Deck 5: The Wrath of Vulcan: Volcanic Eruptions

Question 1

Why is felsic magma much more likely to produce an explosive eruption?

A)Felsic magma is at a higher magma temperature,which will force an explosion.
B)Felsic magma cools at a lower temperature and thus will still be molten upon eruption.
C)Felsic magma has a low viscosity,which will flow easily and erupt at a faster velocity.
D)Felsic magma has a high viscosity,which will tend to stick in and clog volcanic conduits.

Answer 1

D

Question 2

The Columbia River Plateau is an example of a ________.

A)caldera
B)fissure
C)flood basalt
D)hot spot

Answer 2

C

Question 3

Felsic magma generally forms in ________.

A)the mantle
B)mid-ocean ridges
C)continental crust
D)oceanic crust

Answer 3

C

Question 4

Felsic magma tends to form ________ eruptions.

A)effusive
B)explosive
C)intrusive
D)infusive

Question 5

Explosive or voluminous eruptions may cause the volcano to collapse on the floor of the now-empty magma chamber,producing a broad depression termed a ________.

A)dike
B)lahar
C)caldera
D)fissure

Question 6

The lower the viscosity of a lava the more likely it is to produce an ________ eruption.

A)effusive
B)explosive
C)intrusive
D)infusive

Question 7

Pillow lavas are associated with ________ eruptions.

A)subaerial rhyolitic
B)subaerial basaltic
C)submarine rhyolitic
D)submarine basaltic

Question 8

What properties of the source magma lead to the formation of a shield volcano?

A)low viscosity and mafic composition
B)high viscosity and felsic composition
C)any magma composition so long as it contains a large portion of dissolved volatiles
D)an intermediate composition magma that encounters seawater in the magma chamber

Question 9

The textural term for a basaltic lava flow that has a smooth,ropy appearance is ________.

A)pahoehoe
B)a'a'
C)pumice
D)ignimbrite

Question 10

Based on your knowledge of volcanoes and volcanic products,you can say with confidence that the outcrop in the image below formed ________.

A)on land at a continental hotspot
B)underwater at a subduction zone
C)on land at a continental rift
D)underwater at a mid-ocean ridge

Question 11

Fissure eruptions take place when ________.

A)volatiles effervesce prior to lava flow
B)groundwater interacts with magma
C)basaltic lava clogs the eruptive vent
D)lava erupts out of a long crack in the ground forming a curtain of lava

Question 12

Nonviolent eruptions characterized by extensive flows of basaltic lava are termed ________.

A)pyroclastic
B)effusive
C)explosive
D)plinian

Question 13

Hotspots are produced by mantle plumes that are composed of mafic magma;however,Yellowstone is a hotspot that erupts more explosively because the hotspot ________.

A)is hotter and thus melts more rock
B)rises through the continental crust
C)originates at the core-mantle boundary
D)rises through a mid-ocean ridge

Question 14

The tall polygonal features preserved in the ancient basalt flow in the image below formed because the lava ________.

A)was moving as it cooled,so it fractured
B)erupted underwater and cooled rapidly,forming many fractures
C)was subjected to shaking from earthquakes,and subsequently fractured
D)shrank as it cooled,forming tall polygonal-shaped fractures

Question 15

Which of the following is FALSE? Caldera forming eruptions ________.

A)can be so explosive that a significant portion of the volcano can be destroyed
B)occur when groundwater or seawater enters the magma chamber
C)occur due to fractional crystallization of the magma chamber
D)produce little to no lava at the surface

Question 16

Of the three primary forms of subaerial volcanoes,________ consist of alternating layers of tephra and solidified lava.

A)stratovolcanoes
B)cinder cones
C)shield volcanoes
D)fissure volcanoes

Question 17

The image below shows a lava dome that never left the volcanic crater.What is the likely composition of the rocks that make up this lava dome?

A)felsic
B)intermediate
C)mafic
D)ultramafic

Question 18

In 79 C.E. ,the citizens of Pompeii in the Roman Empire were buried by pyroclastic debris derived from an eruption of ________.

A)Mount Olympus
B)Olympus Mons
C)Mount Vesuvius
D)Mount St.Helens

Question 19

Compared to felsic lavas,mafic lavas have a ________.

A)lighter color
B)lower viscosity
C)lower density
D)higher silica content

Question 20

The Hawaiian island chain is an example of a(n)________.

A)island volcanic arc
B)continental volcanic arc
C)hotspot island chain
D)stratovolcanic assembly

Question 21

Which of the following poses the greatest hazard to human life associated with volcanoes?

A)flowing lava
B)volcanic gas
C)falling ash
D)pyroclastic flows

Question 22

If magma is fracturing rocks as it moves through the subsurface,there would most likely be an increase in ________.

A)recurrence interval
B)volcanic gas emission
C)silica content
D)seismic activity

Question 23

If a volcano lies along a convergent boundary but has not erupted in over 100,000 years,the volcano is considered ________.

A)active
B)dormant
C)extinct
D)dead

Question 24

Whether an eruption will primarily produce lava flows or pyroclastic debris is NOT influenced by the ________ the source magma.

A)viscosity of
B)composition of
C)proportion of volatiles within
D)depth and residence time of

Question 25

Changes in the shape of a volcano can indicate ________.

A)an increase in the heat flow from the magma
B)an extinct volcano becoming active
C)a magma chamber filling or emptying
D)the release of gases from the magma

Question 26

Volcanoes are considered dormant if they ________.

A)still have a magma source but show no signs of impending eruption
B)no longer have a magma source and therefore will never erupt again
C)have an active magma source and are currently erupting
D)have an active magma source but will never erupt again

Question 27

The image below shows a ________,which is a large piece of pyroclastic debris ejected during an eruption,with a smooth texture due to the fact that it was partially molten when ejected.

A)block
B)bomb
C)lapilli
D)xenolith

Question 28

The average time between eruptions is called a(n)________.

A)repose interval
B)prediction
C)forecast
D)assessment

Question 29

The cloud that rises from the vent of an actively erupting volcano is composed of ________.

A)smoke from wildfires inside the volcanic crater
B)smoke from wildfires on the outer slopes of the volcano that funnel into the crater
C)fine volcanoclastic debris (ash)suspended in the air
D)a continuous fountain of dark,basaltic lava

Question 30

Volcanic bombs are ________.

A)volcanic fragments that were ejected while still soft or molten
B)explosive bodies of lava with high volatile content
C)volcanic fragments that were already solid rock before being ejected during an eruption
D)used by geologists to set off small eruptions in volcanoes that are deemed potentially dangerous

Question 31

A mixture of air,hot ash,and pumice lapilli that rushes down the side of a volcano in a scalding avalanche is termed a(n)________.

A)ash fall
B)lahar
C)pyroclastic flow
D)convective plume

Question 32

Columnar joints form when ________.

A)a lava flow cools very rapidly,causing the flow to shatter in a chaotic pattern
B)a lava flow encounters groundwater,which causes the flow to rapidly fracture
C)a lava flow erupts under deep water
D)during the final stages of cooling,a lava flow contracts,forming tall polygonal fractures

Question 33

Scientists monitor volcanoes to help predict when eruptions will occur.Which of the following is NOT a potential sign to look for when predicting volcanic eruptions?

A)changes in earthquake activity
B)changes in Earth's magnetic field
C)small changes in the shape of the volcano
D)increases in gas and steam emissions

Question 34

Ash,cinders,and blocks are all types of ________.

A)pyroclastic debris
B)lava flows
C)Pele's hair
D)volcanoes

Question 35

A fast-moving flow consisting of a mixture of water and volcanoclastic debris is termed a ________.

A)lahar
B)pyroclastic flow
C)flood basalt
D)hyaloclastite

Question 36

Gases that are abundantly emitted by volcanoes include ________.

A)water vapor,carbon dioxide,and sulfur dioxide
B)oxygen,ozone,and water vapor
C)oxygen,hydrogen,and argon
D)carbon dioxide,carbon monoxide,and oxygen

Question 37

Basaltic lavas ________.

A)contain less silica than rhyolitic lavas
B)contain more silica than rhyolitic lavas
C)are more viscous than rhyolitic lavas
D)typically contain a greater proportion of trapped volatiles than rhyolitic lavas

Question 38

What was unusual about the 1986 volcano-related disaster near Lake Nyos in Cameroon?

A)A volcanic eruption involved a lateral blast of volcanoclastic debris that no one anticipated.
B)Pyroclastic flows buried surrounding villages,reminiscent of Pompeii ~1,900 years earlier.
C)Volcanically derived carbon dioxide gas bubbled from the lake and suffocated people and animals nearby.
D)A slurry of lava and lake water flowed rapidly outward from the lake and buried surrounding villages.

Question 39

In 1902 a famous,deadly pyroclastic flow killed thousands of people on the Caribbean island of ________.

A)Puerto Rico
B)Martinique
C)Aruba
D)Jamaica

Question 40

The volcano in the image below is ________.

A)active
B)extinct
C)dormant
D)quiescent

Question 41

Recurrence intervals are often used as estimates of when the next eruption might occur.Explain what a recurrence interval is,how it is calculated,and why it is not the most useful means of forecasting eruptions.

Question 42

Volcanic eruptions release ________,which can block some sunlight from reaching Earth.

A)ash
B)gas
C)magma
D)ozone

Question 43

Which of the following volcanic products can decrease global temperatures?

A)sulphur dioxide
B)mafic magma
C)carbon monoxide
D)ash and aerosols

Question 44

If a volcano was actively releasing a large amount of volcanic gas and then abruptly stopped,what might happen to the volcano in the near future?

A)It will become extinct because the magma supply has been rapidly withdrawn.
B)It will erupt effusively because the supply of volcanic gas has dissipated.
C)It will erupt explosively because the volcanic gases have no way to escape slowly.
D)It will erupt effusively because the gases have made the magma less viscous.

Question 45

The famous "year without a summer" occurred due to the eruption of ________.

A)Mount St.Helens,Washington
B)Mount Tambora,Indonesia
C)Kilauea,Hawaii
D)Mount Fuji,Japan

Question 46

According to the graph below,what occurred after the 1991 eruption of Pinatubo in the Philippines?

A)Global temperatures decreased.
B)Global temperatures increased.
C)Global carbon dioxide increased.
D)Global carbon dioxide decreased.

Question 47

Volcanoes have provided some positive benefits to humankind and life in general over geologic time.Which of the following is NOT true about volcanoes?

A)Volcanic eruptions can enrich soils,making land more fertile.
B)Volatiles from volcanoes provided much of our early oceans' water.
C)Volcanic eruptions have prevented several mass extinctions by cooling Earth's climate.
D)Gases from volcanic eruptions provided much of the content of the early atmosphere.

Question 48

Describe how an explosive volcanic eruption can create a global cooling event.

Question 49

The style of eruption depends on the plate tectonic setting in which the volcano is situated.Compare the different eruption styles you would observe at a divergent versus a convergent plate boundary.Make sure to address composition,viscosity,gas content,and so on in your answer.

Question 50

Describe how explosive eruptions occur.Make sure to address viscosity,gas content,and the process for building pressure.

Question 51

A Minoan civilization,postulated to be the fabled "City of Atlantis," was destroyed by the eruption of ________.

A)Toba,Indonesia
B)Santorini,Greece
C)Krakatau,Indonesia
D)Mount Fuji,Japan

Question 52

List and describe two volcanic hazards,including both a description of the hazard and the possible effects of the hazard.

Question 53

The ash released by explosive volcanic eruptions can also produce ________.

A)infertile land
B)unusual sunsets
C)disruption of magnets
D)mutations in livestock

Question 54

Which volcanic eruption nearly wiped humanity off the planet?

A)1991-Mount Pinatubo,Philippines
B)75Ka- Toba,Indonesia
C)1980-Mount St.Helens,USA
D)1815-Mount Tambora,Indonesia

Question 55

How can volcanic eruptions lower the global temperature on Earth?

A)gases block sunlight
B)gases trap heat
C)ash blocks sunlight
D)ash traps heat