Seismic profiles and sediment cores from sixteen fjords and five lakes in western Norway have been investigated in a search for Holocene massmovement deposits. Tsunami deposits caused by the Storegga Slide (8200 cal. BP) are observed over most of the investigated area, both in fjords and in lakes. Five fjords provide evidence for a 2000-2200 cal. BP mass-movement event. Debris flow deposits and turbidites related to that event occur in Sunnmøre and Sunnfjord, suggesting triggering by one or more earthquakes close to the coast or on land. Similar mass-movement deposits occur in the same geographical area at 11 000-11 700 cal. BP. A period of debris flows, turbidity currents and snow avalanches, interpreted to be related to climatic irregularities, occurred around 2800-3200 cal. BP. Such events are recorded also from other periods, e.g. 1700-1800 cal. BP and 5300-5600 cal. BP, but they only occur in a few basins, and were thus probably related to local weather irregularities rather than regional climatic changes.
Postglacial mass movements and their causes in fjords and lakes in western Norway