Deck 16: Unsafe Ground: Landslides and Other Mass Movements

Question 1

Moisture among sediment grains ________.

A)always increases the likelihood of mass wasting
B)always decreases the likelihood of mass wasting
C)can promote stability if present in small amounts
D)can promote stability if the grains are saturated

Answer 1

C

Question 2

The principal difference between a debris flow and a debris slide is ________.

A)the shape of the path taken by the moving mass
B)the grain size of the moving mass
C)that a debris flow contains abundant water,whereas a debris slide is dry
D)that a debris flow contains pyroclastic debris from a volcanic eruption

Answer 2

C

Question 3

As shown in the figure below,________ may form parallel to slope surfaces in granite and become a failure surface.

A)bedding planes
B)exfoliation joints
C)foliation planes
D)uplift planes

Answer 3

B

Question 4

________ occurs when debris or snow mixes with air to form a chaotic cloud.

A)An avalanche
B)A slump
C)Creep
D)Solifluction

Question 5

Slumps typically arrive ________ at the bottom of a slope.

A)vertically stacked
B)intact
C)flattened
D)jumbled

Question 6

A ________ may form at the head of a slump.

A)toe
B)failure surface
C)scarp
D)mass

Question 7

As ________ occurs,intact rock is broken down into smaller,weaker pieces called sediment.

A)an avalanche
B)cohesion
C)solifluction
D)weathering

Question 8

Well-rounded sand has a smaller ________ than irregularly shaped gravel.

A)cohesion
B)angle of repose
C)mineral stability
D)cross-sectional area

Question 9

Lahars occur on ________.

A)volcanic slopes
B)vertical cliff faces
C)undersea slopes
D)divergent plate boundaries

Question 10

Which of the following types of mass movement takes place most gradually?

A)slump
B)creep
C)rock slide
D)mudflow

Question 11

Unstable slopes start to move when the ________ force exceeds the ________ force that holds the material in place.

A)downslope;gravity
B)resistance;downslope
C)downslope;resistance
D)gravity;resistance

Question 12

The ________ in the sequence of sedimentary rocks shown below may become a failure surface.

A)bedding planes
B)exfoliation joints
C)foliation planes
D)uplift planes

Question 13

Which of the following types of mass movement is least coherent (most like a fluid)?

A)slump
B)creep
C)rock slide
D)mudflow

Question 14

The principal difference between a lahar and a mudflow is the ________.

A)shape of the path taken by the moving mass
B)grain size of the moving mass
C)lahar contains abundant water,whereas the mudflow is dry
D)lahar contains pyroclastic debris from a volcanic eruption

Question 15

The principal difference between a slump and a debris slide is ________.

A)the shape of the path taken by the moving mass
B)the grain size of the moving mass
C)that a slump contains abundant water,whereas a debris slide is dry
D)that a slump contains pyroclastic debris from a volcanic eruption

Question 16

Geologists distinguish among different types of mass wasting based on factors such as the ________ of the moving material and the rate of movement.

A)weight
B)color
C)composition
D)name

Question 17

Which of the following types of mass movement often travels down a curved surface?

A)slump
B)creep
C)rock slide
D)mudflow

Question 18

The principal difference between a debris flow and a mudflow is ________.

A)the shape of the path taken by the moving mass
B)the grain size of the moving mass
C)that a debris flow contains abundant water,whereas a mudflow is dry
D)that a debris flow contains pyroclastic debris from a volcanic eruption

Question 19

For dry,fine-grained sediments,the angle of repose is typically between ________ and ________ degrees.

A)10;17
B)15;22
C)20;27
D)30;37

Question 20

The immediate cause of incidents of mass movement is ________.

A)electromagnetic attraction
B)gravity
C)magnetism
D)friction

Question 21

Which of the following situations would be the most susceptible to slope failure?

A)a large mansion built on top of a gentle sloping hill covered with vegetation
B)a hotel built on a flat surface with a large river flowing next to the hotel
C)a large resort built on top of a cliff directly above the ocean
D)a small house built on top of a steep slope in a desert region

Question 22

Which situation would most likely host a slope failure?

A)a dry slope composed of gravel with an angle of repose of 30°
B)a saturated slope composed of gravel with an angle of repose of 27°
C)a saturated slope composed of sand with an angle of repose of 35°
D)a saturated slope composed of sand with an angle of repose of 37°

Question 23

Why does adding a small amount of water to a substance increase its cohesion but adding a lot of water decrease its cohesion?

A)A small amount of water decreases surface tension,allowing the grains to bond together,whereas too much water will increase surface tension and force the grains away from each other.
B)A small amount of water increases surface tension and holds the grain together.Too much water between the grains will eliminate surface tension.
C)Water has a small electrostatic force that disrupts the gravitational attraction of the grains and forces them to move away from each other.
D)A small amount of water will precipitate cement into the pores of the material,whereas too much water will not allow that cement to form.

Question 24

You are a geologist trying to determine if the slope your client's house sits on is stable.You determine that the angle of repose of the hillside is 35°.Which of the following situations would be considered stable?

A)The slope is composed of saturated sand.
B)The slope is composed of dry sand.
C)The slope is composed of damp sand.
D)The slope is composed of dry gravel.

Question 25

Slope failures are more likely to occur in ________ than in ________.

A)forests;deserts
B)mountains;deserts
C)deserts;mountains
D)deserts;forests

Question 26

Ground shaking can transform wet sediments into liquid-like slurries in a process known as ________.

A)liquefaction
B)slumping
C)undercutting
D)sloping

Question 27

________ can occur where undercutting by waves removes support from beneath cliff overhangs.

A)Landslides
B)Lahars
C)Rock falls
D)Mudslides

Question 28

A slope in a ________ environment would be much more likely to experience ________ and thus more susceptible to slope failure.

A)humid;loss of vegetation
B)humid;weathering
C)dry;an increase in water
D)dry;weathering

Question 29

Which of the following situations would be the least susceptible to slope failure?

A)a gently sloping hill in a dry desert region
B)a gently sloping hill with a river at the bottom of the hill
C)a steeply sloping hill overlooking the ocean
D)a steeply sloping hill in a dry desert region

Question 30

Why does the removal of material at the base of a slope decrease its stability?

A)Removing material decreases the surface tension between grains.
B)The force of gravity decreases,and the slope will fail.
C)The slope now has a much lower angle of repose.
D)The slope now exceeds the angle of repose.

Question 31

Slope failures are most likely to occur in ________ conditions.

A)dry,mountainous
B)dry,flat
C)wet,mountainous
D)wet,flat

Question 32

Which area would be most likely to host a slope failure?

A)the coast of Florida
B)a desert in California
C)mesas in Arizona
D)the coast of California

Question 33

Imagine you have just bought some property and notice that the trees on the slope have curved trunks.What type of landslide event do you likely have on your property?

A)solifluction
B)creep
C)slump
D)mudflow

Question 34

Which areas are most susceptible to slope failure?

A)saturated vertical road cuts
B)slopes at 30° next to rivers
C)saturated and vegetated slopes
D)unsaturated vertical road cuts

Question 35

A rock slide into a reservoir triggered catastrophic flooding of the landscape below which dam?

A)Vaiont (Italy)
B)Aswan (Egypt)
C)Hoover (Nevada)
D)Glen Canyon (Arizona)

Question 36

The most important factor in determining if an area will be subject to mass movement is ________.

A)relief
B)gravity
C)weather
D)water content

Question 37

Which of the following figures shows an area that would be most susceptible to slope failure?

A)a
B)b
C)c
D)d

Question 38

Liquefaction is most likely to occur in which type of area?

A)mountains in Florida
B)the coast of California
C)the coast of Texas
D)a desert in California

Question 39

Which of the following increases the risk of mass movement?

A)adding a small amount of moisture to loose,dry sediment
B)waves breaking before they reach sea cliffs
C)flooding the sediment with water to the point of saturation
D)reducing the grade of the slope

Question 40

Which of the following situations is the most likely candidate for the occurrence of mass movements?

A)a flat,desert area with little vegetation
B)a gentle slope along the coastline that is across a highway from the surf zone
C)gently sloping hills in the tropics
D)a mountain terrain in a humid environment

Question 41

How can you use a landslide hazard map to help buy a piece of property?

A)to determine if there are large rivers running by the property
B)to determine if the property is in a high-risk zone for landslides
C)to determine if the property is near a high-risk flood zone
D)to determine if the property has been exposed to fires recently

Question 42

Which of the following situations may lead to slope failure?

A)the addition of a small amount of water to a slope
B)installing a chain-link fence over a slope
C)undercutting a slope by a bulldozer
D)regrading a steep slope to create a gentler slope

Question 43

What is the most effective means of mitigating the risk of a slope failure for slope shown in the figure below?

A)Apply shotcrete.
B)Revegetate with new plants.
C)Install riprap.
D)Dewater the slope.

Question 44

Installing perforated pipes (pipes with holes in them)into a hillside can be an effective way of reducing ________.

A)the angle of repose
B)the weight of material
C)undercutting
D)the subsurface water

Question 45

After finishing a new construction project,why is the first task often to install new landscaping around the area?

A)The plants will provide nutrients for animals that will carry away the soil.
B)The roots will grow into the slope and work to keep the slope intact.
C)The plants will add additional weight to the slope and keep it stable.
D)The roots take in oxygen and release it into the soil to increase surface tension.

Question 46

In the figure below,what would be the most effective way to stabilize the slope,assuming that the slope is in a dry,desert environment?

A)Regrade the slope.
B)Move the road.
C)Add more vegetation.
D)Install riprap.

Question 47

Which of the following factors decreases the risk of mass movement?

A)nearby earthquakes
B)excavation into the base of a hill
C)adding weight to the top of a hill
D)adding vegetation to the side of a hill

Question 48

Imagine you have just bought some property and notice that the trees on the slope have curved trunks.What would be the most effective method to prevent additional movement of the hillside?

A)Regrade the slope.
B)Plant more vegetation.
C)Install riprap.
D)Construct a retaining wall.

Question 49

What is the quickest way to remove the hazard from an avalanche?

A)Shoot at the area with a cannon.
B)Spray the slope with shotcrete.
C)Install riprap at the base.
D)Plant cold-weather-loving plants.

Question 50

In the figure below,what about these two mass-wasting events is similar and what is different?

A)Both involve water,but mass-wasting event b could not have occurred in the mountains.
B)Both occur in the mountains,but mass-wasting event a moved much faster.
C)Both involve water,but the water is in two different phases.
D)Both occur in the mountains but at two very different elevations.