Landslides debris slides

There are two broad causes of mass wasting. One is a sudden failure of the slope sending loosened debris sliding, rolling, falling or slumping down hill and the other is a process called sediment flow where the debris flows down the slope mixed with water or air. Vames (1978) further classified landslides by the type of movement and type of material involved as shown in Table 2.14. 

Slope movements (SM). Slope movements, including underwater landslides, consider a wide variety of gravitational slope processes such as rockfaUs, debris falls, and toppling rock or debris slides, avalanches, and mudslides debris-, earth-, and mudflows and sackungen, complex landslides, and eventually lateral spreads. This category may show up at intensity IV and saturate (i.e., their size does not increase)... 

The criteria used in the description of landslides (Cruden Varnes 1996) follow Varnes (1978) in emphasizing material and movement. A landslide can be described by a word describing the material and a second word describing the type of movement. The major divisions of materials are unchanged from Varnes (1978) rock, debris and earth. Movements have again been divided into five types falls, flows, slides, spreads and topples. 

Often the context implies a particular value of a descriptor, which may then be omitted or descriptors may be dropped if they are not relevant. Second or subsequent movements in complex or composite landslides can be described by repeating terms. Descriptors, which are the same as those for the first movement, may then be omitted from the name. The Frank Shde, for instance, was a complex, extremely rapid, dry rock-fad debris-flow. The type of material may be connected to its type of movement by a hyphen as in debris-flow or left unhyphenated when there is no ambiguity as in the Frank rock fall. The sequence of types of movement, fall then flow, indicates the sequence of movements in the landslide the addition of the complex descriptor to the name distinguishes the landslide from a composite rock-fall debris-flow. The full name of the Frank Slide as given above, implies that the debris flow was both extremely... 

The UNESCO Working Party s definition of a landslide is the movement of a mass of rock, earth or debris down a slope (Cruden, 1991,1997) and recognizes that the phenomena described as landslides are not limited either to the land or to sliding the word has a much more extensive meaning than its... 

In this article, landslide is used as a generic term to include all types of downslope movement of earth material, including types of movement that involve little or no true sliding. Thus, rock falls, debris flows, etc., are considered types of landslides. The classification system of Vames (1978) is used, which categorizes landslides by the type of material involved (soil or rock) and by the type of movement (falls, topples, slides, slumps, flows, or spreads). Other modifiers commonly are used to indicate velocity of movement, degree of internal disruption, state of activity, and moisture content. 

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