Deck 15: Running Water

Question 1

What is the largest immediate volcanic threat to human life and property?

A) incandescent lava fountains and lava flows like at Kilauea since 1983
B) stratospheric ash clouds that pose a hazard to international airline travel
C) being encased in plaster like the former victims of Pompeii
D) proximity on the ground to explosive eruptions like Mount St. Helens, Pinatubo, and Nevado de Ruiz

Answer 1

D

Question 2

Which are usually the most abundant gases emitted during mafic volcanism?

A) chlorine and sodium
B) water and carbon dioxide
C) neon and ammonia
D) oxygen and nitrogen

Answer 2

B

Question 3

The greatest rate of volcanism and largest accumulations of volcanic deposits are associated with

A) rhyolitic lava domes
B) ash clouds dispersed in the stratosphere
C) giant cinder cones
D) flood basalts from fissure eruptions

Answer 3

D

Question 4

Which of the following is associated with deep mantle plumes?

A) Vesuvius and the other volcanoes of Italy
B) Mt. St. Helens and other volcanoes of the Cascade Mountains
C) the volcanoes of Hawaii and the thermal activity in Yellowstone National Park
D) the very young cinder cones scattered across the southwestern United States

Question 5

What volcanoes dominate in the Galapagos, Iceland, and Kenya?

A) stratospheric
B) shield
C) composite cone
D) cinder cones

Question 6

Which statement best describes the big Hawaiian volcanoes?

A) They lie directly above an active subduction zone where the Pacific plate is sinking into the mantle.
B) They lie along the crest of the East Pacific Rise, a mid- ocean ridge or spreading centre.
C) They are situated in the interior of a large, Pacific plate above a mantle plume deep in the mantle.
D) They lie directly above a transform plate boundary that cuts deeply into the mantle.

Question 7

Which of the following statements concerning cinder cones is false?

A) They are small volcanoes with fairly steep sides but large central craters.
B) They are often asymmetric with the higher rim in the downwind direction.
C) The cinders and other pyroclastic particles are consolidated into welded tuff.
D) They are built mostly or entirely during one eruptive cycle.

Question 8

How quickly are volcanoes like Paricutin in Mexico or Mt. Edziza in central B.C. built?

A) in a single eruption within a few hours
B) in several eruptive cycles over 10's of thousands of years
C) in a single eruption within a few days
D) in a single eruptive cycle lasting about a year or more

Question 9

What is the correct environment for the geologically recent, volcanic activity in the Yellowstone National Park area?

A) related to plate subduction
B) intraplate, mantle plume volcanism
C) related to a transform plate boundary
D) related to divergent plate boundary

Question 10

What is the largest, known volcano in the Solar System?

A) Mauna Loa, Hawaii, Earth
B) Mauna Kea, southern hemisphere, Mars
C) Mount Olympus, Greece, Earth
D) Olympus Mons, Mars

Question 11

Which of the following best describes seamounts and islands of the deep ocean basins?

A) andesitic pyroclastic rocks submerged when the mountains sank below sea level
B) domed gabbro intrusions and massive, submarine, rhyolitic, pyroclastic cones
C) piles of basaltic lava flows built up from the ocean floor by multiple summit and flank eruptions
D) huge granite batholiths intruded beneath the ocean floor

Question 12

How are the Icelandic volcanoes related to plate tectonics?

A) They lie on a spreading centre where two plates are converging.
B) They lie along a subduction zone where two plates are diverging.
C) They lie on a subduction zone where two plates are converging.
D) They lie on a spreading centre where two plates are moving apart.

Question 13

What are massive, gently sloping volcanoes built of successive, mafic lava flows?

A) stratospheric
B) composite cones
C) shield
D) cinder cones

Question 14

Volcanic lapilli are particles .

A) of incandescent lava that attain aerodynamic shapes and weigh up to 200 tons
B) also called cinders, the size of small stones, 2 to 64 mm across
C) of fused flattened silica rich glass shards and stretched out gas bubbles
D) angular rock fragments larger than 64 mm

Question 15

What volcanoes have the highest elevations?

A) shield
B) cinder cones
C) stratospheric
D) composite cones

Question 16

Gas rich andesitic magmas generate composite cones made up of .

A) multiple overlapping rhyolite domes rimming a central caldera
B) conical shaped lava flows
C) abundant coarse pyroclastics and short, thick, viscous lava flows
D) abundant basalt dykes and thick accumulations of low viscosity flows

Question 17

Oxidized, reddish, vesicle rich, mafic lapilli that pile up to form cinder cones are called .

A) blocks
B) bombs
C) scoria
D) pumice

Question 18

Which of the following best describes Shiprock, a famous volcanic feature in New Mexico which is sacred to the Navaho?

A) an extinct, highly symmetrical, composite cone
B) a very recently active, basaltic cinder cone
C) an erosionally resistant volcanic neck, remains of a volcanic pipe, and radiating dykes
D) an extinct, massive, rhyolitic shield volcano

Question 19

Which type of mafic flow has a rough, jagged, clinkery surface and advances slowly at speeds less than 50 m/hour?

A) block and ash flow
B) scoria
C) aa
D) pahoehoe

Question 20

Volcanic bombs originate .

A) as blocks of volcanic rock ejected from an erupting volcanic crater
B) as erupted magma blobs that partly congeal before falling to the ground
C) as ash particles that join together in the eruptive plume and fall as cobble- sized objects
D) as laser- guided, granite blocks launched from a supersonic jet

Question 21

What destroyed the city of St. Pierre, Martinique in 1902?

A) a nuée ardente
B) heavy ashfall
C) mudflows
D) mafic lava flows

Question 22

Which of the following is a major dissolved volatile constituent in both magmas and volcanic gases?

A) carbon monoxide
B) hydrogen chloride
C) methane
D) water

Question 23

What are large, fairly steep- sided cones composed of lavas and pyroclastic layers?

A) composite cones
B) cinder cones
C) shield
D) stratospheric

Question 24

What kind of material is most commonly added to the landscape in explosive volcanic eruptions?

A) pyroclastics, ash, bombs, and broken rock
B) volcanic gases and fumarolic deposits
C) thin fluid mafic flows that can travel 10's of kilometers
D) volcanic plugs that form inside craters

Question 25

Approximately how long has B.C.'s Mt. Garibaldi, in the Canadian part of the Cascades volcanoes, been dormant?

A) since 1967
B) since 1912
C) since May 1980
D) since the last Ice Age

Question 26

Which one of the following is made of abundant pyroclastic materials?

A) composite cone or stratovolcano
B) fissure- related flood basalts
C) basaltic shield volcano
D) rhyolite dome

Question 27

What drives explosive volcanic eruptions?

A) expanding superheated volcanic gases
B) collapsing eruption columns
C) high pressures from the melting region far beneath the volcano
D) andesitic magma's extremely low viscosity

Question 28

On May 18, 1980, which Cascades volcano blew its top with the largest eruption in North America in recorded history?

A) Mt. Rainier, WA
B) Mount St. Helens, WA
C) Kilauea, HI
D) Mt. Garibaldi, B.C.

Question 29

Which natural phenomenon occurs for several years after major explosive volcanic eruptions such as Tambora and Krakatoa?

A) heavy falls of volcanic ash within 100 km of the volcano
B) unusually warm weather in the tropics and subtropics
C) volcanic gases linger in the atmosphere
D) a worldwide rise in sea level of one to three centimeters

Question 30

Which one of the following best describes volcanism in the Cascade Range of northern California through Washington and its northerly extension as the Garibaldi Belt in SW B.C.?

A) related to plate subduction
B) related to a mid- ocean ridge system
C) related to deep, transform faults
D) related to a mantle plume

Question 31

The Columbia Plateau in Washington and Oregon is what type of volcanic feature?

A) a caldera filled with rhyolite lava flows
B) a thick stack of welded- luff layers
C) flood basalt plateau
D) a field of large composite cones

Question 32

Which statement about the May, 1980, eruption of Mount St. Helens is false?

A) Plumes of ash rose high into the stratosphere during the major eruptive events.
B) Mudflows (lahars) accompanied the major eruptive events going tens of kilometres.
C) The event devastated a wide swath of timberland on the north side of the mountain.
D) During the eruptive period, the mountain peak was substantially built up by new lava flows and pyroclastic debris.

Question 33

What volcanic events formed Crater Lake, OR? When did they take place?

A) The crater of a large, extinct cinder cone filled with water; 5 million years ago.
B) Caldera collapse followed major ash and pyrodastic- flow eruptions; 7700 years ago.
C) A powerful explosion blew away the top of a composite cone; 10 million years ago.
D) Landslides and volcanic mudflows dammed the Mazama River; 500 years ago.

Question 34

How do volcanic bombs originate?

A) as ash particles that join together in the eruptive plume and fall as cobble- sized objects
B) as blocks of old shattered volcanic rock ejected from an erupting volcanic crater
C) as high temperature residue violently expelled from the melting region, all the way up the volcanic conduit
D) as semi- molten magma blobs that get erupted, streamlined, and partly congeal before falling to the ground

Question 35

How was Crater Lake, Oregon formed?

A) caldera collapse of the top of Mt. Mazama after the eruption 7700 years ago partly emptied the magma chamber
B) when sea floor spreading permitted seawater to flood into the newly formed volcanic rift
C) as a remnant of the "great flood"
D) a prehistoric eruption of Mount St. Helens

Question 36

How are volcanic conduits formed?

A) by erosion from hot gases that carry hard abrasive rocks and ash upwards
B) by superheated gases melting a pipe through the older rocks of the volcano
C) by injecting molten magma up through the volcano to clear a path
D) The vent is kept clear by continuous eruption and the walls are formed by deposits.

Question 37

What are the two varieties of basaltic lava flows?

A) bombs, blocks
B) tuff, breccia
C) aa, pahoehoe
D) cinders, pumice

Question 38

What is the direct control on whether a volcano will erupt violently or quietly send out a few flows?

A) the duration of the quiet interval since its last violent eruption
B) what the total volume of the volcano has at the time of eruption
C) the composition of the magma, its temperature, and dissolved gas content
D) the population density

Question 39

At the same temperature, why are magmas with high silica contents more viscous?

A) The magmas with high silica content are also richer in iron and too dense to flow.
B) Any magma with more than 50% silica content is too sticky to flow.
C) Because high viscosity magma will flow more readily and rhyolites flow the farthest.
D) They are more linked together in chains and nets that are strong enough to resist flow.

Question 40

The 1991 Pinatubo eruption in the Philippines caused global temperatures to drop over the next year. What caused this phenomenon?

A) The eruptive cloud destroyed parts of the Earth's protective ozone layer.
B) Sulfur dioxide was released and formed aerosols in the atmosphere.
C) Radioactive atoms blown into the atmosphere froze as they decayed.
D) The eruption added large amounts of carbon dioxide to the atmosphere.

Question 41

The recent (geologically) volcanic activity in Yellowstone National Park is _ .

A) related to a divergent plate boundary
B) related to a transform plate boundary
C) related to intraplate, mantle plume volcanism
D) related to plate subduction

Question 42

Which best describes a caldera?

A) a collapse pit less than 1 km2 on the summit of a volcano
B) a small, steep- sided, volcanic depression bored out by an eruptive plume
C) a large depression hundreds of km across full of volcanic deposits
D) a large circular volcanic depression caused by collapse after a large scale, explosive felsic eruption

Question 43

Which was the most powerful, explosive volcanic eruption of historic time?

A) Vesuvius, Italy, 79 A.D.
B) Nevado del Ruiz, Columbia, 1985
C) Mt. Pele, Martinique, 1902
D) Tambora, Indonesia, 1815

Question 44

Which magma association with the volcanic landform is false?

A) glassy volcanic domes - felsic
B) composite cones - andesitic
C) cinder cones - mafic
D) volcanic plateaus and shields - felsic

Question 45

What natural disaster contributed to the disappearance of the Minoan civilization and gave rise to the legend of The Lost Island of Atlantis mentioned in Plato's writings?

A) It was buried by thick ash deposits from the volcanic eruption of Thera about 1600 B.C. and sank as the caldera beneath the island collapsed.
B) It was buried by thick ash deposits from Mt. Vesuvius in 79 B.C.
C) It was obliterated by volcanic dust storms from North Africa in the sixth century A.D.
D) It washed away in a giant tsunami about 79 A.D.

Question 46

Which correctly describes the size and thickness variation in pyroclastics relative to the composite cone they came from?

A) Size decreases, but deposits thicken downslope and then thin with distance.
B) Size increases, and the deposits get thicker away from the vent.
C) Size and thickness both decrease uniformly away from the central vent.
D) Size increases then decreases with distance, but deposits are the same thickness.

Question 47

Which kind of volcanism is typical of mid- ocean ridge systems?

A) explosive; composite cones
B) explosive; felsic, pyroclastic flows
C) submarine; mafic lava flows
D) subversive fissure eruptions and flood basalts

Question 48

Which volcano is a very large, gently sloping mound composed mainly of mafic lava flows?

A) shield
B) cinder cone
C) stratospheric
D) composite cone

Question 49

How fast do hot fluid basalt flows typically advance?

A) < 5 m/hour
B) > 100 m/second
C) 10 to 300 m/hour
D) > 30 km/hour

Question 50

What is the most abundant type of magma erupted at oceanic spreading centres?

A) mafic
B) andesitic
C) felsic
D) pyroclastic

Question 51

is a major dissolved volatile constituent in both magmas and volcanic gases.

A) Carbon monoxide
B) Hydrogen chloride
C) Methane
D) Water

Question 52

What kind of volcano is Mount Garibaldi?

A) a basaltic shield volcano
B) a basaltic cinder cone
C) a composite cone
D) a small, welded tuff cone

Question 53

Which one of the following statements concerning volcanic blocks and bombs is true?

A) Blocks are broken fragments of solid rocks; bombs have smaller sizes than lapilli.
B) Bombs and blocks are both smaller than lapilli and cinders.
C) Bombs are guided to Earth by laser beams; blocks fall anywhere.
D) Bombs are ejected as magma lumps; blocks are ejected as solid fragments.

Question 54

What are small basaltic cones built during one short, eruptive episode?

A) stratospheric
B) composite cones
C) cinder cones
D) shield volcanoes

Question 55

What volcanic environment generated both Mt. Pelee and Montserrat?

A) the Mid- Atlantic Ridge
B) the Andes arc
C) the Lesser Antilles arc
D) the Italian flood basalt province

Question 56

The ocean basin is rimmed by the most subduction zones.

A) Pacific
B) Arctic
C) Indian
D) Atlantic

Question 57

What was the maximum distance travelled by erupted materials from the last major eruption of Mount St. Helens?

A) approximately 1200 km into Alberta and Montana
B) 18,000 m into the Stratosphere
C) around the world for several days
D) 400 m down the flank of the volcano

Question 58

What type are the volcanoes of the Cascades and Alaska's Aleutian Islands?

A) shield
B) cinder cones
C) composite cones
D) stratospheric

Question 59

Kilauea and Mauna Loa are what kind of volcanoes?

A) andesitic composite cones
B) explosive, rhyolitic volcanoes
C) basaltic shield volcanoes
D) small, basaltic cinder cones

Question 60

Which statement is most correct concerning volcanic effects on our atmosphere?

A) Pollution of the atmosphere by sulfur compounds contributes significantly to acid rain.
B) Gases from volcanoes condense to make natural fertilizer, boosting plant growth.
C) If it were not for active volcanism there would be no free oxygen in the atmosphere.
D) Active volcanism is responsible for maintaining atmospheric levels of nitrogen.

Question 61

Which one of the following shows the correct order (left to right) of decreasing magma viscosity?

A) felsic, andesitic, mafic
B) andesitic, felsic, mafic
C) mafic, andesitic, felsic
D) mafic, felsic, andesitic

Question 62

What is the dominant lava type erupted along mid- ocean ridges?

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

Question 63

What was the approximate volume of rock and ash ejected by the last violent eruption of Mount St. Helens?

A) 18,000 km3
B) 400 km3
C) 400 m3
D) 1 km3

Question 64

Which kind of volcano is closely associated with convergent plate boundaries and subduction zones?

Question 65

The 1943- 44 eruption of Paricutin in Mexico was characterized by which one of the following sets of volcanic phenomena?

A) pyroclastic eruptions; nuée ardente flows
B) cinder cone building; mafic aa lava
C) welded- tuff deposition; caldera formation
D) mudflows; explosive ash eruptions

Question 66

Which one of the following statements is false?

A) Mafic magmas in general have higher temperatures than felsic magmas.
B) Melting temperatures of silicate rocks increase with increased pressure.
C) Melting temperatures of silicate rocks are lowered by small amounts of water.
D) When magma reaches the surface, its dissolved gas content increases.

Question 67

Which type of volcanoes are found along the Cascade and Andean Ranges?

Question 68

The average composition of rocks composing a large composite cone is similar to which magma?

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

Question 69

Which kind of eruptive activity is most likely to be highly explosive?

A) lava flows from a large cinder cone complex
B) eruptions of big, continental margin, composite cones
C) lava flows from a large shield volcano on an oceanic island
D) fissure eruptions feeding lava to flood basalt accumulations

Question 70

Which region has the greatest concentration of currently active volcanoes?

A) Pacific "Ring of Fire"
B) Siberia
C) Red Sea area
D) coastal plain of west Africa

Question 71

In general, which of the following types of magma will be more likely to erupt explosively?

A) a very fluid komatiitic magma
B) an intermediate andesitic magma with a low water content
C) a highly viscous felsic magma
D) a relatively low viscosity mafic magma

Question 72

How far can nueés ardentes travel from their source vents?

A) up to 10 km
B) > 100 km
C) < 1 km
D) > 1000 km

Question 73

What type of volcano is shown in the diagram below?

Question 74

Which type of mafic lava flow has a fairly smooth, flow folded, ropy surface?

A) pahoehoe
B) scoria
C) block and ash flow
D) aa

Question 75

Which two factors tend to increase the explosive potential of a magma body beneath a volcano?

A) low viscosity; low dissolved gas content
B) high viscosity; low dissolved gas content
C) low silica content, low viscosity
D) high viscosity and dissolved gas