Locat said what is likely the deadliest landslide in Quebec's history occurred in 1908 in Notre-Dame-de-la-Salette, Que., about 40 kilometres northeast of Ottawa, and killed 33 people. In 1971, a landslide in another part of that city killed 31 people and led to the abandonment of the community of St-Jean-Vianney. Last summer, more than 70 households were evacuated in La Baie, Que., part of the city of Saguenay, after a landslide destroyed an empty house, and officials feared further slides. Landslides are also common in Quebec's Saguenay region. Wildfires can also contribute to landslides, he said, by changing the vegetation cover and soil conditions, leading to more water infiltration and killing trees whose roots hold the soil together. "A really unusually heavy rainfall could trigger an unusually large landslide."
"We think that more frequent rainfall or more intense rainfall is going to make landslides more frequent and potentially more intense themselves," he said. McDougall, like Locat, also posits that climate change will increase the likelihood of landslides in Quebec but he said research to support that hypothesis is ongoing. "When they get disturbed, their structure can change, basically turning them from a solid into a fluid that can flow long distances," he said. Scott McDougall, a professor at the University of British Columbia who studies landslides and related geohazards, said those clay soils are very sensitive. That clay soil can become unstable, and landslides are part of the natural evolution of that type of landscape, Locat said. Landslides also occur around Gatineau, Que., near Ottawa in the Charlevoix region, northeast of Quebec City and the Gaspé Peninsula.Īll of those regions are located on a clay plain left by a sea that disappeared around 10,000 years ago. Lawrence River valley - a region where they are particularly common in the province - are caused by erosion that is the result of human activities, he said. "Erosion is the trigger of many landslides along watercourses and so climate change could have an effect on the frequency and significance of water level increases and, perhaps, an impact on superficial landslides," Locat said.Ībout 40 per cent of landslides in Quebec's St. Locat said two factors lead to superficial landslides: erosion of soil at the bottom of slopes - caused by water but also human activity - which makes them more steep, and saturation of the soil at the top of slopes, which causes material to slide downward. Quebec risks having more "superficial landslides," Locat said, which generally involve soil conditions that are particularly susceptible to erosion and to being rapidly saturated with water. That landslide, Locat said, appears to have been caused by erosion along the Éternité River and saturation of the embankment above the river, both of which triggered sandy material on top of the clay soil to slide downward. On Saturday, torrential rain in Quebec's Saguenay-Lac-St-Jean region contributed to several landslides, including one that led to the death of two people. "The impact of climate change on landslides in Quebec will be mainly related to precipitation," Locat, co-founder of a research laboratory at the university that studies natural risks, said in a recent interview.
His research suggests that increase in precipitation, coupled with an expected rise in extreme rain events, will make the occurrence of landslides in the province more likely. Jacques Locat, a professor emeritus at Université Laval, says climate change models predict that southern Quebec will receive between five per cent and 14 per cent more rain by 2050. MONTREAL - Climate change is likely to increase the frequency of weather events that cause landslides in Quebec, like the one that killed two people a week ago in the Saguenay-Lac-St-Jean region, said a researcher who studies natural risks.
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