Deck 11: Deformation of Rocks

Question 1

Which option describes a possible oil and gas trap?

A) an anticline made entirely of sandstone with an organic earth covering
B) a reverse fault with a sandstone layer and a shale layer underneath
C) an anticline with a sandstone layer and a shale layer on top
D) a syncline with a coal layer at the bottom, a sandstone middle, and a shale layer on top

Answer 1

C

Question 2

The oldest rocks are exposed along the axis of

A) a syncline.
B) an anticline.
C) a dip.
D) a plunging fold.

Answer 2

B

Question 3

Figure 11.13
According to Figure 11.13, which option correctly describes the movement of two pins on either side of a plane in a block of clay submitted to tensional stress?

A) They remain in the same position.
B) They move farther from the plane.
C) They move closer to the plane.
D) They slide along at the same distance from the plane in opposite directions.

Answer 3

B

Question 4

Choose the option that correctly orders the fluids from the one that sits at the bottom of a sandstone reservoir to the one that is closest to the low-porosity shale at the top of the reservoir.

A) oil, gas, water
B) gas, water, oil
C) water, gas, oil
D) gas, oil, water

Question 5

The distinction between a joint and a fault is

A) the separation distance.
B) the distance that rock moves on each side of the line.
C) joints do not involve breaking rock and faults do.
D) joints are filled in with precipitated mineral crystals and faults are not.

Question 6

At greater depths, rocks are

A) stronger and more brittle.
B) weaker and more plastic.
C) weaker and more brittle.
D) stronger and more plastic.

Question 7

Figure 11.16
Which is not a reason for the hydraulic fluid around the cylinder in the experimental apparatus for measuring rock strength (as in Figure 11.16)?

A) to imitate tectonic stresses within Earth
B) to imitate surrounding rock pressures
C) to imitate pressures of depth
D) to imitate deep, confining pressures within Earth

Question 8

Why are some faults named "reverse" faults?

A) The rock moves in one direction, then reverses and moves in another direction.
B) The rock moves in opposite directions on each side of the fault.
C) The rock on the hanging wall moves opposite to the direction it does in a normal fault.
D) The rock on the hanging wall moves perpendicular to the direction of a thrust fault.

Question 9

Figure 11.13
According to Figure 11.13, which option correctly describes the movement of two pins on either side of a plane in a block of clay submitted to shear stress?

A) They remain in the same position.
B) They move farther from the plane.
C) They move closer to the plane.
D) They slide along at the same distance from the plane in opposite directions.

Question 10

A brittle deformation

A) is a shattering motion that occurs at a fault.
B) is a break that occurs at a relatively small strain.
C) is a plastic deformation that occurs under high pressure.
D) is a deformation that may reverse to its original form.

Question 11

Which of the following occurs as a result of compression?

A) elongation
B) strain
C) shortening
D) strength

Question 12

If a geologist creates a geologic map of an area and then draws a cross-section of that area, what type of scientific process is shown?

A) interpretation
B) observation
C) conclusion
D) experimentation

Question 13

Faults that show a combination of dip-slip and strike-slip movement are

A) reverse faults.
B) strike-dip faults.
C) oblique-slip faults.
D) diagonal-strike faults.

Question 14

Deformation under low stress, below yield strength, is often

A) elastic.
B) plastic.
C) irreversible.
D) compressive.

Question 15

Choose the option that places the rock types in order from most brittle at surface temperature to most plastic.

A) rock salt, schist, basalt
B) granite, limestone, marble
C) quartzite, mudstone, sandstone
D) shale, basalt, sandstone

Question 16

A(n) ________ forms where rocks both fold and tilt.

A) syncline
B) anticline
C) dip
D) plunging fold

Question 17

Which term is defined as a measure of the amount of stress that a material can endure before it fails by breaking or flowing?

A) elongation
B) strain
C) shortening
D) strength

Question 18

Figure 11.20
Which option would incorrectly complete the following statement? According to Figure 11.20, to shorten marble by five percent

A) requires one fewer kilobar if the material is wet than when it is dry.
B) requires about two fewer kilobars if the material is wet and hot than when it is dry at room temperature.
C) requires about two fewer kilobars if it is hot and dry than when it is cold and dry.
D) requires about one fewer kilobar if it is hot and dry than when it is cold and dry.

Question 19

Figure 11.14
In a sandbox with a crankable division, which of the following may be illustrated?

A) Normal faults fold in the area under compression and reverse faults form where the sand is pressed together.
B) Normal faults fold in the area under tension and reverse faults form where the sand is given more space.
C) Normal faults fold in the area under compression and reverse faults form where the sand is given more space.
D) Normal faults fold in the area under tension and reverse faults form where the sand is pressed together.

Question 20

Which piece of measured evidence would not help geologists produce geologic cross sections in order to interpret subsurface geology?

A) subsurface layers
B) orientation of rock layers
C) orientation of folds
D) faults

Question 21

According to the elastic rebound theory, what may occur before a major earthquake?

A) minor shocks
B) deformation of rock in shear directions and bending rock
C) deformation and bending of rock into anticlines
D) deformation and bending of rock into synclines

Question 22

An M7 earthquake has ________ times more energy than an M5 earthquake.

A) 2
B) 100
C) 32
D) 1024

Question 23

You are asleep and are awakened to hear dishes rattling, and you feel a sensation that resembles a heavy truck striking your building. On the Modified Mercalli Intensity Scale, what intensity is the earthquake you've experienced?

A) IV
B) VII
C) IX
D) XI

Question 24

"Tsunami" refers to

A) huge waves at sea that diminish somewhat and reach land.
B) a sudden buildup of wave amplitude in shallow water.
C) high-amplitude, high-frequency waves that reach shore.
D) a series of waves that reach the shore in fast succession, causing extreme damage.

Question 25

Liquefaction occurs when

A) rock heats enough that it behaves like a liquid.
B) rivers and water bodies overrun and dissolve earth materials during a quake.
C) grains of earth materials settle downward during shaking and wet ground becomes fluid.
D) grains rise up to the surface in groundwater during an earthquake and cause mass movement.

Question 26

Which of the following is not a factor that is considered when comparing the strength of the oceanic and continental lithosphere?

A) laboratory rock-strength data
B) varying thickness of the continental and oceanic crust
C) chemical composition and water content
D) varying pressure under the ocean and the continents

Question 27

Evaluate this statement: "Earthquake damage depends primarily on the magnitude of the quake."

A) This statement is true.
B) This statement is true, but earthquake damage also depends on the proximity to the epicenter and the characteristics of materials through which the earthquake passes.
C) This statement is false; the most important factor in earthquake damage is the quality of building materials used.
D) This statement is false; the most important factor in earthquake damage is the location's proximity to the epicenter.

Question 28

The word "graben" originates from

A) the German word for "ditch."
B) the English word for "grab."
C) the German word for "tumble."
D) the Japanese word for "nest."

Question 29

On the Modified Mercalli Intensity Scale, destroyed bridges, bent rails, and most buildings destroyed are indicative of ________ intensity?

A) IV
B) VII
C) IX
D) XI

Question 30

Earthquake damage occurs when

A) stress exceeds strain of materials.
B) stress exceeds strength of materials.
C) strain exceeds strength of materials.
D) strength exceeds strain of materials.

Question 31

Tension results in strike-slip faults when

A) the fractures are parallel to the stress direction.
B) the fractures are perpendicular to the stress direction.
C) suitable reverse faults are acted upon.
D) suitable normal faults are acted upon.

Question 32

Which action would geologists take in order to determine the Richter magnitude of an earthquake?

A) analyze seismic instrument readouts
B) take core samples at several spots and from different distances from the epicenter
C) assess financial costs of rebuilding roads, buildings, and public areas in the quake zone
D) interview people who experienced the quake

Question 33

What type of data to date is most useful for earthquake prediction?

A) study of rock types
B) study of earthquake patterns in other locations
C) monitoring known precursor events
D) monitoring world-wide seismic data and extrapolating patterns

Question 34

Arched folds where limbs dip away from the hinge line are called

A) inclines.
B) anticlines.
C) synclines.
D) reclines.

Question 35

What action would geologists take when creating a Modified Mercalli Intensity map of an earthquake?

A) analyze seismic instrument readouts
B) take core samples at several spots and from different distances from the epicenter
C) assess financial costs of rebuilding roads, buildings, and public areas in the quake zone
D) interview people who experienced the quake

Question 36

Put the steps in the correct order. 1. Stress exceeds rock yield strength. 2. Potential energy is released as motion energy. 3. Strong rocks absorb large stresses during elastic strain. 4. Rock breaks.

A) 3, 2, 1, 4
B) 3, 1, 2, 4
C) 3, 1, 4, 2
D) 3, 2, 4, 1

Question 37

What does earthquake intensity measure?

A) amplitude of seismic waves
B) reach of the quake from the epicenter in km
C) cost of reconstruction
D) damage and secondary effects of the quake

Question 38

"Horst," meaning "nest," is a suitable word for the rock formation it describes because

A) these rock formations are also in ditches or valleys, like nests.
B) these rock formations are typically in protected valleys.
C) these rock formations are pushed up to a high place, and horsts are nests in high places.
D) these rock formations are circular and cupped like nests.

Question 39

Arched folds where limbs dip toward the hinge line are called

A) synclines.
B) reclines.
C) anticlines.
D) inclines.

Question 40

Strength

A) decreases with depth.
B) increases with depth because of pressure, then decreases at further depths because of temperature.
C) increases with depth.
D) decreases with depth because of pressure, then increases at further depths because of temperature.

Question 41

Faults are:

A) cracks where displacement has occurred.
B) fracture planes along which rocks used to move but don't any longer.
C) fractures in the bedrock.
D) fracture planes along which rocks move.

Question 42

The Richter magnitude is based on

A) the amount of damage caused.
B) the maximum amplitude recorded.
C) the difference in arrival times of S and P waves.
D) the distance from the epicenter.

Question 43

Dip-slip faults include normal, reverse and thrust faults.

Question 44

Judge the following sentence according to the criteria given below. There is a link between mining and faults because minerals precipitate from water percolating along faults.

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

Question 45

The rocks above the fault are called the hanging wall.

Question 46

A seismic station records an earthquake that has a maximum surface wave amplitude of 50 mm and the S-wave arrives 2 seconds after the P-wave. The Richter magnitude of this earthquake is

A) 3.
B) 4.
C) 5.
D) 6.

Question 47

The rocks below a fault are called the footwall.

Question 48

The block of rock above an inclined fault plane is called the ________.

A) footwall
B) hanging-wall
C) strike-wall
D) dipwall

Question 49

Oppositely dipping sides of the fold of a rock are called its limbs.

Question 50

A normal fault forms when:

A) the hanging wall rock moves downward compared to the footwall.
B) the hanging wall rock moves up along a dip-slip fault compared to the footwall.
C) the fault dips at an angle steeper than 45 degrees.
D) the fault dips at an angle less than 45 degrees.

Question 51

A measure of earthquake size that corresponds to the energy released during the earthquake is called the

A) focus.
B) epicenter.
C) intensity.
D) magnitude.

Question 52

A seismic station records an earthquake that has a maximum surface wave amplitude of 1 mm and the S-wave arrives 2 seconds after the P-wave. The Richter magnitude of this earthquake is

A) 1.
B) 1.5.
C) 2.
D) 2.5.

Question 53

Joints are:

A) cracks where some displacement of the rock occurred.
B) cracks where no displacement of the rock occurred.
C) fractures where some displacement has occurred.
D) fractures where no displacement has occurred.

Question 54

The San Andreas fault has shifted rocks hundreds of kilometers. For example, plutonic rocks on the Pacific Ocean (western)side of the fault have been displaced from southern California to northern California, relative to rocks on the North American (eastern) side. The San Andreas fault is classified as a

A) normal dip-slip fault.
B) reverse dip-slip fault.
C) right-lateral strike-slip fault.
D) left-lateral strike-slip fault.

Question 55

Strike-slip faults include right-lateral, left-lateral and thrust faults.

Question 56

Cracks where displacement of rock has occurred are called

A) faults.
B) sills.
C) joints.
D) dikes.

Question 57

A seismic station records an earthquake that has a maximum surface wave amplitude of 20 mm and the S-wave arrives 40 seconds after the P-wave. The Richter magnitude of this earthquake is

A) 4.5.
B) 5.
C) 5.5.
D) 6.

Question 58

Cracks where very little or no displacement of rock has occurred are called

A) faults.
B) sills.
C) joints.
D) dikes.

Question 59

All of the seismic hazards in the United States are located west of the Rocky Mountains.

Question 60

In a normal fault, the footwall moves ________ relative to the hanging-wall.

A) down
B) up
C) right
D) left

Question 61

How can earthquakes cripple emergency services, transportation networks, water and gas utilities, and communication?

Question 62

Does the "Ring of Fire" include any part of the United States? Where?

Question 63

Grabens are:

A) blocks of crust jostled upward along normal faults.
B) blocks of crust jostled downward along normal faults.
C) blocks of crust jostled left along normal faults.
D) blocks of crust jostled right along normal faults.

Question 64

Thrust faults are formed by horizontal movement along the strike direction of the fault plane.

Question 65

In an earthquake, what causes the most damage and deaths?

Question 66

What caused the giant tsunami in the Indian Ocean in 2004?

Question 67

Movement along a dip-slip fault causes an abrupt vertical displacement of the ground surface called a fault scarp.

Question 68

Most of the energy released in an earthquake is released:

A) during the foreshock.
B) during the aftershock.
C) during the foreshock and the aftershock.
D) during a single mainshock.

Question 69

What is the amplitude in an earthquake?

Question 70

What is the downside of using moment magnitude as an earthquake measurement?

Question 71

The elastic rebound theory explains earthquakes as sudden brittle failure following the buildup of elastic strain.

Question 72

Currently, what is the best method for predicting earthquakes within the crucial 2 hour time period?

Question 73

Oil and gas, like groundwater, move through pore spaces in rock.

Question 74

The Modified Mercalli Intensity Scale is a quantitative measure of an earthquake.

Question 75

Intensity measures the violence of ground shaking during an earthquake in terms of the extent to which people felt the earthquake.

Question 76

Why is it good to measure the magnitude, rather than intensity, of an earthquake?

Question 77

A reverse fault forms when:

A) the hanging wall rock moves downward compared to the footwall.
B) the hanging wall rock moves up along a dip-slip fault compared to the footwall.
C) the fault dips at an angle steeper than 45 degrees.
D) the fault dips at an angle less than 45 degrees.

Question 78

Magnitude is:

A) a measure of earthquake size that is related to the energy released during the earthquake.
B) a directly measured physical quantity.
C) a value that is calculated from measurements taken during an earthquake.
D) determined using the amplitude of P and S waves.

Question 79

Horsts are:

A) blocks of crust jostled upward along normal faults.
B) blocks of crust jostled downward along normal faults.
C) blocks of crust jostled left along normal faults.
D) blocks of crust jostled right along normal faults.

Question 80

What is the best construction method for a building situated in an earthquake prone area?