Practice 3rd Exam Geol 1121, Summer 2016 Multiple Choice



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Practice 3rd Exam - Geol 1121, Summer 2016
Multiple Choice

Identify the choice that best completes the statement or answers the question.
____ 1. Geologists who specifically study earthquakes are called ____________.

a.

seismologists

c.

vulcanologists

b.

paleontologists

d.

speleologists

____ 2. Earthquakes are a result of ____________.



a.

a sudden change in atmospheric pressure

b.

mantle upwelling

c.

erosion

d.

lithosphere-plate movement

____ 3. Faults that have moved recently or are likely to move in the future are referred to as ____________.



a.

passive

c.

normal

b.

active

d.

reverse

____ 4. A primary force opposing motion on all faults is ____________.



a.

magnetic attraction among iron-rich minerals

b.

gravity

c.

friction

d.

van der Waals force

____ 5. Movement on a fault may occur without generating earthquakes.



a.

true

b.

false

____ 6. Faulting and earthquakes are examples of ____________.



a.

brittle behavior

b.

ductile behavior

____ 7. A surface along which rock on opposed sides is offset by earthquake-induced slip is called a ____________.



a.

joint

c.

fold

b.

fault

d.

wall

____ 8. The intersection between a fault plane and the ground surface is called the ____________.



a.

dip line

c.

fault trace

b.

plunge

d.

seismic interface

____ 9. If, during an earthquake, a hanging wall slides upward relative to a footwall, the fault is termed ____________ if the fault is steep (closer to vertical than horizontal).





a.

normal

c.

strike slip

b.

reverse

d.

thrust

____ 10. If a fault is nearly vertical in orientation and the two walls of rock on opposite sides slide past one another horizontally, the fault is termed ____________.





a.

normal

c.

strike slip

b.

reverse

d.

thrust

____ 11. If, during an earthquake, a hanging wall slides upward relative to a footwall, the fault is termed ____________ if the fault is shallow (much closer to horizontal than vertical).





a.

normal

c.

strike slip

b.

reverse

d.

thrust

____ 12. Of the following, which causes the most earthquakes?



a.

the sudden formation of a new fault

c.

the explosion of a volcano

b.

a sudden slip on an existing fault

d.

a giant landslide

____ 13. Aftershocks following a major earthquake ____________.



a.

may continue for days after the initial earthquake

b.

are mostly much smaller than the original earthquake

c.

may occur on the same fault as the original earthquake, or a different fault

d.

All of the above are correct.

____ 14. Periods of intermittent sliding on a fault as a result of the release of stress during episodes of displacement, followed by stress buildup to the point that the fault is reactivated, is termed ____________.



a.

chaotic faulting

c.

stick-slip behavior

b.

thrust faulting

d.

reverse faulting

____ 15. The stress that builds on a preexisting fault that has previously ruptured _____________.



a.

is great enough to cause new fractures

b.

must overcome the force of friction to cause an earthquake

c.

is analogous to a broken stick

d.

is nonexistent

____ 16. A fault cannot slip forever because __________ .



a.

it exhibits no elastic behavior

b.

once the elastic bending that has built up is released, the blocks no longer move

c.

the vibration caused by the slipping eventually ceases

d.

friction eventually slows and stops the movement

____ 17. The quantity of offset that occurs along a fault is termed ____________.



a.

fault gouge

c.

displacement

b.

the fault gauge

d.

accumulation

____ 18. At any point along the fault plane surface of an oblique (nonvertical) fault, the ____________.





a.

hanging wall lies vertically above the footwall

b.

footwall lies vertically above the hanging wall

c.

hanging wall lies to the left of the footwall

d.

footwall lies to the left of the hanging wall

____ 19. If, during an earthquake, a footwall slides upward relative to a hanging wall, the fault is termed ____________.





a.

normal

c.

strike slip

b.

reverse

d.

thrust

____ 20. All discovered faults are likely to experience earthquakes in the next few hundred years.



a.

true

b.

false

____ 21. Which type of fault does NOT, by definition, have a fault trace?



a.

normal fault

b.

reverse fault

c.

blind fault

d.

None of the above are correct; all faults have recognizable traces.

____ 22. In order for an earthquake to occur where you live, which of the following must be true?



a.

You live in a seismic belt.

b.

Energy must be released in the Earth’s crust.

c.

You live on the Pacific Ocean.

d.

Slip must occur along a fault.

____ 23. Body waves include ____________.



a.

both S- and P-waves

c.

both surface and interior waves

b.

both L- and R-waves

d.

P-waves only

____ 24. A coiled spring would be useful in illustrating a ____________ wave.





a.

surface

c.

shear

b.

body

d.

compressional

____ 25. Which type of seismic wave has the highest velocity?



a.

L-wave

c.

R-wave

b.

P-wave

d.

S-wave

____ 26. Earthquake waves that pass through the interior of Earth are termed ____________.



a.

interior waves

c.

surface waves

b.

R-waves

d.

body waves

____ 27. Surface waves ____________.



a.

travel more rapidly than body waves

b.

produce most of the damage to buildings during earthquakes

c.

are the first waves initially produced in an earthquake

d.

are the first waves to arrive at a seismograph station after an earthquake

____ 28. Generally, which type of earthquake waves travel fastest?



a.

interior waves

c.

surface waves

b.

R-waves

d.

body waves

____ 29. As a seismologist examining a seismogram, you would know that the third set of waves displayed ____________.



a.

would cause the most damage

b.

are S-waves

c.

are P-waves

d.

are an indication that the major earthquake is over and that the aftershocks have begun

____ 30. Seismometers, being able to detect ground movements of a millionth of a millimeter, are useful to governments worldwide for detecting not only earthquakes, but _______________.



a.

landslides

c.

avalanches

b.

nuclear bomb tests

d.

bombing raids

____ 31. All else being equal, an earthquake that strikes in the eastern United States would produce shaking that would be felt ____________ than one that occurred in the western United States.



a.

over a greater distance

c.

over the same distance

b.

over a lesser distance




____ 32. This fundamental principle of physics is the basis behind the effectiveness of a seismometer.



a.

The change of momentum of a body is proportional to the impulse impressed on the body, and happens along the straight line on which that impulse is impressed.

b.

The mutual forces of action and reaction between two bodies are equal, opposite, and collinear.

c.

Every body persists in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed.

d.

To every action there is always an equal and opposite reaction.

____ 33. The key to finding the location of an earthquake’s epicenter is measuring the ____________.



a.

difference between the time that the P-wave arrives and the time that the S-wave arrives at the seismometer station

b.

total time it takes for the P-wave and then the S-wave to arrive at the seismometer station

c.

difference between the time the S-wave has reached one seismometer station and the time the S-wave has reached another station

d.

difference between the time the P-wave has reached one seismometer station and the time the P-wave has reached another station

____ 34. The point within Earth where an earthquake takes place is termed the ____________.



a.

hypocenter (focus)

c.

eye of the fault

b.

epicenter

d.

vertex

____ 35. The point on Earth’s surface directly above the point where an earthquake occurs is termed the ____________.



a.

hypocenter (focus)

c.

eye of the fault

b.

epicenter

d.

vertex

____ 36. How many seismic stations are necessary to find the epicenter of an earthquake?



a.

one

c.

three

b.

two

d.

four

____ 37. Which earthquake severity scale takes vibration caused only by the S-waves into account when estimating the size of an earthquake?




a.

Richter scale

c.

seismic-moment magnitude scale

b.

Mercalli scale




____ 38. Vertical motion seismographs record earthquakes through the production of a squiggly diagram called a ____________.



a.

wave sheet

c.

pictogram

b.

seismogram

d.

camera lucida

____ 39. Which earthquake intensity scale assesses the effects of an earthquake on humans and human-made structures?



a.

Richter scale

c.

seismic-moment magnitude scale

b.

Mercalli scale




____ 40. Which earthquake severity scale takes into account the type of rock that has been fractured?



a.

Richter scale

c.

seismic-moment magnitude scale

b.

Mercalli scale




____ 41. An earthquake occurs with an epicenter in the town of New Madrid, Missouri, in the interior of the North American Plate. Where might the hypocenter of this earthquake plausibly be found?



a.

in New Madrid (“hypocenter” and “epicenter” mean precisely the same thing)

b.

10 km south of New Madrid

c.

20 km beneath New Madrid

d.

200 km beneath New Madrid

____ 42. Which earthquake severity scale measures the amplitude of deflection of a seismograph pen, standardized to an idealized distance of 100 km between epicenter and seismograph?



a.

Richter scale

c.

seismic-moment magnitude scale

b.

Mercalli scale




____ 43. Which of the following scales was used to measure the intensity of the listed earthquakes?





a.

Mercalli

c.

Richter

b.

Seismic-moment

d.

None of the above are correct.

____ 44. Which earthquake severity scale varies from locality to locality for a single earthquake?



a.

Richter scale

c.

seismic-moment magnitude scale

b.

Mercalli scale




____ 45. If you heard on the news today that an earthquake measured an 8.2 on the Richter scale, what other conclusions could you make based on knowledge garnered from this chapter?



a.

that this was the only type of earthquake magnitude scale used

b.

that there will be “moderate to serious damage” based on a subjective assessment of damage and effects

c.

that, according to the Modified Mercalli Intensity Scale, maximum intensity will be at levels IX to X

d.

that the earthquake will be described as “great”

____ 46. According to the moment magnitude scale (Mw)—a magnitude 8 earthquake results in 1,000 times greater amplitude than a magnitude ____________ earthquake.



a.

9

c.

7

b.

5

d.

4

____ 47. Earthquakes are likely to occur along ____________.



a.

convergent-plate boundaries only

c.

transform-plate boundaries only

b.

divergent-plate boundaries only

d.

All of the above are correct.

____ 48. A tsunami is ____________.





a.

an earthquake-generated sea wave that can sometimes destroy coastal cities thousands of kilometers from its source

b.

a sloshing of water back and forth within a lake or bay

c.

the amount of change in elevation of local sea level caused by a surging wave

d.

the tendency of wet, clay-rich soils to behave like a liquid during an earthquake

____ 49. On December 26, 2004, a magnitude 9 earthquake generated a tsunami that devastated coastlines along the ____________.



a.

Atlantic Ocean

c.

Indian Ocean

b.

Arctic Ocean

d.

Pacific Ocean

____ 50. What geological setting(s) would you expect to produce seismic activity?



a.

rift valley

c.

collisional mountain belt

b.

basin

d.

All of the above are correct.

____ 51. Medium- and deep-focus earthquakes occur along ____________.



a.

convergent-plate boundaries only

c.

transform-plate boundaries only

b.

divergent-plate boundaries only

d.

All of the above are correct.

____ 52. Earthquakes that occur in a band called a ____________ can be used to track the motion of subducted oceanic lithosphere.



a.

Wegener belt

c.

Wadati-Benioff zone

b.

seismic gap




____ 53. Virtually all of the deaths attributed to major earthquakes have resulted from the collapse of buildings.



a.

true

b.

false

____ 54. Sandy substrate is susceptible to ____________ during an earthquake.



a.

displacement

c.

liquifaction

b.

collapse

d.

faulting

____ 55. Short-term predictions of earthquake behavior ____________.



a.

have saved millions of lives in the past decade alone

b.

have been largely unreliable

c.

are primarily based on the behavior patterns of farm animals

d.

are correct approximately 50% of the time

____ 56. Long-term prediction of earthquake behavior ____________.



a.

is based on past earthquake activity

b.

works on the principle that zones of past seismicity will be active in the future

c.

includes the notion of seismic gaps—places where an earthquake is “overdue”

d.

All of the above are correct.

____ 57. Why do some earthquakes last longer than others?



a.

The substrate in which it occurs is stronger.

b.

The distance from the epicenter is greater.

c.

The frequency of the waves is greater.

d.

The distance from the focus is greater.

____ 58. Which of these areas of the United States would you expect to have the highest occurrence of seismic activity?





a.

Southeast

c.

Northeast

b.

West

d.

Central

____ 59. How can damage and injury be minimized in areas prone to seismic activity?



a.

earthquake zoning

c.

warning systems

b.

engineering controls

d.

All of the above are correct.

____ 60. Seismic retrofitting is the process of __________.



a.

predicting earthquakes

b.

strengthening existing buildings and structures

c.

mapping areas prone to earthquakes

d.

releasing energy

____ 61. Geophysics is the study of _________.



a.

how magma moves within the Earth

b.

how Earth’s layers change through time

c.

the interior of Earth using seismicity, magnetics, and gravity

d.

the surface of Earth using seismicity, magnetics, and gravity

____ 62. Which layer of the Earth has the highest density?



a.

outer core

c.

mantle

b.

inner core

d.

crust

____ 63. S-waves travel ________ than P-waves; however, unlike P-waves, they _______ travel through liquids.



a.

slower; can

c.

faster; can

b.

slower; can’t

d.

faster; can’t

____ 64. If a P-wave is traveling through the Earth and encounters a molten magma chamber, what will happen to the velocity of the P-wave?



a.

It will slow down.

c.

It will stay the same speed.

b.

It will speed up.

d.

It will drop to zero.

____ 65. If a seismic wave is refracted upward at a boundary, what can be said about the material the wave is traveling through?



a.

The wave is moving through two materials of the same velocity.

b.

The wave is moving from a faster material into a slower material.

c.

The wave is moving from a slower material into a faster material.

d.

The wave is traveling through a molten magma chamber.

____ 66. If a P-wave is traveling through sandstone and then encounters peridotite, the P-wave will ________________.



a.

slow down

c.

remain at the same speed

b.

speed up

d.

not travel through the peridotite

____ 67. If an S-wave is traveling through rock when it encounters a magma chamber, the S-wave will ________________.



a.

slow down

c.

remain at the same speed

b.

speed up

d.

not travel through the magma

____ 68. The core consists of two layers: the ______ inner core and ______ outer core.



a.

iron; nickel

c.

solid; liquid

b.

nickel; iron

d.

liquid; solid

____ 69. The picture below shows a seismic tomography image of the western United States. What is the relative temperature of the blue regions (darker grey regions not outlined in black) versus the red regions (darker grey regions outlined in black)?





a.

The blue regions are warmer than the red regions.

b.

The red regions are colder than the blue regions.

c.

The red regions are warmer than the blue regions.

d.

The colors are not indicative of temperature, only velocity.

____ 70. What causes the velocity of a P-wave to slow down when it enters the outer core?



a.

The outer core is a much more dense material than the mantle.

b.

The outer core is a much less dense material than the mantle.

c.

The outer core is liquid, and thus the wave slows down.

d.

The P-wave no longer has to compete with the S-wave for energy.

____ 71. You are studying the seismic data from Mars when you notice that there are no S-waves recorded from 130° through 180° on the opposite side of the planet. What does this information tell you about the interior of Mars?



a.

There is a layer of solid material in the interior of Mars.

b.

There is a layer of liquid material in the interior of Mars.

c.

There is a layer with a higher velocity material than the crust below.

d.

There is a layer with a lower velocity material than the crust below.

____ 72. In the following graph, why does the line for S-waves NOT appear in the outer core?





a.

S-waves can’t travel through the outer core because it is solid.

b.

S-waves can’t travel through the outer core because it is liquid.

c.

S-waves disappear after being reflected at the core–mantle boundary.

d.

S-waves can’t travel that far into the Earth due to the high amount of iron.

____ 73. In the seismic tomography cross section below, where is the subducting Juan de Fuca Plate, considering that the subducting plate is much cooler than the surrounding material?





a.

#4: blue blob at the far right side of the picture that extends straight down into the image

b.

#2: blue blob at the left side of the picture that extends down at an angle into the image

c.

#1: red blob at the far left side of the picture that extends straight down into the image

d.

#3: red blob in the center of the picture that extends straight down into the image

____ 74. Earth’s gravity is best represented by an equipotential surface that contains bumps and depressions where areas of more or less gravity appear over the Earth, this representation is called the _________.



a.

reference geoid

c.

isostasy

b.

gravitational potential

d.

geoid

____ 75. If a gravity anomaly is negative, what does that imply about the material underground?



a.

The material is much more dense rock.

c.

The material is an underground ore.

b.

The material is much less dense rock.

d.

The material is composed of mantle.

____ 76. In the picture below, when the ship is filled with cargo it sinks into the water until the mass of water displaced is equal to the mass of the cargo. The ship is then said to be ____________.





a.

an equipotential surface

c.

equal to the geoid

b.

a self-exciting dynamo

d.

in isostatic equilibrium

____ 77. If a ship weighs 52,000 tons and is in isostatic equilibrium when 6,000 tons of cargo is added, what is the total mass of water that will be displaced by the ship after the cargo is added?



a.

6,000 tons

c.

58,000 tons

b.

12,000 tons

d.

52,000 tons

____ 78. The following picture is that of a gravity map of the United States. What do the dark grey regions mean in terms of the density of the material below?





a.

high-density rock

c.

rock of high magnetization

b.

low-density rock

d.

rock of low magnetization

____ 79. A mountain range made of granite would produce a(n) _____________ gravity anomaly.



a.

positive

c.

isostatic

b.

negative

d.

magnetized

____ 80. Why would the gravity anomaly over a deep-ocean trench be negative?



a.

because the bathymetry of the trench dips very far below sea level

b.

because dense crust is being pulled into the trench, leaving less dense sediments above

c.

because water fills the space above the subducting slab and is much less dense than rock

d.

because the buoyant magma created at the subduction zones is less dense than the rock

____ 81. A positive magnetic anomaly is produced when the measured magnetic field strength is ___________ the expected magnetic field strength.



a.

greater than

c.

the same as

b.

less than

d.

the opposite of

____ 82. Earth’s magnetic field is produced in the ___________.



a.

crust

c.

outer core

b.

mantle

d.

inner core

____ 83. If a ship towing a magnetometer passes over a piece of crust with a “normal” polarity, what will the magnetic anomaly look like?



a.

The magnetic anomaly will be greater than Earth’s.

b.

The magnetic anomaly will be lower than Earth’s.

c.

The magnetic anomaly will exactly match Earth’s.

d.

The magnetic anomaly will be exactly zero.

____ 84. If you measure the magnetization of an area of igneous rocks and find a large negative anomaly, what does that imply about the rocks?



a.

They were formed during a time of normal polarity of the magnetic field.

b.

They were formed during a time of reversed polarity of the magnetic field.

c.

They were formed on the ocean floor where the rocks are closer to the core.

d.

They were formed on the continental crust in a complex pattern of magnetization.

____ 85. Why are magnetic anomalies of continental crust so much more complicated than those of oceanic crust?



a.

The continents are much older and thus have had more time for the minerals to become magnetized.

b.

The continents contain abundant iron minerals, whereas the oceanic crust does not contain any iron minerals.

c.

The continents contain a random orientation of minerals that become magnetized when they interact with the magnetic field.

d.

The continents contain a complex distribution of igneous intrusions, lava flows, and iron-rich sediments.


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