Large-scale investigation into iceberg-tsunamis generated by various iceberg calving mechanisms

Heller, Valentin; Attili, Tommaso; Chen, Fan; Gabl, Roman; Wolters, Guido

Abstract

© 2020 Elsevier B.V. Mass balance analysis of ice sheets is a key component to understand the effects of global warming with iceberg calving as a significant contributor. Calving recently generated tsunamis of up to 50 m in amplitude endangering human beings and coastal infrastructure. Such iceberg-tsunamis (IBTs) have been investigated based on 66 unique large-scale experiments conducted in a 50 m × 50 m large basin at constant water depth h. The experiments involved five iceberg calving mechanisms: A: capsizing, B: gravity-dominated fall, C: buoyancy-dominated fall, D: gravity-dominated overturning and E: buoyancy-dominated overturning. The kinematics of the up to 187 kg heavy plastic blocks mimicking icebergs was measured with a motion sensor and the wave profiles were recorded with wave probes at up to 35 locations. The IBTs from the gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from mechanisms A, C and E. Empirical equations for preliminary hazard assessment and mitigation for the maximum wave height, amplitude and period for both the near- and far-field are derived for the five calving mechanisms individually and combined. The relative released energy, Froude number and relative iceberg width are the most influential dimensionless parameters in these equations. A maximum wave height decay trend close to (r/h)−1.0 is observed, with r as the radial distance, in agreement with the theoretical wave decay from a point source. The empirical equations are applied to a past event resulting in a good agreement and the upscaled wave periods to typical Greenlandic conditions overlap with the lower spectrum of landslide-tsunamis. However, empirical equations for landslide-tsunamis were found to be of limited use to predict IBTs in the far-field supporting the need of the newly introduced empirical equations for IBT hazard assessment and mitigation.

Citation

Heller, V., Attili, T., Chen, F., Gabl, R., & Wolters, G. (2021). Large-scale investigation into iceberg-tsunamis generated by various iceberg calving mechanisms. Coastal Engineering, 163, https://doi.org/10.1016/j.coastaleng.2020.103745

• Journal Article Type: Article
• Acceptance Date: Jun 7, 2020
• Online Publication Date: Jun 25, 2020
• Publication Date: Jan 1, 2021
• Deposit Date: Jul 3, 2020
• Publicly Available Date: Jun 26, 2021
• Journal: Coastal Engineering
• Print ISSN: 0378-3839
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 163
• Article Number: 103745
• DOI: https://doi.org/10.1016/j.coastaleng.2020.103745
• Keywords: Greenland; Iceberg calving; Iceberg-tsunami; Impulse wave; Landslide-tsunami; Outlet glacier; Physical modelling
• Public URL: https://nottingham-repository.worktribe.com/output/4745843
• Publisher URL: https://www.sciencedirect.com/science/article/abs/pii/S0378383919305010