The effects of calving icebergs on (tsunami) waves: results large-scale tests now published in Nature

Published: 30 January 2019

Global warming causes increased risks of iceberg calving, which can generate large tsunamis endangering human beings and coastal infrastructure. Researchers from England, Switzerland, Germany, Austria and the Netherlands carried out an experimental study at Deltares to model the wave features caused by falling ice masses. The tests provided insight into the physical processes and the magnitude of generated tsunamis. The results are now published in Nature Scientific Report.

Study of five ice falling ice mechanisms

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. The researchers investigated five mechanisms with large scale laboratory tests at Deltares in Delft. All tests were performed at Deltares’ three-dimensional Delta Basin, because waves of this kind are mainly generated in open water bodies. These falling mechanisms that were studied were: 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.

The unique large-scale laboratory experiments showed that iceberg-tsunami heights from gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from A, C and E.

Measuring tsunamis

Guido Wolters, Deltares project leader and co author of the Nature article: ‘Thirty-five gauges were placed in a semi-circle around a dedicated release structure for two ice blocks in our Delta Basin in order to measure the tsunamis. The results were linked to existing data about landslide tsunamis and rockfalls, and used to improve numerical tsunami simulations.’

Valentin Heller of the University of Nottingham (left) and Guido Wolters of Deltares (right) next to the 1 to 200 scale plastic block that was used to simulate the waves of a 160 x 100 m ice chunck.

HYDRALAB+

The model tests were part of the European HYDRALAB+ project that is focussed on climate adaptation. Deltares is leading the HYDRALAB+ consortium of 24 research institutes.

About the Nature article

Read the full paper “Large-scale experiments into the tsunamigenic potential of different iceberg calving mechanisms” in Nature Scientifice Report here:
https://www.nature.com/articles/s41598-018-36634-3

Authors: 
Valentin Heller (University of Nottingham), Fan Chen (University of Nottingham), Markus Brühl (Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Germany), Roman Gabl (University of Edinburgh), Xuexue Chen (Delft University of Technology), Guido Wolters (Deltares) and Helge Fuchs (Laboratory of Hydraulics, Hydrology and Glaciology Switserland)