Seismische Crosshole Tomographie zum Verständnis von Sedimentationsprozessen in glazial übertieften Tälern

Abstract

Within the framework of the ICDP-DOVE project, a robust, seismic, multi-parameter P-SV Full Waveform Inversion (FWI) approach in a crosshole setup was developed for high-resolution characterization of sedimentation processes in overdeepened valleys. The FWI is applied to field data at ICDP site 5068_1 (Tannwald, Germany). The P and SV FWI using novel (an)isotropic smoothness-constraints can resolve sediment layers and local high-velocity anomalies within the basin down to a thickness of ~1 m. The FWI models are superi-or in resolution compared to first arrival traveltime tomography (TTT) models and can be cor-related with geological interpretations and sonic logs at the borehole locations. Above Molasse sediments, TTT and acoustic FWI results image a vertical stratification of the basin sediments consisting of alternating fine and sand layers as well as diamicts. Local velocity anomalies are interpreted as sand lenses and loosely packed gravels that were deposited in a fold.