Question 1

The lowest temperatures and highest SiO2 contents occur in rhyolitic magma,material so viscous that it commonly does not flow.

Accepted Answer

A) True 
 B)False

Question 2

What is the cause of volcanism at Italy's Vesuvius,Stromboli,Vulcano,and Etna?

Accepted Answer

A) The subduction of Mediterranean sea floor beneath Europe. 
B) The subduction of Mediterranean sea floor beneath Africa. 
C) The continent-continent collision of Africa and Europe. 
D) 
Rifting along Mid-Atlantic Ridge. 
A) The subduction of Mediterranean sea floor beneath Europe. 
B) The subduction of Mediterranean sea floor beneath Africa. 
C) The continent-continent collision of Africa and Europe. 
D) 
Rifting along Mid-Atlantic Ridge.

Question 3

Lava domes form when high viscosity magma with low volatile content cools quickly,forming a hardened dome a few meters to a kilometer or so in height.

Accepted Answer

A) True 
 B)False

Question 4

When it comes to volcanic hazards,the key problem is how easily the dissolved gases can escape from the magma.

Accepted Answer

A) True 
 B)False

Question 5

The viscosity of magma is lowered by __________.

Accepted Answer

A) increasing temperature 
B) decreasing crystal content 
C) decreasing SiO2 content 
D) All of the choices are correct. 
A) increasing temperature 
B) decreasing crystal content 
C) decreasing SiO2 content 
D) All of the choices are correct.

Question 6

Rock may melt by _______________.

Accepted Answer

A) lowering the pressure on it 
B) raising its temperature 
C) increasing its water content 
D) All of the choices are correct. 
A) lowering the pressure on it 
B) raising its temperature 
C) increasing its water content 
D) All of the choices are correct.

Question 7

Areas of geyser activity include _______.

Accepted Answer

A) Iceland 
B) Yellowstone Park in the United States 
C) North Island of New Zealand 
D) Kamchatka Peninsula of Russia 
E) All of these are correct. 
A) Iceland 
B) Yellowstone Park in the United States 
C) North Island of New Zealand 
D) Kamchatka Peninsula of Russia 
E) All of these are correct.

Question 8

Gas bubbles decrease in number and volume as magma keeps rising upward to lower pressures,helping to propel magma upward through fractures or pipes toward an eruption.

Accepted Answer

A) True 
 B)False

Question 9

Airborne pyroclasts have their finest grains settle down from the atmosphere first,closest to the volcano,followed by progressively coarser material at greater distances away.

Accepted Answer

A) True 
 B)False

Question 10

Crater Lake,Oregon,fills the caldera of ____________ which collapsed about 7600 years ago.

Accepted Answer

A) Mt.Mazama 
B) Mt.Shasta 
C) Mt.St.Helens 
D) Mt.Baker 
E) Mt.Rainier 
A) Mt.Mazama 
B) Mt.Shasta 
C) Mt.St.Helens 
D) Mt.Baker 
E) Mt.Rainier

Question 11

The highest temperatures and highest SiO2 contents are in basaltic magma,giving it the lowest viscosity and easiest fluid flow.

Accepted Answer

A) True 
 B)False

Question 12

The most famous of all volcanoes probably is Vesuvius,and the most famous of its eruptions are those of 79C.E. ,which buried the cities of ____________.

Accepted Answer

A) Pompeii and Herculaneum 
B) Naples and Rome 
C) Naples and Milano 
D) Petra and Florence 
A) Pompeii and Herculaneum 
B) Naples and Rome 
C) Naples and Milano 
D) Petra and Florence

Question 13

Magma at depth does not contain gas bubbles because the high pressure at depth keeps gas dissolved in solution.

Accepted Answer

A) True 
 B)False

Question 14

Beneath continents,rising basaltic magmas are contaminated by sediments and continental-crust rocks,altering magma compositions;the resultant andesitic-to-rhyolitic magmas have high contents of SiO2,relatively low temperatures,and high viscosity,which make it difficult for gases to escape,causing explosive eruptions.

Accepted Answer

A) True 
 B)False

Question 15

A caldera collapse occurs ________________.

Accepted Answer

A) before the eruption starts 
B) in the middle of the eruption 
C) after the magma chamber is mostly empty 
D) millions of years after the volcano's final dying eruption 
E) at the onset of Vulcanian activity 
A) before the eruption starts 
B) in the middle of the eruption 
C) after the magma chamber is mostly empty 
D) millions of years after the volcano's final dying eruption 
E) at the onset of Vulcanian activity

Question 16

Over _________ of Earth's magma extruded through volcanism takes place at the oceanic spreading centers.

Accepted Answer

A) 90% 
B) 80% 
C) 70% 
D) 60% 
E) 50% 
A) 90% 
B) 80% 
C) 70% 
D) 60% 
E) 50%

Question 17

Hot spots can be under the oceans,under the continents,in the center of plates,and at spreading centers.

Accepted Answer

A) True 
 B)False

The lowest temperatures and highest SiO₂ contents occur in rhyolitic magma,material so viscous that it commonly does not flow.

What is the cause of volcanism at Italy's Vesuvius,Stromboli,Vulcano,and Etna?

Lava domes form when high viscosity magma with low volatile content cools quickly,forming a hardened dome a few meters to a kilometer or so in height.

When it comes to volcanic hazards,the key problem is how easily the dissolved gases can escape from the magma.

The viscosity of magma is lowered by __________.

Rock may melt by _______________.

Areas of geyser activity include _______.

Gas bubbles decrease in number and volume as magma keeps rising upward to lower pressures,helping to propel magma upward through fractures or pipes toward an eruption.

Airborne pyroclasts have their finest grains settle down from the atmosphere first,closest to the volcano,followed by progressively coarser material at greater distances away.

Crater Lake,Oregon,fills the caldera of ____________ which collapsed about 7600 years ago.

The highest temperatures and highest SiO₂ contents are in basaltic magma,giving it the lowest viscosity and easiest fluid flow.

The most famous of all volcanoes probably is Vesuvius,and the most famous of its eruptions are those of 79C.E. ,which buried the cities of ____________.

Magma at depth does not contain gas bubbles because the high pressure at depth keeps gas dissolved in solution.

A caldera collapse occurs ________________.

Over _________ of Earth's magma extruded through volcanism takes place at the oceanic spreading centers.

Hot spots can be under the oceans,under the continents,in the center of plates,and at spreading centers.

Natural Disasters and the Human Population

Internal Energy and Plate Tectonics

Earthquake Geology and Seismology

Plate Tectonics and Earthquakes

Earthquakes Throughout the United States and Canada

Volcano Processes and Deadly Events

Tsunami Versus Wind-Caused Waves

External Energy Fuels Weather and Climate

Tornadoes, Lightning, Heat, and Cold

Hurricanes

Climate Change

Floods

Fire

Mass Movements

Coastal Processes and Hazards

Impacts With Space Objects

Filters

Exam 6: Volcanic Eruptions: Plate Tectonics and Magmas

The lowest temperatures and highest SiO2 contents occur in rhyolitic magma,material so viscous that it commonly does not flow.

What is the cause of volcanism at Italy's Vesuvius,Stromboli,Vulcano,and Etna?

Lava domes form when high viscosity magma with low volatile content cools quickly,forming a hardened dome a few meters to a kilometer or so in height.

When it comes to volcanic hazards,the key problem is how easily the dissolved gases can escape from the magma.

The viscosity of magma is lowered by __________.

Rock may melt by _______________.

Areas of geyser activity include _______.

Gas bubbles decrease in number and volume as magma keeps rising upward to lower pressures,helping to propel magma upward through fractures or pipes toward an eruption.

Airborne pyroclasts have their finest grains settle down from the atmosphere first,closest to the volcano,followed by progressively coarser material at greater distances away.

Crater Lake,Oregon,fills the caldera of ____________ which collapsed about 7600 years ago.

The highest temperatures and highest SiO2 contents are in basaltic magma,giving it the lowest viscosity and easiest fluid flow.

The most famous of all volcanoes probably is Vesuvius,and the most famous of its eruptions are those of 79C.E. ,which buried the cities of ____________.

Magma at depth does not contain gas bubbles because the high pressure at depth keeps gas dissolved in solution.

A caldera collapse occurs ________________.

Over _________ of Earth's magma extruded through volcanism takes place at the oceanic spreading centers.

Hot spots can be under the oceans,under the continents,in the center of plates,and at spreading centers.

Natural Disasters and the Human Population

Internal Energy and Plate Tectonics

Earthquake Geology and Seismology

Plate Tectonics and Earthquakes

Earthquakes Throughout the United States and Canada

Volcano Processes and Deadly Events

Tsunami Versus Wind-Caused Waves

External Energy Fuels Weather and Climate

Tornadoes, Lightning, Heat, and Cold

Hurricanes

Climate Change

Floods

Fire

Mass Movements

Coastal Processes and Hazards

Impacts With Space Objects

Filters

The lowest temperatures and highest SiO₂ contents occur in rhyolitic magma,material so viscous that it commonly does not flow.

The highest temperatures and highest SiO₂ contents are in basaltic magma,giving it the lowest viscosity and easiest fluid flow.