mass movement - exam 1 Flashcards
(31 cards)
the downslope movement of rock, regolith, and soil under the direct influence of gravity
mass movement
cause the slope to cross the threshold from stability to instability. not the sole cause of a mass movement event, just the last factor
a trigger
the steepest angle at which an accumulation of granular particles remains stable
angle of repose
intense ground shaking during earthquakes can cause water saturated surface materials to lose their strength and behave as fluid like masses that flow, this process is called
liquefaction
the different ways material move during mass movement
fall
slide
flow
when the movement in a mass movement event involves the free fall of detached individual pieces, it is termed a
fall
mass movements in which there is a distinct zone of weakness separating the side material from the more stable underlying material
slide
the most rapid type of mass movement is
rock avalanches
a slide in which the surface of a rupture is a concave upward curve resembling the shape of a spoon and the descending material exhibits a downward and outward rotation
rotational slide
a slide in which a mass of material moves along relatively flat surfaces such as joints, faults, or bedding planes. such slides exhibit little rotation or backward tilting
translational slide
the term used to describe material that moves downslope as a viscous, often turbulent, fluid
flow
most flows are saturated with water and typically move as
lobes or tongues
often, flows of saturated mud and debris are incorrectly labeled
mudslides
the downward sliding of a mass of rock or unconsolidated material that moves as a unit along a curved surface
slump
slump is an example of a
rotational slide
slump commonly occurs because a slope has been
oversteepened
occurs when blocks of bedrock break lose and slide down a slope
rockslide
occurs when blocks of largely unconsolidated material break lose and slide down a slope
debris slide
debris flows are sometimes called ____ ____ when the material is primarily fine grained
mud flows
a relatively rapid type of mass movement that involves a flow of soil and regolith containing a large amount of water
debris flow
debris flows composed mostly of volcanic materials on the flanks of volcanoes are called
lahars
the repeated expansion and contraction of the surface material causes a net downslope migration of soil and rock particles
creep
-increased water
-undercutting of slope
-human causes
-earthquakes
-volcanoes
factors that initiate rapid mass wasting processes
ground that remains permanently frozen for many years
permafrost
