Deck 3: Earthquakes

Question 1

The fastest seismic waves are

A) shear waves.
B) secondary waves.
C) compressional waves.
D) Love waves.
E) Rayleigh waves.

Answer 1

C

Question 2

On the moment magnitude scale,a magnitude 7 earthquake releases about

A) twice as much energy as a magnitude 6 earthquake.
B) 10 times as much energy as a magnitude 6 earthquake.
C) 25 times as much energy as a magnitude 6 earthquake.
D) 32 times as much energy as a magnitude 6 earthquake.
E) 100 times as much energy as a magnitude 6 earthquake.

Answer 2

D

Question 3

Earthquake energy

A) radiates primarily upward from the focus.
B) mostly travels along the fault plane.
C) radiates outward from the focus in all directions.
D) travels primarily downward from the focus.
E) travels directly to Earth's surface, then radiates outward along the surface.

Answer 3

C

Question 4

The boundary between the North American Plate and the Juan de Fuca Plate under Vancouver Island is a

A) normal fault.
B) strike-slip fault.
C) transform fault.
D) subduction zone.
E) hanging wall.

Question 5

Which of the following major cities is NOT in an earthquake prone area?

A) Tokyo
B) Istanbul
C) London
D) Mexico City
E) Jakarta

Question 6

Of the following choices,where would be the most prudent place to purchase property,to minimize risk of damage due to earthquakes?

A) the Marina District of San Francisco
B) downtown Mexico City
C) west Oakland, California, on the waterfront
D) Richmond, BC, which is built on river sediments
E) just north of San Francisco, on bedrock

Question 7

The 1964 Alaska M 9.2 earthquake was far larger than the 1989 Loma Prieta earthquake at M 6.9,yet the Loma Prieta earthquake was far more costly,even when adjusted for inflation.Why?

A) That area of Alaska is all bedrock whereas San Francisco is all built on loose sediments.
B) The shaking lasted three times as long in San Francisco as it did in Alaska.
C) Most of the shaking motion in San Francisco was vertical while in Alaska, the motion was horizontal.
D) San Francisco is closer to sea level and large portions of the city dropped below sea level suddenly.
E) The population and infrastructure density in Alaska was much lower than in San Francisco.

Question 8

The New Madrid Earthquakes are examples of

A) intraplate earthquakes.
B) interplate earthquakes.
C) subduction zone earthquakes.
D) stability earthquakes.
E) aftershocks.

Question 9

The ground motion from a magnitude 6 earthquake is approximately

A) twice as much as ground motion from a magnitude 5 earthquake.
B) 10 times as much as ground motion from a magnitude 5 earthquake.
C) 20 times as much as ground motion from a magnitude 5 earthquake.
D) 30 times as much as ground motion from a magnitude 5 earthquake.
E) 100 times as much as ground motion from a magnitude 5 earthquake.

Question 10

The 1960 giant earthquake in Chile released approximately as much energy as

A) a thermonuclear bomb.
B) the United States uses in one year.
C) the Sun emits every hour.
D) a hurricane releases over its full life.
E) world annual energy consumption.

Question 11

A seismic gap is

A) a region within a tectonic plate with no active faults.
B) a region on the boundary of a tectonic plate with no active faults.
C) a fault that does not produce offsets at Earth's surface.
D) a "missing" portion of a fault that has not yet been mapped.
E) a segment along an active fault that has not experienced seismic activity recently.

Question 12

What geologic evidence for past earthquakes could you observe in salt marshes on the coast of Washington State?

A) measurable offsets along strike-slip faults
B) alternating layers of tidal mud and tidal marsh deposits
C) earthquake-triggered landslides from steep dunes
D) uplifted rocky terraces
E) the remains of destroyed cities

Question 13

To locate the epicentre of an earthquake,what is the minimum number of seismograms that you need (from different locations)?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 14

An earthquake forecast

A) is a prediction of when and where an earthquake will happen.
B) predicts the magnitude of the next earthquake for a particular region.
C) outlines the damage to human infrastructure expected in the next earthquake in a particular region.
D) states the risk to human populations in earthquake-prone regions based on the geological materials on which most of the buildings are constructed.
E) states the probability of an earthquake of particular magnitude occurring in an area within a specified time.

Question 15

The San Andreas fault

A) is a divergent plate boundary.
B) is a transform plate boundary.
C) is a subduction zone.
D) is part of the Cascadia subduction zone.
E) is in Alaska.

Question 16

In which major Canadian city are you most likely to experience a subduction-related earthquake?

A) Vancouver
B) Montreal
C) Ottawa
D) Halifax
E) Toronto

Question 17

Mexico City is particularly susceptible to earthquake damage because

A) most of the buildings do not meet building codes.
B) the city is built on ancient lake sediments, which amplify seismic shaking.
C) the city is built directly across a major strike-slip fault, like the San Andreas Fault.
D) Mexico City is built at a plate tectonic boundary.
E) earthquakes typically dislodge massive landslides into Mexico City from the surrounding mountains.

Question 18

Approximately how frequently do earthquakes of magnitude 8 or greater occur?

A) once a month
B) once a year
C) once every 5 years
D) once every 10 years
E) once every 20 years

Question 19

On which tectonic plate is the city of Los Angeles,California located?

A) North American Plate
B) Juan de Fuca Plate
C) Gorda Plate
D) Pacific Plate
E) Explorer Plate

Question 20

At present,an earthquake warning system could provide up to a one minute warning to regions far enough away from the epicentre of an earthquake.Such a warning system is based on the difference between

A) P-wave and S-wave velocities.
B) P wave and surface wave velocities.
C) radio wave and seismic wave velocities.
D) sound wave and seismic wave velocities.
E) ultrasonic wave and seismic wave velocities.

Question 21

A section of an otherwise active fault zone that has not experienced an earthquake is

A) a normal fault.
B) a seismic gap.
C) dormant.
D) a subduction zone.
E) a transform fault.

Question 22

Of the seismic waves,P waves

A) travel fastest.
B) do the most damage.
C) move from side to side.
D) do not travel through the core.
E) are shear waves.

Question 23

Normal fault earthquakes

A) occur mostly at subduction zones.
B) occur mostly at divergent plate boundaries.
C) are commonly large.
D) are commonly deep.
E) occur mostly on land.

Question 24

Energy in the form of deformation strain energy is released during an earthquake by the process of

A) eruption.
B) faulting.
C) subsidence.
D) plate tectonics.
E) continental drift.

Question 25

S waves

A) are shear waves.
B) travel through the core.
C) travel faster than compression waves.
D) only occur on the Earth's surface.
E) cannot be detected by seismographs.

Question 26

At any given seismograph station

A) the S waves arrive before the P waves.
B) the surface waves arrive first.
C) the P waves arrive first.
D) the P waves are always largest.
E) distance to earthquake is determined using the size of the P waves.

Question 27

A great earthquake is one

A) that lasts more than 5 minutes.
B) with magnitude 8 and greater.
C) that kills more than 100,000 people.
D) that causes a tsunami.
E) that has many different effects, such as landslides, liquefaction, etc.

Question 28

If you're indoors and you feel shaking from an earthquake,of the following choices,where is the safest place to be?

A) in an elevator
B) next to a window
C) in a doorway with a door attached to it
D) near a tall cabinet
E) under a table

Question 29

In the 1985 Mexico earthquake buildings with 10-20 storeys literally tore themselves apart because

A) they were badly constructed.
B) they were not finished.
C) the rocks beneath them were hard.
D) they had the same natural frequency as the materials on which they were built.
E) the earthquake occurred right under the city.

Question 30

The magnitude of an earthquake is a measure of

A) the amount of ground displacement.
B) the energy released.
C) the duration of the earthquake.
D) the ground displacement and the energy released.
E) the position of the earthquake.

Question 31

When seismic waves travel from hard materials into softer ones

A) they undergo amplification.
B) they speed up.
C) they cause the rocks to liquify.
D) they change from P to S waves.
E) they cause landslides.

Question 32

When a building has the same natural vibration frequency as earthquake motion this causes

A) surface waves.
B) resonance.
C) refraction.
D) ground rupture.
E) faulting.

Question 33

The Modified Mercalli Intensity scale

A) is a measure of the total damage done by an earthquake.
B) is a measure of how people and property are affected by an earthquake.
C) is a measure of the amount of energy released.
D) is an open ended (no limit) scale.
E) is used to determine earthquake magnitude.

Question 34

In a normal fault

A) the hanging wall moves sideways past the footwall.
B) the hanging wall moves down relative to the footwall.
C) the footwall moves up relative to the hanging wall.
D) has no hanging wall or footwall.
E) is a high-angle thrust fault.

Question 35

Compressional seismic waves are

A) surface waves.
B) Love waves.
C) S waves.
D) P waves.
E) Rayleigh waves.

Question 36

Fault creep

A) occurs only on strike-slip faults.
B) is gradual movement along a fault without noticeable earthquakes.
C) releases energy ensuring that no large earthquakes occur on the fault.
D) occurs only in seismic gaps.
E) does not cause any damage to structures.

Question 37

The process of locating the position of an earthquake using seismic records from three locations is called

A) plate tectonics.
B) triangulation.
C) magnitude determination.
D) seismology.
E) echo location.

Question 38

When water-saturated loose sediment is shaken during an earthquake

A) it solidifies.
B) it loses its cohesion and fails.
C) it reduces the amount of seismic energy.
D) it absorbs more water.
E) it becomes stronger.

Question 39

Which of the following factors affects the amount of shaking an area experiences during an earthquake?

A) earthquake magnitude
B) distance to the focus
C) directivity of the rupture
D) local rock and coil characteristics
E) all of the above

Question 40

The Richter scale

A) is no longer used.
B) is a measure of earthquake intensity.
C) is linear.
D) was developed in Japan.
E) is a measure of earthquake damage.

Question 41

If you live in a house built on unconsolidated sediments,in an earthquake,you can expect to experience a higher Modified Mercalli Intensity than your neighbors whose house is built on bedrock.

Question 42

The Modified Mercalli Intensity Scale measures the

A) magnitude of an earthquake without consideration of ground conditions.
B) degree to which an earthquake affects people, property and the ground.
C) energy released in a seismic event.
D) horizontal and vertical displacement at the epicentre.
E) intensity of seismic waves in the Earth's crust.

Question 43

Faults are classified as inactive if they have not moved in the past ________ years.

A) 10,000
B) 1 million
C) 1,600
D) 11,600
E) 2.6 million

Question 44

Earthquake intensity describes the effects of shaking on people and structures.

Question 45

Most transform boundaries occur on continents.

Question 46

On the moment magnitude scale,earthquake magnitude is determined by the intensity of shaking.

Question 47

Of the four types of seismic waves produced by earthquakes,these types of waves roll the ground like waves at sea.

A) P waves
B) S waves
C) Love waves
D) body waves
E) Rayleigh waves

Question 48

In the 1906 San Francisco earthquake what percentage of the damage was due to the fires that were a secondary effect of the quake?

A) 5%
B) 10%
C) 25%
D) 50%
E) 80%

Question 49

The Richter scale is the most common earthquake magnitude scale used by seismologists.

Question 50

Earthquake warning systems provide

A) as little as 15 seconds to one minute advanced warning.
B) as little as 15 seconds to five minutes advanced warning.
C) as much as one day advanced warning of an impending earthquake.
D) an accurate forecast of seismic events.
E) a practical prediction tool for seismic events.

Question 51

Which of the following is NOT considered a type of fault?

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

Question 52

Which of the following is the correct sequence for the four stages of an earthquake cycle?

A) inactivity, accumulated strain, mainshock, aftershocks
B) accumulated strain, foreshock, inactivity, mainshock
C) inactivity, accumulated strain, foreshock, mainshock
D) accumulated strain, mainshock, aftershocks, energy dispersion
E) inactivity, accumulated strain, mainshock, energy dispersion

Question 53

Blind faults cause ruptures at Earth's surface in unexpected places.

Question 54

The most powerful seismic event in recent history was recorded in

A) 1960, Chile.
B) 1985, Mexico City.
C) 2011, Japan.
D) 1964, Alaska.
E) 2004, Indonesia.

Question 55

Which of the following is a primary effect of an earthquake?

A) liquefaction
B) surface rupture
C) land-level change
D) tsunamis
E) landslides

Question 56

Which of the following human activities is known to cause earthquakes?

A) dam construction
B) draining of swampland
C) irrigation
D) farming
E) mining

Question 57

An earthquake of magnitude 5 has a shorter return period than an earthquake of magnitude 4.

Question 58

Movement along dip-slip faults is primarily vertical.

Question 59

A change in magnitude of one (1)on a standard seismograph,corresponds to ________ times more ground displacement and ________ times more energy released.

A) two, two
B) five, five
C) 10, 32
D) two, 10
E) 100, 10

Question 60

The term "major" as a descriptor would be applied to earthquakes with a magnitude of

A) 9 or higher.
B) 8 and higher.
C) 8 t.8.9.
D) 6 to 6.9.
E) 7 to 7.9.

Question 61

In the 1989 Loma Prieta earthquake,buildings in the Marina district experienced significant damage because they were built on landfill debris from the 1906 earthquake.

Question 62

The distribution of earthquakes on Earth is random.

Question 63

Most fires associated with earthquakes are started in urban areas.

Question 64

The Queen Charlotte fault off the coast of Vancouver Island is a normal fault.

Question 65

Shear waves can travel through solids and liquids,but not through gases.

Question 66

Horizontal shaking from earthquakes causes more damage than vertical shaking.

Question 67

Vancouver Island is currently flexing upward due to the accumulation of strain along the Cascadia subduction zone.

Question 68

Some human activities trigger earthquakes.

Question 69

Sudden earthquakes are unlikely along faults where tectonic creep occurs.

Question 70

When movement occurs along a normal fault,the hanging wall drops down compared to the footwall.

Question 71

Precursors,such as foreshocks,always precede large earthquakes.

Question 72

The time lag between the arrival of the different types of seismic waves is a function of distance from the earthquake focus.

Question 73

Earthquake focus and epicentre are the same thing.

Question 74

Shear waves move faster than surface waves.

Question 75

Long-term slip rates along most major North American faults are well-known.

Question 76

Earthquakes are one of the greatest natural hazards,responsible for over two million deaths in the 20th century alone.

Question 77

Intraplate earthquakes occur at the boundary between plates.

Question 78

Tectonic creep occurs on faults that move without generating earthquakes.

Question 79

Earthquake damage in the 1985 Mexico earthquake was greatest in small (1-2 storey)buildings.

Question 80

Typically,earthquake tragedy in one community stimulates other communities to put more resources toward earthquake preparedness.