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Volcanoes

Volcanoes. Chapter 8 Section 2 Pgs. 219 - 224. How volcanoes form. Fissure – crack in the crust, where a conduit forms which acts like a pipe magma travels through Magma is forced upward toward Earth’s surface by denser surrounding rock

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Volcanoes

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  1. Volcanoes Chapter 8 Section 2 Pgs. 219 - 224

  2. How volcanoes form • Fissure – crack in the crust, where a conduit forms which acts like a pipe magma travels through • Magma is forced upward toward Earth’s surface by denser surrounding rock • Causes an eruption where magma, solids, and gas are spewed out to form cone-shaped mountains

  3. Lava – magma flowing on Earth’s surface through a vent or opening • Craters – circular hole of volcano • Tephra – bits of rock or solidified lava dropping from the air • Reservoir – where magma is stored • Summit – highest point • Vent - opening where lava flows

  4. Where Plates Collide • Volcanoes form by a collision of large plates of crust and upper mantle • Oceanic plate sinks under another plate, rocks melt, forms chambers of magma

  5. Volcanic Risk Maps • Used to prepare people and visitors about unsafe areas

  6. Volcanic Eruptions • Violent or quiet • Lava high in silica produces explosive eruptions • Lava high in iron and magnesium produces more fluid eruptions • The amount of water vapor and gases impact eruptions

  7. Shield Volcanoes • Largest type of volcano • Gently sloping volcano that emits mostly basaltic lava (very fluid) that is long-lasting, gentle eruptions, explosions minimal

  8. Mauna Loa, HI • Made from 5 shield cones • Largest volcano on Earth – Mauna Loa in Hawaii, 6 miles tall

  9. Cinder Cone Volcanoes • Smallest volcano, very steep with large craters • Formed by moderate to explosive eruptions of tephra

  10. Cinder Cone Volcano • Pu ‘ u ka Pele – Hawaii • Mostly found on the sides of shield volcanoes

  11. Composite Volcano • Steep sides • Formed by alternating layers of violent eruptions of tephra and quieter eruptions of lava

  12. Composite Volcano • Most active volcano – Mt. St. Helens in the western part of the state of Washington

  13. Extreme Volcanoes • Largest volcano in the Solar System – Olympus Mons on Mars, 17 miles tall and over 320 miles across.

  14. Questions • Hawaii is an example of what type of volcano? • What are the three types of material that a volcano can emit? • The eruption of Mount Vesuvius buried what town in 79 A.D.? • How did people die in the aftermath of the famous Mount Vesuvius eruption? • Mount St. Helen’s erupted violently in 1980. On what continent is this volcano found?

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