Improving the characterization of overdeepened Alpine valleys by combining seismic reflection imaging and waveform inversion

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What types of small-scale Quaternary structures are hidden within the sedimentary succession of the overdeepened Alpine valleys? How heterogeneous is the bedrock topography of overdeepened valleys? Why are upright standing trees distributed all across the bottom of Lake Altaussee? State-of-the-art seismic methods struggle to answer these and other open questions that arose within the ICDP-project Drilling Overdeepened Alpine Valleys (DOVE). In particular at the sites Schäftlarn (Germany) and Bad Aussee (Austria), the limitations in resolution and accuracy of parameter determination hamper answering these questions. Therefore, we intend to improve the characterization of the sedimentary succession of overdeepened Alpine valleys by combining high-resolution seismic reflection imaging (HRSR) and full waveform inversion (FWI). Our concept comprises a methodological development of (1) an interplay of both methodologies that will constrain the FWI with information from the HRSR, and enables sophisticated processing with velocities from FWI. (2) A workflow will overcome prerequisites of FWI, i.e. the low frequency content that is usually excited by explosive sources, which are subject to legal regulations. It will enable the interplay to other sites, where only vibratory data exist. Finally, we will (3) test the applicability of the concept at other DOVE sites and ensure a comparable characterization of the DOVE sites. Within the project, we will acquire P-wave seismic data using vibratory and explosive sources as well as S-wave seismic data using vibratory sources at sites Schäftlarn and Bad Aussee. State-of-the-art HRSR processing of the vibratory data and FWI of the explosive data will give the first insight into the sedimentary interior of the two overdeepened valleys, where no high-resolution seismic data exist so far. At these structures, we will develop and realize our concept. Partners within the project are the Bavarian and Austrian Geological Surveys as well as the University of Natural Resources and Live Sciences Vienna.