Frontiers in Earth Science | |
Active Faulting in Lake Constance (Austria, Germany, Switzerland) Unraveled by Multi-Vintage Reflection Seismic Data | |
S. Heuberger1  H. Pomella2  T. Schwestermann2  R. Allenbach3  M. Wessels4  M. Herwegh5  C. Affentranger5  F.S. Anselmetti5  S.C. Fabbri5  K. Lindhorst6  S. Krastel6  U. Wielandt-Schuster7  Herfried Madritsch8  | |
[1] Department of Earth Sciences, ETH Zürich, Zürich, Switzerland;Department of Geology, University of Innsbruck, Innsbruck, Austria;Federal Office of Topography Swisstopo, Wabern, Switzerland;Institut für Seenforschung der LUBW, Langenargen, Germany;Institute of Geological Sciences and Oeschger Centre of Climate Change Research, University of Bern, Bern, Switzerland;Institute of Geosciences, Christian-Albrechts-Universität zu Kiel, Kiel, Germany;Landesamt für Geologie, Rohstoffe und Bergbau Baden-Württemberg, Freiburg i. Br., Germany;National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen, Switzerland; | |
关键词: coring; earthquakes; seismic hazard; seismic stratigraphy; active faults; glacial overdeepening; | |
DOI : 10.3389/feart.2021.670532 | |
来源: DOAJ |
【 摘 要 】
Probabilistic seismic hazard assessments are primarily based on instrumentally recorded and historically documented earthquakes. For the northern part of the European Alpine Arc, slow crustal deformation results in low earthquake recurrence rates and brings up the necessity to extend our perspective beyond the existing earthquake catalog. The overdeepened basin of Lake Constance (Austria, Germany, and Switzerland), located within the North-Alpine Molasse Basin, is investigated as an ideal (neo-) tectonic archive. The lake is surrounded by major tectonic structures and constrained via the North Alpine Front in the South, the Jura fold-and-thrust belt in the West, and the Hegau-Lake Constance Graben System in the North. Several fault zones reach Lake Constance such as the St. Gallen Fault Zone, a reactivated basement-rooted normal fault, active during several phases from the Permo-Carboniferous to the Mesozoic. To extend the catalog of potentially active fault zones, we compiled an extensive 445 km of multi-channel reflection seismic data in 2017, complementing a moderate-size GI-airgun survey from 2016. The two datasets reveal the complete overdeepened Quaternary trough and its sedimentary infill and the upper part of the Miocene Molasse bedrock. They additionally complement existing seismic vintages that investigated the mass-transport deposit chronology and Mesozoic fault structures. The compilation of 2D seismic data allowed investigating the seismic stratigraphy of the Quaternary infill and its underlying bedrock of Lake Constance, shaped by multiple glaciations. The 2D seismic sections revealed 154 fault indications in the Obersee Basin and 39 fault indications in the Untersee Basin. Their interpretative linkage results in 23 and five major fault planes, respectively. One of the major fault planes, traceable to Cenozoic bedrock, is associated with a prominent offset of the lake bottom on the multibeam bathymetric map. Across this area, high-resolution single channel data was acquired and a transect of five short cores was retrieved displaying significant sediment thickness changes across the seismically mapped fault trace with a surface-rupture related turbidite, all indicating repeated activity of a likely seismogenic strike-slip fault with a normal faulting component. We interpret this fault as northward continuation of the St. Gallen Fault Zone, previously described onshore on 3D seismic data.
【 授权许可】
Unknown