The history of MASW

Abstract

The story of “Multichannel analysis of surface waves to map bedrock” was based on a project of opportunity. Surface waves have always been the bane of near-surface reflection seismologists, even more so than petroleum exploration seismologists because of the close offsets and small two-way traveltimes we routinely deal with. With the development of MASW at the Kansas Geological Survey in the mid-1990s, surface waves have proven their utility as signal rather than noise on multichannel seismograms used for many near-surface applications. Extending the original 1D velocity estimation method to a 2D imaging and mapping technique was first demonstrated in this article. Prior to this paper, the utility, accuracy, and precision of the newly developed MASW method to estimate 1D shear-wave velocity functions had been demonstrated in several studies and publications. One of the most significant of these studies was a field test in the Vancouver, Canada area, orchestrated by Jim Hunter of the Geological Survey of Canada (which included the first blind test of the method with ground truth). This test turned out to be both the blue-ribbon success this method needed to enhance its credibility and a credit to Hunter's insight and vision. The success of that test spurred the team that authored this paper to extend the potential of this 1D method of estimating shear-wave velocities into a large-scale 2D imaging technique specifically designed for near-surface problems.