More details of Lyngen slide
Accident Inspection of Kåfjord landslide - updated
Accident at Sorbmegaise landslide in Alta, where five people died and one survived, was inspected by police, Norwegian People’s Aid and NGI Wednesday 21 March.
NGI representative depicted up to the 2 m high fracture edge in 36 degree slope. (photo on web site)
This is a preliminary description and assessment of some points, after representatives of the police, the Norwegian People’s Aid and NGI Wednesday 21 March inspected the area in the mountains Sorbmegaisa in Djupvik in Alta municipality, where the fatal avalanche occurred on Monday 19 March this year. Comprehensive report with photos and video will come later.
First, finding places at the bottom of the landslide mapped. The 6 people who were taken by the landslide was dispersed by 530 m between the highest and lowest finds place (between contour 674 and 832). The landslide was 50-200 m wide at the site. Measurements showed that the 4 lying at the bottom of the avalanche was buried 3.6 m deep. The two that were far up in the avalanche were buried so deep, and one of them survived.
The avalanche went far past the place and down on a lake where it broke the ice and a mixture of snow and water went any further. Avalanche stopped at ca. contour 600 and walked about 570 meters. Discharge angle was 21.6 degrees. The avalanche was estimated 2 km.
After studies at the bottom of the avalanche was the study group brought to the top of the mountain by helicopter. Stian Edvardsen Kvalsvik (Norwegian People’s Aid) and Kjetil Lien Bratt (NGI) abseil down to one violation of the edge 1170 m (100 m below the top). Fracture edge was here 2 m high and 36 degrees steep terrain. Subsequently, several breaches edges investigated.
The landslide was triggered when a faint and quite loose layer of crystals cup went to break. This layer was about. 5 cm thick and lay between two hard layer. This is a persistent weak layer that the inspection was loose and unstable.
Ski tracks of the group that was taken by the landslide was a traverse to the left (seen from below) just above the 2 m high fracture edge. Ski tracks was 200 m further to the ski tracks to 2 of the skredtatte disappeared when a new breach of border. Fracture edge at this point was only 10 cm thick, but increased rapidly in thickness to ca. 1.5 m Terrenghelningen was here 32 degrees. Bruddforplantningen may have started here and given the avalanche 200-400 m to each side for about the same height level. There are an estimated 20 separate violations edges that are not contiguous in the mountain. Bruddforplantningen meant that the avalanche was very large.
It is believed that those who were taken by the landslide were scattered over the mountainside when the avalanche released. One of the victims had avalanche bag (airbag). He was found near the bottom of the avalanche of 6 m depth was significantly deeper buried than the other.