Slope-failure Analysis and Classification: Review of a Century of Effort

The geoscience literature is replete with bewildering descriptions and classifications resulting from a century of analysis of gravitative transfer of materials downslope. The complexity of mass-movement phenomena has led to a profusion of confusing terminology that this paper attempts to clarify. International recognition of the hazard to life and property posed by slope failure highlights the need for increased precision in its description in a quest for prediction, control, and remediation of the diverse phenomena. The most useful classifications are those that employ as their primary criteria the type of movement (e.g., fall, topple, slide, spread, flow) and the type of material (e.g., rock, debris, earth) involved, with secondary considerations of velocity and the amount and phase of H2O. Recently, interest has focused on the massive, subaqueous failures that can generate huge tsunamis, as well as the massive, dangerous collapses of volcanoes. Future slopefailure research is expected to incorporate quantitative and geotechnical assessments of process mechanics, including remote sensing, numerical indices and modeling, and advanced assessments of flow rheology.