RECONSTRUCTING COMPLEX MOVEMENT AT THE MINK CREEK LANDSLIDE USING DETAILED TERRAIN MODELS

The Mink Creek landslide occurred in sensitive glaciomarine clays in northwestern British Columbia in 1993/94. The landslide involved some 2.5 million cubic meters of material and had a travel distance of 2.5 degrees. We reconstruct this movement by analyzing changes in Janbu's stability number between various ground surfaces and rupture surfaces. We support our reconstructions with shear strength, sediment characteristics and morphological observations. The landslide involved complex spreading, flowing, and vertical subsidence along various rupture surfaces. Distinctions between spreading and flowing are consistent with our modelled changes in the stability number governed by variable heights between rupture surfaces and ground surfaces. Ultimately, a reduction in this height along a sloping rupture surface was sufficient to reach a threshold between translational and rotational sliding. Once this threshold was achieved further retrogression of the landslide became impossible.