GEOLOGY QUIZ (4, 10, 11)
VOLCANOES
EARTH QUAKES
GEOPHYSICAL PROPERTIES
1) Volcanoes are beneficial to humanity in many ways. All of the following are benefits
EXCEPT:
A) many volcanic soils prove fertile for agriculture.
B) some volcanoes provide sources of clean energy.
C) volcanoes give scientists insight into subterranean rock composition.
D) some gases released by volcanoes are toxic to humans.
2) An active volcano is any volcano that:
A) has not been worn away by erosion.
B) is currently erupting or has erupted recently (in geological terms).
C) has not erupted recently (in geological terms) but is likely to erupt in the future.
D) is located on an active tectonic plate boundary.
3) If a volcano has not erupted in the past few thousand years, but is likely to erupt sometime in
the future, it is considered to be:
A) active.
B) dormant.
C) extinct.
D) none of the above.
4) All of the following events could indicate an impending eruption EXCEPT:
A) discovery of new hot springs around the volcano.
B) a measurable bulge or swelling of the volcano.
C) swarms of small earthquakes in the region.
D) a highly eroded, volcanic peak.
5) The principal factor(s) influencing upward magma migration before cooling is (are):
A) the magmatic water content.
B) the magmatic gas content, combined with magma viscosity.
C) the climate and temperature regime that affects the land surrounding the volcano.
D) the time since the last eruption, combined with the density of the rocks overlying the volcano.
6) The term viscosity refers to:
A) how heat and pressure influence a liquid's gas content.
B) a liquid's resistance to flow.
C) how dense a liquid is.
D) how a liquid moves upward against gravity.
7) The most quiet and least dangerous volcanic eruptions involve:
A) fountains and flowing streams of lava.
B) showers of fine ash particles.
C) fallout of volcanic blocks the size of automobiles.
D) glowing avalanches of volcanic rock fragments.
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8) Which magma type produces the most lava flows?
A) Rhyolitic.
B) Andesitic.
C) Basaltic.
D) None of the above.
9) Which of the following is composed of six-sided polygonal columns of rock?
A) Columnar jointing.
B) Nuée ardente.
C) Pahoehoe lava flow.
D) 'A'a lava flow.
10) Which of the following is a likely product of a subaqueous basaltic eruption?
A) Pahoehoe.
B) 'A'a.
C) Pillow structures.
D) Pumice.
11) A nuée ardente can best be described as a:
A) flow of hot pyroclastic material.
B) flow of hot lava.
C) flow of trapped air.
D) rain of tephra particles.
12) A lahar can best be described as a:
A) flow of gas and hot ash.
B) flow of hot lava.
C) volcanic mudflow.
D) rain of tephra particles.
13) Whether they are basaltic or rhyolitic, almost all volcanoes have both:
A) lava flows and ash flows.
B) volcanic domes and calderas.
C) pahoehoe and aa flows.
D) volcanic cones and craters.
14) The greatest danger to Hawai'i from the undersea volcano Loihi is:
A) ash-flow eruptions.
B) earthquake swarms.
C) tsunamis.
D) explosive steam eruptions.
15) A volcanic dome forms when:
A) a large volcanic mountain is rounded off by erosion.
B) a shield volcano takes on a relatively symmetrical dome shape.
C) faulting causes uplift of a volcano.
D) rising magma cools and hardens within a volcano's crater.
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16) Pyroclastic eruptions are likely to occur in all of the following locations EXCEPT:
A) above subducting plate boundaries.
B) along transform boundaries.
C) above continental intraplate hot spots.
D) within intracontinental rift zones.
17) Which of the following statements regarding volcanoes is NOT true?
A) Magma of gentle volcanoes has a higher silica content and a higher viscosity than magma of
violent volcanoes.
B) Violent volcanoes tend to occur at convergent plate boundaries, whereas gentle volcanoes
tend to occur at divergent plate boundaries.
C) Rhyolitic volcanoes usually form calderas, while basaltic volcanoes form shield cones.
D) Basaltic volcanoes have more gentle slopes than rhyolitic volcanoes.
18) What is the most common way of predicting volcanic eruptions?
A) Drop in sea level.
B) Harmonic tremors.
C) Water wells suddenly dry up.
D) Abnormal animal behavior.
19) Most earthquakes are caused by:
A) magma moving forcefully through underground caverns.
B) the release of accumulated strain energy in rocks undergoing plastic deformation.
C) the release of accumulated strain energy in rocks undergoing elastic deformation.
D) excess lithostatic pressure on rocks buried deep within the Earth.
20) Which of the following statements about earthquakes is NOT true?
A) An earthquake's focus is the place within the Earth where rocks shift in response to stress.
B) An earthquake's epicenter is in the exact center of the fault that causes the earthquake.
C) Aftershocks are caused by continued reverberation of rock after a major earthquake.
D) After an earthquake, rocks along a fault temporarily lock in place and resist further
movement, causing earthquakes to be sporadic rather than continuous.
21) If an earthquake occurs, the first waves to arrive at a seismograph are the:
A) P waves.
B) S waves.
C) side-to-side surface waves.
D) rolling surface waves.
22) All of the following are differences between the Richter scale and the Mercalli intensity
scale EXCEPT:
A) the Richter magnitude decreases as distance from the epicenter increases, while the Mercalli
measurement remains the same regardless of distance.
B) the Richter scale measures the size of earthquake waves, whereas the Mercalli scale
measures the amount of damage.
C) the Richter scale is logarithmic, while the Mercalli scale is linear.
D) the Richter scale uses quantitative data, whereas the Mercalli scale uses qualitative data.
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23) The Richter scale measures which characteristic of earthquakes?
A) Observed destructiveness or intensity.
B) The amount of energy released or magnitude.
C) The total energy or seismic moment.
D) Preliminary magnitude from seismographic trace.
24) Earthquakes measuring 5 and 7 on the Richter scale differ in wave amplitude by:
A) 2 times.
B) 10 times.
C) 100 times.
D) 1000 times.
25) The magnitude of most of the Earth's earthquakes is from ________ on the Richter scale.
A) 1.0 to 2.0
B) 2.0 to 3.0
C) 3.0 to 3.9
D) 4.0 to 4.9
26) To locate the epicenter of an earthquake, a seismologist must determine all of the following
EXCEPT:
A) the velocity of both P waves and S waves.
B) the depth of the earthquake and the type of fault from which it originated.
C) the difference in travel times between P waves and S waves.
D) the distance from the epicenter to at least three different seismological stations.
27) Ground displacement during the 1906 San Francisco earthquake was:
A) 15 feet laterally.
B) 25 feet laterally.
C) 39 feet vertically upward.
D) 53 feet vertically downward.
28) All of the following are damaging effects of earthquakes EXCEPT:
A) landslides involving unstable rock, rock fragments, or soil.
B) liquefaction, the release of flood waters by the destruction of a dam.
C) vertical ground displacement along dip-slip faults.
D) displacement of fences through ground shifts in which a block of earth moves laterally.
29) Liquefaction during an earthquake primarily affects:
A) fine-grained clays and silts.
B) foliated metamorphic rocks.
C) rock fragments detached from bedrock.
D) thick sedimentary rock layers.
30) All of the following are true of tsunami EXCEPT:
A) they can travel at speeds greater than 500 miles per hour.
B) they are caused by undersea earthquakes.
C) they are often responsible for the destruction of ships at sea.
D) they can often form waves more than 100 feet high.
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31) When Benioff-Wadati zones are plotted on a map, they show:
A) elastic modulus values in rocks within a subduction zone.
B) semiconcentric zones of varying degrees of earthquake damage.
C) earthquake numbers decreasing away from areas of oceanic rifting.
D) earthquake foci becoming progressively deeper inland from ocean trenches.
32) Major earthquakes are likely in all of the following tectonic settings EXCEPT:
A) divergent boundaries.
B) transform boundaries.
C) subduction zones.
D) continental collision boundaries.
33) Japan is the site of about 15% of the Earth's seismic energy release because it is located:
A) where the Eurasian plate descends beneath the Pacific plate.
B) at the continental collision boundary between the Eurasian and Pacific plates.
C) where the Pacific plate descends beneath the Eurasian plate.
D) at the transform boundary between the Pacific and Eurasian plates.
34) San Francisco is the site of numerous earthquakes because it is located:
A) where the Pacific plate descends beneath the North American plate.
B) at the transform boundary between the Pacific and North American plates.
C) where the North American plate descends beneath the Pacific plate.
D) in a rift zone between the North American and Pacific plates.
35) The magnitude of the powerful New Madrid, Missouri earthquake event of early 1812 may
have exceeded:
A) 8.0.
B) 7.0.
C) 6.0.
D) 5.0.
36) All of the following are known to have been human causes of earthquakes EXCEPT:
A) man-made reservoirs, because of the extreme weight of the water.
B) man-made reservoirs, because of water seeping into and lubricating fractured bedrock.
C) the injection of liquid waste into bedrock, because of the added lubrication to deep faults.
D) draining of wetlands, because of the removal of lubricating fluids from shallow faults.
37) In an earthquake-prone region, the safest house would be a:
A) log cabin built on bedrock.
B) log cabin built on loose soil.
C) brick house built on bedrock.
D) brick house built on loose soil.
38) The deepest drill hole, located in northern Russia, extends how far into the crust?
A) 7 kilometers.
B) 11 kilometers.
C) 13 kilometers.
D) 15 kilometers.
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39) Which of the following statements concerning S waves is NOT true?
A) The speed of an S wave depends on the elasticity of the media through which it travels.
B) S waves do not have enough energy and speed to pass through liquids or gases.
C) S waves may change their direction of travel when they encounter a material of different
rigidity.
D) S waves temporarily displace materials they pass through with a shearing stress.
40) In North America, the thinnest crust is only:
A) 20-30 kilometers thick.
B) 40-50 kilometers thick.
C) 60 kilometers thick.
D) 70 kilometers thick.
41) The location of the thinnest continental crust in North America is located in:
A) North Carolina.
B) Iowa.
C) California.
D) Nevada.
42) Formation of the oceanic crust involves all of the following processes EXCEPT:
A) effusive eruptions of basalt.
B) intrusion of granite at oceanic subduction zones.
C) intrusion of gabbro at divergent plate boundaries.
D) deep-sea sedimentation.
43) Seismic tomography studies detect warmer interior regions as indicated by which
phenomenon?
A) Higher seismic velocities.
B) Earlier seismic wave arrival times.
C) Bending of seismic waves paths.
D) Lower seismic velocities.
44) The Mohorovičić discontinuity (the Moho) is:
A) the boundary between oceanic and continental crust.
B) a region of low seismic velocity.
C) the boundary between the crust and the mantle.
D) the boundary between sedimentary rocks on the Earth's surface and the deeper plutonic
rocks.
45) The mantle accounts for what percentage of the Earth's total volume?
A) 60%.
B) 70%.
C) 80%.
D) 90%.
46) The asthenosphere is considered the low-velocity zone because:
A) circulation of material within asthenosphere convection currents moves extremely slowly.
B) seismic waves travel more slowly through it than through any other region in the Earth's
interior.
C) in this thin layer of mantle, P-wave velocity is slower than in the crust.
D) seismic waves travel more slowly through it than through other parts of the mantle.
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47) Which of the following statements about the lower mantle is NOT true?
A) The lower mantle is solid because its temperatures are lower than those in the
asthenosphere.
B) P waves reach a velocity of 13.6 kilometers per second at the base of the mantle.
C) The rocks near the base of the lower mantle are more rigid than those near the top of the
lower mantle.
D) The rocks of the lower mantle are most likely magnesium silicates and oxides.
48) Knowing the exact depth of a point within the Earth's interior enables us to calculate:
A) pressure.
B) density.
C) temperature.
D) composition.
49) The North American mid-continent gravity high marks the location of an ancient:
A) volcanic mountain range.
B) continental suture zone.
C) continental rift zone.
D) concentration of metallic ore.
50) The principle of isostasy is used to describe:
A) the buoyancy of portions of the Earth's crust as they float on the asthenosphere.
B) changes in seismic wave velocities relative to the density of the media through which they
travel.
C) changes in gravitational attraction dependent on latitude and altitude.
D) changes in polarity of the Earth's magnetic field.
ESSAY QUESTIONS - ANSWER TWO QUESTIONS (5-10 SENTENCES)
1) Briefly explain how we know the structure of the Earth's interior.
2) Discuss the relationships among depth, pressure, temperature, and physical state in the
Earth's interior.
3) How do geologists determine the Earth's interior temperatures?
4) How did the cataclysmic eruption of Krakatau in 1883 affect global climate?
5) How do volcanic craters form?
6) What causes earthquakes?
7) Describe the fundamental principle by which a seismograph works.
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