Complete Test Bank Ch8 A Violent Pulse Earthquakes - Geology Essentials 6e Complete Test Bank by Stephen Marshak. DOCX document preview.
CHAPTER 8: A Violent Pulse: Earthquakes
LEARNING OBJECTIVES
8A. Describe an earthquake, and explain where the energy released during an earthquake comes from.
8B. Relate earthquakes to specific geologic settings, in the context of plate tectonics theory.
8C. Draw a sketch illustrating how a seismometer operates, and explain what the squiggles on a seismogram mean.
8D. Distinguish among the different kinds of seismic waves, and show how the arrival times of seismic waves can indicate where an earthquake occurred.
8E. Explain the difference between the intensity and magnitude of an earthquake, and how these indicators of earthquake size can be determined.
8F. Discuss the many ways in which earthquakes cause damage and injury.
8G. Distinguish between tsunamis and storm waves, and explain how large tsunamis can cause so much damage.
8H. Determine whether a prediction of an earthquake is worth listening to, and explain the difference between a prediction and an early warning.
8I. Identify steps that can help you and others prevent earthquake damage and avoid injury.
MULTIPLE CHOICE
1. Geologists who specifically study earthquakes are called
a. | seismologists. | c. | volcanologists. |
b. | paleontologists. | d. | speleologists. |
2. Most earthquakes are a result of
a. | a sudden change in atmospheric pressure. | c. | erosion of bedrock. |
b. | mantle upwelling. | d. | movement of rocks along faults. |
3. Faulting and earthquakes are examples of what type of deformation?
a. | brittle | c. | ductile |
b. | elastic | d. | fluid |
4. The energy that is released during an earthquake travels through the Earth as vibrations termed _______.
a. | gravity waves |
b. | tsunamis |
c. | seismic waves |
d. | sound waves |
5. Faults that have moved recently or are likely to move in the future are referred to as ________ faults.
a. | passive | c. | normal |
b. | active | d. | reverse |
6. The quantity of motion that occurs along a fault is termed
a. | fault gouge. | c. | displacement. |
b. | the fault gauge. | d. | accumulation. |
7. Periods of intermittent sliding on a fault because of stress release during episodes of slip, followed by stress buildup to the point that the fault is reactivated, are termed
a. | chaotic faulting. | c. | stick-slip behavior. |
b. | thrust faulting. | d. | reverse faulting. |
8. The intersection between a fault plane and the ground surface is called the
a. | dip line. | c. | fault trace. |
b. | plunge. | d. | seismic interface. |
9. Aftershocks after a major earthquake
a. | may continue for days, weeks, or years after the initial earthquake. |
b. | are equivalent in magnitude to the original earthquake. |
c. | always occur on the same fault as the original earthquake. |
d. | typically occur only on reverse faults in subduction zones as a result of high pressures. |
10. The point within the Earth where an earthquake originates is termed the
a. | hypocenter (focus). | c. | eye of the fault. |
b. | epicenter. | d. | vertex. |
11. The point on the Earth’s surface directly above the point where an earthquake occurs is termed the
a. | hypocenter (focus). | c. | eye of the fault. |
b. | epicenter. | d. | vertex. |
12. The displacement that occurs during the largest earthquakes can be as long as
a. | several millimeters. | c. | several meters. |
b. | several centimeters. | d. | several kilometers. |
13. During an earthquake, if the hanging wall slides upward relative to the footwall, the fault is termed a ________ fault if the fault is steep (closer to vertical than horizontal). Refer to the figure below for an example of such a feature.
a. | normal | c. | strike-slip |
b. | reverse | d. | thrust |
14. During an earthquake, if a hanging wall slides downward relative to a footwall, the fault is termed a ________ fault. Refer to the figure below for an example of such a feature.
a. | normal | c. | strike-slip |
b. | reverse | d. | thrust |
15. If a fault is nearly vertical in orientation and the two walls of rock on opposite sides slide past one another horizontally, the fault is termed a ________ fault. Refer to the figure below for an example of such a feature.
a. | normal | c. | strike-slip |
b. | reverse | d. | thrust |
16. Faults occur in many locations, but most faults had displacement in the distant past and are unlikely to move again in the future. This means that most faults are
a. | active faults. |
b. | thrust faults. |
c. | inactive faults. |
d. | submarine faults. |
17. At any point along the surface of any nonvertical fault, as is shown in the figure below, the
a. | hanging wall lies vertically above the footwall. |
b. | footwall lies vertically above the hanging wall. |
c. | hanging wall lies to the left of the footwall. |
d. | footwall lies to the left of the hanging wall. |
18. Before an earthquake, rocks can respond to applied stress to a small degree by bending and warping without breaking. This is termed _________.
a. | elastic behavior | c. | seismic velocity |
b. | faulting | d. | brittle deformation |
19. An earthquake occurs with an epicenter in the town of New Madrid, Missouri, in the interior of the North American Plate. What is the most likely location of the hypocenter?
a. | in New Madrid (hypocenter and epicenter mean precisely the same thing) |
b. | 20 km south of New Madrid |
c. | 20 km beneath New Madrid |
d. | 200 km beneath New Madrid |
20. A ____________ is a scientific instrument used to record the ground motions produced by an earthquake.
a. | seismic wave | c. | tidal gauge |
b. | seismometer | d. | strain gauge |
21. Which type of seismic wave has the fastest velocity?
a. | L-wave | c. | R-wave |
b. | P-wave | d. | S-wave |
22. Generally, which of the following types of earthquake waves travel with the slowest velocity?
a. | S-waves |
b. | P-waves |
c. | surface waves |
d. | All earthquake waves travel at the same speed. |
23. Body waves include
a. | both S- and P-waves. | c. | both surface and interior waves. |
b. | both L- and R-waves. | d. | P-waves only. |
24. As shown in the figure below, a coiled spring would be useful in illustrating any ________ wave.
a. | surface | c. | shear |
b. | body | d. | compressional |
25. Earthquake waves that pass through the Earth’s interior are termed
a. | interior waves. | c. | surface waves. |
b. | R-waves. | d. | body waves. |
26. Earthquake waves that travel along the Earth’s surface are termed
a. | interior waves. | c. | surface waves. |
b. | S-waves. | d. | body waves. |
27. Surface waves
a. | travel more rapidly than body waves. |
b. | produce most of the damage to buildings during earthquakes. |
c. | are the first waves produced in an earthquake. |
d. | are the first waves to arrive at a seismograph station after an earthquake. |
28. At a minimum, how many seismic stations are necessary to locate the epicenter of an earthquake?
a. | one | c. | three |
b. | two | d. | four |
29. A long delay between the arrival of P-waves and S-waves at a seismometer means that
a. | the earthquake only produced P-waves. |
b. | the focus of the earthquake was very deep in the Earth’s crust. |
c. | the seismometer is located far from the earthquake. |
d. | the earthquake had a very small displacement. |
30. Which earthquake scale measures the amplitude of deflection of a seismograph pen, standardized to an idealized distance of 100 km between the epicenter and the seismograph?
a. | the Richter scale | c. | the moment magnitude scale |
b. | the Mercalli scale | d. | the surface-wave magnitude scale |
31. Which earthquake severity scale varies from locality to locality for a single earthquake?
a. | the Richter scale | c. | the moment magnitude scale |
b. | the Mercalli scale | d. | the surface-wave magnitude scale |
32. According to the moment magnitude scale (Mw), the amplitude of ground shaking during
a magnitude 8 earthquake would be 1,000 times greater than a magnitude ________ earthquake.
a. | 9 | c. | 7 |
b. | 5 | d. | 4 |
33. Which earthquake scale is used to assess the effects of an earthquake on humans and human-made structures?
a. | Richter scale | c. | moment magnitude scale |
b. | Mercalli scale | d. | surface-wave magnitude scale |
34. On average, there are _______occurrences of light and minor earthquakes compared to the number of major and great earthquakes each year.
a. | many thousands more | c. | about the same number of |
b. | approximately ten times as many | d. | many fewer |
35. The vast majority of earthquakes occur
a. | along transform-plate boundaries only. | c. | along passive margins. |
b. | near hot spots. | d. | along any plate boundary. |
36. Earthquakes that occur in a band called the ________ can be used to track the motion of subducted oceanic lithosphere.
a. | Wegener belt | c. | Wadati–Benioff zone |
b. | seismic gap | d. | Richter zone |
37. Which geological setting is likely to experience the least amount of seismic activity?
a. | a rift valley | c. | a collisional mountain belt |
b. | a transform boundary | d. | the interior of a tectonic plate |
38. Most medium- and deep-focus earthquakes occur at
a. | convergent-plate boundaries. | c. | transform-plate boundaries. |
b. | divergent-plate boundaries. | d. | hot spots. |
39. Which of the following hazards is most likely to occur several days to weeks after an earthquake?
a. | fire |
b. | liquefaction |
c. | disease |
d. | foreshocks |
40. Wet and unconsolidated substrates are uniquely susceptible to ________ during an earthquake.
a. | displacement | c. | liquefaction |
b. | collapse | d. | faulting |
41. A tsunami is
a. | a seawave generated by an earthquake, landslide, or submarine volcanic eruption that may destroy coastal cities thousands of kilometers from its source. |
b. | a sloshing of water back and forth within a lake or a bay. |
c. | a wave caused by unusually large tidal forces. |
d. | the tendency of wet, clay-rich soils to behave like a liquid during an earthquake. |
42. Tsunamis are more destructive than wind-driven storm waves primarily because
a. | tsunamis always have larger heights (amplitude). |
b. | tsunamis have longer wavelengths and thus larger volumes of water are involved. |
c. | the tides that cause tsunamis can be very erratic and unpredictable. |
d. | tsunamis also generate seismic waves that can destroy buildings. |
43. Tsunamis are most commonly generated by sudden _________ movement of the seafloor during an earthquake.
a. | strike-slip |
b. | horizontal |
c. | vertical |
d. | circular |
44. Short-term predictions of earthquake behavior have
a. | saved millions of lives in the past decade alone. |
b. | been largely unreliable. |
c. | been primarily based on the behavior patterns of farm animals. |
d. | been correct approximately 50 percent of the time. |
45. The average length of time between earthquakes along a fault is termed the ______.
a. | elastic strain |
b. | S-P time |
c. | seismic gap |
d. | recurrence interval |
46. Earthquake early warning systems
a. | are based on long-term predictions of earthquakes, allowing planners to schedule evacuations. |
b. | alert people just before an earthquake takes place, allowing them to evacuate buildings. |
c. | alert people when an earthquake has taken place, possibly giving them seconds to get to a safer place. |
d. | do not yet exist, but the technology is something seismologists are working on. |
47. Determining where roads and building should be built based on where land is stable and less prone to landslide or liquefaction during an earthquake is an example of ________.
a. | earthquake zoning |
b. | earthquake engineering |
c. | seismic hazard mapping |
d. | seismic retrofitting |
48. What kind of information is shown on a seismic hazard map?
a. | the probability that different regions will experience a large earthquake |
b. | the likely magnitude of future earthquakes in different regions |
c. | the distribution of small and large earthquakes in different regions |
d. | the locations of large earthquakes in the past |
49. Designing and retrofitting building to withstand the effects of earthquakes is a type of
a. | earthquake zoning. |
b. | earthquake engineering. |
c. | seismic hazard mapping. |
d. | seismic retrofitting. |
50. Seismic retrofitting is the process of
a. | predicting future earthquakes. |
b. | strengthening existing buildings and structures. |
c. | mapping areas prone to earthquakes. |
d. | fitting earthquake data after an event to see if it should have been predicted. |
1. How is the epicenter of an earthquake different from the focus? Why are both terms useful?
2. Sketch a seismogram that has recorded an earthquake. Be sure to label the arrival of each of the three main types of seismic waves (P-waves, S-waves, and surface waves).
3. Compare and contrast P- and S-waves.
4. How is the Mercalli intensity scale used to determine the magnitude of an earthquake? What errors might be associated with this technique?
5. Why do deep-focus earthquakes occur along convergent plate boundaries? Why are they absent along divergent or transform boundaries?
6. Where do earthquakes occur? Please explain your answer in the context of plate tectonics. Are there exceptions?
7. Describe two earthquake-related hazards.
8. Explain why “tidal wave” is actually a poor term for tsunamis.
9. What is an early earthquake warning system, and why does this differ from a short-term earthquake prediction tool?
10. Why is an empty field a very safe place to be in an earthquake?