Integrated hazard assessment of lake tsunamis triggered by subaqueous and subaerial landslides

Abstract

Historical chronicles together with geophysical, geotechnical, and sedimentological investigations have demonstrated that both subaqueous and subaerial landslides can lead to tsunamis on lakes. Previous work has shown that lakes in the alpine and peri-alpine settings in Switzerland provide prime preconditions for subaqueous mass movements, due to the glacially excavated basin geometry, the continuous sediment supply, and the related mechanical characteristics of the slopes. In addition, steep alongshore topography favours subaerial mass movements. The increasing settlement and infrastructure development along the shores and the lake tsunami history emphasize that assessing the tsunami hazard on Swiss peri-alpine lakes is essential. In a holistic approach that combines limnogeological, geomorphological, seismological, geotechnical, geospatial techniques with hydrodynamic simulations, we construct a workflow for the assessment of the landslide-tsunami hazard on peri-alpine lakes. GPU-accelerated numerical simulation using the freely available software BASEMENT allows for a rapid calculation of various inundation parameter distributions, considering uncertainties in landslide parameters. In the workflow, tsunami generation can be simulated both for subaqueous and subaerial mass movements. Hence, the hazard of lake tsunamis can be assessed comprehensively. Next to presenting the workflow, we provide recommendations for future work.