface scattering. Scattered events displayed at a horizontal/vertical scale of 1:1 are easily mistaken for subhorizontal, geologic reflections. Methods of recognizing scattered events and removing them, if possible, are therefore crucial to correct geological interpretation of GPR data.