Ch 6 Homework
If bubbles cannot escape easily from a magma, the resulting eruption is likely to
Be explosive
This relatively small volcanic feature consists of solidified lava and some volcanic ash. What kind of volcano is it?
None of these (scoria cone, shield volcano, composite volcano, caldera)
The largest concentration of composite volcanoes on Earth is located along the
Pacific Ring of Fire
Which of the following is NOT true about shield volcanoes in the landscape?
They are large mountains with steep slopes. Incorrect answers: They can construct some of the world's largest volcanoes. They can be large or small. All of these choices are correct.
The eruption that occurred on Mount St. Helens was triggered by
a huge landslide, caused a lateral blast that knocked down trees and buildings.
Which of the following is NOT a typical eruption style during the growth of a composite volcano?
caldera collapse
Flood basalts influence life on Earth because
large volumes of flood basalts are erupted during a short time. eruptions can release large amounts of gas that cool the atmosphere. eruptions can release large amounts of gas that warm the atmosphere.
What tectonic setting is interpreted to be the cause of volcanism at Yellowstone?
movement of North America over a mantle plume
This figure shows an eruption of high-viscosity (viscosity) magma that probably has a felsic or intermediate (composition) and would form pumice (resulting rock type).
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This figure shows an eruption of high-viscosity (viscosity) magma that probably has a felsic or intermediate (composition) and would form rhyolite or andesite (resulting rock type).
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This figure shows an eruption of low-viscosity (viscosity) magma that probably has a mafic (composition) and would form scoria (resulting rock type).
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Figure A shows a scoria cone (type of volcano) that forms from a lava fountain(type of eruption).
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Figure B shows a shield volcano (type of volcano) that forms from eruption of basaltic lava flows (type of eruption).
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Figure C shows a composite volcano (type of volcano) that forms from eruption of viscous, felsic lava (type of eruption).
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Figure D shows a volcanic dome (type of volcano) that forms from eruption of lava and ash (type of eruption).
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his figure shows a lava flow (type of volcanic feature) that forms from eruption of low-viscosity, mafic lava (type of magma).
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What type of volcanic eruption is shown in this photograph?
A pyroclastic column
Which of the following is a hazard but not a risk, according to the textbook?
A scoria cone that erupts hot molten fragments on an unpopulated Pacific island
Which of the following sites near a volcano might be relatively less dangerous?
A site on a ridge as opposed to a site in a valley.
The most common volcanic rock found in lava flows on composite volcanoes is
Andesite
Which represents the largest igneous eruptions on Earth?
Flood basalts
Which of the following materials is NOT produced by erupting volcanoes?
Sandstone
This volcano is broad and low, and is composed of basaltic lava flows. What kind of volcano is it?
Shield
Which of the following volcanoes is generally the largest?
Shield
Which of the following occurs in a lava tube?
The surface of the lava flow solidifies to form a roof over the moving lava. Lava tubes insulate a lava flow, allowing it to flow farther. If a lava tube drains, it becomes a tube-shaped cave.
Which of the following are ways that viscosity affects gases in magma?
Viscous magma prevents gas from escaping easily.
Which of the following is common in most calderas?
a large, circular depression with steep walls thick sequences of volcanic ash rounded mountains that are volcanic domes
Which of the following factors indicates a high risk for volcanic mudflows or lahars?
a volcano with a thick covering of snow or ice
Which of the following hazards is probably NOT associated with this volcano? Mt. St. Helens (Dome and conduit, lava flows and dikes, pyroclastic rocks and mudflows)
destruction by fast-moving lava Incorrect: pyroclastic flows collapse of a volcanic dome eruption column lava Correct mudflows
This volcano is relatively small and composed of volcanic cinders. What kind of volcano is it?
scoria cone
Which of the following are characteristics typical of volcanic domes?
steep-sided. rubble-covered surface, often occur in clusters
