2D Full Waveform Inversion Applied to a Strongly-Dispersive Love Wave Field Dataset
D. Köhn, D. Wilken, D. De Nil, T. Wunderlich, W. Rabbel and L. Werther
Event name: 80th EAGE Conference and Exhibition 2018
Session: FWI III - Multiparameter, Anisotropy...
Publication date: 11 June 2018
Info: Extended abstract, PDF ( 4.27Mb )
Price: € 20
The full waveform inversion (FWI) of strongly dispersive Love wave data is a challenging task. Amplitude, phase and dispersion information not only depends on the density and shear modulus distribution in the subsurface, but also significantly on intrinsic damping. This is especially a problem in near surface data applications with complex underground structures and low Qs values. Therefore, the FWI of a dispersive Love wavefield demands an accurate initial visco-elastic model and careful data pre-processing. Another key ingredient of a successful time-domain FWI is the sequential inversion of frequency filtered data in order to mitigate the non-linearity of the inverse problem. Common FWI strategies are based solely on either low- or bandpass filtered data. In this study we introduce a workflow consisting of a combined low- and bandpass filter strategy to achieve an appropriate data fit of the low-frequency Love wave and high-frequency refracted SH-wavefield. The applicability of this FWI strategy and the importance of a visco-elastic medium description is demonstrated for SH field data from the transect over a medieval 2D canal structure in southern Germany. The resolved canal shape and small scale structures in the inversion results are verified by an archaeological excavation.