Alpine Debris Flows in Northern Scandinavia

ABSTRACT

The effects of an extreme rainfall triggering debris flows (mudflows) in the mountains S of Abisko, N Sweden, in 1979, are evaluated with regard to geomorphological impact. Several older events of debris flows in the same area during postglacial time are evident in the morphology of the slopes. Where such flows have occurred repeatedly, debris accumulations superficially similar to alluvial cones and referred to as debris flow cones are built. An attempt at dating old flows by means of lichenometry indicated at least four earlier events within the last 2700 years in Nissunvagge. A map of the spatial pattern of known rainfall-triggered mass movements in northern Lappland is presented to support the hypothesis of geomorphic impact of extreme rainfall in three area size classes called regions, cells and spots.