|
mass movement
|
A downhill movement of soil or fractured rock under the force of gravity.
|
|
|
detritus
|
Loose rock or mineral material that is dislodged from bedrock by mechanical means and transported from its place of origin.
|
|
|
earthflow
|
A detachment of soil and broken rock and its subsequent downslope movement at slow or moderate rates in a stream- or tongue like form.
|
|
|
mudflow
|
A flow of water-saturated earth material possessing a high degree of fluidity during movement. A less-saturated flowing mass is often called a debris flow. A mudflow originating on the flank of a volcano is properly called a lahar.
|
|
|
avalanche
|
A large mass of material falling or sliding rapidly due to the force of gravity. In many cases, water acts as a catalyst and/or lubricant. Avalanches often are classified by what is moving, such as a snow, ice, soil, or rock avalanche. A mixture of these materials is commonly called a debris flow.
|
|
|
debris avalanche
|
A flow of unsorted masses of rock and other material downslope under the influence of gravity. Water is commonly involved as a catalyst and/or lubricant. For example, a rapid mass movement that included fragmented cold and hot volcanic rock, water, snow, glacial ice, trees and other debris and hot pyroclastic material was associated with the May 18 1980 eruption of Mt. St. Helens. Most of the deposits in the upper valley of the North Fork Toutle River and in the vicinity of Spirit Lake are from the debris avalanche resulting from the eruption.
|
|
|
landslide
|
An abrupt movement of soil and bedrock downhill in response to gravity. Landslides can be triggered by an earthquake or other natural causes. Undersea landslide can cause tsunami.
|
|
|
debris flow
|
A type of landslide made up of a mixture of water-saturated rock debris and soil with a consistency similar to wet cement. Debris flows move rapidly downslope under the influence of gravity. Sometimes referred to as earth flows or mud flows.
|
|
|
rockslide
|
A landslide involving mainly large blocks of detached bedrock with little or no soil or sand.
|
|
|
slump
|
A type of landslide in which a mass of rock breaks away along a curved surface and rotates more or less intact downslope. The sliding mass of rock is called a slump block.
|
|
|
slump block
|
See slump
|
|
|
rockfall
|
Falling, bouncing, and rolling of debris down slope.
|
|
