Slope failure hazard in Canada's Atlantic Provinces: A review

Abstract

Slope failures present a hazard around the world, with considerable impact on communication/ transportation corridors, resource sectors, and coastal and urban development. Although poorly documented in much of Atlantic Canada, mass movements are known to have resulted in 71 fatalities in Newfoundland. In the Ferryland, Newfoundland, disaster of around 1823, 42 fishermen were reportedly killed when a cave roof collapsed onto them. Debris floods and flows are widespread in areas of higher relief in both Newfoundland and Cape Breton Island, and tend to be most hazardous for highway engineering and community development. Rotational slumps in glaciomarine clays are evident along the major river valleys of Labrador and are an important consideration during hydroelectric development. In other areas of Atlantic Canada, earthflows affect transportation routes and involve movement of saturated sediment during spring thaw. Along the Gulf of St. Lawrence, Northumberland Strait and the Bay of Fundy coastlines, friable rocks, glaciotectonic activity, frost wedging, and coastal erosion have resulted in many small failures and incremental retreat of coastal cliffs. Ongoing climate change will have an impact on slope failure activity. Increasing summer frequency and intensity of thunderstorms and hurricane events, increased winter precipitation in some locations, and possible erratic freeze-thaw events would result in an increase in debris flows triggered by precipitation, and rockfalls triggered by freeze-thaw. Human utilization of coastal areas is also contributing to the frequency and hazard of slope failures across Atlantic Canada. © Atlantic Geology 2013.