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A Waveform Inversion Strategy for Surface Wave Analysis in the Presence of High Velocity Contrasts
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 76th EAGE Conference and Exhibition 2014, Jun 2014, Volume 2014, p.1 - 5
Abstract
Surface waves are useful for near-surface seismic characterisation. Media containing high velocity contrasts and irregular lateral variations still represent a challenge for local 1D approaches. As an alternative, inversion methods based on waveform modelling can be considered. The choice of an initial velocity model for classical full waveform inversion is difficult in the presence of surface waves. Here, we propose a waveform inversion approach using two different objective functions. A modified objective function is used before the classical full waveform inversion. The modified objective function consists of the least-squares misfit between the amplitude of a local 2D Fourier transform of observed and modelled data considering a sliding window. The choice of an initial velocity model is easier in this approach than in classical full waveform inversion. By using this approach, we can assess the contribution of back-scattered waves to the estimation of a highly contrasted velocity model. Scattered waves are useful information and results are better when the late scattered arrivals are inverted after the direct events.