Wladimir SARLIN - FAST - From granular collapse to shallow water waves

Tsunamis are among the most destructive natural disasters for human coastal settle- ments. While events generated by earthquakes are well known, several past or potential occurrences of high amplitude waves arising from large-scale landslides have also been re- ported in the last decades. In particular, the famous 1958 Lituya Bay tsunami, featuring the highest recorded wave run-up of 524 m, is reminiscent of the need for understanding how these disasters arise. A relevant approach to this end is to model experimentally the landslide as a flow of granular materials [1–3]. This talk will present two connected experimental studies. In the first, the two- dimensional collapse of a dry granular column is investigated, with the purpose of gaining insights into the rich dynamics of the problem. In the second, impulse waves triggered by a granular collapse are studied, revealing the existence of three shallow water wave regimes. By combining the spreading motion of the grains and the wave hydrodynamics, a predictive model for the maximum amplitude of the generated wave is introduced and discussed.

[1]  A. Bougouin, R. Paris, and O. Roche. “Impact of fluidized granular flows into water: Implications for tsunamis generated by pyroclastic flows”. In: Journal of Geophysical Research: Solid Earth 125.5 (2020), e2019JB018954

[2]  Hermann M. Fritz, Fahad Mohammed, and Jeseon Yoo. “Lituya Bay landslide impact generated mega-tsunami 50th anniversary”. In: Pure and Applied Geophysics 166.1 (2009), pp. 153–175.

[3]  Matthias Rauter et al. “Granular porous landslide tsunami modelling – the 2014 Lake Askja flank collapse”. In: Nature Communications 13.1 (2022), p. 678.