Simulation of tsunami induced by a submarine landslide in a glaciomarine margin: the case of Storfjorden LS-1 (southwestern Svalbard Islands)

Abstract

A modelling approach to understand the tsunamigenic potentiality of submarine landslides will provide new perspectives on tsunami hazard threat, mostly in polar margins where global climatic change and its related ocean warming may induce future landslides. Here, we use the L-ML-HySEA (Landslide Multilayer Hyperbolic Systems and Efficient Algorithms) numerical model, including wave dispersion, to provide new insights into factors controlling the tsunami characteristics triggered by the Storfjorden LS-1 landslide (southwestern Svalbard). Tsunami waves, determined mainly by the sliding mechanism and the bathymetry, consist of two initial wave dipoles, with troughs to the northeast (Spitsbergen and towards the continent) and crests to the south (seawards) and southwest (Bear Island), reaching more than 3 m of amplitude above the landslide and finally merging into a single wave dipole. The tsunami wave propagation and its coastal impact are governed by the Storfjorden and Kveithola glacial troughs and by the bordering Spitsbergen Bank, which shape the continental shelf. This local bathymetry controls the direction of propagation with a crescent shape front, in plan view, and is responsible for shoaling effects of amplitude values (4.2 m in trough to 4.3 m in crest), amplification (3.7 m in trough to 4 m in crest) and diffraction of the tsunami waves, as well as influencing their coastal impact times.