Hazards posed by large mass movements at Mount Meager volcano, Canada

Large mass movements at volcanoes are major hazards. A volcanic collapse can transform into a highly mobile debris avalanche and travel long distances with devastating effects far from the volcanic edifice. Removal of large volumes of rock from a volcano by landsliding can decompress the magmatic system and trigger an eruption. Mount Meager is an unstable complex of young volcanoes in southwestern British Columbia, Canada. It is considered to be one of the most geologically active areas in Canada, with a long record of historic and pre-historic landslides and a large eruption about 2430 years ago. During the summer of 2010, the south flank of Mount Meager collapsed, generating a 53 million m3 debris avalanche, the largest historical landslide in Canada. From air photo analysis and field mapping, we documented 60 years of deformation prior to the event, characterized by a transition from slow …