The unstable rock slope above the village of Flåm shows signs of active
and postglacial gravitational deformation over an area of 11 km2.
We performed detailed structural field mapping, annual differential
Global Navigation Satellite System (GNSS) surveys, and generated
a detailed topographic model based on airborne and terrestrial laser
scanning. Kinematic analyses of the structural data indicates that
deformation is complex and varies over the slope. Both sliding and
toppling are locally feasible. Using differential GNSS, 18 points
were measured annually over a period of up to 6 years. Two of these
points show an average yearly movement of around 10 mm/year. They
are located at the frontal cliff on almost completely detached blocks.
Large fractures indicate deep-seated gravitational deformation of
volumes up to 80 million m3, but the movement rates in these areas
are below 2 mm/year. Based upon these combined observations, we interpret
that small collapses of blocks along the frontal cliff will be more
frequent. Larger collapses of free-standing blocks along the cliff
with volumes >100,000 m3, thus large enough to reach the fjord, cannot
be ruled out. A large collapse involving more than 10 million m3,
however, is of very low likelihood at present.