Volcanos and Volcanic Hazards

Which of the following are erupted by volcanoes?

-ash -pumice -lava

lava flow

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

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

-crushing/bulldozing buildings -covering roads -burning buildings

Which of the following properties characteristic of caldera?

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

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

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

flood basalts have occurred

-oceanic plateus -brazil -siberia -india

volcanic vents can take which of the following forms?

-roughly circular craters -narrow linear fissures

rock types associated with basaltic volcanoes

-scoria -non vesicular bassalt -vesicular basalt -volcanic bombs

Which of the following accurately describes young lava flows?

-steep flow fronts -rough upper surface

Pyroclastic flow

-tephra billos doen the slopes f 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.

Eruption column

-tephra erupts high into the atmosphere along with large amounts of hot volcanic gases -ash particles drift back down to earth hundreds of kilometer or more from the volcano

Volcanic domes grow

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

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

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

highest level of volcanic hazard to a population?

-town located along a river drainage directly downhill from a volcano -town located very near to a volcano

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

-volatile content of the magma -magma composition

Which of the following are typical hazards associated with scoria cones?

-volcanic ash -falling cinders and volcanic bombs -toxic volcanic gases

Which of the following are typical hazards associated with scoria cones

-volcanic ash -toxic volcanic gases -falling cinders and volcanic bombs

Gas in basaltic magma is the major controlling factor that determines

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

Put the events of the 1980 Mount St. Helen eruption in order

1. earthquake 2. landslide 3. lateral blast and eruption column

Put the events of caldera formation in order. begin with first event

1. magma erupts as ash column, emptying a shallow magma chamber 2. overlying material collapses into emptied chamber in a series of fault block 3. ash and other pyroclastic fill the subsiding crater 4. small rhyolite domes form in caldera

Put the events leading to the formation of crater lake as we know it today

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

rank the following volcanos in order of increasing average . smallest first

1. scoria 2. composite 3. large sheild

List the rocks typically found in caldera, from top downward. begin with rocks at surface and then to furthest below surface

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

rocks found in calderas from surface to below

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

Which of the following processes contribute to the growth of composite volcanoes?

=pyroclastic flows -eruption of lava flows -ash column eruptions

Shield volcano

Broad, gently sloping conical hill or mountain, with fissures along its summit; composed mainly of basaltic lava flows

Basaltic Magma

Gas bubbles escape easily; little pressure builds in the magma; typically nonexplosive eruptions; magma is low viscosity

Composite Volcano

Moderately steep, cone-shaped mountain thousands of meters high with a crater at the top; composed of interlayer lava flows, pyroclastic, and volcanic mudflows

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

Sandstone

Which of the following typically erupted from a volcano?

Scalding hot ash, lava, and gases

The typical form for a composite volcano is a

Steep-sided cone

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

andesite

reduced temperatures and growing season in Europe following the 1783 Laki eruption were primarly caused by

blocking of sunlight by volcanic ash and aerosols

eruptions that are the largest and most violent volcanic phenomena

caldera-forming

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

caldera-forming

huge depressions from which volcanoes erupt are called

calderas

the type of volcanoes that produced pyroclastic flows that killed tens of thousands of people at pompeii

composite

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

continent-continent convergent boundary with a high mountain range (Himalaya)

Most composite volcanoes are found along

convergent plate boundaries

scoria cones are composed primarily of

ejected fragments of vesicular lava

Represents the largest igneous eruptions on Earth, with some covering tens of thousands of square kilometers

flood-basalts

felsic magma

gas bubbles cannot escape easily; high pressure builds in the magma; typically explosive eruptions; magma is high viscosity

The existence of a potentially dangerous situation or event is known as a

hazard

Eruption columns

high-viscosity magmas with relatively high violative contents

lava domes

high-viscosity magmas with relatively low volatile contents

flood-basalt eruptions are fed by

long fissures/dikes

Lava fountains

low-viscosity magmas with relatively high volatile contents

Thin Lava flows

low-viscosity magmas with relatively low volatile contents

older lava flows tend to have surfaces that are ----- than younger lava flows

more subdued and have more soil and plants

Shield volcanoes are built primarily by relatively

nonexplosive outpourings of lava

Whereas the likelihood and magnitude of its impact on society is known as its

risk

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

seismic shaking

Scoria cone

steep-sided, cone-shaped hill hundreds of meters high, with a small crater at the summit; composed of cinders and volcanic bombs. formed from lava fountains. composed of a pile of loose, vesicular lava fragments

Volcanic dome

steep-sided, dome-shaped hill hundred of meters high; composed of fells lava. often occur in clusters. rubble-covered surface

A composite cone would be expected to have slopes that are ---- than those of a shield volcano

steeper

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

the formation of gas bubbles

Which of the following is not a characteristic of an actively erupting volcano?

totally covered in a fresh blanket of clean, white snow

Scoria cone

volcanic ash and gases falling volcanic cinders and bombs

the type of volcano uniquely determines the ------ likely to be experienced by local populations

volcanic hazards

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