Deck 6: Restless Earth: Earthquakes, Geologic Structures, and Mountain Building

Question 1

During an earthquake near Port Royal, Jamaica, the water-saturated sand on which the city was built vigorously shook. As a result, the sand particles lost contact with one another, giving the mixture the consistency of a thick milk shake. Anything supported by the ground, such as buildings and people, either floated or sank. One eyewitness stated: "Whole streets with inhabitants were swallowed up. . . . Some were swallowed quite down, and cast up again by great quantities of water; others went down and were never more seen." This is a description of ________.

A)liquefaction
B)tsunami
C)landslide
D)subsidence

Answer 1

A

Question 2

Earth's core is interpreted to consist mainly of ________.

A)granite
B)basalt
C)iron and nickel
D)mostly solid rock with a small amount of melt due to the temperature-pressure regime

Answer 2

C

Question 3

On a typical seismogram, ________ will show the highest amplitudes.

A)P waves
B)S waves
C)surface waves
D)body waves

Answer 3

C

Question 4

When an earthquake occurs, energy radiates in all directions from its source region, called the ________, the spot in Earth's crust where a fault slips.

A)hypocenter
B)epicenter
C)scarp
D)seismic zone

Question 5

Three of the following statements are wrong. One is correct. Which of the following statements is correct?

A)P waves travel through solids; S waves do not.
B)P and S waves travel through liquids, but P waves do not travel through solids.
C)S waves travel through solids, but only P waves travel through liquids.
D)P and S waves travel through liquids, but S waves do not travel through solids.

Question 6

Approximately how much more energy is released in an earthquake of Richter magnitude 6.5 than in a magnitude 5.5 earthquake?

A)3)2
B)32
C)320
D)3,200

Question 7

Examine the graph. After a P wave (blue line)has been traveling for 5 minutes, how much distance has been covered by an S wave (red line)generated by the same earthquake?

A)1200 km
B)1900 km
C)2500 km
D)3100 km

Question 8

With regard to earthquakes, what distinguishes intensity from magnitude?

A)Intensity is a measure of how much energy is released by the earthquake, but magnitude is a rough measure of local shaking.
B)Magnitude is a measure of how much energy is released by the earthquake, but intensity is a rough measure of local shaking.
C)Intensity and magnitude both depend on people reporting their experiences.
D)Magnitude cannot be measured from a distance using seismograms.

Question 9

The amount of destruction caused by earthquake vibrations is affected by the ________.

A)design of structures like roads and buildings
B)intensity and duration of the seismic vibrations
C)nature of the surface material
D)all of the above

Question 10

Which one of the following statements about the crust is NOT true?

A)It is the thinnest of the major subdivisions.
B)It is thickest where prominent mountains exist.
C)Continental rocks are compositionally different than oceanic rocks.
D)Oceanic crust has an average composition of granite.

Question 11

Which one of the following is true of most tsunamis?

A)They are faster than seismic surface waves.
B)Their wave heights decrease and wavelengths increase as they move into shallower water.
C)They are usually started by sudden movement on a megathrust fault, and have wavelengths that are many kilometers long and wave heights of less than a meter.
D)They only occur in the Pacific Ocean basin.

Question 12

The earthquake belt with the greatest level of activity is the ________.

A)San Andreas Fault
B)Alpine-Himalayan Belt
C)East Pacific Rise
D)Circum-Pacific Belt

Question 13

Where is the epicenter of an earthquake?

A)where the rock on either side of a fault moves
B)on Earth's surface, directly above the hypocenter
C)where the fault meets Earth's surface
D)wherever we find the most damage from the earthquake

Question 14

Which kind of seismic wave is responsible for the most shaking (and thus, the most damage to human structures)?

A)P waves
B)S waves
C)surface waves
D)scarp waves

Question 15

Our greatest source of knowledge about Earth's interior comes from ________.

A)drill holes
B)deep mine shafts
C)seismic waves
D)volcanic eruptions

Question 16

Which kind of seismic wave is fastest-moving?

A)P waves
B)S waves
C)surface waves
D)seismic waves all travel at the same speed

Question 17

Seismic waves travel faster ________.

A)in materials that are more rigid or less compressible
B)deeper in Earth's interior
C)both of the above
D)none of the above

Question 18

The record of an earthquake obtained from a seismic instrument is a(n)________.

A)seismograph
B)seismogram
C)P-S graph
D)epitaph

Question 19

The distance between a seismological recording station and the earthquake source is determined from the ________.

A)earthquake magnitude
B)intensity of the earthquake
C)length of the seismic record
D)arrival times of P and S waves

Question 20

Which of the following statements about the mantle is TRUE?

A)The lithospheric mantle moves independently of the overlying plates.
B)The asthenosphere and lower mantle are made of roughly the same composition material, only it behaves differently in the asthenosphere.
C)The lower mantle is significantly less dense than the upper mantle.
D)The upper mantle is liquid, but the lower mantle is solid.

Question 21

A normal fault has little or no vertical movements of the two blocks.

Question 22

Terranes are relatively small crustal fragments (microcontinents, volcanic island arcs, or oceanic plateaus)that may be accreted to continents when subduction brings them to a trench.

Question 23

In this figure, the letter "C" is the location.

Question 24

The North American Cordillera consists of many terranes which bear magnetic and fossil evidence suggesting they originated far to the south of the modern-day positions.

Question 25

How did the Himalayas form?

A)collision of India and Eurasia
B)stretching of the crust to produce fault block mountains
C)movement on a strike-slip fault
D)collision and accretion of many small terranes including island arcs and microcontinents

Question 26

________ is/are an example of ductile deformation.

A)Folds
B)Dip-slip faults
C)Strike-slip faults
D)Earthquakes

Question 27

Domes are broad circular downwarped structures.

Question 28

Seismic waves may reflect, but not diffract or refract, as they encounter different layers in Earth's interior.

Question 29

These rock layers in this photo have experienced elastic deformation.

Question 30

In a reverse fault, the hanging wall block moves up with respect to the footwall block.

Question 31

This photo shows an anticline.

Question 32

Thrust faults shorten the crust horizontally and thicken it vertically.

Question 33

Mountain belts form by ________.

A)accretion of terranes
B)orogenesis
C)eruption of a continental volcanic arc
D)all of the above

Question 34

An accretionary wedge is a typical feature found along subduction zones.

Question 35

Earth's divergent oceanic ridge system produces a belt of earthquake activity where seafloor spreading generates many frequent quakes of small magnitude.

Question 36

A tsunami looks like a massive, curling wave that towers above the coast before smashing into it.

Question 37

What kind of fold is illustrated in this photograph? At what sort of tectonic boundary situation is it likely to have formed?

A)anticline; divergent
B)syncline; divergent
C)anticline; convergent
D)syncline; convergent

Question 38

What kind of fault is illustrated in this figure?

A)normal fault
B)reverse fault
C)thrust fault
D)strike-slip fault

Question 39

Subduction leads to orogenesis.

Question 40

The mountains and valleys of the Basin and Range Province of western United States formed in response to tensional stresses and normal faulting.

Question 41

The ________ is the cool, brittle, outer layer of Earth that includes the crust and uppermost mantle.

Question 42

Sediment scraped off the subducting plate builds up in a(n)________. A nice example of this can be seen in central California's coast ranges.

Question 43

________ are accreted crustal fragments that have distinct geologic histories from that of the adjoining crust.

Question 44

________ are destructive sea waves induced by earthquakes.

Question 45

Match the earthquake hazard in the first column with the correct location in the second column.

A)regions with unstable slopes
B)coastal regions
C)cities with vulnerable water lines
D)areas of loose sediment
9)tsunami
10)liquefaction
11)landslides
12)fires

Question 46

The ________ is a layer in Earth's interior that is in a liquid state.

Question 47

The iron and nickel that are thought to dominate the core originally came from ________, the "building blocks" that originally formed Earth.

Question 48

How do terranes relate the growth of continental crust over geologic time? What region of North America illustrates this process well?

Question 49

In general, buildings constructed on ________ fare better in an earthquake than buildings constructed on ________, as this material amplifies seismic shaking.

Question 50

The ________ is the site of initial rupturing associated with an earthquake.

Question 51

________ are brittle structures.

Question 52

Horsts and grabens are bounded by ________.

Question 53

The difference between a continent and a microcontinent is ________.

Question 54

Label each of the blanks on the figure showing the source of earthquakes.

Question 55

Earth has ________ distinct kinds of crust.

Question 56

Most orogenesis occurs along ________ plate boundaries.

Question 57

The east coast of present-day North America is a good example of a(n)________ continental margin.

Question 58

Match the items in the first column with the correct descriptions in the second column.

A)permanent changes in rock shape due to stresses that exceed the strength of the rock
B)long, low cliffs produced at Earth's surface where a fault's vertical offset is exposed
C)the spot along a fault where movement takes place during an earthquake
D)a fold that is highest in the middle
E)the spot on Earth's surface directly above a fault where movement takes place during an earthquake
F)a fracture along which blocks of rock move relative to each other
G)a fold that is lowest in the middle
H)a broad upwarped feature that is roughly circular or oval-shaped when viewed from above
1)deformation
2)fault scarp
3)fault
4)hypocenter
5)epicenter
6)anticline
7)syncline
8)dome

Question 59

Describe the steps you would go through to determine the source of an earthquake, provided you had access to three seismographs that recorded the event.

Question 60

A(n)________ is an instrument that is used to record earthquake vibrations.

Question 61

Would earthquakes of similar magnitudes in different regions of the Earth cause approximately the same levels of damage necessarily? In your explanation, consider both geologic and human-induced factors.

Question 62

Which location has its formation depicted in these figures, (a)the Basin and Range, (b)the Himalayas, or (c)the Andes? Discuss the features that support your conclusion.

Question 63

Sketch a cross-sectional view of Earth's interior, and label each of the layers you depict.

Question 64

As you can see from this map, the Ural Mountains exhibit a north-south orientation through Eurasia. They are about the same age as the Appalachian mountains of eastern North America. How does the theory of plate tectonics explain the existence of this mountain belt in the interior of an expansive continental landmass? Compare and contrast the Ural and Appalachian situations, given their similar age.