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Chapter 6: Landslides

Terms in this set (29)

rock avalanche
a type of landslide involving sudden failure of a large mass of rock that rapidly fragments and travels as a streaming mass at high speeds
cause
an internal or external factor that, over time, reduces the stability of a slope and brings it to the point of failure
trigger
is an event that sets off the landslide; it can be considered the final straw
the mechanism of movement, the type of material, the amount of water present, the rate of movement
name the four important variables that classify most landslides
fall
involves bounding of rocks or blocks of sediment from the face of a cliff
slide
downslope movement of a coherent block of rock or sediment along a discrete failure plane
slump
a particular type of slide in which the failure plane is curved upwards
flow
the slow to rapid downslope movement of sediment in which particles move semi-independently of one another
debris flows
mixtures of mud, debris, and water, going down a slope
creep
very slow flow of rock or sediment, at rates ranging from millimetres to dozens of centimetres per year
sackung
a type of slow-moving creep landslides involving movement of large masses of rock
topple
a slow creep-like movement in which a rock mass pivots about a joint
subaqueous (submarine) landslides
underwater landslides
slip plane
surfaces of weakness in the slope material
computing a factor of safety (FS), defined as the ratio of the resisting forces to the driving forces; if the FS is great than 1, the resisting forces exceed the driving forces and the slope is considered stable
slope stability is evaluated by what? when is it considered stable?
type of material, slope angle and topography, climate, vegetation, water, time
driving the resisting forces on slopes are determined by what variables?
v^2 = 2gh
velocity-potential energy equation
rotational and translational
what are the two basic patterns of movements in slides
urbanization and development will increasingly expand into landslide-prone areas, tree cutting will continue in landslide-prone areas, changing global climate patterns will result in increases in precipitation in some regions
3 factors expected to increase landslide incidence and risk are what?
lacustrine and marine silts and clays, Cretaceous shales, and Quaternary volcanic rocks
which Earth materials are particularly prone to landslides?
debris avalanches, debris flows, and earthflows
timber harvesting creates which kinds of landslides?
gabions
steel wire mesh filled with boulders used in coastal defences.
angle of repose; fine sand 35 degrees, coarse sand 40 degrees, angular pebbles 45 degrees
unconsolidated materials cone shape and their degrees?
rotational landslide, translational landslide, block slide, rockfall, topple, debris flow, debris avalanche, earth flow, creep
list the 9 pictures of landslide movements
solifuction
the flow of soil during a thaw cycle from high to lower elevation
leda clay
a sensitive deposit found in Ontario and Quebec, formed 20,000 years ago from melting glaciers and composed of 80% water
IARPCW (identify, avoid, reduce, prevent, control warn)
minimize landslide risk
shotcrete
sprayed cement on mountainsides
human, electrical, tiltmeters, geophones, rain gauges, surveying, satellite
name some landslide warning systems
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