Field studies of unstable slopes in Sunndalen Valley
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Following a helicopter survey of the slopes along the Sunndalen valley and the surroundings in spring 2007, four sites have been selected for further field studies. Two sites, (Gikling and Ottem), were mapped during summer 2007. GPS points for yearly monitoring were emplaced at Gikling. The volume of the unstable slope may be as much as 100 Mm3. At Ottem, a slope instability of about 2 Mm3 was mapped in detail. Scree deposits comprising large blocks along the slope are also unstable. GPS monitoring points were selected at Ottem and will be set out in 2008. Also at Ottem, another larger zone has been observed on aerial photographs. Gravitational fractures appear to have developed along a fold hinge at the edge of the high plateau. This zone should be checked in 2008. The two other sites (Hårstad and Ivasnasen) have been initially examined from their toe zone; detailed field mapping will be undertaken in 2008. The estimated unstable volumes at these two sites are about 5 Mm3. A fifth site called Vollan has been observed on aerial photographs during winter 2007\/2008. The deformed area may cover a large area of 1 to 2 km2 and field investigations of this area are necessary in 2008.