Title: Effect of lateral heterogeneity on surface wave testing: Numerical simulations and a countermeasure
Authors: Lin, Chih-Ping
Lin, Chun-Hung
Department of Civil Engineering
Keywords: surface wave;multi-channel analysis of surface wave;lateral heterogeneity
Issue Date: 1-Jun-2007
Abstract: The surface wave (S-wave) method has gained popularity in engineering practice for determining S-wave velocity depth profiles. A growing trend is towards the application of S-wave testing for spatially 2-D S-wave velocity tomography, ignoring the assumption of horizontally layered medium. A fourth-order velocity-stress finite difference method is used to perform numerical simulations of S-wave testing in earth models with lateral variation. Results show that the lateral heterogeneity induces a non-stationary property in the space domain, resulting in false depth-related dispersion or higher modes if conventional approach based on stationary assumption is used for the dispersion analysis. Artifacts maybe introduced in spatially 2-D S-wave velocity imaging if the effect of lateral heterogeneity is not accounted for. As a potential countermeasure, a high-lateral-resolution S-wave method is proposed to reduce the effect of lateral heterogeneity while maintaining the resolution and depth range of dispersion analysis. It consists of a walk-away survey and a phase-seaming procedure when synthesizing seismograms with different nearest source-to-receiver offset, allowing wide-wavelength dispersion analysis within a small spatial range. The proof of concept is given with several numerical examples. They show that the high-resolution S-wave method can greatly alleviate the effect of lateral heterogeneity and increase spatial resolution. (c) 2006 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.soildyn.2006.10.008
ISSN: 0267-7261
DOI: 10.1016/j.soildyn.2006.10.008
Volume: 27
Issue: 6
Begin Page: 541
End Page: 552
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