68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

TSUNAMIGENIC LANDSLIDES IN QUÉBEC

Session: Landslides and Slope Stability III / Mouvements de terrain et stabilité des pentes III

Jacques Locat, Université Laval (Canada)
Dominique Turmel, Université Laval (Canada)
Jonathan Leblanc, Université Laval (Canada)
Denis Demers, Ministère des Transports (Canada)

This paper will present some of the known cases histories in Québec where a tsunami wave was or could have been generated by a landslide, either subaerial or subaqueous: the 1908 Notre-Dame-de-la-Salette slide, which is the one that caused the greatest number of casualties (34), the La Grande (1987) slide and the Cap Trinité rockslide (Saguenay Fjord). This analysis will provide an opportunity to illustrate the destructive power of these events. The analysis of those in quick clays will show that the actual tsunami mechanics is very much influenced by the fact that the rupture surface is nearly horizontal. It will be shown that the presence of an ice cover can be a significant aggravating factor associated with the generation of a tsunami wave. Finally, some discussion will be made regarding the approach which could be followed to take this hazard into account as part of a landslide hazard assessment procedure in Québec.