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A slump is a form of mass wasting that occurs when a coherent mass of loosely consolidated materials or a rock layer moves a short distance down a slope. [1] Movement is characterized by sliding along a concave-upward or planar surface.
Mass wasting, also known as mass movement, [1] is a general term for the movement of rock or soil down slopes under the force of gravity. It differs from other processes of erosion in that the debris transported by mass wasting is not entrained in a moving medium, such as water, wind, or ice.
Amongst these erosional properties, water is arguably the most effective geologic agent that causes mass-wasting events to occur. Water aids in the downslope movement of surface material by adding weight to the soil and by filling pores which tends to push apart individual grains, decreasing the resistance of the material to movement. [4]
At volcanoes, the term landslide is commonly used for slope movements with shear and displacement in a relatively narrow zone. [7] They can be in the form of debris avalanches, debris flows, slumps and rockfalls. [7] [8] A debris avalanche is a sudden, very rapid flow of rock and soil in response to gravity. It is a common middle stage in the ...
Cracks can also form in the Sherack Formation, causing weakness in the underlying clay, and slumping. The exposed contact between the formations (commonly in the Red River area), and thus the inherent weakness at this contact, causes mass wasting of the river bank. [11] Human activity near the banks of the river then increases failure risks. [1]
Movement is driven by shear stress, which is generated by the mass of the block acting under gravity down the slope. Resistance to movement is the result of the normal load. When the slope fills with water, the fluid pressure provides the block with buoyancy, reducing the resistance to movement.
In 1978, geologist David Varnes noted this imprecise usage and proposed a new, much tighter scheme for the classification of mass movements and subsidence processes. [26] This scheme was later modified by Cruden and Varnes in 1996, [ 27 ] and refined by Hutchinson (1988), [ 28 ] Hungr et al. (2001), [ 29 ] and finally by Hungr, Leroueil and ...
Its speed can range from being barely noticeable to rapid movement. The velocity of the flow is dictated by water content: the higher the water content is, the higher the velocity will be. [ 1 ] Because of the dependency on water content for the velocity of the flow, it can take minutes or years for the materials to move down the slope.