Section 13-2 Review

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Section 13-2 Review

• Page 3301-9

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1

• Summarize the difference between mafic
• and felsic magma.

• Mafic Magma
• magnesium iron
• dark
• less viscous

• Felsic Magma
• silica feldspars
• light
• more viscous

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2

• Explain how the composition of magma
• affects the force of volcanic eruptions.

More viscous magma traps gases more easily than
less viscous magma, which may lead to more
explosive eruptions.
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3

• Compare three major types of lava flows.

• Pahoehoe ropy

• Aa jagged

• Blocky Lava large chunks

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Pahoehoe
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Aa
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4

• Define pyroclastic material, and list three
• examples.

Pyroclastic material consists of fragments of
rock that form during an explosive eruption.
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Pyroclastic Material

• volcanic ash/dust

volcanic bombs
lapilli
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Volcanic Ash
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Bomb
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• Identify the three main types of volcanic
• cones.

• shield volcano

• cinder cones

• composite volcano

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Types of Volcanoes
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Shield Volcano
Mauna Loa - Hawaii
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Cinder Cone
http//video.google.com/videoplay?docid5804326697
533034741qcinderconeeruptionhlen
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Composite Volcano
http//video.google.com/videoplay?docid3977416382
972126736qmtsthelenseruptionhlen
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• Describe how calderas form.

A caldera forms when the magma chamber of a
volcano empties, causing the volcanic cone to
collapse in upon it, or when magma is ejected
violently and the cone is destroyed.
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Caldera
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Crater Lake
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7

• List three events that may precede a
• volcanic eruption.

• earthquake activity

• rock temperatures increase

• volcano area bulges

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8

• Would quiet eruptions or explosive
• eruptions be more likely to increase the
• steepness of a volcanic cone? Explain
• your answer.

Explosive eruption are more likely to increase
volcano height, because the pyroclastic materials
rise upward and fall close to the volcanic vent.
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• Why would a sudden increase of
• earthquake activity around a volcano
• indicate a possible eruption.

Sudden earthquake activity could be caused by
magma moving upward through the rock around the
volcano.
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The End
On Io a moon of Jupiter