NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-10-159-2010 A simple qualitative approach for mapping regional landslide susceptibility in the Faroe Islands Dahl M.-P. J. 1 2 Mortensen L. E. 2 Veihe A. 1 Jensen N. H. 1 Department of Environmental, Social and Spatial Change, Roskilde University, Universitetsvej 1, P.O. Box 260, 4000 Roskilde, Denmark Jarðfeingi (Faroese Earth and Energy Directorate), Brekkutun 1, 0110 Tórshavn, Faroe Islands 01 02 2010 10 2 159 170 Copyright: © 2010 M.-P. J. Dahl et al. 2010 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://nhess.copernicus.org/articles/10/159/2010/nhess-10-159-2010.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/10/159/2010/nhess-10-159-2010.pdf

The Faroe Islands in the North Atlantic Ocean are highly susceptible to landslides. Following recent landslide incidents, Jarðfeingi (Faroese Earth and Energy Directorate) has pointed out, that the risk of human lives or of property being lost or affected by landslides may be increasing. This paper aims at presenting and testing a simple qualitative approach for mapping regional landslide susceptibility in the Faroe Islands, using few key parameters. The susceptibility model holds information about both landslide initiation areas and runout zones. Landslide initiation areas are determined from slope angle thresholds (25°–40°) and soil cover data, while runout zones are delineated using the angle of reach approach taking into account the presence/absence of geological benches in the runout path, which has not been considered in earlier studies. Data input is obtained from a landslide database containing 67 debris flows throughout the Faroe Islands. Angle of reach values differ significantly with the presence/absence of geological benches in the runout path. Two values of angle of reach, 21.5° and 27.6°, are used for calculating runout zones. The landslide susceptibility model is tested in a study area at the town of Klaksvík in the northern part of the Faroe Islands. A map validation comparing predicted susceptibility zones with a validation-dataset of 87 actual landslides in the study area reveal that 69% and 92%, respectively, of actual landslide initiation areas and runout zones are correctly predicted. Moreover 87% of the actual landslides are included in the overall predicted landslide susceptibility areas.

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