ABSTRACT

This paper presents some of the known case 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 (33), the La Grande (1987) slide and the Cap Trinité rockslide (Saguenay Fjord). This analysis provides an opportunity to illustrate the destructive power of these events. The analysis of those landslides that happened in quick clays show that the actual tsunami mechanics are very much influenced by the fact that the rupture surface is nearly horizontal. It is shown that the presence of an ice cover can be a significant aggravating factor for the consequences 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.