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Volcano Notes

Volcano Notes. Anatomy of a volcano. tephra. vent/crater. lava. pipe. l ayers of volcanic material. magma chamber. 3 Types Volcanic Materials. Magma - hot - melted rock (molten) - beneath the Earth’s surface. 2 . Lava - hot - molten rock

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Volcano Notes

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  1. Volcano Notes

  2. Anatomy of a volcano tephra vent/crater lava pipe layers of volcanic material magma chamber

  3. 3 Types Volcanic Materials • Magma- hot - melted rock (molten) - beneath the Earth’s surface

  4. 2. Lava- hot - molten rock - flowing on Earth’s surface

  5. 3. Tephra-lava that is blasted into the air - turns solid as it falls back to the ground

  6. Examples of tephra: ash, cinders, and volcanic bombs (*pyroclastic material*)

  7. Some volacanic eruptions are violent and explosive…

  8. Some are quiet eruptions

  9. 3 Factors that Affect the Explosiveness of Volcanoes 1. Amount of trapped gases and water vapor

  10. Just like a closed soda can, the pressure builds when shaken. • In a volcano, the more gas that is trapped, increases pressure, and makes the eruption more explosive

  11. 3 Factors that Affect the Explosiveness of Volcanoes Composition and viscosity of magma The elements and minerals that make up the melted rock determine how explosive an eruption will be. High amounts of silica increase the viscosity of the magma.

  12. Basaltic magma is relatively liquid (low viscosity ; low silica content) when melted and is not usually explosive

  13. Rhyolitic magma is very thick (high viscosity ; high silica content) when molten, and therefore very explosive

  14. 3 Factors that Affect the Explosiveness of Volcanoes 3. Temperature of the magma (affects viscosity and explosiveness)

  15. 3 Volcano Types • Volcano shape and size is related to: • Type of material in an eruption • Gas content • How often the volcano erupts

  16. 1. Shield Volcano • Gradual slope (gives “shield” shape) • Layers of lava built up over time • Low to moderately explosive • Ex. Hawaiian Island volcanoes

  17. 2. Cinder Cone Volcano • Very steep slopes • Made of tephra (accumulated cinders and rock particles) • Moderate to highly explosive • Ex. Wizard Island • Crater Lake, Oregon

  18. 3. Composite Volcano (Stratovolcano) • Steep slopes • Made of layers of tephra and lava • Moderate to highly explosive • Ex. Mt. St. Helens • Cascade volcanoes

  19. Image credits • Slide 2 volcano: http://cgz.e2bn.net/e2bn/leas/c99/schools/cgz/accounts/staff/rchambers/GeoBlogBytes%20Blog%20Resources/Year%209/Volcano_structure.png • Slide 4 mtsthelens: http://www.driever.nl/foto/achtergronden/JLM-NatGeo-Mount-St-Helens-1980-May-18.jpg • Slide 4 maunaloa: http://en.wikipedia.org/wiki/File:Aa_channel_flow_from_Mauna_Loa.jpg • Slides 9 & 10 shield and cindercone: Tasa Graphics CD • Slide 11 stratovolcano: http://www.biocrawler.com/w/images/4/4f/Stratovolcano.jpg

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