2D Full Waveform Inversion of Recorded Shallow Seismic Rayleigh Waves on a Significantly 2D Structure

Abstract

Elastic full waveform inversion (FWI) of shallow seismic surface waves has the potential to infer lateral variation of the shallow subsurface which is important e.g. for geotechnical site characterization. First successful applications of a FWI to surface waves show the high potential of this method. In preparatory studies we have identified essential prerequisites for an inversion of field data: Viscoelastic damping and 3D to 2D correction filters. For the first time it is possible for us to apply FWI to shallow seismic field data. 2D full waveform inversion is reasonably applicable to field data acquired on 2D structures. We present a shallow seismic 2D survey on a transverse section of a vertical fault located on the southern rim of the Taunus (near Frankfurt on the Main, Hesse, Germany) which is a dominantly 2D feature of the subsurface. Next we apply the FWI to this shallow seismic field dataset. We are starting the inversion with strongly lowpass filtered data of 10 Hz. Within this frequency bandwidth we obtain reasonable inversion results. However, by adding higher frequencies the inversion is apparently trapped in a local minimum. We try to overcome this problem by preconditioning and smoothing.