Large-scale experiments into the tsunamigenic potential of different iceberg calving mechanisms.
Heller VEnvironmental Fluid Mechanics and Geoprocesses Research Group, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK. Valentin.heller@nottingham.ac.uk.
Chen FEnvironmental Fluid Mechanics and Geoprocesses Research Group, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD, UK.
Brühl MLeichtweiß-Institute for Hydraulic Engineering and Water Resources (LWI), Department of Hydromechanics and Coastal Engineering, Technische Universität Braunschweig, Beethovenstraße 51a, 38106, Braunschweig, Germany.
Gabl RSchool of Engineering, Institute for Energy Systems, University of Edinburgh, Edinburgh, EH9 3DW, UK.
Chen XDepartment of Hydraulic Engineering, Delft University of Technology, Stevinweg 1, 2628 CN, Delft, The Netherlands.
Wolters GDeltares, Coastal Structures and Waves, Boussinesqweg 1, 2629 HV, Delft, The Netherlands.
Fuchs HLaboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, 8093, Zurich, Switzerland.
English
Mass balance analysis of ice sheets is a key component to understand the effects of global warming. A significant component of ice sheet and shelf mass balance is iceberg calving, which can generate large tsunamis endangering human beings and coastal infrastructure. Such iceberg-tsunamis have reached amplitudes of 50 m and destroyed harbours. Calving icebergs interact with the surrounding water through different mechanisms and we investigate five; A: capsizing, B: gravity-dominated fall, C: buoyancy-dominated fall, D: gravity-dominated overturning and E: buoyancy-dominated overturning. Gravity-dominated icebergs essentially fall into the water body whereas buoyancy-dominated icebergs rise to the water surface. We find with unique large-scale laboratory experiments that iceberg-tsunami heights from gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from A, C and E. A theoretical model for released iceberg energy supports this finding and the measured wave periods upscaled to Greenlandic outlet glaciers agree with field observations. Whilst existing empirical equations for landslide-tsunamis establish estimates of an upper envelope of the maximum iceberg-tsunami heights, they fail to capture the physics of most iceberg-tsunami mechanisms.