A continuous, high-resolution 8500-yr snow-avalanche record from western Norway

Abstract

A record of Holocene snow-avalanche activity has been reconstructed from the presence of coarse (>1 mm) minerogenic particles in lake sediment cores retrieved from Vanndalsvatnet in western Norway. At this site, snow avalanches bring minerogenic debris and macroscopic plant remains from the adjacent valley side south of the lake onto the lake ice. When the lake ice melts during late spring, the debris sinks to the lake bottom. A flux record of the number of minerogenic particles >1mm per unit time, obtained by combining two sediment cores from the lake, shows a significant increase in snow-avalanche activity after ~2000 cal. BP. Prior to that, periods with enhanced snow-avalanche activity around the lake occurred ~8500-8300, 8200-7900, 7300-6300, 5900-5400, 5000-4600, 3700-3400, 3100-2800, 2700-2600 and 2500-2300 cal. BP. The snow-avalanche record from western Norway has been compared with a record of Holocene snow-avalanche activity in the Møre area in western Norway, a record of Holocene river floods in eastern Norway, and Holocene debris-flow events in southern Norway. Knowledge of the past magnitude and frequency of extreme weather events, such as snow avalanches, may help making climate model simulations and scenarios of extreme weather events more reliable.