Geotechnical and geomorphological analyses of landslide risks and proposing Saint-Jean-Vianney as a UNESCO-recognized GeoRisk site

The territory surrounding Saint-Jean-Vianney includes two catastrophic landslides that occurred in 1663 and 1971. Stabilization work immediately after the 1971 landslide has ensured the site’s present security. In particular, a set of gabions maintain the level of the Aux Vases River upstream of the 1971 landslide and remain key to site security. However, are they well maintained? Moreover, the mechanisms of these landslides remain poorly understood, in particular the possible role of groundwater in triggering these events. It is therefore difficult to assess when the boundary conditions for the next major landslide will be reached or whether Highway 172, located a few hundred metres north of the 1971 landslide, will be impacted. Plans by the City of Saguenay to establish a geotourism park in this area provide sufficient justification to undertake new studies focused on the safety of the site before setting up this geopark. Thus, the first part of the project is to evaluate landslide risk at this site. The second part will evaluate the possibility of having Saint-Jean-Vianney recognized as a GeoRisk (GeoHazard) site by governmental and world authorities (UNESCO).