VOLCANIC ERUPTIONS

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VOLCANIC ERUPTIONS
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NEW VOCABULARY

• MAFIC
• FELSIC
• SILICATE
• VISCOSITY
• PYROCLASTIC MATERIAL

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TODAYS OBJECTIVES

• Explain how the composition of magma affects
  volcanic eruptions and lava flows
• Explain what viscosity is
• Describe the 3 types of volcanic eruptions
• Describe the 5 major types of pyroclastic
  material

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TYPES OF MAGMA

• There are 2 types of magma
• MAFIC Rich in magnesium and iron. Is dark in
  color
• FELSIC Rich in SILICATE minerals. Is light in
  color
• SILICATE These minerals are made mostly of the
  element silica.

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MAFIC ROCKS
FELSIC ROCKS
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Volcanic Eruptions

• VISCOSITY a materials resistance to flow. Can
  be thought of as how thick a material is.
• How easily does water flow from a cup?
• How easily does syrup flow from a bottle?
• The water is less viscous than the syrup!

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Did you get it?

• Turn to your neighbor and put the following
  materials in order from lowest to highest
  viscosity
• Chocolate Syrup
• Honey
• Ketchup
• Maple Syrup
• Mayonnaise
• Peanut Butter
• Water

• Water 1.0
• Maple Syrup 150
• Chocolate Syrup 500
• Honey 10,000
• Ketchup 50,000
• Mayonnaise 50,000
• Peanut Butter 150,000

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TYPES OF ERUPTIONS

• Quiet Eruptions
• Non-explosive
• Mafic magma
• Example Oceanic eruptions

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TYPES OF ERUPTIONS

• Lava Flows
• Specific to mafic magma
• Cools quickly to form a crust on the outside of
  the flow
• There are 3 types of lava flows
• Pahoehoe (PA-hoh-ee-hoe-ee) least viscous, looks
  like rope
• Aa (Ah-Ah) more viscous than Pahoehoe, is jagged
  and chunky
• Blocky Lava more viscous than Aa because it has
  more silica, breaks into blocks

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TYPES OF ERUPTIONS

• Explosive Eruptions
• Form from felsic magmas
• Have a large amount of trapped gases
• When they explode they throw PYROCLASTIC MATERIAL
  into the air
• PYROCLASTIC MATERIAL Fragments of rock that form
  during a volcanic eruption

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TYPES OF PYROCLASTIC MATERIAL

• Pyroclastic material is named because of the size
  of the particles
• Volcanic Dust very fine, like flour
• Volcanic Ash more like the size of sugar
• Lapilli like small pebbles
• Volcanic Bombs red hot clots of lava that
  solidify in the air
• Volcanic Blocks large pieces of rock that are
  blasted from the vent

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Concept Check write the following questions in
your notes

• What is the main factor that determines how
  explosive a volcano is?
• Magma Viscosity
• What are the 3 types of eruptions?
• Quiet Eruptions
• Lava Flows
• Explosive Eruptions
• What are the 5 types of Pyroclastic Material?
• Vocanic Dust, Volcanic Ash, Lapilli, Volcanic
  Bombs, Volcanic Blocks

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Tomorrow..

• Types of volcanoes
• Other intrusive activities