Deck 9: The Wrath of Vulcan: Volcanic Eruptions

Question 1

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 volcaniclastic debris (ash)suspended in the air
D)a continuous fountain of dark,basaltic lava

Answer 1

C

Question 2

Basaltic lavas ________.

A)contain more iron and magnesium 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

Answer 2

A

Question 3

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

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

Answer 3

A

Question 4

Basaltic lavas that solidify at the surface before flow ceases fracture irregularly,producing a sharp-surfaced,blocky,and irregular lava rock named ________.

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

Question 5

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 6

The difference between tephra and tuff is that ________.

A)tephra is created in ash falls,whereas tuff is created in pyroclastic flows
B)tephra is unlithified,whereas tuff is lithified
C)tephra is always felsic to intermediate,whereas tuff is always mafic
D)tephra is formed at stratovolcanoes while tuffs are formed at cinder cones

Question 7

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 8

Rhyolitic lavas ________.

A)do not flow as far from the vent as basaltic lavas do
B)are commonly found at oceanic hot spots
C)are associated with volcanoes that almost never emit pyroclastic debris
D)are commonly found on shield volcanoes

Question 9

The characteristic "rotten egg" smell of many active volcanoes is derived from ________.

A)iron and magnesium within lava
B)carbon dioxide gas
C)stale water within the magma chamber
D)hydrogen sulfide gas

Question 10

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

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

Question 11

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 12

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 13

Pillow lavas are associated with ________.

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

Question 14

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

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

Question 15

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 16

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 17

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

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

Question 18

The lithification of material from a pyroclastic flow forms a rock called ________.

A)tephra
B)ignimbrite
C)lapilli
D)air-fall tuff

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

Pele's hair ________.

A)consists of thin strands of basaltic glass
B)acquires aerodynamic torpedo-like shapes during flight out of the volcanic vent
C)forms only at the leading edge of basaltic lava flows
D)forms when volcanic ash erupts into a rain cloud

Question 21

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

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

Question 22

Of the three primary forms of subaerial volcanoes,________ have the most gently sloping sides,due to the low viscosity of the basaltic lavas that form them.

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

Question 23

Of the three primary forms of subaerial volcanoes,________ consist of a simple pile of tephra often formed in a single eruption.

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

Question 24

A volcanic eruption that is emitted from the sides of a volcano is termed a(n)________ eruption.

A)phreatic
B)vulcanian
C)effusive
D)flank

Question 25

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 26

Olympus Mons,the largest known volcano in our Solar System,is an example of a ________.

A)stratovolcano
B)cinder cone
C)shield volcano
D)fissure volcano

Question 27

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 28

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 29

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 30

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)crater
B)lahar
C)caldera
D)fissure

Question 31

Mt.Fuji in Japan is an example of a ________.

A)stratovolcano
B)cinder cone
C)shield volcano
D)fissure volcano

Question 32

Which of the following is NOT true? Phreatic 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 33

The Columbia River Plateau is an example of a ________.

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

Question 34

Which of the following is true concerning the 1980 eruption of Mt.St.Helens?

A)The eruption was a complete surprise to geologists and provided no forewarning.
B)The eruption produced the largest basalt flow of the 20th century anywhere on Earth.
C)The eruption began with a lateral blast of debris that was ejected at the speed of sound.
D)No lahars were produced because the eruption occurred in the winter.

Question 35

Which U.S.national park is home to a large volcanic caldera formed through a very large explosive eruption 630,000 years ago?

A)Yosemite
B)Carlsbad Caverns
C)Acadia
D)Yellowstone

Question 36

Of the three primary forms of subaerial volcanoes,________ are sometimes referred to as composite volcanoes.

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

Question 37

Of the three primary forms of subaerial volcanoes,________ are typically the largest in area.

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

Question 38

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 39

As compared to subaerial basaltic lavas,submarine basaltic lavas differ in that they ________.

A)produce violent pyroclastic debris flows
B)produce large crystals of pyroxene and plagioclase
C)form pillow-like mounds because they cannot flow as far from their source
D)form long but irregular sheets of a'a'

Question 40

Phreatic 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 or pyroclastic debris erupts by bursting through the sides of the volcano

Question 41

Which of the following is NOT true? Hot-spot volcanoes ________.

A)can arise from the ocean floor
B)can arise on continents
C)can arise in the interior of lithospheric plates
D)always produce mafic lava flows

Question 42

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

A)A volcanic eruption involved a lateral blast of volcaniclastic 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 43

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 44

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 45

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 46

The largest known volcanic eruption in the last million years occurred at ________.

A)Toba Volcano (Indonesia)
B)Mt.St.Helens (USA)
C)Mt.Pinatubo (Philippines)
D)Yellowstone Caldera (USA)

Question 47

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

A)island volcanic arc
B)continental volcanic arc
C)hot-spot island chain
D)stratovolcanic assembly

Question 48

Olympus Mons,the largest known volcano in our Solar System,is found on ________.

A)Earth
B)Mars
C)Venus
D)Io,a moon of Jupiter

Question 49

Iceland rises above the Atlantic Ocean as a result of ________.

A)normal mid-ocean ridge activity
B)a submarine hot spot located within the interior of a plate
C)a submarine hot spot located along a mid-ocean ridge
D)subduction of an oceanic plate underneath the continental Eurasian Plate

Question 50

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)Gasses from volcanic eruptions provided much of the content of the early atmosphere.