Summary
Stiksmoen is located on a west-facing slope at approximately 120 m a.s.l. in the southern end of
Aurlandfjord (Flåm municipality, Vestland county). The unstable rock slope is bounded by a well-developed backscarp, wide open in the north and open but less developed in the southern sector. The lower
limit is mapped close to the foot of the frontal cliff of the unstable rock mass. The upper and central part
of the instability is characterized by the presence of several open cracks, 10 to 15 meters deep. High
rockfall activity is observed in the frontal cliff, with the detached blocks forming a block field. Structural
and geophysical surveys allowed for the reconstruction of the sliding surface of Stiksmoen and the
computation of its volume (ca. 0.4 million m³). Extensometers, dGNSS, ground-based and satellite-based
radar measurements show similar displacement rates in the upper-central part and on the lower-frontal part
of the unstable rock mass. The obtained displacement rates range from 0.9-2.5 cm/y towards the west, with
a dip of ca. 30°. The degree of development of the Stiksmoen unstable rock slope, its structural
characteristics and displacement rate result in a high hazard level. A sudden collapse of the whole unstable
rock mass would result in rocks propagating mostly towards the fjord and a small proportion in WSW
direction (towards Viki). The direct impact of the rock mass into the fjord would cause a displacement
wave that could result in the loss of lives. The high hazard level and the potential consequences in the
direct and secondary impact area result in a high-risk level for Stiksmoen.
