Underwater landslides occur on the steep underwater slopes of deltas in lakes and the sea as well as on the slopes of the Continental Shelf. Damage may be caused to structures sited on the edge of deltas when underwater landslides involve the delta surface. At Woodfibre, British Columbia such a landslide caused damage to wharves and wharehouses in 1955. Underwater landslides may also cause landslide-generated waves. In 1975, at Kitimat, a large failure on the underwater slope of the Kitimat delta generated an 8 m wave that swept around the shores of Kitimat Arm and damaged wharf facilities.
Earthquakes can be landslide triggers.
The 1946 Vancouver Island earthquake, for example, triggered many rockfalls and several rock avalanches. The earthquake triggered a rock avalanche from Mount Colonel Fosterwhich entered Landslide Lake generating a displacement wave that destroyed mature forest up to 3 km from the lake. In eastern Canada, the 1663 earthquake in the St. Lawrence region triggered many landslides in Leda Clay. A huge underwater landslide, triggered by the 1929 Grand Banks earthquake, severed submarine cables on the sea floor and caused a tsunami which killed 27 people when it struck the Burin Peninsula of Newfoundland. Snow avalanches occur widely in the mountains of western Canada where they threaten transportation routes in the winter.