Deck 9: Mass Wasting

Question 1

Pore pressure refers to the effect in which water forces grains apart.

Answer 1

True

Question 2

The driving force for mass wasting is gravity.

Answer 2

True

Question 3

Viscosity is the resistance to movement of the material.

Answer 3

False

Question 4

Relief is a term used to describe the horizontal distance between valley floor and mountain top.

Question 5

Mudflows frequently occur on young volcanoes covered with ash.

Question 6

Surface tension created by a small amount of water in soil decreases its shear strength.

Question 7

Creep is very slow downslope movement of soil.

Question 8

The term "debris," implies that coarse-grained fragment predominates in the soil.

Question 9

Within the United States, fewer people have died as a result of landslides than other geologic hazards, such as earthquakes and tornadoes.

Question 10

Humans can trigger earthflows by adding water to soil from septic systems or by over watering lawns.

Question 11

In cold climates freezing and thawing contribute to downslope soil movement.

Question 12

In an earthflow soil moves downslope as a coherent mass.

Question 13

Landslides are natural phenomena that humans can either cause or prevent.

Question 14

A mudflow is a flowing mixture of soil and water usually moving down a channel.

Question 15

Landslides that take place underwater are called waterslides.

Question 16

The type of material involved doesn't matter in how a mass wasting event is classified.

Question 17

A debris flow is a very rapidly moving turbulent mass of broken up bedrock.

Question 18

Permafrost occurs at depths that range from a few centimeters to a few meters below the ground surface.

Question 19

When soil is saturated with water it becomes heavier and less viscous and more likely to flow downslope.

Question 20

The term "mass wasting" refers to the improper use of Earth materials in a manner that is in conflict with the principles of conservation and environmental stewardship.

Question 21

Mudflows generally contain __.

A) only mud-sized particles
B) primarily water with some mud-sized particles, but no larger grains
C) primarily mud-sized particles with some water, but no larger grains
D) primarily mud-sized particles with some water, but certainly no particles greater than sand size
E) primarily mud-sized particles with some water, but may also contain particles as large as boulders

Question 22

Two factors that contribute significantly to soil creep are water in the soil and ___.

A) freeze-thaw cycles
B) hot climates
C) the presence of boulders in the soil
D) the presence of feldspar in the soil

Question 23

_____ commonly trigger mass wasting events.

A) Humans
B) Earthquakes
C) Hurricanes
D) Wind
E) Glaciers

Question 24

A _____ involves movement along a curved surface.

A) rotational slide
B) rock fall
C) boulder slide
D) creep
E) debris flow

Question 25

_____ is the flow of water-saturated soil over impermeable material.

A) Solifluction
B) Landslide
C) Rockslide
D) Creep

Question 26

In ____, soil in which fine grains predominate moves downslope as a viscous fluid.

A) landslides
B) avalanches
C) rockfalls
D) earthflows
E) creep

Question 27

______ is ground that remains frozen for many years.

A) Soil
B) Permafrost
C) Laterite
D) Caliche
E) Moraine

Question 28

The impermeable layer beneath saturated soil subject to solifluction may be ______.

A) the A-horizon
B) dehydrated
C) caliche
D) permafrost
E) coal

Question 29

In areas where the daily temperature regularly varies above and below the freezing temperature of water, the freeze-thaw cycle __.

A) facilitates soil creep
B) facilitates rock weathering
C) promotes the opening of cracks and joints in rock that may lead to rock falls
D) Both facilitates soil creep and facilitates rock weathering are correct.
E) All of the choices are all correct.

Question 30

Slide is a term that means that the descending mass __.

A) disintegrates as it moves down the slope
B) circulates as a fluid as it moves down the slope
C) must, by definition, remain entirely intact and move as a perfectly rigid block
D) remains intact

Question 31

Permafrost is __.

A) a type of glacial soil
B) a result of the freeze-thaw cycle
C) material below the ground surface that remains continuously frozen over the course of many years
D) a persistent coating of ice on top of the ground surface
E) an expensive and very stylish brand of freezer

Question 32

Much of the damage from China's Mary, 2008 earthquake was from ______.

A) mudflow
B) dam failure
C) landslides
D) creep
E) human activity

Question 33

List the following flow terms in the order of decreasing velocity (fastest first): mudflow, debris avalanche, creep, and earthflow.

A) debris avalanche, earthflow, mudflow, creep
B) debris avalanche, mudflow, earthflow, creep
C) creep, earthflow, mudflow, debris avalanche
D) mudflow, earthflow, debris avalanche, creep
E) mudflow, debris avalanche, earthflow, creep

Question 34

When soil is saturated with water ____ increases.

A) pore pressure
B) surface tension
C) viscosity
D) density

Question 35

_______ is (are) associated with permafrost.

A) Thixiotropy
B) Solifluction
C) Avalanches
D) Quicksands
E) Expansive clays

Question 36

Shear strength __.

A) is the total force/stress resisting movement
B) is the same as shear resistance
C) increases as the amount of water in soil increases
D) is related to slope angle

Question 37

In a translational slide, the descending mass __.

A) slides as a generally intact block down a curved failure surface
B) moves along a plane approximately parallel to the slope of the surface
C) simply moves from one location to another, without specifying the mode of motion
D) is moving and circulating within the flowing mass, behaving as a viscous fluid
E) moves as a perfectly rigid block on top of a liquid layer

Question 38

Resistance to movement or deformation of soil is called __.

A) solifluction
B) stiffness quotient
C) stress resistance
D) shear strength
E) rigidity

Question 39

Most solifluction takes place __.

A) in most areas that have permafrost.
B) in some areas that may not have permafrost
C) in all areas that do not have permafrost
D) is not associated in any way with permafrost

Question 40

When a stream, wave action, or excavation by humans undercuts the base of a slope, slope failure may occur because __.

A) ground water will be drained out of the slope
B) the weight of the slope will have been reduced
C) the shear force/stress on the base of a potential landslide mass will have been increased
D) downslope support of the slope materials will have been reduced or eliminated
E) the normal force/stress across the base of a potential landslide mass will have been reduced

Question 41

Assuming that all other conditions are identical, a slope that is ___ is more stable.

A) more nearly vertical
B) more steeply inclined
C) more gently inclined
D) Slope angle has nothing to do with slope stability.

Question 42

One way to prevent slope failure is to __.

A) drain ground water from the slope
B) re-grade the slope so that it is more gently inclined
C) pin the rock onto the slope with rock bolts or other devices
D) retain or establish vegetation to protect the slope
E) All of the answers are correct.

Question 43

The Gros Ventre slide in 1925 generated a secondary hazard, namely __, whose failure was responsible for the destruction of the town of Kelly, Wyoming.

A) a debris flow
B) a landslide dam that impounded a river
C) a mudflow
D) an over-steepened slope
E) an undercut hillslope

Question 44

If movement becomes very rapid, a rockslide may break up and become __.

A) a debris flow
B) a rock avalanche
C) a rock fall
D) a soil slip
E) a mudflow

Question 45

A rock avalanche begins its downslope journey __.

A) as a result of an earthquake
B) near the top of a volcano
C) due to the undercutting of a slope
D) as a result of a snow or ice avalanche
E) as bedrock

Question 46

The 1928 failure of the St. Francis Dam near Los Angeles was due to _____.

A) presence of foliation planes in one abutment of the dam
B) landslides associated with the reservoir
C) excessive water pressure at the base of the dam
D) one abutment was built against rock that disintegrated in water
E) All of the answers are correct.

Question 47

A(n) _____ is a general term that tells nothing about the processes involved.

A) avalanches
B) rockfalls
C) landslide
D) creep
E) solifluction

Question 48

If, over a period of time, your home develops doors that stick, cracked walls, broken pipes, and cracked driveways, ____ may be occurring.

A) frost wedging
B) translation gliding
C) a debris flow
D) soil creep
E) sublimation

Question 49

Mudflows are ___ likely to occur in arid regions than in wet climates.

A) more
B) less
C) just as

Question 50

____ generally makes a slope more susceptible to mass wasting of soil.

A) New vegetation
B) Construction
C) Humid climates
D) Creep
E) Solifluction

Question 51

Mudflows are ___ likely to occur in areas not protected by vegetation.

A) more
B) less
C) just as
D) Mudflow occurrence is not related to average rainfall or vegetative cover.

Question 52

A region with high relief (the distance between high and low points in an area) has a ______ rate of debris flow.

A) higher
B) lower
C) Relief has nothing to do with slope stability.

Question 53

Which of the following factors are how geologists, engineers, and others classifying mass wasting?

A) viscosity, shear strength, translational movement
B) rate of movement, shear strength, gravity
C) type of material, shear strength
D) rate of movement, type of material, type of movement
E) gravity, shear strength, slip motion

Question 54

A(n) apron of fallen rock fragments called ___ is generally found at the base of a slope affected by rockfall.

A) loess
B) talus
C) grus
D) alluvial
E) fluvial

Question 55

Heavy irrigation on a hillslope will cause __.

A) increase in pore-fluid pressure
B) increase in weight of the slope
C) decrease in shear strength
D) increase in shear force/stress
E) All of the answers are correct.

Question 56

A(n) _____ is the rapid sliding of a mass of bedrock along an inclined surface of weakness.

A) debris flow
B) rockslide
C) avalanche
D) rockfall
E) creep

Question 57

A region prone to frequent earthquakes is ____.

A) more likely to have debris flows
B) less likely to have debris flows
C) Earthquake frequency has little influence on the frequency of debris flows.

Question 58

Among techniques used to prevent rockfalls along highways is to _____.

A) cover with a shed
B) spray the exposed roadside with cement
C) remove slide-prone rock
D) step the slope back
E) All of the answers are correct.

Question 59

As a result of the landslide at the Vaiont Dam, northern Italy, in 1963, approximately 3000 people died __.

A) as their houses that had been built on the landslide were destroyed
B) as their houses were buried by the landslide
C) when the landslide impacted and destroyed the dam structure
D) when slope failure allowed the dam structure to be pushed downstream by the water pressure of the reservoir
E) as a huge wave of water was displaced from the reservoir by the landslide

Question 60

The rate of movement in creep is usually __.

A) a centimeter or less per year
B) a centimeter or so per week
C) a centimeter or so per day
D) around a meter per day
E) around a meter per hour