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Summarize the difference between mafic and felsic magma.
Mafic Magma
 magnesium & iron
 dark
 less viscous
Felsic Magma
 silica & feldspars
 light
 more viscous

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.

Compare three major types of lava flows.
• Pahoehoe – ropy
• Aa – jagged
• Blocky Lava – large chunks

Define pyroclastic material, and list three examples.
Pyroclastic material consists of fragments of rock that form during an explosive eruption.

volcanic ash/dust volcanic bombs lapilli

Identify the three main types of volcanic cones.
 shield volcano
 cinder cones
 composite volcano

Mauna Loa - Hawaii

http://video.google.com/videoplay?docid=5804326697533034741&q=cinder+cone+eruption&hl=en

http://video.google.com/videoplay?docid=3977416382972126736&q=mt+st+helens+eruption&hl=en

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.

List three events that may precede a volcanic eruption.
 earthquake activity
 rock temperatures increase
 volcano area bulges

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.

On “Io” a moon of
Jupiter