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Types of Volcanic Eruptions

Types of Volcanic Eruptions. Two factors determine the type of eruption : Amount of water vapor & other gases in the magma The chemical composition of the magma. Volcanoes .

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Types of Volcanic Eruptions

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  1. Types of Volcanic Eruptions Two factors determine the type of eruption: • Amount of water vapor & other gases in the magma • The chemical composition of the magma

  2. Volcanoes SPI 5.2.5 Describe internal forces such as volcanoes, earthquakes, faulting, and plate movements that are responsible for the earth’s major geological features such as mountains, valleys, etc.

  3. Explosive Eruptions • Rarer but very destructive. • Clouds of hot debris, ash, and gas rapidly shoot out. • Molten rock pieces and ash can be blown into the air.

  4. Explosive Eruptions • Water content of the magma is high

  5. Explosive Eruptions • Silica content of the magma is high- • it’s thick, • flows slow, and • tends to plug vents • Enough pressure= explosion!

  6. Examples: • Mt. St. Helens • Mt. Fuji • Mt. Pinatubo

  7. Non-explosive Eruptions • Most common • Produce relatively calm flows of lava

  8. Non-explosive • Lowersilica content (thinner lava)

  9. Non-explosive • …and has low water content • Examples: Hawaii

  10. Video: a typical Hawaiian eruption

  11. Shield volcanoes • Huge! Made from lava layers • Large base, gentle slope • Form non-explosive eruptions- runny lava spreads over a large area • Life span of a million years or more • Example: Hawaii’s Mauna Kea

  12. Sketch a shield Volcano:

  13. Shield Volcanoes Mauna Kea

  14. Shield Volcanoes Mauna Kea

  15. Shield Volcanoes The Mauna Loa volcano in Hawaii—the largest volcano on Earth—has the broad expanse characteristic of shield volcanoes. It spreads across half the island of Hawaii. Shield volcano on Mars; Taken from space

  16. Cinder cones • Made of loose pyroclastic material from moderately explosive eruptions • When lava hits the ground, it sticks rather than flows • This builds a steep cone with a small base • Life span of a few years because they erode away easily • Example: Mexico’s Paricutín

  17. Cinder cones

  18. Cinder Cones:

  19. Cinder Cone Volcanoes

  20. Composite or strato • One of the most common kinds • Form from explosive pyroclastic material followed by quieter flows of lava- creates alternating layers • Broad bases, sides that get steeper towards the top • Life span of a million years or more

  21. STrato/Composite Example: Mt. Fuji in Japan

  22. Sketch a composite Volcano:

  23. More Composite (strato) Volcanoes : Mt. Rainier

  24. Composite/strato volcanoes

  25. Video Clip: Types of volcanoes

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