Mass Movements Flashcards
(33 cards)
Free fall
- Material detaches from a slope and then free falls through the air, or bounces and rolls downslope
Slide
- Material (either rock or regality) that slides along a surface of rupture
Flow
Continuous movement of rock, regolith, or both that behaves as a high viscosity liquid
Rock falls are…
extremely rapid
Debris/earth falls are..
Rapid to extremely rapid
Rock slides are…
Very slow to extremely rapid
Debris/earth slides are…
Very slow to very rapid
Rock slumps are…
Extremely slow to moderate
Debris/earth slumps are…
Very slow to very rapid
Distinguishing the speed of motion:
- Slow (cree
What factors make up the criteria for the classification scheme or mass movements?
- Nature of the mixture of solids (rock, debris, or earth materials)
- Type of motion (fall, slide or flow)
- Velocity of motion (avalanche, flow, or creep)
Creep
Is slow and only detected by dislocation or bending of features at the surface
Debris Avalanches:
Are very rapid flows of rock, regolith, vegetation and/or sometimes ice
Flow
Are the continuous movements of rock, regolith, or both which behaves like a high viscosity liquid. Flow occurs on different scales
Rock creep:
Is extremely slow to slow (slow flows)
Debris/earth creep:
Is extremely slow to slow
Debris/earth flow:
Is very rapid
Debris avalanche (rock and regolith):
Is very rapid to extremely rapid
When are rock falls common?
They are common where rock is highly jointed and on a steep slope
Talus
Is the loose material that piles up at the base of steep slopes. Lack of vegetation/soil on talus indicates that material is actively accumulating
Planar slides:
Move downslope in contact with a surface of rupture, typically along bedding planes, foliation, or joint planes oriented parallel to the slope
Slump:
Is the curved rotational slide surfaces that are scoop shaped and usually form in regolith, poorly consolidated, or weak rock where bedding/joints do not influence failure
What forces AFFECT slope stability?
- Gravity force
- Friction
- Cohesion
Gravity force:
In order for motion to happen, the gravity force parallel to the surface must be greater than the resisting strength