Section 13-2 ReviewSection 13-2 Review

Page #330:1-9Page #330:1-9

#1#1

Summarize the difference between mafic

and felsic magma.

Mafic Magma magnesium & iron dark less viscous

Felsic Magma silica & feldspars light more viscous

#2#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#3

Compare three major types of lava flows.

• Pahoehoe – ropy

• Aa – jagged

• Blocky Lava – large chunks

PahoehoePahoehoe

AaAa

#4#4

Define pyroclastic material, and list three

examples.

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

Pyroclastic MaterialPyroclastic Materialvolcanic ash/dust

lapilli

volcanic bombs

Volcanic AshVolcanic Ash

BombBomb

#5#5

Identify the three main types of volcanic cones.

shield volcano

cinder cones

composite volcano

Types of VolcanoesTypes of Volcanoes

Shield VolcanoShield Volcano

Mauna Loa - Hawaii

Cinder ConeCinder Cone

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

Composite VolcanoComposite Volcano

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

#6#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.

CalderaCaldera

Crater LakeCrater Lake

#7#7

List three events that may precede a

volcanic eruption.

earthquake activity

rock temperatures increase

volcano area bulges

#8#8Would 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#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 EndThe End

On “Io” a moon of Jupiter