Chapter 6

Which of the following are locations where flood basalts are known to have occurred?

- India - Siberia - Brazil - Oceanic plateaus

Which of the following is not a major controlling factor on volcanic eruption style?

- age of the volcano

T or F: All hills made of volcanic rocks are volcanoes

False - some of these hills may be covered in lava flows.

Mount St. Helens erupted catastrophically in:

May 1980

The largest concentration of composite volcanoes on Earth is located along the:

Pacific Ring of Fire

Carbon dioxide, hydrogen sulfide, and sulfuric acid are __________ associated with volcanic eruptions that are hazardous to humans, livestock, and crops.

gases

What method did villages use to try to stop a lava flow from closing their harbor on the island of Heimaey, Iceland, in 1973?

pumping seawater onto the flow to try to cool it - the lava flow did stop in time; itʻs debatable if the seawater was effective in slowing the flow

Which of the following would be evidence that a volcano has been inactive for a long period of time?

well-developed soils on volcanic rocks

Which of the following are ways in which older calderas typically become harder to recognize?

- Burial by younger rocks - Disruption by faulting - Erosion

Which of the following are erupted by volcanoes?

- Pumice - Ash - Lava

Lava flowing in __________ in Hawaiʻi can remain hot and fluid for so long that it flows all the way to the ocean.

- lava tubes

Volcanic eruptions can produce huge floods by:

melting of ice sheets

Shield volcanoes are built up primarily by relatively:

- nonexplosive outpourings of lava

What type of volcano is Mount Rainier?

Composite

Which of the following plate boundaries is least likely to produce composite volcanoes?

Continent-continent convergent boundary with a high mountain range (Himalaya) - recall that subduction ceases with continental collision.

T or F: A typical eruption is likely to kill millions of people at a time.

False - A typical eruption could kill thousands, not millions

Gases more easily remain dissolved in liquids at __________ pressures.

High - high pressures outside of the liquid must be overcome by the outward pressure of the gases trying to escape the liquid. The higher the surrounding pressure, the higher the internal pressure must be in the liquids for the gas to escape.

The volcanic rocks associated with domes are felsic to intermediate in composition, and hence are classified as rhyolite and:

andesite

Almost 40k people were killed by the 1883 eruption of Krakatau, Indonesia. Krakatau was a ________ that formed a caldera.

composite volcano - The shape of the volcano is a clear indicator that this is a composite volcano.

Which of the following is not a hazard typically associated with scoria cones?

fast-moving lava flows Typically associated with scoria cones? - falling cinders and volcanic bombs - toxic volcanic gases - volcanic ash

The massive amount of basaltic magma involved in flood basalt comes to the surface from the mantle via _________

fissures

The existence of a potentially dangerous situation or event is known as a(n) ______________, whereas the likelihood and magnitude of its impact on society is known as its ________________.

hazard; risk

Volcanism culminating in the Yellowstone eruptions of the past 2M years has produced a set of overlapping calderas that stretch in an arc to the southwest from Yellowstone to southeastern Oregon, suggesting that NAmerica has been riding to the southwest over a _________ for at least the past 12.5 M years.

hot spot

Prior to an eruption, the surface of a volcano may rise centimeters to hundreds of meters as a result of:

injecting magma inflating the mountain

Which of the following are ways in which volcanic domes may appear in the landscape?

- thick, flow-like masses - symmetrical, steep-sided hills - steep-sided eroded hills of glassy rock

Which of the following techniques are used to monitor changes int he shape of volcanoes that may indicate magma movement and imminent danger of eruption?

- tiltmeter usage to determine changes in slope - radar imaging to detect small changes in topography - GPS station monitoring.

Which of the following were hazardous effects produced in mainland Europe by the huge 1783 eruption at Laki, Iceland?

- unusually cold winter - crop failures and famine - reduced summer sunlight - the reduced light caused many crops to fail, leading to food shortages and starvation.

Which of the following rock types are associated with basaltic volcanoes?

- volcanic bombs - nonvesicular basalt - scoria - vesicular basalt

Which of the following materials commonly are found in composite volcanoes?

- volcanic tephra - lahars and landslide deposits - volcanic tuff - andesitic lava flows

List the rocks typically found in calderas, from top to bottom. Begin with the rocks at the surface and continue to the rocks the farthest below the surface.

- volcanic tuff - hard, welded volcanic rock - finely crystalline granite

Gas in basaltic magma is the major controlling factor that determines ___________

- what landforms it will create - what rock types it will form

Put the events of the 1980 Mount St. Helens eruption in order. The earliest event on top and proceed to the last.

1. Earthquake. 2. Landlslide. 3. Lateral blast and eruption column.

Put the events of caldera formation in order. Begin with the first event on top, and end with the last.

1. Magma erupts as ash column, emptying a shallow magma chamber. 2. Overlying material collapses into emptied chamber in a series of fault blocks. 3. Ash and other pyroclastics fill the subsiding crater. 4. Small rhyolite domes form in caldera.

Put the events leading to the formation of Crater Lake as we see it today. Put the earliest event at the top and proceed to the latest.

1. Massive ash column eruption of a composite volcano empties the magma chamber. 2. Overlying volcano collapses into the resulting void. 3. Scoria cone forms in the caldera. 4. Rain and snowmelt fill the caldera, producing a large and deep lake.

_________ volcanoes produced pyroclastic flows that killed tens of thousands of people at Pompeii & St. Pierre.

Composite

_________, located in the state of WA, i the most active volcano in the Cascade Range of the Pacific Northwest.

Mount St. Helens

Match the volcanic feature with the hazard.

Scoria cone - volcanic ash and gases - falling volcanic cinders and bombs Lava flow - bulldozing and crushing of houses and other structures - burial of roads

The potential hazards associated with a volcano can be assessed by studying various characteristics and the history of the volcano. Match the characteristic with what type of information it provides.

Shape - Steep slopes indicate high viscosity, explosive magma; gentle slopes indicate less explosive magma. Rock type - Chemical analysis determines magma composition and potential for explosiveness. History - The sequence of layers and isotopic dating can indicate the timing and frequency of eruptions.

Scoria cones are composed primarily of:

ejected fragments of vesicular lava

Nonexplosive eruptions of basaltic magmas produce:

lava flows

Long, thin lava flows are typically produced by:

low-viscosity lavas

Spaced-based satellites can be used to remotely monitor volcanoes by:

measuring and detecting changes in temperatures and heat emitted by the volcano - satellites can also be used to detect changes in elevation caused by the motion of magma

A very dangerous hazard associated with composite volcanoes is a(n) _______________ flow, created when an eruption column becomes too dense and collapses, allowing ash, gas, and rocks to move very quickly down the side of a volcano.

pyroclastic

The A.D. 79 eruption at Mount Vesuvius in Italy, which killed about 25k people in Pompeii and Herculaneum, consisted mainly of _________ that roared down the slopes of the composite volcano.

pyroclastic flows

Which of the following lists the four types of volcanoes shaped like hills and mountains?

scoria cone, shield, composite, dome

Magma rising through the crust fractures rocks, producing rhythmic, repeating ___________

seismic shaking

The typical form for a composite volcano is:

steep-sided cone

The magma feeding Mount Rainier and the other Cascade volcanoes results from melting associated within the Cascadia _______ zone, which is an ocean-continent ____________ boundary.

subduction; convergent

The higher the gas pressure builds in a magma,

the more explosive an eruptions it is likely to produce

Steep-sided hills of viscous lava that pile up over volcanic vents are known as:

volcanic domes

Which of the following were warning signs prior to the catastrophic eruption of Mount St. Helens in May 1980?

- Earthquakes - Formation of a bulge on its flanks

Which of the following represent deadly historical caldera-forming eruptions?

- Krakatau, Indonesia - Santorini

Rank the following eruption styles in order of increasing explosively. Start with the least explosive on top and proceed to the most explosive eruption style.

- Lava flows - Lava fountains - Eruption columns

Which of the following are the main volcanoes that make up the Big Island of Hawaiʻi.

- Mauna Kea - Kilauea - Mauna Loa

The downfall of which ancient civilization in the Mediterranean closely followed the caldera-forming eruption at Santorini?

- Minoan

Which of the following are examples of composite volcanoes?

- Mount Etna, Italy - Mount Fuji, Japan - Mount Kilimanjaro, Tanzania

Which of the following accurately describe the Columbia River flood basalts?

- They were produced at high eruption rates from large fissures. - the largest individual flows cover over 50k square miles.

Which of the following are methods used to monitor a volcano?

- Using satellites and other remote sensing methods to monitor the volcano - a team of scientists with different fields of study collecting a variety of data about the volcano - using field visits to the volcano to collect rocks and other data

Which of the following are properties characteristic of calderas?

- bounded by steep escarpments. - form from collapse of overlying ground into emptied magma chamber. - large, basin-shaped volcanic depression.

Which of the following phenomena are monitored to predict volcanic eruptions?

- changes in topography - changes in gas output - heat flow changes - ground shaking

Which of the following are ways in which volcanic domes are commonly destroyed?

- collapse of the steep flanks into block and ash flows - internally derived explosions from trapped gas pressure

Which of the following accurately describe most shield volcanoes?

- composed of a succession of lava flows. - broad and gently sloping form

Which of these are ways in which lava flows destroy human-made structures?

- covering roads - crushing/bulldozing buildings - burning buildings

Which of the following best describe a young scoria cone?

- dark, fresh-looking lava - little soil buildup on slopes - central crater at top of a conical hill

Which of the following are characteristics of actively erupting volcanoes?

- fragments of molten rock blasting into the air - glowing orange lava flowing downhill - billowing clouds of ash rising into the air

Which of the following commonly precede a volcanic eruption?

- increased gas flow from a volcano - increased heat flow from the volcano - steam eruptions from the volcanic crater

Which of the following describe Kilauea?

- its lava flows are creating new land. - itʻs a shield volcano - it has a caldera, a crater, and fissures.

Which of the following are volcanic hazards made worse by being located along a river valley directly downhill from a volcano?

- lava flows - small pyroclastic flows - mudflows

Which of the following are the two ways in which volcanic domes grow?

- magma injected into the interior expands and breaks up the overlying cooled lava - thick flows of lava break out and flow down the steep surface of the dome.

Which of the following are hypothesized sources of the magma that produce flood eruptions?

- melted lithosphere over a mantle plume - plume material from deep in the mantle that melts at shallow depths - melted asthenosphere from around the plume in the shallow mantle

Select from below the typical components of a composite volcano.

- mudflow deposits - lava flows - pyroclastic flows

Which of the following volcanic hazards are posed to the surrounding areas by Mount Rainier?

- pyroclastic flows - mudflows - lava flows

Which of the following accurately describe young lava flows?

- rough upper surface - steep flow fronts

Volcanic vents can take which of the following forms?

- roughly circular craters - narrow linear fissures.

Which of the following are typically erupted from a volcano?

- scalding hot ash, lava, and gases

Rank the following volcanoes in order of increasing average size. Put the smallest volcano on top and proceed to the largest.

- scoria cone - composite volcano - large shield volcano

Which of the following are characteristics typical of volcanic domes? Assume a relatively young dome.

- steep-sided - often occur in clusters - rubble-covered surface

Shield volcanoes have low slopes primarily because:

- the low viscosity of basaltic magma allows it to flow downhill for long idstances

Which of the following are true of the Mauna Loa and Kilauea volcanoes?

- they are shield volcanoes - they erupt basaltic lava flows - they have erupted dozens of times in the past two centuries

Which of the following is not true of basaltic lava flows?

- they pile up in steep, cone-shaped hills.

Match the magma type with the corresponding eruption type.

Basaltic Magma - Fluid lava flows from shield volanoes; low viscosity. Felsic Magma - Explosive eruptions from composite volcanoes; high viscosity.

What type eruptions can erupt more than 1k cubic kilometers of magma, resulting in the collapse of the overlying ground into a large crater.

Caldera-forming

Mount St. Helens is a volcano in the ______ Range in the Pacific Northwest.

Cascade

Ash layers from the three most recent caldera-forming eruptions at Yellowstone (2.1, 1.3, and 0.64 million years ago) stretch:

From Canada to Mexico

________ are common on composite volcanoes because of their abundant clay, loose rocks, moisture, and steep slopes.

Debris flows, landslides, and lahars

Contrast eruption columns with pyroclastic flows by putting the descriptions in the category.

Eruption Column - Ash particles drift back down to Earth hundreds of kilometers or more from the volcano. - Tephra erupts high into the atmosphere along with large amounts of hot volcanic gases. Pyroclastic flow - Tephra billows down the slopes of the volcano in ground-hugging flows at speeds of over 100 km/hr. - Ash layers are deposited only on and adjacent to the slopes of the volcano.

Match the magma type with its gas bubble behavior.

Felsic Magma - Gas bubbles can't escape easily; high pressure builds in the magma; typically explosive eruptions; magma is high viscosity. Basaltic Magma - Gas bubbles escape easily; little pressure builds in the magma; typically nonexplosive eruptions; magma is low viscosity.

What represents the largest igneous eruptions on Earth, with some covering tens of thousands of square kilometers?

Flood basalts

______ eruptions are fed by a series of large fissures.

Flood-basalt

According to the fossil record, ______ events have coincided with the approximate times when flood basalts were eruping.

Mass extinction - The Decccan Traps in India are coincide with the extinction of the dinosaurs at the end of the Mesozoic, and the Siberian Traps with the Great Dying at the end of the Cenozoic.

Match the eruption products with their appropriate magma descriptions.

Thin lava flows - Low-viscosity magmas with relatively low volatile contents Lava domes - High-viscosity magmas with relatively low volatile contents Lava fountains - Low-viscosity magmas with relatively high volatile contents Eruption columns - High-viscosity magmas with relatively high volatile contents

T or F: The volcanic hazards associated with a volcano are dependent upon the type of volcano

True - different types of magmas produce different types of hazards.

T or F: Proximity to certain types of plate boundaries is the major factor making some places more prone to volcanic hazards than others.

True - for example, volcanoes are very common near subduction zones.

T or F: The same volcano may produce both explosive and nonexplosive eruptions.

True - sometimes a magma is gassy, and sometimes it is not so gassy.

___________ can be detected remotely from the characteristic shaking produced as they rush down valleys around a volcano

Volcanic mudflows

Which U.S. national park has a "supervolcano" evidenced by hydrothermal activity, frequent earthquakes, and historical ash beds that reach as far as Canada to Mexico?

Yellowstone

Moun Pelee, which killed about 30k people with pyroclastic flows in 1902, is a ________ volcano located over a subduction zone.

composite