Detection Of Near-Surface Voids Using Surface Wave

Abstract

Ground roll is displayed, on an uncorrelated field record obtained using a monotonic sweep, in increasing or decreasing order of frequency with each frequency well separated from all others. Phase velocity and attenuation characteristics of each frequency contain the average elastic property of near-surface materials down to approximately half the wavelength. Uncorrelated field record, therefore, by itself can be associated with a two-dimensional display of the change in near-surface elastic property. Through the redundancy in data acquisition and a simple data processing step, the uncorrelated field records can be transformed into a stacked section that can be correlated directly to image of the change in elastic property of near-surface materials with respect to a certain reference location. This method can be effectively used to detect near-surface anomalies of various kinds.