Geomorphology and event-stratigraphy of recent mass-movement processes in Lake Hallstatt (UNESCO World Heritage Cultural Landscape, Austria)
Published:June 11, 2020
Michael Strasser, T. Berberich, S. Fabbri, M. Hilbe, J-J. S. Huang, S. Lauterbach, M. Ortler, H. Rechschreiter, A. Brauer, F. Anselmetti, K. Kowarik, 2020. "Geomorphology and event-stratigraphy of recent mass-movement processes in Lake Hallstatt (UNESCO World Heritage Cultural Landscape, Austria)", Subaqueous Mass Movements and their Consequences: Advances in Process Understanding, Monitoring and Hazard Assessments, A. Georgiopoulou, L. A. Amy, S. Benetti, J. D. Chaytor, M. A. Clare, D. Gamboa, P. D. W. Haughton, J. Moernaut, J. J. Mountjoy
Download citation file:
We report the first-ever basin-wide geomorphological characterization of a high-resolution bathymetry map in a steeply incised valley-occupying intra-mountainous lake in the Eastern Alps. The resulting new geomorphological map of Lake Hallstatt is then combined with high-resolution reflection seismic and sedimentary core analyses to document, characterize and date recent (<200 years) subaquatic landslides. The area is located in the UNESCO World Heritage Cultural Landscape of the Hallstatt–Dachstein area, famous for its well-documented medieval and prehistoric human settlement history. This allows us to calibrate observed mass-transport deposits (MTDs) in the high-resolution sedimentary archive (sedimentation rates c. 0.5 cm a−1) of this deep lake dominated by clastic sedimentation.
The hydro-acoustic data document a multitude of different MTDs linked to rock falls, subaqueous slope failures and shore collapses. Sediment cores document laminated background sediments intercalated with distinct event deposits that can be linked to historically documented major flood events and moderately strong earthquakes. Our study suggests that the larger MTDs result from earthquake-triggered subaquatic delta slope instabilities and that the deeper subsurface provides evidence of even larger mass-movement processes, yet to be validated by longer cores. Thus, Lake Hallstatt is a potential natural laboratory for studying causes and consequences of subaquatic landslides in steeply incised intra-mountainous lakes and comparable fjord settings.
Figures & Tables
Subaqueous Mass Movements and their Consequences: Advances in Process Understanding, Monitoring and Hazard Assessments
CONTAINS OPEN ACCESS
This volume focuses on underwater or subaqueous landslides with the overarching goal of understanding how they affect society and the environment. The new research presented here is the result of significant advances made over recent years in directly monitoring submarine landslides, in standardizing global datasets for quantitative analysis, constructing a global database and from leading international research projects. Subaqueous Mass Movements demonstrates the breadth of investigation taking place into subaqueous landslides and shows that, while events like the recent ones in the Indonesian archipelago can be devastating, they are at the smaller end of what the Earth has experienced in the past. Understanding the spectrum of subaqueous landslide processes, and therefore the potential societal impact, requires research across all spatial and temporal scales. This volume delivers a compilation of state-of-the-art papers covering topics from regional landslide databases to advanced techniques for in situ measurements, to numerical modelling of processes and hazards.