Differences in Shear-Wave Velocity due to Measurement Methods: A Cautionary Note

Introduction The increasing importance of shear wave velocity ( Vs ) in shallow subsurface materials for determining the seismic shaking characteristics of a site (Borcherdt, 1994; Anderson et al. , 1996) has led to a search for new, more efficient methods of measuring Vs . One of these new techniques, called “CXW” by Poran et al. (1994), uses surface-wave dispersion to infer the shear-wave velocity profile at a site. This technique has been used extensively in the Los Angeles Basin, and the profiles have been incorporated in the geotechnical database by Vucetic and Doroudian (1995). Examination of these profiles and comparison with profiles measured using traditional downhole and crosshole techniques shows that the profiles measured using the CXW technique are not similar to profiles measured using more established methods. This note is a spin-off of an effort at the California Department of Conservation, Division of Mines and Geology (DMG) to develop a statewide map...