Practice 3rd Exam Geol 1121, Summer 2016 Multiple Choice

____ 2. Earthquakes are a result of ____________.

____ 3. Faults that have moved recently or are likely to move in the future are referred to as ____________.

____ 4. A primary force opposing motion on all faults is ____________.

____ 5. Movement on a fault may occur without generating earthquakes.

____ 6. Faulting and earthquakes are examples of ____________.

____ 7. A surface along which rock on opposed sides is offset by earthquake-induced slip is called a ____________.

____ 8. The intersection between a fault plane and the ground surface is called the ____________.

____ 9. If, during an earthquake, a hanging wall slides upward relative to a footwall, the fault is termed ____________ if the fault is steep (closer to vertical than horizontal).

____ 10. 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 ____________.

____ 11. If, during an earthquake, a hanging wall slides upward relative to a footwall, the fault is termed ____________ if the fault is shallow (much closer to horizontal than vertical).

____ 12. Of the following, which causes the most earthquakes?

____ 13. Aftershocks following a major earthquake ____________.

____ 14. Periods of intermittent sliding on a fault as a result of the release of stress during episodes of displacement, followed by stress buildup to the point that the fault is reactivated, is termed ____________.

____ 15. The stress that builds on a preexisting fault that has previously ruptured _____________.

____ 16. A fault cannot slip forever because __________ .

____ 17. The quantity of offset that occurs along a fault is termed ____________.

____ 18. At any point along the fault plane surface of an oblique (nonvertical) fault, the ____________.

____ 19. If, during an earthquake, a footwall slides upward relative to a hanging wall, the fault is termed ____________.

____ 20. All discovered faults are likely to experience earthquakes in the next few hundred years.

____ 21. Which type of fault does NOT, by definition, have a fault trace?

____ 22. In order for an earthquake to occur where you live, which of the following must be true?

____ 23. Body waves include ____________.

____ 24. A coiled spring would be useful in illustrating a ____________ wave.

____ 25. Which type of seismic wave has the highest velocity?

____ 26. Earthquake waves that pass through the interior of Earth are termed ____________.

____ 27. Surface waves ____________.

____ 28. Generally, which type of earthquake waves travel fastest?

____ 29. As a seismologist examining a seismogram, you would know that the third set of waves displayed ____________.

____ 30. Seismometers, being able to detect ground movements of a millionth of a millimeter, are useful to governments worldwide for detecting not only earthquakes, but _______________.

____ 31. All else being equal, an earthquake that strikes in the eastern United States would produce shaking that would be felt ____________ than one that occurred in the western United States.

____ 32. This fundamental principle of physics is the basis behind the effectiveness of a seismometer.

____ 33. The key to finding the location of an earthquake’s epicenter is measuring the ____________.

____ 34. The point within Earth where an earthquake takes place is termed the ____________.

____ 35. The point on Earth’s surface directly above the point where an earthquake occurs is termed the ____________.

____ 36. How many seismic stations are necessary to find the epicenter of an earthquake?

____ 37. Which earthquake severity scale takes vibration caused only by the S-waves into account when estimating the size of an earthquake?

____ 38. Vertical motion seismographs record earthquakes through the production of a squiggly diagram called a ____________.

____ 39. Which earthquake intensity scale assesses the effects of an earthquake on humans and human-made structures?

____ 40. Which earthquake severity scale takes into account the type of rock that has been fractured?

____ 41. An earthquake occurs with an epicenter in the town of New Madrid, Missouri, in the interior of the North American Plate. Where might the hypocenter of this earthquake plausibly be found?

____ 42. Which earthquake severity scale measures the amplitude of deflection of a seismograph pen, standardized to an idealized distance of 100 km between epicenter and seismograph?

____ 43. Which of the following scales was used to measure the intensity of the listed earthquakes?

____ 44. Which earthquake severity scale varies from locality to locality for a single earthquake?

____ 45. If you heard on the news today that an earthquake measured an 8.2 on the Richter scale, what other conclusions could you make based on knowledge garnered from this chapter?

____ 46. According to the moment magnitude scale (Mw)—a magnitude 8 earthquake results in 1,000 times greater amplitude than a magnitude ____________ earthquake.

____ 47. Earthquakes are likely to occur along ____________.

____ 48. A tsunami is ____________.

____ 49. On December 26, 2004, a magnitude 9 earthquake generated a tsunami that devastated coastlines along the ____________.

____ 50. What geological setting(s) would you expect to produce seismic activity?

____ 51. Medium- and deep-focus earthquakes occur along ____________.

____ 52. Earthquakes that occur in a band called a ____________ can be used to track the motion of subducted oceanic lithosphere.

____ 53. Virtually all of the deaths attributed to major earthquakes have resulted from the collapse of buildings.

____ 54. Sandy substrate is susceptible to ____________ during an earthquake.

____ 55. Short-term predictions of earthquake behavior ____________.

____ 56. Long-term prediction of earthquake behavior ____________.

____ 57. Why do some earthquakes last longer than others?

____ 58. Which of these areas of the United States would you expect to have the highest occurrence of seismic activity?

____ 59. How can damage and injury be minimized in areas prone to seismic activity?

____ 60. Seismic retrofitting is the process of __________.

____ 61. Geophysics is the study of _________.

____ 62. Which layer of the Earth has the highest density?

____ 63. S-waves travel ________ than P-waves; however, unlike P-waves, they _______ travel through liquids.

____ 64. If a P-wave is traveling through the Earth and encounters a molten magma chamber, what will happen to the velocity of the P-wave?

____ 65. If a seismic wave is refracted upward at a boundary, what can be said about the material the wave is traveling through?

____ 66. If a P-wave is traveling through sandstone and then encounters peridotite, the P-wave will ________________.

____ 67. If an S-wave is traveling through rock when it encounters a magma chamber, the S-wave will ________________.

____ 68. The core consists of two layers: the ______ inner core and ______ outer core.

____ 69. The picture below shows a seismic tomography image of the western United States. What is the relative temperature of the blue regions (darker grey regions not outlined in black) versus the red regions (darker grey regions outlined in black)?

____ 70. What causes the velocity of a P-wave to slow down when it enters the outer core?

____ 71. You are studying the seismic data from Mars when you notice that there are no S-waves recorded from 130° through 180° on the opposite side of the planet. What does this information tell you about the interior of Mars?

____ 72. In the following graph, why does the line for S-waves NOT appear in the outer core?

____ 73. In the seismic tomography cross section below, where is the subducting Juan de Fuca Plate, considering that the subducting plate is much cooler than the surrounding material?

____ 74. Earth’s gravity is best represented by an equipotential surface that contains bumps and depressions where areas of more or less gravity appear over the Earth, this representation is called the _________.

____ 75. If a gravity anomaly is negative, what does that imply about the material underground?

____ 76. In the picture below, when the ship is filled with cargo it sinks into the water until the mass of water displaced is equal to the mass of the cargo. The ship is then said to be ____________.

____ 77. If a ship weighs 52,000 tons and is in isostatic equilibrium when 6,000 tons of cargo is added, what is the total mass of water that will be displaced by the ship after the cargo is added?

____ 78. The following picture is that of a gravity map of the United States. What do the dark grey regions mean in terms of the density of the material below?

____ 79. A mountain range made of granite would produce a(n) _____________ gravity anomaly.

____ 80. Why would the gravity anomaly over a deep-ocean trench be negative?

____ 81. A positive magnetic anomaly is produced when the measured magnetic field strength is ___________ the expected magnetic field strength.

____ 82. Earth’s magnetic field is produced in the ___________.

____ 83. If a ship towing a magnetometer passes over a piece of crust with a “normal” polarity, what will the magnetic anomaly look like?

____ 84. If you measure the magnetization of an area of igneous rocks and find a large negative anomaly, what does that imply about the rocks?

____ 85. Why are magnetic anomalies of continental crust so much more complicated than those of oceanic crust?