Deck 8: Earthquakes and Earths Interior

Question 1

The Richter magnitude of an earthquake is determined from the ________.

A)duration of the earthquake
B)intensity of the earthquake
C)arrival time of P and S waves
D)amplitude of the largest seismic wave

Answer 1

D

Question 2

Aftershocks occur because ________.

A)seismic energy continues to build up for a period of time after a major earthquake
B)the day after a large earthquake there are tidal forces that continue to create additional earthquakes
C)the area surrounding a region that experienced a large earthquake needs time to adjust to the displacements on the main fault
D)there are always small earthquakes on major faults,but we do not notice them until there is a large event that makes us aware of them

Answer 2

C

Question 3

Megathrusts between subducting oceanic crust and an overriding plate are a potential source of tsunamis because ________.

A)the earthquakes on these faults are underwater and could displace large amounts of water from the oceans
B)the earthquakes on these faults are underwater and could release large amounts of water from the asthenosphere
C)one side of the fault is on land and the other is underwater so an earthquake could cause a landslide or tsunami depending on which side moved
D)oceanic crust is "thrust" over the continent along a megathrust so that forces the land downward producing a tsunami

Answer 3

A

Question 4

When an earthquake occurs,energy radiates in all directions from its source.The source is also referred to as the ________.

A)inertial point
B)epicenter
C)focus
D)seismic zone

Question 5

During the 1906 San Francisco earthquake,the movement of the Pacific Plate was approximately ________.

A)1 cm
B)10 cm
C)1 meter
D)10 meters
E)100 meters

Question 6

________ is the maximum possible damage designation on the Mercalli scale.

A)XII
B)3
C)X
D)10

Question 7

Major earthquakes are often followed by somewhat smaller events known as ________.

A)aftershocks
B)foreshocks
C)tremors
D)hyposhocks

Question 8

In the 1906 San Francisco earthquake,much of the damage was due to fires because ________.

A)a cow kicked over a lantern in a barn and started the fires
B)water lines were badly damage so that firemen could not put out the fires
C)electric power lines fell and caused sparks that started fires
D)the shaking caused gas lines to rupture everywhere and these ignited to cause huge fire storms in the city

Question 9

Earthquakes along the San Andreas fault zone,for example,are repetitive-they reoccur in roughly the same regions over and over again-separated by decades or centuries because ________.

A)there are areas that are weak and always break when small amounts of energy are applied to them
B)stress continues to build up all the time and when it is great enough to overcome friction there will be an earthquake and then the process will start over again
C)faults are always moving or creeping so an earthquake will occur whenever two sides meet that have the right properties for an earthquake
D)plate boundaries move at regular rates so the interactions across plate boundaries are predictable and regular

Question 10

The Mercalli Scale is a scale from ________.

A)1 to 12 that rates the energy required for faulting to occur
B)1 to 10 that rates the energy released by an earthquake
C)I to XII that rates the structural damage due to an earthquake
D)I to X that rates the total energy released during the main quake and all aftershocks

Question 11

P waves ________.

A)propagate only in solids
B)are faster than S waves and surface waves
C)have higher amplitudes than do S waves
D)produce the strongest ground shaking

Question 12

Which one 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)P and S waves travel through solids and P waves travel through liquids.
D)P and S waves travel through liquids,but S waves do not travel through solids.

Question 13

Overall,this type of seismic wave is the most destructive.

A)P wave
B)S wave
C)surface wave
D)tsunami

Question 14

Faults are "locked" because ________.

A)earthquakes only form when the rocks are free to move
B)high confining pressure increases friction on the fault
C)otherwise they would have earthquakes all the time
D)elastic rebound occurs on faults
E)major faults occur at plate boundaries that only move occasionally

Question 15

In elastic rebound theory,what must occur to produce an earthquake?

A)Enough stress must build up over time on a fault to overcome friction.
B)Rocks must break in order to produce slip on a fault.
C)The ground needs to absorb enough water to lubricate the surface of the fault.
D)Tidal forces need to be at a maximum to increase the energy applied to the fault.

Question 16

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

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

Question 17

________ have the highest velocities

A)Primary waves (P-waves)
B)Secondary waves (S-waves)
C)Surface waves
D)Refracted S-waves

Question 18

Modern seismographs rely on ________ to record the ground motion from an earthquake.

A)density
B)mass
C)inertia
D)buoyancy

Question 19

The position on Earth's surface directly above the earthquake source is called the ________.

A)epicenter
B)inertial point
C)focus
D)seismic zone

Question 20

The earliest seismographs were designed by the Chinese nearly 2000 years ago to measure ________.

A)the magnitude of an earthquake
B)the intensity of an earthquake
C)the direction to the earthquake focus
D)the depth of an earthquake focus

Question 21

The best building material to use in an earthquake prone region is ________.

A)brick
B)concrete
C)wood
D)stone

Question 22

Long term earthquake prediction is based on ________.

A)observations of things like animal behavior,radon gas emissions,and changes in topography
B)the assumption that large faults break in a cyclical manner
C)measurements of the plate motions and rate of stress accumulation
D)measurements of strain accumulation

Question 23

Earthquake prediction is ________.

A)not possible
B)possible for short times before some earthquakes based on things like animal behavior,but the U.S.does not make use of this method.
C)somewhat good for very long term statistical analyses based on ideas like mapping seismic gaps
D)generally good if you live in an area along a plate boundary because we know how fast the plates are moving and can measure the stress accumulation

Question 24

The 2011 earthquake and tsunami in Japan killed approximately 21,000 people while the 2010 earthquake in Haiti killed approximately 316,000 people because ________.

A)the earthquake in Haiti was a larger magnitude (released more energy)than the one in Japan
B)the earthquake in Haiti generated a very large tsunami that killed most of the people
C)the construction methods in Haiti were not as good as those used in Japan
D)the population of Haiti was much greater than that of northern Japan where the earthquake occurred
E)All of the above were factors.

Question 25

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

A)900 times
B)10 times
C)100 times
D)30 times

Question 26

Why is the Moment magnitude scale favored over the Richter magnitude scale?

A)The moment magnitude carries the calculated values out to more decimal places so it is more precise.
B)The Richter magnitude is based on older models of seismographs that are no longer used to record earthquakes.
C)The Richter magnitude always underestimates the amount of energy released by an earthquake.
D)The Moment magnitude measures the total energy released by an earthquake.

Question 27

Which of the following is determined by measuring the amplitude of waves recorded from an earthquake?

A)epicenter
B)focus or hypocenter
C)magnitude
D)intensity

Question 28

Seismic gaps are places where scientists think that ________.

A)faults are storing elastic strain
B)faults are storing stress
C)faults are creeping smoothly
D)earthquakes are unlikely to occur

Question 29

Large megathrust earthquakes in the mountainous regions flanking the Mediterranean sea are generally due to ________.

A)the collision of the African Plate with Eurasia
B)the collision of the African Plate with Southeast Asia
C)the collision of the Indian Plate with Eurasia
D)the collision of the Indian Plate with Southeast Asia

Question 30

A tsunami can occur ________.

A)when an earthquake occurs along a coastline like in Japan or Indonesia
B)when an earthquake occurs in the seafloor like along an oceanic plate boundary
C)when an explosive volcanic eruption occurs in someplace like Hawaii or Alaska
D)any time there is an earthquake anywhere
E)All of the above are correct.

Question 31

Which of the following is determined by making direct observations in the area affected by an earthquake?

A)epicenter
B)focus or hypocenter
C)magnitude
D)intensity

Question 32

One measurement that is widely used to determine how far the focus of an earthquake is from the seismograph where it is recorded is ________.

A)the amplitude of the P-wave
B)the amplitude of the S-wave
C)the difference in travel time between the P and the S wave
D)the difference in amplitude between the P and the S wave

Question 33

If you are on a beach,you might recognize that a tsunami is approaching because ________.

A)waves will gradually get higher and higher as the tsunami approaches
B)waves will gradually get closer together and approach the beach faster than normal
C)the water will withdraw from the beach farther than usual
D)the water will run up on the beach farther than usual

Question 34

Structural damage from seismic vibrations would be worse ________.

A)where buildings were built to code on solid rock
B)where older buildings were built on a thick layer of sediment
C)where the focus is about 800 kilometers below the surface
D)where buildings are made mostly of wood

Question 35

Short term earthquake prediction research has focused on ________.

A)looking at when and where earthquakes have occurred in the past to develop a model for the timing of future earthquakes
B)measuring the rate of motion on various faults and the strength of the rocks along the faults to determine when the stress buildup will exceed the strength of the rocks
C)looking for precursors such as changes in topography,animal behavior,foreshocks,radon emission,etc.,that might signal an imminent earthquake
D)measuring vertical changes in elevation along faults to determine whether a fault zone is inflating before a major rupture

Question 36

Which of the following is not a significant factor contributing to the damage caused by an earthquake?

A)the construction techniques and materials used in the region
B)the proximity to a plate boundary
C)the duration of the vibrations
D)the types of ground materials that are built on in the region

Question 37

The figure below shows the intensity of an Earthquake in northern California that affected much of the same areas that were damaged by the 1906 earthquake in a very similar manner.Based on this information,________.

A)people should not be allowed to build homes in the intensity VIII regions because the U.S.taxpayer has to pay to rebuild after such an earthquake
B)people who live in the high intensity regions should be required to carry earthquake insurance
C)construction methods are clearly inadequate in the high intensity areas,and all homes in those areas need to be reinforced
D)in general,the current building codes are adequate,but people should be aware of the hazards in this area

Question 38

Liquifaction,where normally solid material behaves more like a fluid during an earthquake,occurs because ________.

A)pore spaces between particles in unconsolidated sediments close and displace fluids
B)rock particles dissolve and mix with the fluids in the subsurface to become a liquid
C)friction from the vibrations melt rock and produce magmas
D)cracking in the rocks allows fluids to flow into the area and increase the amount of liquids in the subsurface

Question 39

Felt earthquakes usually last for ________.

A)less than 1 second (they are instantaneous)
B)1 to 10 seconds
C)10 to 60 seconds
D)1 to 10 minutes

Question 40

Earthquakes with a very deep focus are usually located along ________.

A)a divergent plate boundary such as the Mid-Atlantic Ridge
B)a transform boundary such as the San Andreas
C)a hot spot chain such as the Hawaiian Islands
D)a convergent boundary such as the Peru-Chile trench

Question 41

P wave S wave surface wave body wave

Question 42

Examine the words and/or phrases for each question below and determine the
relationship among the majority of words/phrases. Choose the option which does not fit the pattern.


-crust biosphere core mantle

Question 43

focus seismograph epicenter fault

Question 44

The earth's major layers formed because ________.

A)the chemical composition of the solar nebula changed over time
B)the earth was heated after its formation resulting in melting and redistribution of major chemical compositions
C)radioactive decay caused materials to change over time and resulted in the layering
D)the earth's mantle grew like a crystal forming around the earth's core but the crust was exposed to space and stayed more like the original material

Question 45

Which of the following is not a way that seismic waves travel in the earth?

A)refraction
B)reflection
C)diffusion
D)diffraction

Question 46

What is the major difference between the crust and the lithosphere?

A)The crust is cool and the lithosphere is hot.
B)The crust is located above the lithosphere.
C)The crust is located between the lithosphere and the asthenosphere.
D)The crust is compositionally distinct from the mantle,but the lithosphere is the rigid part of the crust and mantle.
E)The crust is the rigid part of the earth and the lithosphere will flow.

Question 47

The epicenter of an earthquake is on the surface of the Earth directly above the focus.

Question 48

The earth's major layers formed because ________.

A)the chemical composition of the solar nebula changed over time
B)the earth was heated after its formation resulting in melting and redistribution of major chemical compositions
C)radioactive decay caused materials to change over time and resulted in the layering
D)the earth's mantle grew like a crystal forming around the earth's core but the crust was exposed to space and stayed more like the original material

Question 49

Earthquakes result from the sudden release of elastic energy previously stored in rocks surrounding a zone of fault movement.

Question 50

There are thousands of earthquakes around the world every day.

Question 51

The deepest well that has ever been drilled on the earth is ________ deep,about 1/500th of the radius of the earth.

A)12.3 km
B)20.7 km
C)31.4 km
D)40.5 km

Question 52

The next large earthquake on the San Andreas Fault zone in California is considered likely to be ________.

A)in San Francisco because large earthquakes there are thought to occur every 75 years and the last large earthquake was in 1906
B)in northern California because the last major earthquake was in central California and the plate boundary is moving the stress to the northwest.
C)in Southern California because it has been nearly 300 years since the last major earthquake in that area
D)All of the fault system is considered equally likely because the plate motion is uniform and all areas are affected equally.

Question 53

core asthenosphere mantle lithosphere

Question 54

What is the probability that a large earthquake (M > 6.7)will occur in the San Francisco area between 2003 and 2032?

A)23%
B)44%
C)62%
D)85%

Question 55

Oceanic crust is composed primarily of ________.

A)granite
B)basalt
C)sandstone
D)andesite

Question 56

During the earliest history of the earth,________ .

A)the earth did not have any radioactive material
B)the temperature increased so that iron and nickel melted
C)almost all of the material was radioactive,and it decayed to the compositions we have today.
D)the earth was cold and lacked any source of heat.

Question 57

Modified Mercalli energy Richter amplitude

Question 58

Large earthquakes almost always produce new faults because the old faults tend to "heal" in the long time that separates most large earthquakes.

Question 59

S waves can travel through solid and liquid media.

Question 60

tsunami fire liquefaction amplitude

Question 61

The upper part of the ________ has the approximate composition of granite.

Question 62

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

Question 63

A few days before a major earthquake in China,one village in the area reported the streets were filled with migrating toads that might have indicated the impending event.

Question 64

________ averages roughly 7 km thick.

Question 65

We are fortunate in the United States that large tsunamis do not affect most of our coastal regions except in Hawaii.

Question 66

In the open ocean,Tsunamis travel at about the same speed as a commercial airliner.

Question 67

The Richter earthquake magnitude scale is based on the energy released by the earthquake.

Question 68

The upper part of the ________ has the approximate composition of peridotite.

Question 69

________ has an average density of 2.7 g/cc.

Question 70

A magnitude scale is a measure of the energy released.It does not measure the extent of building damage or loss of life.

Question 71

Most earthquakes occur along ________ plate boundaries.

Question 72

Oceanic crust is less dense than continental crust.

Question 73

Turnagain Heights,was badly damaged by a landslide during the 1964 Alaskan earthquake.

Question 74

Strike-slip faults are common along ________ plate boundaries.

Question 75

During the Alaskan earthquake of 1964,the buildings that survived the best were made of wood.

Question 76

________ averages 35 to 40 km in thickness.

Question 77

The ocean ridge systems that make up the major divergent plate boundaries are a source of frequent large earthquakes and tsunamis.

Question 78

________ is the rigid,cool outer approximately 100 km of the earth.

Question 79

________ makes up the largest part of the volume of the earth.

Question 80

The velocity of seismic waves generally increases with depth in the earth.