Chapter 13 Flashcards
block slide
- the mass remains basically coherent
debris slide
- the sliding mass disintegrates
lateral spreading
- the underlying material files and flows, causing the overlying coherent material to break apart
What do you call the process of removing loose rock to prevent rock falls?
- scaling
____ avalanches occur when snow layers develop. _____ avalanches occur when loose, powdery snow accumulates.
- slab
- loose powder
Which construction-related activities can trigger mass movements?
- tunnelling
The downward movement of the ground surface due to compaction or cave collapse is called _____.
- subsidence
What do you call a single mass movement which exhibits characteristics of flows, falls, and slides?
- complex event
Which of the following are used to classify different types of mass movement?
- speed movement
- water content
The law of ______ states that two bodies are attracted to each other with a force directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
- gravity
Which of these ask an example of water acting as an external factor in decreased slope stability?
- rain runoff
Which of the following are external processes that increase the odds of a slope failure?
- addition of mass high on a slope
- slope steepening
- rain runoff
- removal of lower slope support
Which of the following factors contribute to the weakness of quick clays?
- low salt content
- water content above 505
- very fine grained
- weak structure
Clay minerals are typically formed through the process off ____.
- chemical weathering
A clay that loses nearly all of its shear strength after being disturbed is called a ____ clay.
- sensitive
Both snow and earth material start moving in the starting zone where ____.
- slopes are the steepest
Adding buttresses to provide extra support is an effective mitigation strategy in the following cases:
- crumbly rock
- overhanging rock
Underlying ____, such as structural weaknesses, will push a slope to the bring of failure. It takes a ____, such as an earthquake, to make the slope fail.
- causes
- trigger
When engineers cut into the base of a slope to make way for new road, this is an example of a(n) ____ process that increases the likelihood of a slope failure.
- external
The two types of slides are ____ slides, which occur on curved slip surfaces, and ___ slides, which occur on planar surfaces.
- rotational
- translational
Which of the following are types of flow?
- mudflow
- debrisflow
- debris avalanche
- creep
Building sturdy snow sheds built over sections of road vulnerable to avalanches is an example of which mitigation strategy?
- protect against the hazard
The conditions of ra slab avalanche occur when ____.
- a warm, dense layer of snow sits on a cold, low-density layer
- a layer of heavily cemented snow sits on top of loose snow
- two layers of snow are separated by a melt-freeze crust
Which of the following are hardware components designed to reinforce the body of a slide?
- rock bolt
- cylinder pile
You run the greatest risk of getting caught in an avalanche when you ski or snowboard ___.
- in backcountry areas
What is the slowest but most widespread form of slope failure?
- creep
Why do the Canadian Prairies have a high landslide susceptibility index?
- there are loose sediments at the surface of the ground
During a slab avalanche, the sliding slabs will typically break up, transforming the movement from a slide into a ____.
- flow
What kind of mass movement is caused by the liquefaction of sensitive clays?
- lateral spread
What type of mass movements are associated with downward and outward movement?
- slides
- flows
The rupture surface of a rotational slide is _____.
- concave facing upwards
Which of the following are considered to be internal causes of slope failure?
- pore water
- decreasing cohesion
- weak rock
- adverse geologic structures
In what type of snow do loose-powder avalanches typically occur?
- low-cohesion snow
Snow avalanches can be compared to landslides. Loose powder avalanches move like a ___, and slab avalanches move like a _____.
- flow
- slide
A flow is distinguished from a slide in that ____.
- the material in a slide remain relatively intact, whereas the material in a flow moves as a viscous fluid.
When water flows through rocks, it can physically erode loose material to form a network of caverns. This process is known as _____.
- piping
The inherent weaknesses of the materials making up a hillside are collectively thought of as ____ factors controlling slope stability.
- internal
Water that is found within pore space and fractures in rocks is called ____.
- groundwater
What idk the distinctive shape of loose-powder avalanches?
- inverted “V” shape
A _____ is a type of mass movement in which the descending mass remains relatively intact and moves along a curved slip surface.
- rotational slide
______ is the tendency of a body to remain at rest until an external force is applied.
- inertia
Which of these hypotheses proposed to example how long-run out sturzstroms move so far and fast?
- frictional heating within the flow melts some materials
- steam fluidizes the material
- air trapped under the flow acts as a lubricant
- high water content fluidizes the material
Which of the following are factors that can increase the likelihood of a snow avalanche?
- steep slope
- thick accumulation of snow
Which of the following are suggested solutions to the sinking of Venice?
- inflate sands underlying the city by injecting carbon dioxide or seawater
- bring in sediment to raise the ground level
- construct moveable floodgates
Which of the following localities experienced a lateral spread?
- Rissa, Norway
Why does the ground surface of a slope move up and down?
- the soil is constantly swelling and shrinking
The surface that separates the saturated zone (where all void spaces are filled with groundwater) from the unsaturated zone (where void spaces hold both water and air) is called the ____ _____.
- water table
Slow subsidence of the land surface occurs when _____.
- water or oil are pumped from below the ground
Subsidence in Mexico City is caused by ____.
- removal of ground water from below the city.
When sand grains become supersaturated with pressurized water, the water can push the grains apart, leaving them with no strength. When this water-pressurized sand forms on a flat surface or in a depression, it becomes ____ .
- quicksand
Where did Leda clays initially form?
- they deposited in a marine environment
What factors are hypothesized to have contributed to the 1903 Frank Slide?
- mining operations
Which of the following could provide the initial energy that allows a mass of earth or rock to overcome inertia and friction and begin moving downslope?
- heavy rain, earthquake, a bulldozer
What type of mass movement is responsible for the formation of talus slopes?
- falls
When a rotational slide occurs, the head of the slide will typically ____.
- move downward and rotate backwater
Water can weaken a rock by ____ minerals that form the rock’s cement.
- dissolving
What type of mass movements are associated with Leda clays?
- lateral spreads
What triggers most avalanches?
- natural accumulation of snow during or shorty after a snow storm
Overpressurized for water in a pile of sediments can cause slope failure because ____.
- the water will start to move upward, lifting the sediments with it
Why is the popular hypothesis of sturzstroms riding on a cusion of air thought to be unlikely?
- similar events occur not he moon and mars, where Eno or very little air is available
A 100kg boulder rests upon a 40 degree slope. What is the component of the gravitational force perpendicular to the slope acting on the boulder?
- 751N
Sedimentary rocks often have porosities of up to 30%. When the pore spaces are filled with ____, the downward force on the slope increases, which can lead to slope failure.
- water
Which type of snow is cohesive?
- wet snow
- aging snow
the St.Jean-Vianney spread occurred ____.
- in an area where a previous lateral spread had occurred
What criterion is used to rank snow avalanches?
- mass of snow displaced
The Cap-Aux-Diamants cliff in Quebec City is prone to rock falls because of ____.
- the presence of vertical crevices in the rock
Before a boulder or mass of debris can move downhill, the effects of ___ must be overcome.
- inertia and friction
Which of the following would be indicators that creep is occurring on a hill slope?
- bedrock layers deformed downslope
- telephone poles leaning downslope
- bent tree trunks
A 100kg boulder rests upon a 40 degree slope. What is the driving force acting on the boulder?
- 630N
When pressure is applied to a pile of sediments, the grains will pack together more tightly, taking up less volume. Water, however, simply stores the pressure. Why is this?
- water is nearly incompressible
What is the smallest size of avalanches called?
- sluff
What do you call the mechanical disintegration of rock by repeated freeze-thaw cycles?
- congelifraction
What do you call the mass movement caused by the thawing of the top layer of permafrost?
- gelifluction
An important clue to how a sturzstroms can travel so fast and far come from the Elm event in Switzerland. It was observed that chunks of debris ____.
- maintained their relative positions instead of becoming jumbled by the flow.
Following the deadly 1910 avalanche, how has the risk of snow avalanches in Rogers Pass been mitigated?
- a tunnel has been built to avoid the part of the pass the most prone to avalanches
What is the working principle of the avalanche flotation bag system?
- the bag inflates and helps the user to stay near the snow surface
What type of mass movement is the 1903 Frank slide?
- debris avalanche
What should you do if you are caught in a rip current?
- swim parallel to the shoreline
Most mass-movement fatalities are caused by events that
- are fast moving
Which of these are examples of pre-existing geologic conditions that can cause a slope to be weak?
- ancient slide surfaces
- a clay layer parallel to the slope surface
- daylight bedding
- a fault surface
acoustic fluidization
- a theorized process where sound waves trapped inside a dry, fallen mass lessen internal friction to enable fluid-like flow.
bedrock
- solid rock lying beneath loose soil or unconsolidated sediment
carbonic acid
- a common but weak acid (H2C03) formed by carbon dioxide (CO2) dissolving in water (H2O).
chemical weathering
- the decomposition of rock sunder attack of base or acid-laden waters
Clay minerals
- very small (under 0.0039o mm in diameter) minerals with sheet or book-like internal crystalline structure. Many varieties absorb water or ions into their structure, causing swelling.
cohesion
- a property of sediments where particles stick together
congelifraction
- the mechanical disintegration of rock due to the pressure exerted by the freezing of water contained in pores, fractures, and/or bedding planes
creep
- the low, gradual, more or less continuous movement of ice and soil under gravity
debris flow
- loose sediment plus water that is pulled downslope directly by gravity
falls
- mass movements where the bodies move downward nearly vertically under the influence of gravity
flows
- mass movements were the moving bodies of material behave like a fluid
friction
- the resistance to motion of two bodies in contact
groundwater
- the volume of water that has soaked the subsurface, filling fractures with other pores
lateral spread
- a translational slide in which a subsurface layer behaves like a fluid, causing the overlying material to move down gentle slopes
limestone
- a sedimentary rock composed mostly of calcium carbonate (CaCO3), usually precipitated form warm saline water. Limestone on continents may later be dissolved by acidic groundwater to form caves
mass movements
- the large-scale transfers of materials downslope under the pull of gravity
permafrost
- soil or rock that remains frozen throughout the year
pore-water pressures
- pressure buildups in groundwater that offset part of the weight of overlying rock masses
porosity
- the percentage of voice space in a rock or sediment
retrogressive sliding
- sliding in which the rupture extends in the direction opposite to the movement of the displaced material
rotational slides
- downward-and-outward movements of masses on top of concave-upward failure surfaces; also called slumps
sensitive clays
- clays that can suddenly lose strength and liquefy when disturbed
sinkholes
-circular depressions on the surface created where acidic water has dissolved limestone
slate
-mud changed to hard rock by the high temperatures and pressures of metamorphism
slides
- mass movements where the bodies of material move on top of failure surfaces
sluff
- a small avalanche usually made up of loose snow
slumps
-downward-and-outward movements of masses on top of concave-upward failure surfaces; also called rotational slides.
snowpack
- a column of snow and ice on the ground, including both the new snow and the previous snow and ice that has not melted
soil
- the surface layers of sediment, organic matter, and mineral particles.
sturzstroms
- long-runout flows of huge masses of earth materials at great speeds
subsides
- mass movements wehre the materials sink slowly or catastrophically
talus slopes
- large piles of boulders that accumulate at the foot of cliffs
topple
- a mass movement where the body pivots forward from its base as if it were top heavy
translational slides
- downward movement of masses on top of inclined planar surfaces
water table
- the upper surface of the groundwater body. It is nearer the surface during heavy rain intervals and deeper below the surface during droughts.
