Impact of Small Shear Wave Velocity Variations on Surface Wave Phase Velocity Inversion
A. Wang, M. Le Feuvre, D. Leparoux and O. Abraham
Event name: 24th European Meeting of Environmental and Engineering Geophysics
Session: Modelling, Inversion and Data-processing in Near Surface Geophysics A
Publication date: 09 September 2018
Info: Extended abstract, PDF ( 726.76Kb )
Price: € 20
Surface wave methods have attracted a lot of geophysicists’ attention for the purpose of monitoring civil engineering structures, because they represent the most energetic part of the seismic signal, and contain information on shallow media. In order to infer the mechanical properties of the medium as a function of depth, an inverse procedure is required that minimizes a misfit function between observed and modeled data. However, a small change of model parameters can have low effects on observed surface waves data. This study focuses on the inversion of phase velocity dispersion curves of two-layer media with small to moderate variations of shear velocities. We use a simple two-layer model, where the shear velocity and thickness of the top layer are respectively 600 m/s and 8 m, and the shear velocity of bottom layer is 1100 m/s. Results show that it is difficult to distinguish inversion results when variation of shear velocity of the shallower layer is lower than 2%, and 10% for the deeper layer in our study case. These results emphasize the difficulty of estimating small to moderate evolution of medium, especially for deeper layers.