A structural investigation of the Hope Slide, British Columbia, using terrestrial photogrammetry and rock mass characterization

On the 9th January 1965, from the southwestern slope of Johnson ridge, 150 km west of Vancouver, approximately 15 km from Hope along the BC Highway 3, a 44 million m3 rock slide fell in two separate events, between 4 am and 7 am (VON SACKEN, 1991); the movement assumed the behavior of a rock avalanche. The sliding mass fell down, filling the Outram Lake, destroying and burying several km of the BC highway 3, sweeping away and killing four people, which were unfortunately never found. As a result of the slide, the valley floor was raised of about 70 m with respect to the original topography. Hope Slide represents the major historical rock avalanche in Canada. This work summarizes the results of a geological, structural and geomorphological survey of Hope Slide, obtained with long-range terrestrial digital photogrammetry (TDP) which allows, through the elaboration of pairs of images, the building of tridimensional models of the object.