Shallow landslides and their dynamics in coastal and deepwater environments, Norway

Abstract

In this manuscript, we present the first results of integrated slope stability studies to investigate smaller-scale mass movement processes in different physiographic settings of Norway. These include coastal areas (Sørfjord, Finneidfjord), and pristine open ocean settings in intermediate (Vesterålen) and deep waters (Lofoten) on the Norwegian margin. Triggers, pre-conditioning factors and sedimentary processes associated with these landslides are currently not well constrained. The landslides occur either in clusters or isolated, and have variable geomorpho- logic expressions and run-out. These smaller landslides appear to be comparatively recent phenomena. However, failures likely happened repeatedly and recurrence may affect coastal communities or jeopardize offshore installations. New data indicate that the landslides developed within thin, gently-dipping sediment units that served as slip planes. Some soil samples from these units may show strain-softening behaviour, higher plasticity and higher sensitivity compared to other units. The slide-prone layers in Sørfjord can furthermore be related to specific depositional processes. Shallow gas - Although clearly present in Sørfjord - is not considered a key factor. © Springer Science+Business Media B.V. 2012.