Deck 6: Volcanoes Tectonic Environments and Eruptions

Question 1

Hotspot volcanoes in an oceanic plate ____.

A)create large amounts of serpentine as they react with groundwater
B)tend to form large lava flows from wet basalt
C)are among the most explosive of volcanoes
D)originate from melted rhyolite in the seafloor
E)originate from deep peridotite, which rises as a plume of dry basalt

Answer 1

E

Question 2

Volcanic eruptions are likely to be more explosive for magmas that have ____.

A)high viscosity and a low amount of volatiles
B)high viscosity and a high amount of volatiles
C)low viscosity and a high amount of volatiles
D)low viscosity and a low amount of volatiles
E)any viscosity with a high amount of volatiles

Answer 2

B

Question 3

Shield volcanoes are characterized by steep slopes.

Answer 3

False

Question 4

Volcanic ash is always injected into the upper atmosphere and therefore, does not immediately affect the area around the eruption.

Question 5

The magma that erupts from the divergent boundary of the Mid-Atlantic ridge produces ____.

A)thin basalt lava flows
B)thin rhyolite lava flows
C)andesite volcanoes
D)peridotite shield volcanoes
E)peridotite lava flows

Question 6

Lava domes and continental calderas cannot produce pyroclastic flows.

Question 7

The volume of magma expelled in an eruption depends on ____ of the magma.

A)the temperature and volatiles but not the viscosity
B)the temperature and viscosity but not the volatiles
C)both the viscosity and volatiles
D)only the volatiles
E)the temperature, viscosity, and volatiles

Question 8

Most hazardous volcanoes occur near subduction zones.

Question 9

Basaltic magma generally produces non-explosive eruptions.

Question 10

Which type(s) of magma result in erupted material that is mostly in the form of ash?

A)rhyolite only
B)andesite only
C)basalt only
D)both andesite and basalt
E)both basalt and rhyolite

Question 11

Stratovolcanoes are generally the smallest category of volcanoes.

Question 12

A hot rock deep in Earth may melt if it is subjected to an increase in pressure.

Question 13

Compared to other types of magma, basalt ____.

A)has lower viscosity, but equivalent silica content
B)has lower viscosity and higher silicate content
C)has higher viscosity and lower silicate content
D)has higher viscosity and higher silicate content
E)has lower viscosity and lower silicate content

Question 14

The two most abundant gasses in magmas are ____. ​

A)sulfur dioxide and carbon dioxide ​
B)water vapor and oxygen
C)oxygen and carbon dioxide
D)methane and carbon dioxide
E)water vapor and carbon dioxide

Question 15

A subduction zone provides an environment that affects the types of volcanoes that develop there because ____.

A)the subducting slab is subjected to high pressure
B)the continental slab is composed of denser material than the subducting slab
C)the magma will reach the surface more quickly
D)the subducting crust is high in silicates
E)there is a high water content in the rock of the subducting slab

Question 16

The viscosity of different types of magma is controlled by the peridotite content.

Question 17

Most volcanic ash consists of curved shards of glass.

Question 18

Pahoehoe lava has a ropy, smooth, or billowy surface.

Question 19

Basaltic magma eruptions usually take which form?

A)lava flows
B)pale ash flows
C)lahar
D)steam-rich explosions
E)ash-rich explosions

Question 20

When comparing the characteristics of common magmas or lavas, ____.

A)rhyolite has the lowest water content
B)andesite has the lowest viscosity
C)basalt has the highest silicate content
D)rhyolite has the highest viscosity
E)basalt has the lowest temperature

Question 21

Which statement is most correct?

A)Lava domes and cinder cones are always found in resurgent caldera.
B)Lava domes often grow on the side of shield volcanoes; cinder cones often grow on the side of stratovolcanoes.
C)Cinder cones often grow on the side of shield volcanoes; lava domes often grow on the side of stratovolcanoes.
D)Lava domes and cinder cones can both be found around all other volcanic types.
E)Lava domes and cinder cones are always isolated structures far from other volcanoes.

Question 22

Rhyolite magma usually erupts in which form?

A)thin, fast lava flows
B)thick, fast lava flows
C)thick, slow lava flows
D)fast ash flows
E)fine ash columns

Question 23

Material from _______________-basalt lava flows can contain hundreds of cubic kilometers of material.

Question 24

Stratovolcanoes have relatively steep sides because ____.

A)they are composed of compacted ash
B)they are composed of strong basalt with little ash
C)their magma has moderate viscosity so lavas flow a short distance before cooling
D)their explosions are fast and catastrophically explosive
E)they grow slowly, as new magma pushes them higher, often without eruption

Question 25

A caldera is formed ____.

A)when seawater reacts with hot basalt
B)in volcanoes which do not have enough steam pressure to support solidified magma
C)from pyroclastic flows
D)when volcanoes form in freshwater lakes
E)by the collapse of a magma chamber

Question 26

The ropy, basalt-rich, and steam-charged lava flows found in volcanoes like Kilauea are called ____ lava.

A)aa
B)maar
C)lahar
D)pumice
E)pahoehoe

Question 27

Small to moderate sized volcanoes formed of rhyolite above subduction zones are ____.

A)shield volcanoes
B)cinder cones
C)lava domes
D)stratovolcanoes
E)resurgent caldera

Question 28

The andesite volcanoes that form on the U.S. west coast below the Cascadia subduction zone are good examples of ____.

A)cinder cones
B)stratovolcanoes
C)shield volcanoes
D)resurgent caldera
E)lava domes

Question 29

A low, bowl-shaped crater encircled by a low rim is a(n) ____.

A)pahoehoe
B)​aa
C)maar
D)lahar
E)pumice

Question 30

_______________ is black or brownish black, contains significant amounts of calcium and iron, and flows fluidly.

Question 31

Small, explosive basalt volcanoes formed at continental rifts and the flanks of shield volcanoes are ____.

A)resurgent caldera
B)lava domes
C)cinder cones
D)stratovolcanoes
E)shield volcanoes ​

Question 32

Cinder cones are formed when ____.

A)seawater leaches into the magma plume of a stratovolcano
B)low-viscosity basalt encounters groundwater near the surface
C)a magma chamber collapses, building magma pressure
D)a volcanic eruption creates large amounts of ash
E)high-viscosity rhyolite interacts with surface soil

Question 33

_______________ comes in many pale shades of color, is very silica rich, and produces very thick, stiff flows.

Question 34

Basaltic lava flows that are charged with little steam and crystallize before reaching the surface are called ____ lava.

A)pahoehoe
B)maar
C)aa
D)lahar
E)pumice

Question 35

Rift zones where a volcano spreads in different wedge-shaped sections are characteristic of ____.

A)cinder cones
B)stratovolcanoes
C)resurgent caldera
D)shield volcanoes
E)lava domes

Question 36

A resurgent dome ____.

A)forms in the collapsed magma chamber of a stratovolcano or shield volcano
B)is a precursor to an eruption of a shield volcano
C)is a precursor to an eruption of a stratovolcano
D)is a pumice formation created by the release of volatile gasses
E)forms inside of a continental caldera

Question 37

Pumice is ____.

A)created in explosive eruptions involving viscous magma and high amounts of volatiles
B)the solidified form of a lahar that has reached the sea
C)compacted volcanic ash
D)"clinkers" of basalt formed in slow lava flows
E)created in slow eruptions involving fluid magma and low amounts of volatiles

Question 38

Pyroclastic flows are dangerous because they ____.

A)contain poisonous sulfur compounds
B)cause magma chamber collapse
C)move very fast, and extend a long distance
D)move very fast over a short distance
E)move at unpredictable speeds

Question 39

The term _______________ refers to how fluid magma is.

Question 40

The term _______________ refers to a surface marked by rubble and a clinker, and results from a Hawaiian basaltic lava flow.

Question 41

The text discusses six styles of volcanic eruption. Choose one and describe the causes of an eruption of this style, the danger they represent, and the characteristics of an eruption.

Question 42

A mix of volcanic ash and water that pours downslope from a volcano is a(n) _______________.

Question 43

A small volcano with steep sides produced by low-viscosity magma is a(n) _______________. (two words)

Question 44

After a large volume of magma is ejected, the magma chamber will often collapse to form a(n) _______________.

Question 45

How are pyroclastic flows created and why are they dangerous?

Question 46

Subduction zones are common sources of volcanoes. Explain the key details of the process of volcano formation along subduction zones.

Question 47

Montserrat, an island on the edge of the Caribbean plate and South American plate, is dominated by the Soufriere Hills volcano. The volcano is moderate-sized with moderately steep slopes. Beginning in July of 1995, the volcano began erupting in a style associated with magma contacting surface water. The magma vent hardened in a rounded shape out of rock containing a mix of rhyolite and basalt, stopping the eruption after 18 weeks. The collapse of one side of the dome sent ash and mud streaming down over the capital city and main airport, rendering them uninhabitable. Describe the events above using as many terms from the chapter as possible.

Question 48

Volcanoes with large, steep-sided cones, called _______________-volcanoes, often form near subduction zones.

Question 49

Name and describe the three types of major volcanoes (exclude lava domes and continental calderas). Identify their rock composition, shape, and the viscosity and composition of the magma that created them.

Question 50

When an eruption cloud spills downslope from the crater rim, it forms a(n) _______________ flow.