Deck 11: Mass Wasting

Question 1

In what ways are slope stability maps useful to planners and developers?

Answer 1

Slope stability maps are used to determine where certain types of buildings and other structures should or should not be built and to indicate how slope stability might be improved,if structures are built where stability is compromised.

Question 2

Why is La Conchita,California particularly vulnerable to landslides?

Answer 2

The slope behind the small community is composed of soft,weak,and porous sediments that are not well lithified.An avocado orchard that sits at the top of the hill introduces irrigation water into the slope; this part of California sometimes experiences heavy rainfall,and the slope has been undercut by a road.

Question 3

What types of changes in a slope can lead to mass wasting?

Answer 3

Mass wasting can occur due to changes in slope gradient or vegetation cover,increased water content,weakening by weathering,and overloading.

Question 4

What are some ways by which a slope can become oversteepened?

Question 5

Why can mudflows be very dangerous?

Question 6

How does a slump differ from a rock slide?

Question 7

If you were surveying hillside property on which you planned to build a home,what are some of the evidences of former mass wasting you would look for?

Question 8

How can vegetation affect the likelihood of mass wasting?

Question 9

What factors collectively define a slope's shear strength?

Question 10

What are the most common triggering mechanisms for mass wasting?

Question 11

On the basis of what three criteria are mass movements classified?

Question 12

What methods can be used to stabilize a hillside?

Question 13

Briefly explain why a region that is tectonically active may be particularly vulnerable to mass wasting.

Question 14

Briefly explain why saturated clay is a very unstable slope material.

Question 15

Why is the Uniform Building Code important for reducing mass wasting losses?

Question 16

What is the most important step that can be taken to minimize or eliminate mass wasting or damage from it?

Question 17

What human activities contribute to or cause mass wasting?

Question 18

What is a slope stability map?

Question 19

Because water can be so important in mass movement,what is one of the most effective and inexpensive ways of reducing mass wastage risk and damage?

Question 20

How can slow mass movements be detected?

Question 21

Landslide is

A) a general term for mass movements of earth materials.
B) a specific term for a mass movement of a defined type and speed.
C) a specific term used for mass movements on a volcano.
D) a specific term for the rapid movement of snow and ice downslope.

Question 22

Periodic freezing and thawing of the upper ground surface when the weather is cold can lead to _______.

Question 23

Mass movement in which material move as a viscous fluid or plastically is termed _______.

Question 24

_______ adds weight to the slope material,decreases inter-grain friction,and lubricates the base of an unstable slope.

Question 25

The steepest angle a slope can maintain without collapsing is known as the slope's ______________.

Question 26

____________________ are sometimes used to fasten unstable bedrock to stable strata.

Question 27

The material accumulated at the base of cliffs where rocks fall is known as ____________________.

Question 28

A rapid down slope mass movement of snow and ice is called a(n)____________________.

Question 29

A flow that is up to 30 percent water and at least 50 percent clay-sized particles is a _______.A flow with less water but larger particles is a _______.

Question 30

In the ____________________ method of protecting slopes,material is removed from the top of the slope and used as fill at the base.

Question 31

Clays that spontaneously liquefy and flow like water are called ____________________ clays.

Question 32

Give an example of a way in which mass wasting can affect human activity.

Question 33

Geologists call the down slope movement of material under the direct influence of gravity ____________________.

Question 34

A slope material's strength and cohesion,the amount of internal friction between grains,and any external support of the slope define a slope's

A) mass wasting.
B) angle of repose.
C) dynamic equilibrium.
D) shear strength.

Question 35

Creep is most effective and significant in a(n)____________________climate.

Question 36

Ground that remains permanently frozen is called ____________________.

Question 37

Most mass wasting is enhanced or promoted by ____.

A) erosion
B) weathering
C) flash floods
D) wind erosion
E) plate tectonics

Question 38

Damage to homes by mass wasting

A) strikes wealthy and poor people equally.
B) is rare because the potential dangers on different slopes are well studied.
C) is more likely to affect poor people since they cannot afford to build on the most stable slopes.
D) is most likely to strike urban areas.

Question 39

Mass movement in which rocks fall through the air are known as ____________________.

Question 40

When a slope dips in the same direction as the strata or a prominent joint set the type of mass wasting that is likely to occur is _______ _______.

Question 41

Most block slides occur because the strata are highly fractured.

Question 42

Most major landslides ____.

A) are caused by earthquakes
B) are caused by volcanic eruptions
C) have natural causes
D) are due to human activity and poor engineering
E) none of these

Question 43

All other factors being equal,what is the chance of mass wasting increased by?

A) the amount of material involved
B) the lack of friction on the slope
C) the angle of the slope
D) the kind of event which initiates the mass wasting
E) whether there exists a positive or negative gravity anomaly

Question 44

Permafrost lies beneath ____ percent of the land surface on Earth.

A) 0
B) 10
C) 20
D) 40
E) 50

Question 45

Some mass wasting occurs at almost imperceptibly slow rates.

Question 46

A loud thunderclap may be sufficient to trigger a landslide of an unstable slope.

Question 47

Drainage on a slope

A) reduces the weight of material.
B) lowers pore pressure.
C) is effective and inexpensive.
D) All of these.

Question 48

Creep occurs only on weathered or soil-covered surfaces of moderate slope.

Question 49

In the cut-and-fill method,

A) benches are cut into a hillside.
B) material is removed from the up a slope and placed at the base.
C) retaining walls are constructed and anchored into bedrock.
D) rock bolts are fastened to stable bedrock.

Question 50

Slumps occur most commonly in well-consolidated material.

Question 51

After gravity,what is the major cause of mass wasting?

A) slope gradient
B) weakening by weathering
C) overloading
D) vegetation loss
E) increased water content

Question 52

The removal of vegetation is a significant cause of slope failure and mass wasting.

Question 53

Water

A) decreases friction between grains.
B) causes a loss of cohesion.
C) adds weight.
D) all of these.

Question 54

Slow mass movement transports a greater volume of material than does rapid mass movement.

Question 55

Mass wasting is most likely to occur in what climate?

A) arid warm regions
B) humid tropical regions
C) arctic regions
D) temperate regions
E) none of these

Question 56

Mass wasting does NOT occur on ____.

A) unstable material
B) near-level slopes
C) steep slopes.
D) gradual slopes.
E) It occurs on all of these.

Question 57

The type of mass wasting that is responsible for the greatest amount of property damage is what?

A) creep
B) slumps
C) rock fall
D) slides
E) avalanches

Question 58

Solifluction is not a serious economic problem because it occurs mainly in unpopulated areas.

Question 59

Creep is the most economically damaging and widespread type of material flow.

Question 60

Among the types of slides are ____.

A) slumps
B) block slides
C) mudflows
D) slumps and block slides
E) all of these

Question 61

Falls,slumps,and slides may turn into flows.

Question 62

Geologists choose the one best method for stabilizing a slope among the many that are available.

Question 63

Most large mass movements can be prevented given sufficient study and planning.