Classification of debris flow phenomena in the Faroe Islands

Abstract

Landslides and debris flow phenomena in particular constitute a threat to human activities in the Faroe Islands. As a contribution to ongoing landslide risk management research, this paper proposes a classification scheme for debris flow phenomena in the Faroe Islands. The scheme, produced through a multidisciplinary study involving geomorphological fieldwork and qualitative collection of indigenous landslide knowledge, presents physical characteristics to classify debris flow phenomena into groups named with Faroese terms. The following landslide definitions are proposed. Brekku-skriðulop (English translation: hillslope debris flow): a very rapid to extremely rapid non-channelised downslope movement of remoulded colluvium and eventually fragmented rock, initiated as a debris slide in colluvial soil (type 1) or from rock fall (type 2). Áar-skriðulop (English translation: channelised debris flow): a very rapid to extremely rapid channelised downslope movement of remoulded colluvium and/or talus/fluvial material and eventually fragmented rock, initiated as a debris slide in colluvial soil (type 1), from rock fall (type 2) or from mobilisation of talus/fluvial material (type 3). The scheme, which is compatible with international landslide classification systems, significantly increases the knowledge of debris flow phenomena and promotes a consistent terminology of these within the Faroe Islands.

Keywords:

• landslide classification
• Faroe Islands
• debris flows
• debris avalanches
• landslide risk
• indigenous knowledge

Acknowledgements

This study has been funded by Roskilde University, Jarðfeingi (Faroese Earth and Energy Directorate) and the Danish Agency for Science Technology and Innovation, Case number 09-063155. Pictures were kindly provided by the Faroese Office of Public Works and Margreta Clementsen. Furthermore, the authors wish to thank Ritta Bitsch for making graphical preparations and Paul Thorn for providing valuable comments.