Landslides

Geohazards are natural processes that occur on Earth that society has to adapt to. Due to Norway's geological history and resulting landscape, landslides are the natural hazard that causes most loss of life and economic loss. Society can adapt to natural hazards by mitigation and prevention. Mapping of the geological and environmental conditions that can lead to landslides is the most essential part of prevention and is carried out at NGU.
Figure 2: A farm was destroyed and a local road interrupted by a debris avalanche on 15 November 2013 in Årsetdalen, Møre og Romsdal county. Luckily nobody was injured or lost his life. Photo: Gro Sandøy, NGU
Figure 2: A farm was destroyed and a local road interrupted by a debris avalanche on 15 November 2013 in Årsetdalen, Møre og Romsdal county. Luckily nobody was injured or lost his life. Photo: Gro Sandøy, NGU

Landslides occur nearly every day in mountain environments. Most of the landslides are not observed or registered because they do not cause any damage or harm. However, they can destroy farmland (Figure 1), damage infrastructure (Figure 2)  and result in injury or even death of people. In Norway, there have been more than 33,000 registered landslides, which have caused more than 1100 casualties.

Jordskred fra Heimgårdsberget den 26. juni 2008 i Signaldalen, Troms fylke. Dette skredet ødela jordbruksland, men stoppet foran gården. Heldigvis ble ingen av innbyggerne skadet. Foto: Iain Henderson, NGU
Figure 1:Debris avalanche from
Heimgårdsberget on June 26th 2008 in
Signaldalen, Troms county.
This slide destroyed farmland but stopped
in front of the farm. Fortunately, the
inhabitants were not injured and escaped
with a fright. Photo Iain Henderson, NGU.
Gruppering av skred som følge av den nasjonale planen for kartlegging av skredfare
Figure 3: Grouping of landslides following the national plan for
landslide hazard mapping.

 

The Norwegian word for landslide "skred" includes all kind of materials including rock, soils of all types, as well as snow and ice (Figure 3). NGU is the national authority for mapping and managing geological data in Norway and hence carries out mapping of geological conditions that might lead to landslides. This work is financed by the Norwegian Water and Energy Directorate (NVE). NGU maps unstable rock slopes that might collapse as rock avalanches, supports rockfall, debris-flow and snow avalanche hazard mapping by landslide-specific Quaternary geological mapping, and also maps areas where marine sediments that can form quick clay landslides. The mapping of submarine landslide deposits and landslide-prone sediments in lakes, fjords and the sea is part of the mapping activities. The landslide team at NGU uses various techniques to support geological field mapping and these techniques are being further developed at NGU. The landslide team (Figure 4) has a broad expertise, cooperates with multiple national and international institutions and carries out method development and research that strongly contributes to NGU's scientific profile.

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The geohazard and earth observation team 2015. (from left); Ivanna Penna, John Dehls, Raymond Eilertsen , Kari Sletten,  Reginald Hermanns, Gro Sandøy, Knut Stalsberg , Martina Böhme, Thierry Oppikofer, Inger Lise Solberg, Paula Hilger, Lena Rubensdotter (
not present when the picture was taken: Anne Liinamaa Dehls). Photo: Raymond Eilertsen, NGU