Deck 7: Mass Wasting and Subsidence

Question 1

Which of the following is NOT a basis for classifying slope movements?

A) type of material
B) how the material moves
C) moisture content
D) velocity
E) rock vs. soil

Answer 1

moisture content

Question 2

What is the ultimate cause of mass wasting?

A) water
B) slope
C) earthquakes
D) gravity
E) wind

Answer 2

gravity

Question 3

Which of the following areas is NOT known to be a region with hydrocompaction problems?

A) Heart Mountain and Riverton areas of Wyoming
B) Fort Collins, Colorado
C) the Columbia Basin in Washington
D) southwest and central Utah
E) the San Joaquin Valley of California

Answer 3

Fort Collins, Colorado

Question 4

What item listed below applies to block glides?

A) rotational slide
B) move on curved, concave upward slide surfaces
C) the most common kind of landslide
D) translational slide
E) self-stabilizing

Question 5

In 1985, 129 people died in a mass-wasting event in Puerto Rico. This was the highest death toll from such an event in U.S. history. What type of mass wasting was involved?

A) block glide
B) debris avalanche
C) mudflow
D) slump earth flow
E) creep

Question 6

What is a dip slope?

A) It has to do with the oil dipstick in a car.
B) The slope of a hill is parallel to the inclined layers beneath the ground surface.
C) This describes depressions in the ground left by slumping.
D) This refers to an abrupt increase in the steepness of the slide plane in a given landslide.
E) This refers to slopes that are steeper than the angle of repose.

Question 7

What was the cause of the 2,500 deaths that occurred near Vaiont Dam, Italy, in 1963?

A) burial by rock debris
B) water flooding due to the breaking of the dam
C) water flooding due to overflow of the dam
D) burial by a mudflow
E) the town sliding into the reservoir

Question 8

What are loose piles of rocks at the base of a steep slope or cliff called?

A) cinder cones
B) talus
C) breccia
D) debris flow
E) regolith

Question 9

In addition to increasing the weight of earth and rock material, what is the net effect of water in a landslide?

A) It decreases the normal force.
B) It increases the frictional resistance.
C) It decreases the gravity (g).
D) It causes consolidation.
E) It causes erosion.

Question 10

If you pile up dry sand, it will always have a slope angle of about 35 degrees? What is this angle called?

A) dip slope
B) dip angle
C) angle of repose
D) angle of inclination
E) angle of declination

Question 11

Which approach addresses the factor that is considered to be "the major culprit"in land instability?

A) draining water from the slide mass
B) excavating
C) redistribution of mass
D) installing retaining walls
E) installing shear keys

Question 12

What is a hydrauger?

A) a sensitive device for detecting movement of landslides
B) a horizontal drain pipe
C) a drilling device for making test borings
D) the opposite of a low drauger
E) a device for testing soil and rock strength

Question 13

What device is commonly used to strengthen cracked or jointed rock masses in tunnels and steep road cuts?

A) pilings
B) plaster
C) rock bolts
D) superglue
E) corrugated metal sheets

Question 14

What is likely to happen, at the surface, if large volumes of water, oil, or gas are removed from layers of rock deep underground?

A) settlement
B) deep subsidence
C) shallow subsidence
D) magmatic intrusion
E) hydrocompaction

Question 15

What is a common approach used to deal with collapsible soil when constructing water canals?

A) Waterproof it with an impermeable barrier.
B) Remove all of it and replace it with an engineered fill.
C) Precollapse it by soaking it with water.
D) Use a reinforced concrete lining for the canal.
E) Extend sections of very large diameter pipe through these areas.

Question 16

Judge the following sentence according to the criteria given below: Californian mountain slopes burned by wildfires are not very susceptible to debris flows the following wet season BECAUSE scorched chaparral vegetation releases a waxy liquid that waterproofs the ground.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct, but the reason is incorrect.
D) The assertion is incorrect, but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 17

Which of the following set of circumstances has the greatest risk for debris flows?

A) rainfall for 8 hours with an intensity of 0.2 inches/hour in semiarid California
B) rainfall for 5 hours with an intensity of 0.7 inches/hour in Contra Costa County
C) rainfall for 10 hours with an intensity of 0.4 inches/hour in Marin County
D) rainfall for 12 hours with an intensity of 0.5 inches/hour in Contra Costa County
E) rainfall for 5 hours with an intensity of 0.7 inches/hour in Marin County

Question 18

What are the most common kinds of landslides?

A) block glides
B) creeps
C) debris flows
D) lahars
E) slumps

Question 19

Judge the following sentence according to the criteria given below: The frequency of rockfalls can be expected to increase with climate change BECAUSE retreating alpine glaciers can be expected to expose additional steep bedrock-walls.

A) The assertion and the reason are both correct, and the reason is valid.
B) The assertion and the reason are both correct, but the reason is invalid.
C) The assertion is correct, but the reason is incorrect.
D) The assertion is incorrect, but the reason is correct.
E) Both the assertion and the reason are incorrect.

Question 20

Which of the following is NOT an example of subsidence?

A) submerged land in the Gulf of Alaska
B) the low-lying areas of New Orleans
C) Palace of Fine Arts, Mexico City
D) Baytown, Texas
E) The Leaning Tower of Pisa

Question 21

If expansive soils and subsidence are included, total losses from mass wasting in the U.S. are many times greater than the annual combined losses from earthquakes, volcanoes, floods, hurricanes, and tornadoes.

Question 22

Mass wasting is included under the broader heading of landsliding.

Question 23

The steeper the slope, the greater the potential for mass wasting.

Question 24

Creep is considered to be a type of flow.

Question 25

Debris flows are uncommon in desert areas.

Question 26

Debris flows that occur on volcanoes are called lahars.

Question 27

El Niño years are particularly hazardous for mass wasting in California.

Question 28

Slumps occur primarily in coherent layered rocks with variable physical properties.

Question 29

Forces that tend to keep a landslide in motion are called driving forces.

Question 30

A slope where the driving forces are less than the resisting forces is unstable.

Question 31

When driving forces equal resisting forces, the factor of safety is 1.0.

Question 32

The subsidence mitigation program being implemented for Venice, Italy is elegant because of its simplicity and low-cost.

Question 33

Human-induced subsidence in coastal areas increases flood potential.

Question 34

Dry snow avalanches behave like a fluid.

Question 35

Settlement is the same thing as subsidence.

Question 36

In the U.S., debris flows are limited to the west coast and southwestern states.

Question 37

The mineral benitoite is commonly involved in slope failures.

Question 38

Building codes are an ineffective way to reduce landslide damage and just increase costs.

Question 39

All subsidence problems are human-induced.

Question 40

Some subsidence problems can be reversed by injecting water into the ground.

Question 41

What distinguishes the term landslide from other phenomena included under the general heading of mass wasting?

Question 42

What can you conclude from the fact that the states in the U.S. having the lowest landslide severity are all either in the central part of the country or are in coastal areas?

Question 43

How does the biosphere contribute to soil creep?

Question 44

What is the effect of removing material from the downslope end of a landslide?

Question 45

Why do the rainfall thresholds for debris flows and landslides for California semiarid regions and Contra Costa and Marin Counties in Central California vary?

Question 46

What are some important clues that indicate that a slope has experienced landslide activity in the distant past?

Question 47

What does it mean to "buttress"a landslide?

Question 48

Why are drain holes an essential part of a retaining wall?

Question 49

Why are rock falls one of the most common of mass-wasting processes?

Question 50

What is a legal concern associated with building debris flow diversion devices?