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Volcanoes Chapter 5

Volcanoes Chapter 5. S6E5: Convection currents cause plate movement which causes geologic activity such as volcanoes. What is a VOLCANO?. A weak spot in Earth’s crust where magma comes up to the surface. Where are most of Earth’s major volcanoes located?.

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Volcanoes Chapter 5

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  1. VolcanoesChapter 5 S6E5: Convection currents cause plate movement which causes geologic activity such as volcanoes.

  2. What is a VOLCANO? A weak spot in Earth’s crust where magma comes up to the surface

  3. Where are most of Earth’s major volcanoes located? • In belts around the Earth’s continents and oceans along plate boundaries • One major belt is known as the Ring of Fire, located around the rim of the Pacific Ocean

  4. Volcanoes at Divergent Boundaries • May form in the ocean at mid-ocean ridges • May form on continents at rift valleys

  5. Example:Great Rift Valley in East Africa

  6. Volcanoes at Converging Boundaries Form where 2 plates collide: Oceanic Continental Oceanic  Oceanic The resulting volcanoes create a string of islands called an Island Arc

  7. Examples of Island Arcs: The Aleutian Islands

  8. Another Example of an Island Arc: The Carribean Islands

  9. Volcanic Hot Spots • A volcano forms above a Hot Spot when magma erupts through the crust and reaches the surface

  10. Oceanic Hot Spot:The Hawaiian Islands

  11. Continental Hot Spot: Yellowstone National Park, Wyoming, USA

  12. Volcanic eruption vary depending on the viscosity of the magma • What is viscosity? • The resistance of a liquid to flow. The greater the viscosity, the thicker the flow • Depends on the amount of silica (from 50% - 70%)

  13. Quiet Eruption • Volcano erupts quietly • Low silica magma has low viscosity and flows easily • Example: The Hawaiian Islands

  14. Explosive Eruption • Volcano erupts violently • High silica magma, high viscosity, thick and sticky, does not flow – builds up pressure • Example: Mt Saint Helens • Mount St. Helens about noon on May 18, 1980 after being dormant for 123 years.

  15. Pyroclastic Flow • Volcano erupts violently • Hurls out a mixture of hot gases, ash, cinders, & bombs • Example: Mayon Volcano, Philippines

  16. Three Main Types of Volcanoes: 1. Shield Volcano 2. Cinder Cone Volcano 3. Composite Volcano

  17. Shield Volcano • Gradual, build-up of lava • Wide, gently sloping mountain • Example: Hawaiian Islands Notice the shapes of the shields??? Hummm…

  18. Composite Volcano • Lava alternates with layers of ash in explosive eruptions • Tall, cone-shaped mountain • Examples: Mt. Fuji, Japan and Mt. Saint Helens, Washington, USA

  19. Composite Volcanoes

  20. Comparing Shield & Composite Volcanoes

  21. Cinder Cone Volcano • Erupts violently, producing ash, cinders, and bombs • Loose materials build up around the vent in a steep cone-shaped mountain • Example: Pariciutin, Mexico

  22. Cinder Cone Volcano

  23. Comparing the shapes of Volcanoes!

  24. Check out this volcano link… • http://mail.colonial.net/~hkaiter/volcanoes.html

  25. What is a Caldera? Huge hole left by the collapse of a volcanic mountain

  26. Geothermal Activity • Hot springs & geysers are types of geothermal activity often found in areas of past or present volcanic activity

  27. What are hot springs? • They form when groundwater is heated by nearby magma or hot rock deep underground

  28. Which one is a geyser?

  29. Seriously, what is a geyser? A fountain of water and steam that erupts from the ground • Example: Old Faithful at Yellowstone National Park It erupts ‘faithfully’ every 33 – 93 minutes

  30. Experimenting with Volcanic Eruptions • Volcano Info…build & erupt a volcano…have fun! • http://kids.discovery.com/games/pompeii/pompeii.html

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