ABSTRACT
The Nipigon River landslide was a retrogressive slide that occurred in Northern Ontario, Canada. This landslide is similar in form to those widely reported in Eastern Canada and the Scandinavia countries. However, while those landslides occurred in highly sensitive clays of marine origin, the Nipigon River landslide involved lacustrine silty soils of moderate sensitivity. The landslide was triggered by an initial slide primarily caused by a rise in the groundwater regime in a weak soil. The mechanisms of the subsequent retrogressive landslide have been investigated using existing theories. The investigation shows that application of theories largely derived from experience with marine soils is inadequate. They tend to underestimate the potential of landslide occurrence and the landslide regression distance involving soils of lacustrine origin. Static soil liquefaction is suggested to explain the underestimation.
