Large-scale experiments into the tsunamigenic potential of different iceberg calving mechanisms
Valentin Heller (University of Nottingham)
Fan Chen (University of Nottingham)
Markus Brühl (Technical University of Braunschweig)
Roman Gabl (University of Innsbruck, The University of Edinburgh)
Xuexue Chen (Royal HaskoningDHV, TU Delft - Hydraulic Structures and Flood Risk)
Guido Wolters (Deltares)
Helge Fuchs (ETH Zürich)
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Abstract
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.
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