Ground-penetrating radar refraction imaging with stacked refraction convolution section method

We have evaluated a technique initially developed for the seismic refraction imaging, the stacked refraction convolution section (SRCS), which we have properly adapted to process ground-penetrating radar (GPR) refraction data. Through a mute operation, the subsurface refracting signals, recorded by the receiver from two reciprocal sources, are selected. Following that, a velocity analysis by means of the crosscorrelation of the refracted signals and the convolution of resulting traces is performed. The refraction image in intercept times is successively derived from three main steps, namely: (1) the convolution of the subsurface refracted signals, (2) the crosscorrelation of convolved trace with the reciprocal refracted signal, and (3) the stacking of crosscorrelated traces over all source couples. The technique is not only suitable for the processing of GPR data acquired with two or more reciprocal common source profilesbut it is also convenient for its low acquisition cost in addition to the simplicity of software implementation and short processing times. We have evaluated the technique on a real GPR data set to characterize a near-surface morphostructure associated with a deep-seated gravitational slope deformation affecting Mt. Watles (Upper Venosta Valley, Italy). Results of the SRCS technique were validated against the direct trenching log data up to approximately 3 m in depth and complemented by the reflection processing outputs of common-source and commonoffset data acquired along the line. The SRCS and commonmidpoint processing provide the best reconstruction of the subsurface morphology of a shallow basement (approximately 0.80-1.5 m depth), characterized by a velocity range of 0.070-0.119 m/ns and made of strongly to moderately weathered paragneiss. The full-wave modeling response of the reconstructed model demonstrates good agreement with the recorded signals.