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Section 13-2 Review
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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
#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.
#3
Compare three major types of lava flows.
• Pahoehoe – ropy
• Aa – jagged
• Blocky Lava – large chunks
Pahoehoe
Aa
#4
Define pyroclastic material, and list three
examples.
Pyroclastic material consists of
fragments of rock that form during an
explosive eruption.
Pyroclastic Material
volcanic ash/dust
volcanic bombs
lapilli
Volcanic Ash
Bomb
#5
Identify the three main types of volcanic
cones.
shield volcano
cinder cones
composite volcano
Types of Volcanoes
Shield Volcano
Mauna Loa - Hawaii
Cinder Cone
http://video.google.com/videoplay?docid=5804326697533034741&q=cinder+cone+eruption&hl=en
Composite Volcano
http://video.google.com/videoplay?docid=3977416382972126736&q=mt+st+helens+eruption&hl=en
#6
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.
Caldera
Crater Lake
#7
List three events that may precede a
volcanic eruption.
earthquake activity
rock temperatures increase
volcano area bulges
#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.
#9
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.
The End
On “Io” a
moon of
Jupiter