Deck 3: Earthquakes and Their Causes

Question 1

Which type of earthquake waves shake with the largest amplitudes (largest range of motion)?

A) compressional waves
B) shear waves
C) surface waves
D) P waves
E) S waves

Answer 1

C

Question 2

Which earthquake waves arrive from the source last?

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

Answer 2

C

Question 3

What is the approximate highest frequency of vibration (of back and forth shaking)in earthquakes?

A) 2-3 cycles per minute
B) 2-3 cycles per second
C) 20-30 cycles per second
D) 2,000-3,000 cycles per second
E) 20,000-30,000 cycles per second

Answer 3

C

Question 4

Why are surface waves the most destructive type of earthquake waves to buildings?

A) They are compressional waves.
B) They are shear waves.
C) They first compress the material and then pull it apart.
D) They move with the highest velocities.
E) They have larger amplitudes of shaking.

Question 5

Moment magnitude depends on what main factor(s)?

A) total offset distance on the fault during the earthquake
B) total length of the fault ruptured
C) shear strength of the rocks displaced, total surface area of rocks ruptured, and average slip distance on the fault
D) frequency of movement of the earthquake waves and the total time of shaking
E) amplitude of seismograph swing at the first moment of arrival of shaking

Question 6

What kind of material is subject to liquefaction during an earthquake?

A) clay saturated with saltwater
B) soils that are not saturated with water
C) swelling clay saturated with water
D) loose sand grains with water between the grains
E) poorly compacted artificial fill dumped into the edge of a bay to add usable land

Question 7

Between magnitude 7 and magnitude 8 earthquakes,about how much harder is the shaking (how much increase in the acceleration of the ground)?

A) actually less acceleration because the frequency is lower
B) not much
C) twice as hard
D) about 10 times
E) about 32 times

Question 8

How much more energy is released in a magnitude 7 earthquake than in a magnitude 6 earthquake?

A) about double
B) about 3 times
C) about 10 times
D) about 32 times
E) about 100 times

Question 9

Which type or types of earthquake waves arrive at a distant seismograph most quickly by traveling by moving through the mantle of the Earth?

A) both P and S waves
B) both P and L waves
C) both S and L waves
D) only S waves
E) only P waves

Question 10

What does the Mercalli Intensity Scale depend on?

A) how much damage occurred in an area
B) the intensity of shaking of the seismograph
C) the amplitude of movement of the seismograph needle
D) the strength of rocks broken along the fault
E) the frequency of the earthquake waves as they reach the seismograph

Question 11

Which earthquake waves arrive first?

A) P waves
B) S waves
C) L waves
D) shear waves
E) surface waves

Question 12

If you find a well-exposed fault that moved before seismographs were available,you can infer the approximate magnitude of earthquake by measuring the:

A) largest size tree snapped off by the shaking.
B) average size of the largest rocks moved in the earthquake.
C) strength of the rocks that the earthquake managed to break.
D) total area affected by the tsunami wave produced by the event.
E) total length of fault break during the event.

Question 13

How is the distance to the source of an earthquake determined?

A) by calling many seismograph operators to see who felt it most strongly
B) by subtracting the travel times of P and S waves
C) by measuring the frequency of the P waves as they arrive at a seismograph
D) by measuring the height of the S waves recorded on a seismograph
E) by adding the travel times of the L waves and the Raleigh waves

Question 14

What does the Richter Magnitude Scale depend on?

A) the maximum amplitude of earthquake waves on a seismograph
B) the frequency of P waves recorded on a seismograph
C) the intensity of shaking during the earthquake
D) the amount of destruction by the earthquake
E) the distance to the earthquake focus

Question 15

Which waves have the lowest frequencies?

A) P waves
B) S waves
C) surface waves
D) compressional waves
E) shear waves

Question 16

Which type or types of earthquake waves move only near the surface of the Earth?

A) all earthquake waves
B) P waves
C) surface waves
D) S waves
E) waves from faults that break near-surface rocks

Question 17

A magnitude 7 earthquake has how much higher ground motion than a magnitude 6 earthquake on a seismogram?

A) twice as high
B) 10 times higher
C) 32 times higher
D) about 100 times higher
E) about 1,000 times higher

Question 18

Which types of earthquake waves do the most damage?

A) compressional waves
B) shear waves
C) body waves
D) P waves
E) surface waves

Question 19

Why do parking garages often fail and fall during an earthquake?

A) Garages fall due to a lack of steel reinforcing bars.
B) Garages are made of poor quality concrete.
C) Horizontal spans across the large openings are too long to support the weight of vehicles.
D) Horizontal support beams shake off their vertical columns because they are often not well braced.
E) The vertical concrete supports are too thin to support the load.

Question 20

What is the approximate P-wave velocity through the Earth's mantle?

A) 8 meters per second
B) 80 meters per second
C) 8 kilometers per second
D) 80 kilometers per second
E) 800 kilometers per second

Question 21

Which type of plate boundary has the potential to cause the most destructive earthquakes??

Question 22

Explain the ways in which devastation from an earthquake could be minimized in a community.

Question 23

Why are surface waves the most destructive type of earthquake waves (two different reasons)?

Question 24

Where a tall building is right next to a short building,why is the tall building often damaged? Why does the damage occur and where in the building?

Question 25

Discuss the effects of liquefaction,landsliding,and clay flake collapse on society.

Question 26

Sometimes a single floor of a tall building (above ground floor)collapses in an earthquake even though the floors have identical construction.Why?

Question 27

Discuss the types of earthquake waves and the potential damage each individual one can cause.

Question 28

Which type or types of earthquake waves arrive at a distant seismograph most quickly by traveling through the mantle of the Earth?

Question 29

What is the approximate P-wave velocity through the Earth? Indicate whether your answer refers to the Earth's crust or mantle.

Question 30

What hazard does liquefaction pose,and for who or what?

Question 31

Where do earthquakes typically occur? Explain why they occur where they do.Which coast of North America has highly damaging earthquakes that are less frequent?

Question 32

What is meant by a blind thrust? Provide an example of an earthquake along a blind thrust.

Question 33

In addition to the amount of damage,increases in what factors go along with an increase in earthquake magnitude? List several.

Question 34

How much more energy is released in a magnitude 7 earthquake than in a magnitude 6 earthquake?

Question 35

Name the three main types of earthquake waves.