Submarine chutes on the slopes of fjord deltas

Abstract

The first side-scan sonograph images of submarine landslide chutes from arctic fjords presented here indicate that submarine slopes of fjord head deltas are subject to instability. The chutes transport sediment from the upper delta slopes into deeper water parts of the fjords. Previously, sediment distribution and budgets in the bottom of deepwater fjords were ascribed to settling of suspended sediment supplied by streams and rivers during the short summer melt period. Previous descriptions of submarine mass movements from some subarctic fjords have been limited to isolated major catastrophic events. The sonographs from an arctic fjord suggest that delta-front instability occurs as multiple small-scale events that recur at frequent intervals and are intrinsic to the fjord sedimentation system.