Deck 4: Earthquakes

Question 1

The behavior when the rocks elastically snap back to their previous dimensions with the release of associated stress accompanied with sudden displacement is called

A) Plastic rebound.
B) Elastic bounce back.
C) Elastic rebound.
D) None of the options are correct.

Answer 1

C

Question 2

Aftershocks are

A) Large to small earthquakes that come after a large earthquake.
B) Unlikely to cause damage.
C) Predictable from the primary earthquake's characteristics.
D) Of short duration and occur within a period of a few hours after the major earthquake.

Answer 2

A

Question 3

How well a concrete structure withstands an earthquake depends on

A) The basic design of the structure.
B) The length of the main shock.
C) The material on which the structure is built.
D) All of the choices are correct.

Answer 3

D

Question 4

Earthquake waves are recorded using an instrument called

A) Seismometer.
B) Seismogram.
C) Seismograph.
D) Seismocolumn.

Question 5

S-waves

A) Are shear waves that move more slowly than P-waves.
B) Are first to arrive at seismic monitoring stations.
C) Are more destructive than surface waves.
D) Both b and c are correct.

Question 6

Which of the following scales are used for measuring earthquake intensity?

A) Richter scale
B) Mercalli scale
C) Moment magnitude scale
D) All the choices are correct.

Question 7

Liquefaction is

A) Flooding of coastal areas due to tectonic subsidence.
B) A quicksand-like condition arising in some wet soils during earthquakes.
C) Flooding caused by tsunamis.
D) Flooding caused by dam failure resulting from an earthquake.

Question 8

The magnitude of the earthquake is dependent upon the amount of

A) Ground failure.
B) Ground displacement.
C) Ground motion.
D) Ground damage.

Question 9

Slow,gradual slip along a fault is termed

A) Stress.
B) Creep.
C) Rebound.
D) Focus.

Question 10

Compressional seismic body waves are

A) P waves.
B) S waves.
C) Surface waves.
D) Intensity waves.

Question 11

Tsunamis

A) Are sometimes called "tidal waves" but have nothing to do with tides.
B) Travel very slowly and dissipate a few kilometers from their point of origin.
C) Cross the open ocean as huge breakers, sweeping ships aside.
D) All of the choices are correct.

Question 12

Deep-focus earthquakes occur in subduction zones because

A) Brittle lithosphere is carried to deeper depths in subduction zones.
B) Subduction zones represent particularly homogeneous regions of the earth's crust.
C) The mantle is less dense under subduction zones.
D) Seismic energy propagates toward the center of the earth under subduction zones.

Question 13

Shallow-focus earthquakes commonly occur

A) In subduction zones.
B) Along transform faults, such as the San Andreas fault in California.
C) At spreading ridges.
D) Within the interior of plates.

Question 14

The time difference between the first arrival of P waves and the first arrival of S waves at a particular seismograph recorder

A) Is used along with the maximum amplitude of S waves to determine earthquake magnitude.
B) Is used along with the maximum amplitude of P waves to determine maximum earthquake intensity.
C) Is used to determine how far away the seismograph recorder is from the focus of the earthquake.
D) Both a and c are correct.

Question 15

In a fault when the displacement is horizontal then the type of fault is called

A) Dip-slip fault.
B) Normal fault.
C) Reverse fault.
D) Strike-slip fault.

Question 16

Which of the following statements is not true?

A) There is no predefined upper limit to the Richter scale.
B) On worldwide average, the largest earthquakes, with Richter magnitudes over 8, occur only once every few years.
C) While great earthquakes are rare, there may be hundreds of thousands of small earthquakes each year.
D) There are many more small earthquakes than large ones and the small ones thus account for most of the seismic energy released by earthquakes each year.

Question 17

An inappropriate response of an individual during an earthquake is

A) Get underneath something strong, such as a doorway or heavy table.
B) Run outdoors.
C) Do nothing that will create sparks (do not use light switches, turn on motors of any kind, scrape metal against metal).
D) Attempt to extinguish any open flame (candles, gas stoves).

Question 18

An individual,preparing for the likelihood of an earthquake,should NOT

A) Choose living quarters that will withstand likely seismic waves generated during earthquakes typical of the region.
B) Keep emergency supplies handy and fresh.
C) Know where gas and electric shut-off devices are in the home or apartment.
D) Place tall, heavy furniture next to a bed that is not secured to a wall.

Question 19

An earthquake's epicenter is

A) The point of first break along the fault.
B) The line along which the fault moved.
C) The point on the earth's surface directly above the focus.
D) The point on the far side of the earth, directly opposite the earthquake.

Question 20

The focus of an earthquake

A) Is the same thing as the epicenter.
B) Can be located using only one seismograph.
C) The primary point of rupture in the earth's crust and origin of the earthquake.
D) None of these choices is correct.

Question 21

The New Madrid,Missouri fault zone is a high-risk area on the U.S.seismic-risk map because

A) It is undergoing rapid creep at this time.
B) It is subject to frequent severe earthquakes.
C) It is a large transform fault.
D) It was the site of the largest earthquakes ever reported in the contiguous United States.

Question 22

Evidence of liquefaction includes

A) Tsunamis.
B) Sand boils.
C) Surface waves.
D) Fault scarps.

Question 23

Most of the structural damage from earthquakes worldwide is caused by

A) P waves.
B) S waves.
C) Surface waves.
D) Seismic sea waves.

Question 24

Fluid might be injected along a locked section of fault to

A) Cushion the shock of the next earthquake.
B) Cause the rocks to swell and close the fault.
C) Reduce resistance to shear along the fault, allowing creep to occur.
D) Reduce the risk of fire from an earthquake.

Question 25

After an earthquake,rocks snap back elastically to their pre-stress condition.

Question 26

The San Andreas fault near San Francisco

A) Has been undergoing creep since the 1906 earthquake.
B) Is not of much concern because it is seismically quiet.
C) Is locked and therefore accumulating stress.
D) Is not very dangerous because it only slips a few meters at a time.

Question 27

The United States now has an Earthquake Prediction Panel.Since its establishment,

A) Many lives have been saved by successful earthquake prediction.
B) Residents of fault zones have gradually been moved to safer areas.
C) All citizens of earthquake-hazard areas have been made thoroughly aware of the risks they face.
D) No great earthquakes have been predicted; its effectiveness is not well tested.

Question 28

The seismic-risk map of the United States is based on

A) Frequency of occurrence of past earthquakes only.
B) Severity of past earthquakes and anticipated ground motion in future ones.
C) A prediction of the likelihood of future earthquakes.
D) Observations of precursor phenomena.

Question 29

The largest magnitude historic earthquake in the fifty United States occurred

A) Along the San Andreas fault in 1906.
B) In Anchorage, Alaska, in 1964.
C) Near New Madrid, Missouri, in 1811-1812.
D) Near New York City in 1850.

Question 30

The "earthquake cycle" model is based on assumptions that the rate of stress buildup on a given fault segment is constant and that

A) A given fault segment accumulates about the same amount of strain energy before rupture each time.
B) The interval between successive earthquakes increases over time on each fault segment.
C) The rate of radon accumulation is also constant, leading to periodic rupture from gas pressure.
D) Major earthquakes occur on large fault zones every 30 years.

Question 31

What resulted in most of the damage during the 1906 San Francisco earthquake?

A) Ground failure
B) Tsunami
C) Liquefaction
D) Fire

Question 32

Following the 1989 Loma Prieta earthquake,the risk of a major earthquake on the peninsular segment of the San Andreas fault

A) Is estimated to have increased; that segment remains locked.
B) Has been eliminated because all the built-up stress has been released.
C) Has been reduced as a consequence of active earthquake-prevention measures now being undertaken.
D) Is no longer a fear, because the Loma Prieta quake confirmed the reliability of earthquake-prediction techniques.

Question 33

Which of the following earthquakes was successfully predicted shortly before it occurred (based on anomalous animal behavior)?

A) Haisheng, China (1975)
B) New Madrid, Missouri (1990)
C) Parkfield, California (1993)
D) Kobe, Japan (1995)

Question 34

A locked section of fault is often identified by

A) Creep.
B) Liquefaction.
C) Tsunamis.
D) A seismic gap.

Question 35

A Benioff zone is a region of deeper earthquake foci where geometry reflects a subducting slab of lithosphere.

Question 36

Seismic activity in the Pacific Northwest is associated with

A) Faults.
B) Folds.
C) Divergence.
D) Subduction.

Question 37

Strategies for reducing earthquake-related damage include all of the following except

A) Building strong structures across fault zones to stop fault movement.
B) Establishing a tsunami early warning system.
C) Improving underground drainage in areas with wet soil.
D) Avoiding building on steep slopes near fault zones.

Question 38

The moment magnitude scale may be a better indicator of earthquake severity especially for large earthquakes and those occurring outside of California,where the Richter scale was developed.

Question 39

P waves can travel through solids only; S waves can travel through both liquids and solids.

Question 40

All of the following have been recognized as earthquake precursors except

A) Changes in the ground's surface tilt.
B) Changes in frequency of seismic sea waves.
C) Changes in electrical resistivity of rocks.
D) Changes in radon content of well waters.

Question 41

The filling of a reservoir behind a newly completed dam often generates earthquakes of small to moderate size.

Question 42

A locked section of a fault is a very safe place to live because,by definition,it will not slip.

Question 43

Legislation designed to address earthquake hazards is most often passed immediately after major earthquakes.

Question 44

Once sound building codes are developed for a given area with earthquake hazards,older structures are routinely rebuilt for greater safety.

Question 45

The Northridge and Landers earthquakes may be part of a pattern of increasing seismicity prior to failure along the segment of the San Andreas opposite Los Angeles.

Question 46

The Anatolian Fault Zone in Turkey illustrates the tendency of major faults to break in segments.

Question 47

When one speaks of "earthquake-resistant" buildings,this means buildings that will remain fully functional after an earthquake.

Question 48

The United States is the world leader in earthquake preparedness and public education about earthquake hazards.

Question 49

Southern Alaska remains an area of great earthquake hazard; it is located above a subduction zone.

Question 50

Aftershocks,generally,never result in any major destruction.

Question 51

Unusual animal behavior precedes some,but not all,earthquakes.

Question 52

Scale modeling is a useful tool in designing earthquake-resistant buildings,but its usefulness is limited by the lack of records of actual ground motion during large earthquakes.

Question 53

Because there are no active plate boundaries in or near Canada,that country has no detectable earthquake activity.

Question 54

Fluid injection is a reliable technique that can be used to allow the release of stress that is built up in locked sections of major faults.

Question 55

In 1989,as in 1906,earthquake damage in San Francisco was most severe in areas underlain by fill,as in the Marina district.

Question 56

A tsunami set off by an earthquake occurring on one side of the Pacific Ocean may later be detected on the other side of that ocean.

Question 57

An old,failed rift under the central United States is believed to represent a zone of weakness in the lithosphere and a possible earthquake hazard zone.

Question 58

Faults near coastlines are three times more likely to move,thus causing an earthquake,during high tide than during low tide.

Question 59

Prediction of earthquakes on the San Andreas fault is complicated by the number of other faults in the vicinity,over which displacement may be distributed.

Question 60

The only possibly useful earthquake precursor phenomenon found so far is an increase in numbers of small earthquakes prior to a large earthquake.

Question 61

Tsunami travel times across a large body of water,such as the Pacific Ocean,are typically of the order of several days.