Question 1

Which of the following best explains why some volcanoes erupt so violently?

Accepted Answer

A)   rapid decompression of dissolved gases
B)   rapid temperature drop as magma reaches the surface environment
C)   cooling effect of seawater beneath island arc volcanoes
D)   combustion as nitrogen gas compounds react with atmospheric oxygen
E)   all of the answers listed hereF) B) and E)
G) A) and C)

Question 2

The nature of volcanic eruptions is closely related to plate tectonics and magma type. Which of the following best describes basaltic magma?

Accepted Answer

A)   relatively SiO2 poor and hot
B)   relatively SiO2 poor and cool
C)   relatively SiO2 rich and hot
D)   relatively SiO2 rich and coolE) C) and D)
F) A) and B)

Question 3

Viscosity is the measure of a fluid's resistance to a flow. Which of the following factors affect the viscosity of magmas?

Accepted Answer

A)   temperature and SiO2 content
B)   density and temperature
C)   elevation and density
D)   density and water content
E)   water and SiO2 contentF) None of the above
G) A) and B) A

Question 4

Volcanic ash forms when rock particles and lava droplets are ejected skyward.

Accepted Answer

A) True 
 B)False

Question 5

What best describes the relatively small volcanoes that form when fragments of erupted lava cool and accumulate around a vent?

Accepted Answer

A)   cinder cone
B)   shield volcano
C)   composite cone
D)   lava dome
E)   fissure domeF) A) and C)
G) B) and D)

Question 6

Volcanic tsunamis can form around volcanic islands during large explosive events or massive landslides.

Accepted Answer

A) True 
 B)False

Question 7

Which of the following hazards is LEAST likely to be associated with explosive volcanic eruptions?

Accepted Answer

A)   lava flows
B)   pyroclastic flows
C)   tsunamis
D)   ash fall
E)   mudflowsF) B) and C)
G) B) and E)

Question 8

What best describes a pyroclastic flow?

Accepted Answer

A)   dry avalanche of hot material
B)   lava flow that has caught on fire
C)   hot mudflow
D)   dense ash fall
E)   volcanic tsunami that makes landfallF) B) and C)
G) B) and E)

Question 9

What best explains why volcanic mudflows are so dangerous to humans?

Accepted Answer

A)   they move down stream valleys where people tend to live
B)   the high temperature of the mud
C)   they trigger other types of landslides
D)   all of the answers listed here
E)   they are more fluid and move more rapidly than a normal floodF) A) and C)
G) None of the above

Question 10

Which of the following factors determine whether a volcanic eruption will be explosive or non-explosive?

Accepted Answer

A)   magma viscosity and gas content
B)   depth of magma and elevation
C)   magma viscosity and elevation
D)   depth of magma and rock fractures
E)   gas content and rock fracturesF) A) and E)
G) B) and D)

Question 11

Attempts at predicting volcanic eruptions have largely been unsuccessful.

Accepted Answer

A) True 
 B)False

Question 12

Which of the following tectonic settings is the most likely to generate an explosive volcanic eruption?

Accepted Answer

A)   subduction zone
B)   mid-ocean ridge
C)   oceanic hot-spot
D)   rift valley
E)   fold mountain beltF) B) and D)
G) A) and C)

Question 13

Which of the following volcanoes in the U.S. is most notably for having a history of massive mudflows, which today threatens large numbers of people?

Accepted Answer

A)   Mt. Rainier, Washington
B)   Mt. St. Helens, Washington
C)   Mt. Shasta, California
D)   Mt. Spur, Alaska
E)   Mauna Loa, HawaiiF) A) and E)
G) None of the above

Question 14

Which of the following is NOT a tool that scientists use to predict volcanic eruptions?

Accepted Answer

A)   deep drilling and magma sampling
B)   volcanic gas sampling
C)   monitoring topographic changes
D)   seismic monitoring
E)   monitoring geophysical and groundwater changesF) C) and D)
G) D) and E)

Question 15

Which of the following is an example of a hot-spot, or intraplate volcano?

Accepted Answer

A)   Hawaiian Islands
B)   Mt. St. Helens
C)   the Ring of Fire
D)   Mt. Fuji
E)   Mt. RainierF) A) and C)
G) C) and D)

Question 16

Water vapor is often the most abundant dissolved gas within magma. What best describes the source of water in gas-rich magmas?

Accepted Answer

A)   water-rich sediment in subduction zones
B)   seepage of seawater into oceanic crustal rocks
C)   heavy rainfall in tropical areas
D)   shallow groundwater circulating through continental crustal rocks
E)   all of the answers listed hereF) A) and C)
G) All of the above

Question 17

Which of the following is NOT a common a problem associated with volcanic ash-fall?

Accepted Answer

A)   forest fires
B)   destruction of crops
C)   building collapse
D)   disruption of air travel
E)   filling of stream channelsF) A) and B)
G) B) and C) A

Question 18

Which of the following would most likely result in a lava flow that is hazardous to humans?

Accepted Answer

A)   low viscosity basaltic magma
B)   high viscosity rhyolitic magma
C)   high viscosity andesitic magma
D)   low viscosity andesitic magma
E)   high viscosity basaltic magmaF) All of the above
G) B) and D) A

Question 19

Which of the following terms is used to describe a large circular depression that forms after an eruption when a magma chamber becomes empty and collapses in on itself?

Accepted Answer

A)   caldera
B)   crater
C)   lava pit
D)   tuff-cone
E)   sinkholeF) A) and D)
G) C) and D)

Question 20

There are two basic types of volcanoes, shield and composite cone. Which of the following best describes composite cone volcanoes?

Accepted Answer

A)   relatively small, erupt andesitic magma, and are highly explosive
B)   relatively small, erupt basaltic magma, and are highly explosive
C)   relatively large, erupt andesitic magma, and are non-explosive
D)   relatively large, erupt basaltic magma, and are highly explosive
E)   relatively large, erupt basaltic magma, and are non-explosiveF) None of the above
G) B) and E)

Exam 6: Volcanoes and Related Hazards

Which of the following best explains why some volcanoes erupt so violently?

Correct AnswerverifiedShow Answer

The nature of volcanic eruptions is closely related to plate tectonics and magma type. Which of the following best describes basaltic magma?

Correct AnswerverifiedShow Answer

Viscosity is the measure of a fluid's resistance to a flow. Which of the following factors affect the viscosity of magmas?

Correct AnswerverifiedA

Volcanic ash forms when rock particles and lava droplets are ejected skyward.

Correct AnswerverifiedShow Answer

What best describes the relatively small volcanoes that form when fragments of erupted lava cool and accumulate around a vent?

Correct AnswerverifiedShow Answer

Volcanic tsunamis can form around volcanic islands during large explosive events or massive landslides.

Correct AnswerverifiedShow Answer

Which of the following hazards is LEAST likely to be associated with explosive volcanic eruptions?

Correct AnswerverifiedShow Answer

What best describes a pyroclastic flow?

Correct AnswerverifiedShow Answer

What best explains why volcanic mudflows are so dangerous to humans?

Correct AnswerverifiedShow Answer

Which of the following factors determine whether a volcanic eruption will be explosive or non-explosive?

Correct AnswerverifiedShow Answer

Attempts at predicting volcanic eruptions have largely been unsuccessful.

Correct AnswerverifiedShow Answer

Which of the following tectonic settings is the most likely to generate an explosive volcanic eruption?

Correct AnswerverifiedShow Answer

Which of the following volcanoes in the U.S. is most notably for having a history of massive mudflows, which today threatens large numbers of people?

Correct AnswerverifiedShow Answer

Which of the following is NOT a tool that scientists use to predict volcanic eruptions?

Correct AnswerverifiedShow Answer

Which of the following is an example of a hot-spot, or intraplate volcano?

Correct AnswerverifiedShow Answer

Water vapor is often the most abundant dissolved gas within magma. What best describes the source of water in gas-rich magmas?

Correct AnswerverifiedShow Answer

Which of the following is NOT a common a problem associated with volcanic ash-fall?

Correct AnswerverifiedA

Which of the following would most likely result in a lava flow that is hazardous to humans?

Correct AnswerverifiedA

Which of the following terms is used to describe a large circular depression that forms after an eruption when a magma chamber becomes empty and collapses in on itself?

Correct AnswerverifiedShow Answer

There are two basic types of volcanoes, shield and composite cone. Which of the following best describes composite cone volcanoes?

Correct AnswerverifiedShow Answer

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