PHASE-SCANNING APPROACH TO CORRECT STATIC ERROR IN THE SURFACE WAVE WALK-AWAY METHOD

Synthesized surface wave records obtained from walk-away surveys normally suffer from time shift inaccuracies due to the abrupt variation in the soil stiffness characteristics which is regarded as static error effect. In this paper we present a method that uses a phase scanning procedure in frequency domain which applies the correction in a phase range from 0 to 2�E aimed at alleviating the adverse effect of static error in the dispersion image. At each frequency the method searches for the optimum phase correction resulting in the highest maximum summed amplitude value along the offset range. The maximum summed amplitude-phase velocity curves are selected for all scanning frequencies and then used to construct a corrected dispersion image. Results show that the proposed phase scanning method reduces the distortions caused in the computed dispersion images efficiently and also account for the disturbances introduced by ambient noise.