NGU's approach for the systematic mapping of unstable rock slopes

The determination of hazard and risk level follows a standard approach for the systematic mapping of unstable rock slopes. The goal of this approach is to filter out low-risk sites at an early stage and focus more detailed investigations on potential medium- and high-risk sites.

Figure: Displacement measurements are carried out only on potential medium and high risk sites.

NGU has, since 2005, systematically mapped unstable rock slopes that could cause rock avalanches. The goal of this ongoing mapping activity is to find all rock slopes that could fail catastrophically and to identify areas that could be affected by their failure, in order to communicate possible consequences to the Norwegian society. Since the beginning of 2013, mapping activities have focused on collecting information to be used for the implementation of a hazard and risk classification system recently developed by a team of Norwegian and international experts. The application of this classification system has allowed the development of a systematic mapping approach. Within this approach, low-risk sites are ruled out at an early stage in order to reduce the amount of work and costs of the mapping program, while creating essential knowledge for society. More detailed investigations and displacement measurements focus on potential medium- and high-risk sites only. Therefore, this mapping approach guarantees a similar level of geological information for all unstable rock slopes with the same risk level over the entire country.

  • NGU report 2012.029


Arbeidsflytsdiagrammet viser framgangsmåten for undersøkelser av ustabile fjellpartier.
Work flow diagram for site investigations of unstable rock slopes.