Deck 8: Unstable Land

Question 1

The key driving force behind slope failure is:

A) cohesion.
B) talus.
C) friction.
D) gravity.
E) repose.

Answer 1

D

Question 2

Which of the following factors can help to stabilize unstable slopes?

A) increasing the amount of water
B) increasing the steepness of the slope
C) increasing the vegetation on the slope
D) adding more material to the top of the slope
E) all can help to stabilize a slope

Answer 2

C

Question 3

What is TRUE about the angle of repose?

A) it is characteristic of a given slope
B) it is based on the type of material that comprises the slope
C) it is about 35 degrees for sand
D) it is steeper if the slope is comprised of broken pieces of rock
E) All are true.

Answer 3

E

Question 4

Increasing the water content of a slope can lead to instability.

Question 5

Creep is a faster mass wasting process than debris flows.

Question 6

What is used by geologists to classify slope movements?

A) the type of rock or soil involved
B) how fast the material moves (fast, slow)
C) how the material moves, whether along a track or along a plane
D) the amount of moisture in the material
E) all of the above

Question 7

Use the information provided in the illustration below to answer the following question(s).

-What landsliding process is illustrated?

A) creep
B) slump
C) rock fall
D) block glide
E) rock avalanche

Question 8

Use the information provided in the illustration below to answer the following question(s).

-If you lived in the house, what would you do to lessen the effects of this landsliding?

A) terrace the slope
B) install retaining devices
C) drain water from the slope area
D) increase the amount of vegetation on the slope
E) all of the above

Question 9

Use the information provided in the illustration below to answer the following question(s).

-If you didn't deal with the problem, what tree is the next to slide down the hill?

A) tree 3
B) tree 2
C) tree 1
D) this type of landsliding doesn't affect trees
E) all trees would move together

Question 10

Use the information provided in the illustration below to answer the following question(s).

-Which of the following is NOT a driving force that could cause a slope to slide?

A) adding weight to the top of the slope, while removing weight from the bottom
B) terracing the slope
C) increasing the amount of fluids that flows into the slope
D) increasing the angle of the slope (for example from 45° to 60°)
E) cutting down vegetation on the slope

Question 11

Use the information provided in the illustration below to answer the following question(s).

-What is the name of a landslide that occurs when rocks slide rapidly?

A) creep
B) rockfall
C) debris flow
D) landslide
E) slump

Question 12

Use the information provided in the illustration below to answer the following question(s).

-If a slope has a factor of safety of less than 1:

A) it is unstable.
B) it is heavily vegetated.
C) it is shallow.
D) it is safe to build a house on top of it.
E) it is dry.

Question 13

What is subsidence?

A) when rocks fall rapidly off cliffs
B) forces that oppose gravity and drive slopes to fail
C) sinking or downward settling of the ground
D) individual episodes of mass wasting
E) piles of angular rock fragments

Question 14

Causes of natural subsidence could be:

A) movement along earthquake faults.
B) ground shaking due to volcanic activity.
C) ground shaking due to earthquake activity.
D) solution of carbonate minerals underground that causes sinkholes to form.
E) all of the above.

Question 15

The fastest of all mass movements is:

A) flow.
B) fall.
C) slide.
D) creep.
E) track.

Question 16

Subsidence can be caused by:

A) earthquakes.
B) agricultural practices that cause sediments on the surface of the ground to consolidate or compress.
C) extraction of underground fluids.
D) volcanoes.
E) all of the above.

Question 17

Conditions that may result in a debris flow are:

A) coherent rock on a shallow slope.
B) heavy rain or snowmelt over steep slopes.
C) arid conditions.
D) a heavy cover of vegetation.
E) terracing the slope.

Question 18

In debris flows, material:

A) falls.
B) slumps.
C) slides.
D) moves like a liquid in a track.
E) moves very slowly.

Question 19

Karst terrain is characterized by:

A) subsidence.
B) sinkholes.
C) underground caves and caverns.
D) large areas of carbonate minerals like calcite.
E) all of the above.

Question 20

What is El Nino?

A) an ocean-atmosphere circulation pattern often associated with destructive landslides
B) the downward sinking or settling of the Earth's crust
C) a type of mass wasting process
D) a type of vegetation that helps to stabilize slopes
E) the pressure of water at any particular place in rock material

Question 21

Match the following options to its correct definition.
-cohesion

A) force created by attractions between grains of material
B) blocks of fractured rock that collect at the base of a slope
C) force exerted by water in material
D) type of sediment that can turn into a flowing mass if disturbed
E) a type of rotational slide

Question 22

Match the following options to its correct definition.
-quick clay

A) force created by attractions between grains of material
B) blocks of fractured rock that collect at the base of a slope
C) force exerted by water in material
D) type of sediment that can turn into a flowing mass if disturbed
E) a type of rotational slide

Question 23

Match the following options to its correct definition.
-talus

A) force created by attractions between grains of material
B) blocks of fractured rock that collect at the base of a slope
C) force exerted by water in material
D) type of sediment that can turn into a flowing mass if disturbed
E) a type of rotational slide

Question 24

Match the following options to its correct definition.
-slump

A) force created by attractions between grains of material
B) blocks of fractured rock that collect at the base of a slope
C) force exerted by water in material
D) type of sediment that can turn into a flowing mass if disturbed
E) a type of rotational slide

Question 25

Match the following options to its correct definition.
-pore pressure

A) force created by attractions between grains of material
B) blocks of fractured rock that collect at the base of a slope
C) force exerted by water in material
D) type of sediment that can turn into a flowing mass if disturbed
E) a type of rotational slide

Question 26

Which of the following factors can contribute to mass movement?

A) rainy weather
B) earthquakes
C) wildfires
D) steepening slopes
E) all of the above

Question 27

How have people contributed to landslide problems?

A) Houses add weight to slopes, increasing driving forces for the slope to fail.
B) Excavation may locally steep slopes, interrupting normal drainage patterns.
C) Septic systems or leaking water pipes add fluid to the slope.
D) Clearing vegetation with deep roots decreases the slope's resisting forces.
E) all of the above

Question 28

What are some ways that the person could prevent a landslide from destroying their home?

A) Remove vegetation from unstable slopes.
B) Add water to unstable slopes.
C) Create walls to stabilize the angle of repose of the slope.
D) Burn slopes prior to building.
E) all of the above

Question 29

The presence of curved tree trunks along steep slopes illustrates what mass wasting process?

A) rock fall
B) creep
C) landslide
D) slump
E) debris flow

Question 30

Slump describes the very slow, downhill movement of soil and rocks.

Question 31

Earthquakes cannot trigger landslides.

Question 32

Acid rain can contribute to subsidence.

Question 33

Soil nails, check dams and sabo dams are types of engineering geology methods to prevent mass wasting.

Question 34

What are some mass wasting warning signs that geologists use to develop landslide hazard maps?

A) bare scars in the landscape left by past landslides
B) hummocky terrain
C) curved tree trunks
D) tilted fences and sidewalks
E) cracked foundations and roads

Question 35

What is avoidance?

A) a type of resisting force
B) a type of engineering geology construction method used to stabilize slopes
C) an effective way to construct landslide hazard maps
D) an effective way to reduce landslide hazards by minimizing the number of people working and living near unstable slopes
E) a type of mass wasting process that occurs when soil flows slowly around structures

Question 36

Explain in general terms why landslides occur. What factors influence slope stability?

Question 37

What is the difference between a debris flow and creep? How are landslides or mass movements classified? What information is needed?

Question 38

What are some ways that engineering geologists are involved in landslide prevention?

Question 39

Post-wildfire landslides can be very dangerous. Explain at least 2 ways that fires increase landslide hazards.

Question 40

Describe at least 3 ways in which urban development on hillslides may create landslide hazards.

Question 41

How can a slope be stabilized so that a landslide will not occur? Explain how slope stabilization measures work.

Question 42

Walk around the campus or your neighborhood. Check out hillsides. Can you see evidence of creep or subsidence? See if you can identify how trees, power lines, roads, and sidewalks are affected by the Earth moving. Look for past evidence of the landslides. Do some areas appear to be on the move? Describe what you see.

Question 43

Should humans develop and inhabit areas that are prone to landslides? What is your opinion?