Geology Chapter 6 Learnsmart

Put the events of the 1980 Mount St. Helens eruption in order. Earliest event on top

1.) earthquakes 2.) landslide 3.) lateral blast and eruption column

Put the events of caldera formation in order. Begin with the first event on top

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

Which of the following is a location in which flood basalts erupted?

Columbia Plateau

felsic magma

Explosive eruptions from composite volcanoes, high viscosity

Felsic magma

Gas bubbles cannot 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

Huge circular depressions from which volcanoes erupt are _________; magma also can erupt from cracks, or _________

calderas; fissures

Mount St. Helena is a volcano in the _________ range in the pacific northwest

cascade

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

changes in gas output, heat flow changes, ground shaking, and changes in topography

rock type

chemical analysis determines magma composition and potential for explosiveness

__________ volcanoes produced pyrociastic flows that killed tens of thousands of people at Pompeii and St. Pierre

compostie

Scoria cones are composed primarily of _________

ejected fragments of vesicular lava

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

fissures

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

gases

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

Nonexplosive eruptions of basaltic magma produce ________

lava flows

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

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

Older lava flows tend to have surfaces that are ____________ than younger lava flows

more subdued and have more soil and plants

Proximity to certain types of ________ boundaries is the major factor making some places more prone to volcanic hazards than others

plate

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 quickly down the side of volcano

pyroclastic

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

reduced summer sunlight, unusually cold winter, and crop failures and famine

Which of the following materials is not produced by erupting volcanoes?

sandstone

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

small pyroclastic flows, lava flows, and mudflows

Which of the following is recognizable characteristic of recent calderas?

steep-sided, basin-shaped depression

Potentially explosive composite volcanoes are most common above __________ zones

subduction

True or false: the volcanic hazards associated with a volcano are dependent upon the type of volcano

true

___________ 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 an "super-volcano" evidenced by hydrothermal activity, frequent earthquakes, and historical ash beds that reach as far as Canada to Mexico?

yellowstone

Put the events leading to the formation of Crater Lake as we see it today. Put the first event on the top

1.) massive ash column eruption of composite volcano empties the magma chamber 2.) overlying volcano collapses into the resulting void 3.) socria cone forms in the caldera 4.) rain and snowmelt fill the caldera, producing a large and deep lake

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

1.) scoria cone 2.) composite volcano 3.) large shield volcano

List the rocks typically found in calderas, from the top downward. Begin with rocks on the surface

1.) volcanic tuff 2.) hard, welded volcanic rock 3.) finely crystalline granite

Which of the following U.S. states were covered by parts of the large Columbia Plateau flood basalts?

Idaho, Washington, and Oregon

What is the most active volcano on Earth's surface?

Kilauea

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

andesite

Which of the following contributes to the growth of composite volcanoes?

ash column eruptions, eruption of lava flows, and pyroclastic flows

pyroclastic flow

ash layers are deposited only on and adjacent to the slopes of the volcano and tephra billows down the slopes of the volcano in ground-hugging flows at speeds of over 100km/hr

Which of the following are characteristics of activity erupting volcanoes?

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

Which of the following accurately describe most shield volcanoes?

broad and gently sloping from and composed of succession of lava flows

lava flow

burial of roads, bulldozing and crushing of houses and other structures

___________ eruptions can erupt more than 1,000 cubic kilometers of magma, resulting in the collapse of the overlying ground into a large crater

caldera-froming

The steep symmetrical shape of andesitic Mount Rainer indicated that it is a __________ volcano

composite

Most composite volcanoes are found along ________ plate boundaries

convergent

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

crushing/bulldozing buildings, burning buildings, and covering roads

___________ represent 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

Basaltic magma

fluid lava flows from shield volcanoes; low viscosity

Which of the following are properties characteristic of calderas?

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

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

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

Volcanic mudflows (lahars) are common on composite volcanoes because _____________

large amounts of rain and snowmelt mix with loose ash on steep slopes

When fluid lava erupts onto the surface, it typically produces _____________

lava flows

Which of the following describe a young scoria cone?

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

Which of the following are the two main factors controlling volcanic eruption style?

magma composition and volatile content of the magma

Earthquakes at Mount St. Helens prior to the major eruption in 1980 were caused by ___________

magma rising in the volcano

According to the fossil record, ___________ events have coincided with the approximate times when flood basalts were erupting

mass extinction

Which of the following is not a reason why heat flow and gas output from a volcano tend to increase before eruptions?

melting of snow caps dissolves large amounts of water into the magma

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

minoan

Which of these volcanic hazards associated with Mount rainer is the most dangerous to nearby population centers?

mudflows

Sheild volcanoes are built up primarily by relatively _____________

nonexplosive outpouring of lavas

Which of the following are typcially erupted from a volcano?

scalding hot ash, lava, and gases

When lava flows reach the ocean, they _______________

solidify and add land to an island

Shape

steep slopes indicate high visocity, explosive magma; gentle slopes indicate less explosive magma

The typical form for a composite volcano is a ________

steep-sided cone

The magma feeding Mount Rainer and the other Cascade volcanoes results from melting associates within the Cascadia _________ zone, which is an ocean-continent ________ boundary

subduction; convergent

Eruption column

tephra erupts high into the atmosphere along with large amounts of hot volcanic gases and ash particles drift back down to Earth hundreds of kilometers or more form the volcano

Which factor below largely controls what rock types and landfroms develop from basaltic magma?

the characteristics and behavior of the gas in the magma

Decreasing the pressure on a liquid that contains dissolved gases will result in _______________

the formation of gas bubbles

history

the sequence of layers and isotopic dating can indicate the timing and frequency of eruptions

Which of the following events accompanied the 1883 eruption at Krakatu, Indonesia?

tsunami waves strike ships and nearby coastlines, most of a large island collapses into a caldera, largest and loudest explosion in recorded history occurs, and high eruption column and pyroclastic flows form

Volcanic domes form from the accumulation of ________ lava over a volcanic vent

viscous

Scoria cone

volcanic ash and gases and falling volcanic cinders and bombs