Deck 15: Mass Movements

Question 1

Quick clays are among the least mobile of all deposits and so provide favorable building sites.

Answer 1

False

Question 2

The Houston-Galveston,Texas,area has been sinking.This is related to the _______________.

A)withdrawal of groundwater by pumping
B)dissolution of limestones
C)emptying of a magma chamber
D)weight of all the high-rise buildings and houses
E)dissolution of a salt layer

Answer 2

A

Question 3

The most likely explanation for how highly fluidized rock flows occur is that ________________.

A)the jostling of fragments in the flowing mass provides energy that propagates as trapped sound waves and supports the particles,thus fluidizing the mass (acoustic fluidization)
B)water lubricates the material,allowing it to flow (hydro fluidization)
C)steam lubricates the material,allowing it to flow (aqueous fluidization)
D)the flowing mass rides on a cushion of compressed air (jetting)
E)heat generated by friction melts material within the mass,allowing it to flow (thermal fluidization)

Answer 3

A

Question 4

The Italian city of ____________ is trying to save itself from slow subsidence and sea level rise.

A)Rome
B)Florence
C)Turin
D)Pisa
E)Venice

Question 5

Clays are among the least abundant of all sediments.

Question 6

The volume of soil does not stay constant but instead swells and shrinks.

Question 7

Of the following types of mass movements,which can move fastest?

A)creep
B)translational rockslide
C)avalanche
D)mudflow
E)earth flow

Question 8

Catastrophic subsidence into sinkholes tends to occur more often in areas underlain by ________________.

A)acidic freshwater flowing through limestone
B)basic freshwater flowing through limestone
C)acidic saltwater flowing through sandstone
D)basic freshwater flowing through sandstone
E)basic saltwater flowing through sandstone

Question 9

Many hill-slope masses are weak due to preexisting geologic conditions such as _______________.

A)ancient slide surfaces
B)rock layering dipping less than topographic slopes
C)structures within the rocks,such as fractures,ancient faults,and thin clay seams
D)All of these choices are correct.

Question 10

Freshwater passing through uplifted sediments containing quick clay changes the sea salt content leaving quick clay with all but which of the following?

A)weak structure
B)grains mostly less than 0.002 mm diameter
C)water contents commonly in excess of 50 percent
D)a high salt content
E)All of these choices are correct.

Question 11

The underlying cause of the Rissa,Norway,landslide was ______________.

A)dissolution of salt in the soil
B)too much gypsum in the soil
C)over-steepening of slopes of volcanic ash
D)freezing and thawing of piles of glacial boulders
E)layering of volcanic pyroclasts

Question 12

The sum of all the underlying causes can push a slope to the brink of failure,and then an immediate cause may trigger the movement.Triggers for mass movements include ______________.

A)heavy rains
B)earthquakes
C)thawing of frozen ground
D)the construction projects of humans
E)All of these choices are correct.

Question 13

The materials most commonly associated with earth failures are ______________.

A)clay minerals
B)quartz
C)granite
D)basalt
E)pahoehoe

Question 14

Creep is an ultra-slow,almost imperceptible upslope movement of the soil and uppermost bedrock zones.

Question 15

External processes that increase the odds of a slope failure include ________________.

A)adding mass high on a slope,as in sediment deposition
B)steepening the slope,as by fault movements
C)removing support from low on a slope,as by stream or ocean-wave erosion
D)All of these choices are correct.

Question 16

There are certain times when a hill containing clay minerals is weaker than at other times,and then gravity has a better chance of provoking a slope failure.

Question 17

Humans can cause landslides to occur by ______________________.

A)adding fill dirt high on hill slopes to improve the view,thus adding to the driving mass.
B)removing material from the base of a slope to widen or clear a road or to form a building lot,thus weakening the resisting mass.
C)Both of these are correct.
D)Neither of these are correct.

Question 18

Clay crystals __________________.

A)are very large
B)are very small
C)range from very large to very small
D)are amorphous
E)form isostacies

Question 19

In ________________,masses move down and out by sliding on planes of weakness,such as faults,bedding,or clay rich layers.

A)rock falls
B)translational slides
C)rotational slides
D)debris flows
E)struzstroms

Question 20

Before a landslide mass begins to move downhill,it must overcome ________________.

A)gravity and friction
B)inertia and gravity
C)inertia and friction
D)gravity and creep

Question 21

There are certain times when a hill containing clay minerals is weaker than at other times,and then gravity has a better chance of provoking a slope failure.

Question 22

Creep is an ultra-slow,almost imperceptible upslope movement of the soil and uppermost bedrock zones.

Question 23

Land subsidence is worsened by the cessation of groundwater pumping,because the additional water that is retained underground weakens the rock,making it subside more easily.

Question 24

Water molecules can attach their positive sides against clay minerals because clay surfaces are also positively charged.

Question 25

Basal failure surfaces for landslides typically are either curved in a concave-upward sense or nearly planar.

Question 26

The amount of water in pore spaces has no effect on mass movements of earth materials.

Question 27

Despite what some old movies show,quicksand does not suck people or other objects down.

Question 28

The main types of mass movement are downward,as in falling or subsiding,or downward and outward,as in sliding and flowing.

Question 29

The orientation of rock layering within a hill can either enhance or hinder the chances of slope failure.