A multi-scale resolution of snow-avalanche activity based on geomorphological investigations at Fnjóskadalur, northern Iceland

Abstract

The article describes investigations that highlight snow-avalanche events that have not been reported in historical records. While historical sources are most often the basis for all natural hazard and risk research, alternative methods based on geomorphic investigations are often neglected. Here, we emphasise the use of geomorphic evidence to improve our knowledge of the maximum runout distance reached by snow avalanches as well as the frequency of the events. Investigations were carried out in remote, avalanche-prone areas, where the geomorphic evidence has not been disturbed or removed. Dendrogeomorphic investigations supply annual resolved records of avalanche winters up to the age of the investigated tree stand: over 120 years in northern Iceland. The study of snow-avalanche transported debris may be used to map the extent of the potential snow-avalanche deposition zone, and offer relative dating on a secular scale; stratigraphic profiles do provide results on long timescales, but only provide relative dating. The article discusses the relevance of each method, and concludes that the combination of the three methods can improve the common risk-mitigation approach based on historical records.