Deck 7: Mass Wasting

Question 1

What is mass wasting?

A) Recycling of ancient earth materials to make slopes for development
B) Loss of mass from a soil during chemical weathering
C) Downslope movement of rock, soil, and sediment
D) Land lost due to explosive volcanic eruptions
E) Movement of sediment along the coast due to offshore ocean currents

Answer 1

C

Question 2

Which of the following mass wasting processes does NOT necessarily involve water?

A) Earth flow
B) Debris flow
C) Creep
D) Rock fall

Answer 2

D

Question 3

Which of the following describes a slump?

A) Rocks break off of cliffs and fall to the base of a slope.
B) Rocks and soil move downslope very slowly.
C) Rapid downslope movement of snow and ice, sometimes with the addition of rock, soil, and vegetation
D) Blocks of rock break off and move together, sliding along a curved path.
E) Mud becomes saturated with water and flows quickly into a streambed.

Answer 3

D

Question 4

Which of the following is the most rapid form of mass wasting?

A) Rock fall
B) Rock slide
C) Creep
D) Earthflow
E) Slump

Question 5

In which location would you expect to have the most landslides at the END of the given sequence of events? For all areas, assume that each event (drought, wildfire and heavy rain) is identical.

A) Location in the mountains that first experiences a long drought, then experiences wildfires, and then experiences heavy rain
B) Location in the mountains that first experiences wildfires, then experiences heavy rain, and then experiences a long drought
C) Location in the plains that first experiences a long drought, then experiences wildfires, and then experiences heavy rain
D) Location in the plains that first experiences wildfires, then experiences heavy rain, and then experiences a long drought

Question 6

Does adding vegetation to a slope make it more or less stable?

A) More stable because the roots will draw water deeper into the ground instead of allowing water to saturate the surface
B) More stable because the vegetation roots will hold together loose soil
C) Less stable because the vegetation adds weight to the slope
D) Less stable because the vegetation will keep more water at the surface of the slope
E) It depends on the slope, adding vegetation could make the slope either more or less stable.

Question 7

Which of the following environments is NOT susceptible to mass wasting?

A) A steep and rocky slope
B) A moderate slope made of fill materials
C) A gentle slope with deep soils
D) A slope that has many buildings on it
E) Relatively flat-lying area

Question 8

Which of the following is the slowest mass wasting process?

A) Avalanche
B) Slump
C) Creep
D) Earth flow
E) Fall

Question 9

Which of the following is the most important driving force in landslide?

A) Weight of the slope in the downslope direction
B) Friction
C) Cohesion
D) Viscosity
E) Shear strength

Question 10

Which of the following is NOT a term for a segment type on a slope?

A) Free face
B) Convex
C) Elliptical
D) Concave
E) Talus

Question 11

Adding earth material to the lower part of a slope which has the potential for a landslide would

A) increase the resisting force.
B) decrease the resisting force.
C) increase the driving force.
D) decrease the driving force.

Question 12

In which location would you expect to have the most landslides? For each area, assume the total amount of rain per year is identical.

A) Mountains with very light rain showers every day
B) Mountains with heavy rainstorms followed by long dry periods
C) Plains with very light rain showers every day
D) Plains with heavy rainstorms followed by long dry periods

Question 13

If you see a steep cliff with piles of rocks at the bottom, what kind of mass wasting has occurred?

A) Slump
B) Creep
C) Fall
D) Debris flow

Question 14

Which of the following is NOT a way in which water contributes to slope failure?

A) Water adds cohesion between the grains of the soil causing it to become unstable.
B) Water adds weight to a slope increasing the driving force.
C) Water can erode the base of a slope decreasing stability.
D) Water can mix with the soil causing debris flows.
E) Water can infiltrate slopes causing slumps.

Question 15

Which of the following statements is FALSE about snow avalanches?

A) Snow avalanches are very rare and seldom cause death.
B) Snow avalanches can be caused by people.
C) The incidence of snow avalanches depends on the temperature of the snow.
D) Snow avalanches tend to follow the same paths.
E) Snow avalanches require steep slopes of 25° or more.

Question 16

Would adding mass to the top of a slope in the form of houses or buildings make the mass more or less likely to slide?

A) It would make it less likely to slide because the houses would add pressure on the slope keeping it stable.
B) It would make it less likely to slide because the houses make the slope less steep.
C) It would make it more likely to slide because the houses add weight to the slope making it more unstable.
D) It would make it more likely to slide because the houses would make the slope more steep.
E) Adding mass to the top of a slope would not make a difference in the stability of the slope.

Question 17

If you see a gently sloping hillside with tilting utility poles, broken retaining walls, and trees with curved tree trunks, what type of mass wasting has probably occurred?

A) Avalanche
B) Slump
C) Creep
D) Earth flow
E) Fall

Question 18

The Portuguese Bend landslide in California involved

A) gradual, continuous, downslope movement over a 30 year time period that resulted in damage to many homes.
B) a volcanic mudflow that killed over 20,000 people despite prior warnings of an imminent landslide threat.
C) an enormous debris slide that created a giant wave which killed ~2,500 people in a matter of a few minutes.
D) heavy rains in an area of folded and fractured limestone bedrock with clay layers and underground caves.

Question 19

Which of the following involves downslope movement of a coherent, usually large block of earth material along a planar surface?

A) Rock fall
B) Rock slide
C) Creep
D) Earthflow
E) Slump

Question 20

Which of the following is NOT an important factor in the stability of a slope?

A) Slope steepness
B) Climate
C) Direction of Sun exposure
D) Vegetation
E) Water

Question 21

All non-horizontal slopes have potential for mass wasting of some type.

Question 22

Which of the following human activities can DECREASE the incidence of mass wasting?

A) Grading surfaces to increase the slope
B) Improving drainage from the slope
C) Removing vegetation such as trees and grass from the slope
D) Cutting out a section at the base of a slope to build houses
E) Building a road on a slope

Question 23

If you see a concrete wall with several drain holes through it on the side of a roadway, what is its purpose?

A) To collect rocks from rock falls
B) Support the base of the slope
C) Provide extra weight on the slope
D) Cushion the slope from potential collisions with cars

Question 24

Only one mass wasting type happens at a single time to an individual slope.

Question 25

How do drains help to prevent landslides?

A) Drains keep water at the surface, so that only the upper part of the slope is saturated.
B) Drains divert water away from the slope.
C) Drains pull water deeper into the base of the slope.
D) Drains anchor the soil to the ground keeping it from sliding.
E) Drains do not prevent landslides.

Question 26

In buying a house, why should you be wary of tilted telephone poles?

A) It is a sign of debris flows.
B) It is a sign of rock falls.
C) It is a sign of avalanches.
D) It is a sign of landslides.
E) It is a sign of creep.

Question 27

What is "grading" as it pertains to the stability of a slope?

A) A classification of how likely a slope is to slide
B) The greatest slope that a material can be stable at
C) A classification of the material in the slope
D) Human-induced changes in the slope angle to make it more or less steep
E) A measure of the maximum weight a slope can hold

Question 28

Which of the following is FALSE about the effects of landslides?

A) Landslides can cause flooding when rivers are blocked.
B) Landslides can bury people in debris.
C) Landslides, because of the damage they normally inflict, offer no natural service functions.
D) Landslides can break utility wires and disrupt travel.
E) Landslides can cause damage to homes and roads.

Question 29

Slumps involve sliding of rock or soil along a curved surface.

Question 30

Which area of the U.S. has a highest incidence of landslide activity?

A) Appalachian Mountains
B) Atlantic coastal area
C) Gulf of Mexico coastal area
D) Midwest

Question 31

How is the incidence of landslides expected to change in the future?

A) Incidence of landslides will increase.
B) Incidence of landslides will decrease.
C) Incidence of landslides will stay the same.
D) Incidence of landslides will cease.
E) There is no way to tell whether the incidence of landslides will increase or decrease.

Question 32

A mudflow is usually not dangerous to human life because it moves at speeds that are imperceptibly slow to the eye.

Question 33

The type of mass wasting process that occurs depends on many different factors including the steepness of the slope and the type of material involved.

Question 34

One indication of a rock fall is an accumulation of rocks at the base of a cliff.

Question 35

Which of the following is NOT a factor in how urbanization increases the incidence of landslides?

A) Trees and grasses are removed, leaving the land susceptible to erosion.
B) Roads are constructed altering the permeability of the land.
C) Buildings are placed on slopes, increasing the weight on the slope.
D) Roads are cut at the base of slopes increasing instability.
E) Flood control measures prevent river flooding, which increases the incidence of landslides.

Question 36

Which of the following is NOT a normal purpose of a landslide hazard map of an area?

A) Communities could use it to decide where to place critical facilities.
B) Communities could use it to decide where to place drains or supports.
C) Communities could use it to decide where to build new homes or businesses.
D) Individuals could use it to decide where to purchase a new home.
E) Individuals could use it to decide where their family should meet after a landslide disaster.

Question 37

The term Avalanche only applies to the movement of snow down slopes.

Question 38

Which of the following natural disasters is linked in some way with landslides?

A) Earthquakes
B) Floods
C) Volcanoes
D) Tsunamis
E) Earthquakes, floods, volcanoes, and tsunamis all have some connection with landslides.

Question 39

Which of the following is NOT a sign of a potential landslide?

A) Cracks or terraces on hillside
B) Area of bare soil or rock on hillside
C) Path of cleared vegetation extending down a hill
D) Exposed bedrock with layering parallel to slope
E) Vegetated slope that has not received rain in two weeks

Question 40

Slumps are the only form of mass wasting that are not triggered by excess water.

Question 41

Describe what each area would look like after a fall, a slide and a flow had occurred.

Question 42

Growing plants on a slope will always make it more stable because plant roots add strength and cohesion to the soil.

Question 43

Most snow avalanches are triggered by the victims themselves or by someone in their company.

Question 44

Landslides can be a positive event for forests by creating new habitats for plants and animals.

Question 45

The climate surrounding a slope has very little impact on whether the slope will fail.

Question 46

A slope with sedimentary layering parallel to the ground surface is more stable than a slope with sedimentary layering perpendicular to the ground surface.

Question 47

There is no way to prepare for a landslide because you never know where a landslide will occur.

Question 48

Constructing roads on slopes decreases the incidence of landslides because asphalt generally does not let water soak into the ground.

Question 49

The Portuguese Bend landslide in California involved an area with weak sedimentary rock that has bedding parallel to the slope and a cliff at the front edge where ocean waves eroded into the cliff.

Question 50

What is the difference between a fall, a slide and a flow?

Question 51

Landslides are an example of a geologic hazard in which damage can be greatly reduced if appropriate measures are taken in the area of public policy and landslide control.

Question 52

Slopes that have been cleared of native grasses and other vegetation become more stable.

Question 53

Landslides are a significant hazard on the California coastline and in the Rocky Mountain states.

Question 54

The U.S. Midwest has relatively low risk for landslides mainly because the soils are extremely compacted and therefore strong.

Question 55

Placing a greater weight on the top of a slope can cause mass wasting to occur.

Question 56

In purchasing a house, some steps can be taken to determine whether it is susceptible to a landslide hazard.

Question 57

Snow avalanches usually move down chutes that have previously produced snow avalanches, making it easier to predict where a snow avalanche will occur.

Question 58

Building homes on a slope can increase the mass on the slope and the potential for landslides.

Question 59

Volcanic eruptions are the one example of a natural hazard that cannot produce landslides.

Question 60

People can stabilize a slope through increased drainage and slope supports.

Question 61

Explain the role of climate in the stability of slopes.

Question 62

Explain how landslides are linked to both flooding and fires.

Question 63

Explain how drains minimize the landslide hazard.

Question 64

Urbanization is one human activity that causes landslides. Explain three reasons why urbanization contributes to the incidence of landslides. Some urban areas are already at risk for landslides, describe two things that can be done to minimize the risk of landslides for these areas.

Question 65

Explain the difference between a loose snow and slab avalanche.

Question 66

La Conchita, CA has been a site of two massive landslides within 10 years of each other. Explain what caused the landslides. If you were put in charge of land planning for La Conchita, explain how you would repurpose the land that was affected by the slide? Also, explain what you would put in an education packet for current and future residents of the homes unaffected by the previous slide.

Question 67

Explain the role of water in the stability of a slope.

Question 68

The amount of vegetation has a complex role in slope stability. Explain how the amount of vegetation can both increase and decrease slope stability.

Question 69

La Conchita, CA was a site of two massive landslides within 10 years of each other. One theory for the landslide was that it was caused in part by an Avocado Farm at the top of the slope. Explain two different ways that the cultivation of avocadoes could contribute to the slides. Give 3 suggestions for what the avocado growers could do to reduce the occurrence of future slides in the area.

Question 70

All slope are susceptible to some kind of mass wasting. Explain how mass wasting might affect a very steep slope and a very gentle slope.