Section 13-2 ReviewPage #330:1-8

#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 Materialvolcanic ash/dust

lapilli

volcanic bombs

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

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