Deck 5: Volcanoes and Volcanic Hazards

Question 1

Which of the following statements best describes the big Hawaiian volcanoes?

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

Answer 1

A

Question 2

Volcanic bombs originate .

A)as laser- guided, granite blocks launched from a supersonic jet
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 blocks of volcanic rock ejected from an erupting volcanic crater

Answer 2

B

Question 3

A _ volcano is a very large, gently sloping mound composed mainly of basaltic lava flows.

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

Answer 3

A

Question 4

Which one of the following statements is NOT true?

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

Question 5

The Columbia Plateau in Washington and Oregon is _ _.

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

Question 6

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

A)fissure eruptions; flood basalts fields
B)explosive; rhyolitic, pyroclastic flows
C)explosive; composite cones
D)submarine; basaltic lava flows

Question 7

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

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

Question 8

are usually the most abundant gases emitted during basaltic volcanism.

A)Water and carbon dioxide
B)Neon and ammonia
C)Oxygen and nitrogen
D)Chlorine and sodium

Question 9

The ocean basin is rimmed by the most subduction zones.

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

Question 10

The 1991 Pinatubo eruption in the Philippines caused brilliantly colored sunrises and sunsets to be seen for the next few years. What caused this phenomenon?

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

Question 11

Which type of basaltic lava flow has a fairly smooth, unfragmented, ropy surface?

A)aa
B)scoria
C)pahoehoe
D)pegmatitic

Question 12

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

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

Question 13

The average composition of rocks comprising a large composite cone or stratovolcano is similar to a(n)magma.

A)andesitic
B)rhyolitic
C)ultramafic
D)basaltic

Question 14

Which region has the greatest concentration of currently active volcanoes?

A)European Russia and Siberia
B)the coastal plain of western Africa
C)the area surrounding the Red Sea
D)the circum- Pacific area

Question 15

Which type of basaltic lava flow has its surface covered with sharp- edged, angular blocks and rubble?

A)pahoehoe
B)pillow lava
C)aa
D)scoria

Question 16

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

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

Question 17

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

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

Question 18

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

A)The most powerful explosive event was preceded by a massive landslide.
B)During the eruptive period, the mountain peak was substantially built up by new lava flows and pyroclastic debris.
C)Mudflows accompanied the major eruptive events.
D)Plumes of ash rose high into the atmosphere during the major eruptive events.

Question 19

Mount St. Helens is _ .

A)an explosive stratovolcano
B)a basaltic shield volcano
C)a small, welded tuff cone
D)a basaltic cinder cone

Question 20

Kilauea and Mauna Loa are .

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

Question 21

Why do magmas rise toward Earth's surface?

A)Most magmas are richer in silica than most crustal and upper mantle rocks.
B)Magmas are more viscous than solid rocks in the crust and upper mantle.
C)Magmas are mainly liquid and contain dissolved fluids such as water; most are less dense than the adjacent solid rock.
D)all of the above

Question 22

The Icelandic volcanoes are related to plate tectonics because .

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

Question 23

Which basaltic lava flow has a relatively smooth surface?

Question 24

The 1943 eruption of Paricutin in Mexico was characterized by .

A)pyroclastic eruptions and nueé ardente flows
B)mudflows and explosive ash eruptions
C)welded- tuff deposition and caldera formation
D)cinder cone building and basaltic lava

Question 25

magma is the most abundant type of erupted at oceanic spreading centers.

A)Andesitic
B)Basaltic
C)Pegmatitic
D)Granitic

Question 26

Which of the following best describes Shiprock, a famous volcanic feature in New Mexico?

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

Question 27

Which one of the following statements concerning cinder cones is FALSE?

A)The cinders most commonly are basaltic.
B)The cinders and other pyroclastic particles are consolidated into welded tuff.
C)They are small volcanoes with fairly steep sides.
D)They are built mostly or entirely during one eruptive cycle.

Question 28

Pockets of magmas can be formed by the melting of deep continental crust heated by the intrusion of other magmas. Which of the following correctly describes this process?

A)Intrusion of diorite magma causes basalt magma to melt from peridotite.
B)Intruded rhyolite magma causes basalt magma to form by melting of granite.
C)Intrusion of basaltic magma causes deep crustal rocks to melt, producing andesitic or rhyolitic magmas.
D)All of the above correctly describe the process.

Question 29

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

A)Caldera collapse followed major ash and pyroclastic- flow eruptions; 6000 years ago.
B)A powerful explosion blew away the top of a stratovolcano; 10 million years ago.
C)The crater of a large, extinct cinder cone filled with water; 5 million years ago.
D)Landslides and volcanic mudflows dammed the Mazama River; 500 years ago.

Question 30

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

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

Question 31

Which one of the following best describes volcanism in the Cascade Range, northwestern United States?

A)related to plate subduction
B)related to a mantle hot spot
C)related to a mid- oceanic ridge system
D)related to deep, transform faults

Question 32

is the most abundant gaseous component dissolved in most magmas.

Question 33

Which of the following is associated with deep mantle hot spots?

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

Question 34

tend to increase the explosive potential of a magma body beneath a volcano.

A)Low silica content and low viscosity
B)High viscosity and dissolved gas
C)Low viscosity and low dissolved gas content
D)High viscosity and low dissolved gas content

Question 35

only emit gas.

A)Calderas
B)Parasitic cones
C)Fumaroles
D)Crater

Question 36

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

A)A nueé ardente
B)Mudflows
C)Basaltic lava flows
D)Heavy ashfall

Question 37

Why would a plume of solid silicate rock rising slowly from deep in the mantle begin melting as it neared the base of the lithosphere?

A)Temperatures remain high because of the geothermal gradient.
B)The rock heats up and expands at lower pressures, causing it to liquefy.
C)The lowered pressures cause rapid heat loss accompanied by melting.
D)none of the above

Question 38

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

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

Question 39

In 1980, was the first Cascade Range volcano to erupt since Mt. Lassen, California, in 1915- 16.

A)Mt. St. Helens
B)Mt. Rainier
C)Kilauea
D)Mt. Shasta

Question 40

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

A)rhyolite, andesite, basalt
B)basalt, rhyolite, andesite
C)andesite, rhyolite, basalt
D)basalt, andesite, rhyolite

Question 41

Pyroclastic fragments intermediate in size between ash and bombs are known as .

Question 42

Large, volcanic depressions formed by subsidence and collapse are known as .

Question 43

What is the name of the chain of volcanoes below that forms at an oceanic to oceanic plate boundary?

Question 44

Vents that emit only hot gases and vapors are called _.

Question 45

What type of volcano is shown in the diagram below?

Question 46

What volcanic feature is shown in the diagram below?

Question 47

What kind of volcanoes are Kilauea and the other big Hawaiian volcanoes?

Question 48

is a dangerous, fast moving, hot, turbulent cloud of volcanic gases and fine- sized, pyroclastic particles.

Question 49

Another term for a volcanic mudflow is a(n).

Question 50

What is the name of the chain of volcanoes below that forms at an oceanic to continental plate boundary?

Question 51

What type of volcano is shown in the diagram below?

Question 52

What term describes fragmental volcanic material?

Question 53

denotes a basaltic lava flow covered with angular, congealed lava rubble.

Question 54

Composite volcanic cones are also known as .

Question 55

What type of volcano is shown in the diagram below?

Question 56

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

Question 57

A relatively small, summit depression on a volcano, marking a former eruptive vent, is a(n).