ABSTRACT
Unstable rock slopes that can cause large failures of the rock-avalanche type have been mapped in Norway for almost two decades. Five sites have been previously characterized as high-risk sites based on the expertise of a few researchers. Although more than 250 other sites are known, of which 90 are subjects of periodic displacement measurements, most have not been classified according to hazard or risk. A hazard and risk classification system for unstable rock slopes in Norway was established in 2012 with a related, targeted mapping approach adapted in 2013. This study presents the results of the hazard, consequence and risk classification of the first 22 unstable rock slopes, comprising 48 different failure scenarios from northern, western and southern Norway. These first 22 sites were selected based upon estimated highest risk levels and large attention in the Norwegian public. The hazard level of these 48 failure scenarios varies from low to very high, whereas their consequences range from 0 to 3000 possible casualties. The resulting risk classifications span from low to high risk.
