Question 1

What two main influences on a water-bearing basaltic magma can cause water to separate from a magma to drive an eruption?

Accepted Answer

Decrease in pressure and crystallization.

Question 2

Highly explosive magmas are controlled by which of the following?

Accepted Answer

A)  high magnesium content and high water 
B)  high silica content and high water 
C)  low silica content and high water 
D)  high silica content and low water 
E)  high iron content and low water 
A)  high magnesium content and high water 
B)  high silica content and high water 
C)  low silica content and high water 
D)  high silica content and low water 
E)  high iron content and low water B

Question 3

Which of the two main volcanic gases is heavier than air,collects in low areas,and can asphyxiate people or animals if it is in high concentrations?

Accepted Answer

A)  water vapor 
B)  hydrogen 
C)  carbon dioxide 
D)  ethane 
E)  helium 
A)  water vapor 
B)  hydrogen 
C)  carbon dioxide 
D)  ethane 
E)  helium C

Question 4

How does lava differ from magma?

Accepted Answer

Lava is magma that e

Question 5

What is magma that is forcefully ejected into the atmosphere as particles?

Accepted Answer

A)  lava 
B)  pahoehoe 
C)  plutonic 
D)  pyroclastic 
E)  lahar 
A)  lava 
B)  pahoehoe 
C)  plutonic 
D)  pyroclastic 
E)  lahar

Question 6

What are the two most abundant gases in magmas?

Accepted Answer

Water vapo

Question 7

If you had to choose between enduring a Strombolian eruption and a Vulcanian eruption,which would you choose and why?

Accepted Answer

Even though steam bubbles in the magma c

Question 8

Why were the predictions and mitigation of the hazards for the eruption at Mount Pinatubo so successful? What types of strategies did authorities use to evacuate people?

Accepted Answer

They were successful because they provid

Question 9

If a bulge grows steep enough,it may collapse.Explain how this can trigger an explosive eruption.

Accepted Answer

Collapse of a bulge decreases

Question 10

Why do shield volcanoes have very gently sloping sides?

Accepted Answer

A)  Their andesite composition produces huge ash flows that spread over a large area. 
B)  Their andesite and rhyolite have low viscosity because of their water content, and spread over a low slope. 
C)  Their basalt flows have low viscosity, so the lava solidifies as gentle slopes. 
D)  Their basalt ash spreads out widely in the strong winds over the open ocean. 
E)  Their basalt magmas blow out violently from all of their pent up steam. 
A)  Their andesite composition produces huge ash flows that spread over a large area. 
B)  Their andesite and rhyolite have low viscosity because of their water content, and spread over a low slope. 
C)  Their basalt flows have low viscosity, so the lava solidifies as gentle slopes. 
D)  Their basalt ash spreads out widely in the strong winds over the open ocean. 
E)  Their basalt magmas blow out violently from all of their pent up steam.

Question 11

List the styles of explosive eruptions,and give a brief explanation of two of them.

Accepted Answer

Phreatic: violent steam-driven explosion

Question 12

If a bulge grows steep enough,it may collapse.Explain how this can trigger an explosive eruption.

Accepted Answer

A)  It removes the cover over the magma, so it can escape. 
B)  It slices through some of the gas bubbles, making them pop. 
C)  It doesn't trigger an explosive eruption; it does, however, create a devastating landslide. 
D)  The friction of the landslide heats that part of the magma, so the dissolved water flashes into steam. 
E)  It decreases pressure on gases dissolved in the magma, permitting them to expand. 
A)  It removes the cover over the magma, so it can escape. 
B)  It slices through some of the gas bubbles, making them pop. 
C)  It doesn't trigger an explosive eruption; it does, however, create a devastating landslide. 
D)  The friction of the landslide heats that part of the magma, so the dissolved water flashes into steam. 
E)  It decreases pressure on gases dissolved in the magma, permitting them to expand.

Question 13

What two main factors dictate that an erupting magma will be explosive?

Accepted Answer

High water

Question 14

What two main factors result in more violent eruptions?

Accepted Answer

A)  not too much water and low enough viscosity 
B)  more water and higher viscosity of the magma 
C)  higher viscosity and narrow enough vent 
D)  strong rocks around the vent and more water 
E)  a large enough volcano with low-viscosity magma 
A)  not too much water and low enough viscosity 
B)  more water and higher viscosity of the magma 
C)  higher viscosity and narrow enough vent 
D)  strong rocks around the vent and more water 
E)  a large enough volcano with low-viscosity magma

Question 15

What property(s)of magma determine the magnitude of an eruption?

Accepted Answer

The answer of What property(s)of magma determine the magnitude of...

Question 16

About how fast can erupting steam travel?

Accepted Answer

A)  up to 4 to 7 km per hour 
B)  up to about 14 km per hour 
C)  generally slower than you can run 
D)  between 400 and 700 km per hour; up to 1,200 km per hour 
E)  more than 1,600 km per hour 
A)  up to 4 to 7 km per hour 
B)  up to about 14 km per hour 
C)  generally slower than you can run 
D)  between 400 and 700 km per hour; up to 1,200 km per hour 
E)  more than 1,600 km per hour

Question 17

A basalt magma typically erupts in what form?

Accepted Answer

A)  pale ash flows 
B)  pale air-fall ash 
C)  giant Plinian eruptions that rise 50 km into the atmosphere 
D)  violent steam-rich surge blasts 
E)  lava flows 
A)  pale ash flows 
B)  pale air-fall ash 
C)  giant Plinian eruptions that rise 50 km into the atmosphere 
D)  violent steam-rich surge blasts 
E)  lava flows

Question 18

Which of the following locations five kilometers from the crater of a volcano would likely be safe from a large pyroclastic flow,if any?

Accepted Answer

A)  far side of a steep-sided, 100-meter-high hill 
B)  far side of a five-kilometer-wide lake 
C)  behind a large tree with an 80-centimeter-diameter (2½ feet) trunk 
D)  None of the locations are safe: ash flows can flow over large hills, can cross large expanses of water, and can fell very large trees. 
E)  All of the locations are safe: ash flows cannot flow over large hills, cannot cross large expanses of water, and cannot topple very large trees. 
A)  far side of a steep-sided, 100-meter-high hill 
B)  far side of a five-kilometer-wide lake 
C)  behind a large tree with an 80-centimeter-diameter (2½ feet) trunk 
D)  None of the locations are safe: ash flows can flow over large hills, can cross large expanses of water, and can fell very large trees. 
E)  All of the locations are safe: ash flows cannot flow over large hills, cannot cross large expanses of water, and cannot topple very large trees.

Question 19

Which common volcanic gases are poisonous? Name two.

Accepted Answer

Carbon dioxide in hi

Question 20

How does pahoehoe lava differ from aa lava?

Accepted Answer

A)  Pahoehoe is full of gas holes, and aa is solid lava. 
B)  Pahoehoe has a ragged top, and aa is smooth on top. 
C)  Pahoehoe is ropy-looking, and aa is clinkery. 
D)  Pahoehoe is rhyolite, and aa is basalt. 
E)  Pahoehoe is basalt, and aa is andesite. 
A)  Pahoehoe is full of gas holes, and aa is solid lava. 
B)  Pahoehoe has a ragged top, and aa is smooth on top. 
C)  Pahoehoe is ropy-looking, and aa is clinkery. 
D)  Pahoehoe is rhyolite, and aa is basalt. 
E)  Pahoehoe is basalt, and aa is andesite.

What two main influences on a water-bearing basaltic magma can cause water to separate from a magma to drive an eruption?

Highly explosive magmas are controlled by which of the following?

Which of the two main volcanic gases is heavier than air,collects in low areas,and can asphyxiate people or animals if it is in high concentrations?

How does lava differ from magma?

What is magma that is forcefully ejected into the atmosphere as particles?

What are the two most abundant gases in magmas?

If you had to choose between enduring a Strombolian eruption and a Vulcanian eruption,which would you choose and why?

Why were the predictions and mitigation of the hazards for the eruption at Mount Pinatubo so successful? What types of strategies did authorities use to evacuate people?

If a bulge grows steep enough,it may collapse.Explain how this can trigger an explosive eruption.

Why do shield volcanoes have very gently sloping sides?

List the styles of explosive eruptions,and give a brief explanation of two of them.

If a bulge grows steep enough,it may collapse.Explain how this can trigger an explosive eruption.

What two main factors dictate that an erupting magma will be explosive?

What two main factors result in more violent eruptions?

What property(s)of magma determine the magnitude of an eruption?

About how fast can erupting steam travel?

A basalt magma typically erupts in what form?

Which of the following locations five kilometers from the crater of a volcano would likely be safe from a large pyroclastic flow,if any?

Which common volcanic gases are poisonous? Name two.

How does pahoehoe lava differ from aa lava?

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Earthquake Prediction and Mitigation

Tsunami

Volcanoes: Hazards and Mitigation

Landslides and Other Downslope Movements

Sinkholes, Land Subsidence, and Swelling Soils

Weather, Thunderstorms, And Tornadoes

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Exam 6: Volcanoes: Tectonic Environments and Eruptions

What two main influences on a water-bearing basaltic magma can cause water to separate from a magma to drive an eruption?

Highly explosive magmas are controlled by which of the following?

Which of the two main volcanic gases is heavier than air,collects in low areas,and can asphyxiate people or animals if it is in high concentrations?

How does lava differ from magma?

What is magma that is forcefully ejected into the atmosphere as particles?

What are the two most abundant gases in magmas?

If you had to choose between enduring a Strombolian eruption and a Vulcanian eruption,which would you choose and why?

Why were the predictions and mitigation of the hazards for the eruption at Mount Pinatubo so successful? What types of strategies did authorities use to evacuate people?

If a bulge grows steep enough,it may collapse.Explain how this can trigger an explosive eruption.

Why do shield volcanoes have very gently sloping sides?

List the styles of explosive eruptions,and give a brief explanation of two of them.

If a bulge grows steep enough,it may collapse.Explain how this can trigger an explosive eruption.

What two main factors dictate that an erupting magma will be explosive?

What two main factors result in more violent eruptions?

What property(s)of magma determine the magnitude of an eruption?

About how fast can erupting steam travel?

A basalt magma typically erupts in what form?

Which of the following locations five kilometers from the crater of a volcano would likely be safe from a large pyroclastic flow,if any?

Which common volcanic gases are poisonous? Name two.

How does pahoehoe lava differ from aa lava?

Natural Hazards and Disasters

Plate Tectonics and Physical Hazards

Earthquakes and Their Causes

Earthquake Prediction and Mitigation

Tsunami

Volcanoes: Hazards and Mitigation

Landslides and Other Downslope Movements

Sinkholes, Land Subsidence, and Swelling Soils

Weather, Thunderstorms, And Tornadoes

Climate Change

Streams And Flood Processes

Floods And Human Interactions

Waves,Beaches,And Coastal Erosion

Hurricanes and Nor’easters

Wildfires

Impact of Asteroids and Comets

The Future: Where Do We Go From Here?

Filters