Enhanced Multi-channel Analysis of Surface Wave Data

In this study, we used multi-channel and multi-shot surface wave field records to obtain accurate phase-velocity curves and high resolution 2D shear wave velocity structure within the near-surface deposits. Data acquisition was similar to conventional engineering 2D seismic reflection survey. Every pairs of traces within the shot records are cross correlated. Then cross correlated traces from different shot records corresponding to a certain midpoint were gathered. The resultant gathers contain traces with characteristic phase differences at each midpoint location. Traces with the same receiver separation, at each common midpoint gather, were stacked. This overcomes the problem of degrading lateral resolution in MASW method due to the increase in correlation pairs distance. Finally, a 2D S-wave velocity profile was reconstructed through inversion of dispersion curves. Analyses of waveform data from field observations indicate that the method could greatly improve the accuracy and resolution of subsurface S-velocity structure compared to the conventional surface-wave data analysis methods.