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Chapter 10 Volcanoes

Chapter 10 Volcanoes. What is A Volcano?. A VOLCANO is an opening in Earth ’ s surface that often forms a mountain when layers of lava & ash erupt After many thousands or even millions of years, magma reaches earth ’ s surface and flows out through an opening called a VENT .

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Chapter 10 Volcanoes

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  1. Chapter 10Volcanoes

  2. What is A Volcano? • A VOLCANO is an opening in Earth’s surface that often forms a mountain when layers of lava & ash erupt • After many thousands or even millions of years, magma reaches earth’s surface and flows out through an opening called a VENT. • The steep walled depression around a volcano’s vent is the CRATER.

  3. Magma vs. Lava Magma – molten material inside a volcano Lava – molten material on earth’s surface

  4. Draw & Label the parts of a Volcano

  5. Where do volcanoes occur? • Where plates move APART AKA: Divergent plate boundaries • Where plates move TOGETHER AKA: Convergent plate boundaries

  6. Where do volcanoes occur? 3. HOT SPOTS areas of earth that melt rock & force magma upward

  7. Pacific Ring of Fire area around the pacific plate where earthquakes & volcanoes are common

  8. Active vs. Dormant • Most of Earth’s volcanoes are DORMANT, which means they are not currently active • There are more than 600 active volcanoes in the world • The most active volcano in the world is Kilauea in Hawaii

  9. VIDEO • how volcanoes form

  10. Eruptions • Eruptions can either be quiet or explosive. • Two factors to determine the type of eruption: • Amount of water vapor and other gases trapped in the magma. • Whether the magma is basaltic or granitic.

  11. Trapped Gases • Gases like water vapor and carbon dioxide are trapped in magma by the pressure of the surrounding magma. • As magma nears the surface, pressure is reduced. • Gas escapes easily = quiet eruption • Gas trapped under high pressure = explosive eruption

  12. Magma Composition • Basaltic Magma – contains less silica, very fluid, and produces quiet, nonexplosive eruptions. • Example: Kilauea, Hawaii • Granitic Magma – contains a lot of silica, very thick, and high water content. Gets trapped in vents causing pressure to build up resulting in explosive violent eruptions. • Example: Mount Saint Helens

  13. VIDEOS • Kilauea Eruption • Mount Saint Helen Eruption

  14. TYPE 1: SHIELD VOLCANO • Broad volcano • Gently sloping sides • Quiet Eruption Hawaiian Islands

  15. TYPE 2: CINDER CONE VOLCANO • Explosive eruptions throw lava into the air • Lava then cools & hardens into TEPHRA Paricutin, Mexico - steep, smooth sides - loosely consolidated

  16. TYPE 3: COMPOSITE VOLCANO • Vary between quiet & explosive eruptions • Lava & tephra is repeated over & over Mount Saint Helens

  17. Brain Pop http://www.brainpop.com/science/earthsystem/volcanoes/

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