Retrieving 2D Structures from Surface Wave Data by Means of a Space-varying Spatial Windowing

The Surface Wave (SW) techniques are mainly used to retrieve 1D subsoil models. However, in 2D environments the 1D approach usually neglects the presence of lateral variations and, since the SW path crosses different materials, the resulting model is a simplified description of the site. We propose a processing technique to retrieve 2D structures from SW acquired with a limited number of receivers. Our technique is based on a two step process: first of all several local dispersion curves are extracted along the survey line using a spatial windowing based on a set of Gaussian windows with different shape; the windows maxima span the survey line so that for every window a dispersion curve can be extracted from the seismogram, thus retrieving a set of dispersion curves each of them referring to a different subsoil portion. This space-varying spatial windowing provides a good compromise between wavenumber resolution and the lateral resolution of the obtained local dispersion curves. In the second step of our procedure the retrieved set of dispersion curves is inverted using a laterally constrained inversion (LCI) scheme. This procedure has proven to be effective for the processing of both real and synthetic data.