Deck 5: Volcanoes and Volcanism

Question 1

How is volcanism destructive?

Answer 1

Some volcanic eruptions are explosive,and they blow a lot of material outward.Entire mountains may mostly disappear in a large eruption,and natural landscapes,human infrastructure,and lives can be destroyed in an eruption.

Question 2

Discuss what volcanologists look for in trying to determine if a volcano is about to erupt.

Answer 2

Volcanologists monitor and measure volcanoes that they think might erupt.They look for any evidence that magma is moving upward in the volcano,such as changes in the slope or horizontal distances of volcanic cones.They also look for changes in magnetic or electrical fields and for gas emissions.Most importantly,they look for harmonic tremors.These are not the sharp earthquakes that commonly occur,but they can last hours and indicate magma movement.

Question 3

Describe composite volcanoes.How do they differ from shield volcanoes and cinder cones?

Answer 3

Composite volcanoes are formed of lava flows and pyroclastic layers.The eruptions are intermediate in composition,and because they are more viscous than other eruption types,the sides of the volcanoes tend to be steeper,especially near the top.These eruptions are more explosive than shield volcanoes and larger than cinder cones and so may cause more damage.

Question 4

What is the volcanic explosivity index (VEI),and how is it determined?

Question 5

What are the reasons that volcanism is primarily a constructive process?

Question 6

Why are the volcanoes of Hawaii shield volcanoes the same as spreading ridges?

Question 7

Briefly explain how magma can originate at spreading zones if temperatures at such shallow depths cannot alone produce melting.

Question 8

How could carbon dioxide gas cause so many deaths in Cameroon?

Question 9

Describe shield volcanoes.What are they built of? Where are they found?

Question 10

Describe the volcanoes that form the Hawaiian Islands,especially on the island of Hawaii.

Question 11

How are cinder cones different from the other two major types of volcanoes?

Question 12

What is volcanism,and what types of rocks does it produce?

Question 13

How could you distinguish a volcanic crater from a caldera?

Question 14

Describe igneous activity at convergent plate boundaries.

Question 15

What is vog,and who named it? What are its risks?

Question 16

How is the behavior of gases different in a quiet and an explosive eruption?

Question 17

What is the difference between an active volcano and a dormant volcano?

Question 18

How do columnar joints form?

Question 19

Mauna Loa volcano in Hawaii is huge and has gentle slopes;Mount Rainier in Washington is tall,with much steeper slopes;and Paricutín in Mexico is smaller and has very steep slopes composed of loose pyroclastic material.What type of volcano does each one represent,and what kind of volcanic activity produced it?

Question 20

Look at the map of volcanoes of the world,and describe where most of the world's volcanoes are found.

Question 21

Which magma type usually erupts from fissures?

Question 22

What type of eruption is mainly responsible for producing plateau basalts?

Question 23

Besides monitoring,what other knowledge helps geologists determine what to expect for eruptions from a given volcano?

Question 24

What does harmonic tremor indicate is happening beneath the surface of a volcano?

Question 25

How do pillow lavas form?

Question 26

Give an example of a caldera.

Question 27

Why are there volcanoes on the west coast of North America but not on the east coast?

Question 28

What is a lahar?

Question 29

Why is Crater Lake in Oregon considered to be misnamed?

Question 30

How did recent eruptions of Mount Pinatubo in the Philippines and Kilauea in Hawaii differ?

Question 31

What produces columnar jointing in lava flows?

Question 32

Which type of volcano is Mount St.Helens?

Question 33

According to plate tectonic theory,why are there volcanoes in Hawaii?

Question 34

Would you rather be chased by a pahoehoe flow or an aa flow? Explain.

Question 35

When basalt lava is chilled rapidly in the water in an ocean or lake,it forms bulbous structures called ____________________.

Question 36

What are some of the techniques used to monitor volcanoes?

Question 37

Why are some places (e.g. ,northern California)more likely to experience volcanic eruptions than others (e.g. ,New York)?

Question 38

Distinguish aa from pahoehoe flows.

Question 39

What other bodies in the solar system are thought to possess active volcanoes?

Question 40

Why does most volcanism at spreading ridges go undetected?

Question 41

Sometimes,the pyroclastic material that flows from a volcano is so hot that it fuses together to form a deposit known as ____________________.

Question 42

Cinder cones rarely reach heights greater than ____________________;they are composed of ____________________ material of ____________________ composition.

Question 43

One common but dangerous gas emitted from volcanoes,which was responsible for many deaths in Cameroon,is ____________________.

Question 44

Composite volcanoes are composed of the igneous rock type known as ____________________,which forms from lava of ____________________ composition and viscosity.

Question 45

One indicator of an impending volcanic eruption that precedes all Hawaiian volcanic eruptions is a continuous ground motion called ____________________.

Question 46

Columnar joints caused by the contraction of lava as it cools form typically in a(n)____________________ shape.

Question 47

Volcanic activity that takes place away from plate boundaries is the result of volcanism at a(n)____________________.In the U.S. ,an example of this type of volcanism in the ocean is ____________________;an example on land is ____________________.

Question 48

The two most active volcanic zones are the ____________________ belt and the ____________________ belt.

Question 49

The dominant gas emitted from volcanoes is ____________________.

Question 50

An extinct volcano is one that:

A)existed during a past geological period or epoch.
B)has not erupted during recorded history.
C)has shown no evidence of activity over recorded history.
D)has not erupted during recorded history and has shown no evidence of activity over recorded history.
E)all of these.

Question 51

The type of volcano that is the most common in the two major volcanic belts on Earth is ____________________.

Question 52

The most volcanically active region of the contiguous United States is the ____________________.

Question 53

Shield volcanoes are composed largely of lavas of ____________________ composition,they commonly have slopes that are ____________________,and their eruptions tend to be ____________________ in explosivity.

Question 54

Composite volcanoes are also known as ____________________ and are composed of both ____________________ flows and ____________________ material.

Question 55

Pahoehoe is lava erupted by Hawaiian volcanoes that has a(n)____________________ viscosity and a(n)____________________ appearance.

Question 56

The one place on Earth where mid-oceanic ridge volcanism occurs above sea level is ____________________.

Question 57

Pyroclastic material that is less than 2 mm in diameter is called ____________________.Particles ranging from 2 to 64 mm in diameter are known as ____________________,while ____________________ and ____________________ are pieces larger than 64 mm in diameter.

Question 58

Lavas of ____________________ composition are more likely to produce lava domes.

Question 59

Volcanism occurs along the following two types of plate boundaries: ____________________ and ____________________.

Question 60

At Laki fissure in Iceland,the eruption of the gas ____________________ caused about 75% of the nation's livestock to die,25% of the population to die,and crops to fail.

Question 61

Volcanism profoundly affects the atmosphere,hydrosphere,and biosphere.

Question 62

Earth is the most volcanically active body in our solar system.

Question 63

An example of a caldera is:

A)Mount St.Helens,Washington.
B)Paricutín,Mexico.
C)El Chichon,Mexico.
D)Krakatau,Java.
E)Crater Lake,Oregon.

Question 64

An ash fall occurs when volcanic ash is ejected into the atmosphere and settles to the surface.

Question 65

Lava domes form from:

A)mafic magma.
B)intermediate magma.
C)viscous magma.
D)pyroclastic materials.
E)basalt.

Question 66

Pyroclastic materials include:

A)volcanic bombs,pillow lavas,and volcanic ash.
B)volcanic bombs,lapilli,and volcanic ash.
C)pillow lavas and nuée ardentes.
D)nuée ardentes and lahars.
E)none of these

Question 67

Which is the correct ranking of regions with the most active volcanoes and volcanic activity?
1)Circum-Pacific belt
2)Mid-oceanic ridges
3)Mediterranean belt
4)Isolated sites like the Hawaiian Islands

A)2,1,3,4
B)1,3,2,4
C)2,3,4,1
D)1,2,3,4
E)3,2,1,4

Question 68

A lava tube is a hollow space left when the lava within a flowing tube drains away,leaving only the outside as hardened rock.

Question 69

The chemical composition of all lavas is the same.

Question 70

An example of a composite volcano is:

A)Fujiyama,Japan.
B)Nevado del Ruiz,Columbia.
C)Mount Vesuvius,Italy.
D)Mount St.Helens,Washington.
E)all of the above

Question 71

Nuée ardentes erupt from:

A)supervolcanoes.
B)shield volcanoes.
C)fissures.
D)lava domes.
E)cinder cones.

Question 72

Basalt plateaus erupt from:

A)supervolcanoes.
B)shield volcanoes.
C)fissures.
D)lava domes.
E)cinder cones.

Question 73

The volcanic explosivity index (VEI)is intended to:

A)describe the frequency of volcanoes.
B)be used to forecast eruptions.
C)prevent fatalities and property damage.
D)document the size of eruptions.
E)encourage people not to live near active volcanoes.

Question 74

Intermediate and felsic magmas usually arise where:

A)mafic magma mixes with felsic material.
B)volcanoes lie on continental margins inland of subduction zones.
C)plates diverge as spreading ridges form.
D)volcanoes lie above transform faults.
E)mafic magma mixes with felsic material AND volcanoes lie on continental margins inland of subduction zones.

Question 75

A volcano is considered extinct if it has not erupted for more than 1,000 years.

Question 76

An example of a cinder cone volcano is:

A)Mount St.Helens,Washington.
B)Mayon,Philippines.
C)Paricutín,Mexico.
D)Vesuvius,Italy.
E)Mazama,Oregon.

Question 77

An example of a shield volcano is:

A)Kilauea.
B)Mount St.Helens.
C)Mount Shasta.
D)Mount Mazama.
E)Fujiyama.

Question 78

Most of the approximately 3,300 historic eruptions lasted:

A)less than one month.
B)one to six months.
C)one to two years.
D)more than two years.
E)none of these

Question 79

The three main types of volcanoes are:

A)cinder cones,clastic cones,and stratocones.
B)cinder cones,composite volcanoes,and shield volcanoes.
C)shield volcanoes,composite volcanoes,and Hawaiian-style volcanoes.
D)clastic cones,stratocones,and Hawaiian-style volcanoes.
E)none of the above

Question 80

Most volcanoes are located in:

A)the Mediterranean belt.
B)the mid-oceanic ridges.
C)the circum-Pacific belt.
D)the East African Rift Zone.
E)Indonesia.