Question 1

Which one of the following shows the correct order (left to right) of decreasing magma viscosity?

Accepted Answer

A)  rhyolite,andesite,basalt
B)  andesite,rhyolite,basalt
C)  basalt,rhyolite,andesite
D)  basalt,andesite,rhyoliteE) A) and D)
F) B) and D)

Question 2

The viscosities of magmas increase with increasing percentages of silica.

Accepted Answer

A) True 
 B)False

Question 3

What type of volcanic material is indicative of eruption under water?

Accepted Answer

A)  AA flows
B)  Pyroclastic flows
C)  Pillow lavas
D)  Pahoehoe flows
E)  Lava apronsF) A) and E)
G) A) and B)

Question 4

The recent (geologically) volcanic activity in Yellowstone National Park is ________.

Accepted Answer

A)  related to plate subduction
B)  related to a divergent plate boundary
C)  related to a transform plate boundary
D)  related to intraplate,hot spot volcanismE) B) and C)
F) None of the above

Question 5

In what plate tectonic setting are magmas generated predominantly by fluids fluxing the melting process by decreasing melting temperature?

Accepted Answer

A)  hot spots
B)  spreading ridges
C)  transform faults
D)  convergent plate marginsE) B) and C)
F) A) and C)

Question 6

Which type of plate margin is characterized by volcanos that include basalt,andesite,dacite and rhyolite?

Accepted Answer

A)  hot spots
B)  spreading ridges
C)  transform faults
D)  convergent plate marginsE) A) and C)
F) B) and D)

Question 7

The eruptions of the Hawaiian volcanoes may be described as explosive in comparison to the 1980 Mount St.Helens eruption.

Accepted Answer

A) True 
 B)False  False

Question 8

Mount Pelée on the island of Martinique killed thousands of people in ________.

Accepted Answer

A)  a pyroclastic flow,also called a Nuée Ardent
B)  a caldera collapse
C)  an ash fall that smothered the people living there
D)  a cinder cone eruptionE) All of the above
F) A) and B)

Question 9

________ is the major dissolved volatile constituent in both magmas and volcanic gases.

Accepted Answer

A)  Water
B)  Carbon monoxide
C)  Hydrogen chloride
D)  MethaneE) A) and B)
F) All of the above A

Question 10

Dissolved gases may comprise up to a few percent by weight of a magma.

Accepted Answer

A) True 
 B)False

Question 11

As magma approaches the surface,water contributes to the explosive potential of the eruption because ________.

Accepted Answer

A)  water has a large heat capacity,which allow it to keep the magma hot enough to explode
B)  water dissociates to hydrogen and oxygen at high temperatures but reacts violently at decreasing pressures to produce explosive eruptions
C)  water has a lower density in its solid phase than its liquid phase which makes it explode when pressure decreases
D)  water dissolved in magma flashes to steam as pressure decreases,and the volume increase leads to an explosive potentialE) C) and D)
F) A) and D)

Question 12

The slopes of most cinder cones are usually about 30 degrees because ________.

Accepted Answer

A)  the loose materials ejected from the cone form slopes at the angle of repose
B)  cinder cones are mostly basalt and basalt is too weak to maintain a slope greater than 30 degrees
C)  they are composites of loose material and lava and the viscosity of the lava requires the slopes to form at about 30 degrees
D)  The statement is false; most cinder cones have slopes less than 10 degrees because of the low viscosity of basalt lava flows.E) All of the above
F) C) and D)

Question 13

Which magma type would generally have the lowest viscosity?

Accepted Answer

A)  basalt
B)  andesite
C)  dacite
D)  rhyoliteE) A) and D)
F) A) and C)

Question 14

Most of the active volcanoes on land are located in a belt known as the ________.

Accepted Answer

A)  Ring of Fire
B)  Gulf Coast zone
C)  Mid-Pacific Ridge
D)  Red Sea riftE) A) and D)
F) None of the above

Question 15

The famous destruction of the Roman city of Pompeii was produced by ________.

Accepted Answer

A)  a large cinder cone burying the city in tephra
B)  a composite volcano erupted lava that buried the city,fossilizing people who were overridden by the fast moving flows
C)  a volcanic mudflow from Mt.Vesuvius that buried the people and the city
D)  a pyroclastic eruption from a composite volcano that buried the city in ash and smothered the people living thereE) None of the above
F) A) and D) D

Question 16

Mount Pelee on the Island of Martinique erupted in the early 20th century.Why is this eruption famous?

Accepted Answer

A)  It was the first caldera forming eruption observed by modern scientists.
B)  It produced a major lateral blast that leveled a city,killing many people.
C)  It was a small cinder cone on an island that erupted in a sugar cane field.
D)  The volcano produced a pyroclastic flow that swept down the mountain,killing thousands of people.E) None of the above
F) B) and C)

Question 17

Which of the following is not an accurate statement about the melting process in the earth's interior?

Accepted Answer

A)  Melting of rocks is incomplete with partial melts extracted as magma and solid residues left behind.
B)  Water dramatically lowers the melting temperature of silicate rocks,and addition of water commonly contributes to production of magma.
C)  Upwelling flow in the earth's interior brings higher temperature rocks toward the surface and contributes to decompression melting.
D)  The earth's lower mantle is entirely molten and heat from this zone produces partial melting in the upper mantle,which produces the diverse volcanic rocks we see at the earth's surface.E) A) and B)
F) A) and C)

Question 18

Volcano A erupts rocks with SiO2 content ranging from 49% to 52% whereas volcano B,100km away,erupts materials with SiO2 content of 62-68%.Which statement best characterizes these two volcanos?

Accepted Answer

A)  Both volcanos are shield type volcanos that are characterized by quiescent eruptions.
B)  Both volcanos are violent,explosive volcanos that spread ash continent wide.
C)  Volcano A is likely to be a supervolcano with violent eruptions,whereas volcano B is probably a shield volcano with quiescent eruptions.
D)  Volcano A is probably a shield volcano with typically quiescent eruptions,whereas Volcano B is likely a stratovolcano characterized by violent,explosive eruptions.E) A) and B)
F) A) and C)

Question 19

The main destruction from shield volcanos like Kilauea in Hawaii is slow burial of man-made feature by lava rather than explosive volcanic activity.

Accepted Answer

A) True 
 B)False

Question 20

Match the name of the tectonic feature with the Figure. 
-Hot spot

Accepted Answer

The answer of Match the name of the tectonic feature...

Exam 9: Volcanoes and Other Igneous Activity

Which one of the following shows the correct order (left to right) of decreasing magma viscosity?

Correct AnswerverifiedShow Answer

The viscosities of magmas increase with increasing percentages of silica.

Correct AnswerverifiedShow Answer

What type of volcanic material is indicative of eruption under water?

Correct AnswerverifiedShow Answer

The recent (geologically) volcanic activity in Yellowstone National Park is ________.

Correct AnswerverifiedShow Answer

In what plate tectonic setting are magmas generated predominantly by fluids fluxing the melting process by decreasing melting temperature?

Correct AnswerverifiedShow Answer

Which type of plate margin is characterized by volcanos that include basalt,andesite,dacite and rhyolite?

Correct AnswerverifiedShow Answer

The eruptions of the Hawaiian volcanoes may be described as explosive in comparison to the 1980 Mount St.Helens eruption.

Correct AnswerverifiedFalse

Mount Pelée on the island of Martinique killed thousands of people in ________.

Correct AnswerverifiedShow Answer

________ is the major dissolved volatile constituent in both magmas and volcanic gases.

Correct AnswerverifiedA

Dissolved gases may comprise up to a few percent by weight of a magma.

Correct AnswerverifiedShow Answer

As magma approaches the surface,water contributes to the explosive potential of the eruption because ________.

Correct AnswerverifiedShow Answer

The slopes of most cinder cones are usually about 30 degrees because ________.

Correct AnswerverifiedShow Answer

Which magma type would generally have the lowest viscosity?

Correct AnswerverifiedShow Answer

Most of the active volcanoes on land are located in a belt known as the ________.

Correct AnswerverifiedShow Answer

The famous destruction of the Roman city of Pompeii was produced by ________.

Correct AnswerverifiedD

Mount Pelee on the Island of Martinique erupted in the early 20th century.Why is this eruption famous?

Correct AnswerverifiedShow Answer

Which of the following is not an accurate statement about the melting process in the earth's interior?

Correct AnswerverifiedShow Answer

Volcano A erupts rocks with SiO2 content ranging from 49% to 52% whereas volcano B,100km away,erupts materials with SiO2 content of 62-68%.Which statement best characterizes these two volcanos?

Correct AnswerverifiedShow Answer

The main destruction from shield volcanos like Kilauea in Hawaii is slow burial of man-made feature by lava rather than explosive volcanic activity.

Correct AnswerverifiedShow Answer

Match the name of the tectonic feature with the Figure. -Hot spot

Correct AnswerverifiedShow Answer

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False

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D

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