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VOLCANOES!

Discover the fascinating world of volcanoes! Learn what causes volcanic eruptions, where they occur, and the different types of volcanoes. Explore the factors that affect eruptions, such as lava viscosity and gas pressure. Watch videos to see the formation of shield volcanoes, cinder cones, stratovolcanoes, lava domes, and calderas. Understand the potential hazards, including toxic fumes, ash, pyroclastic flows, landslides, and lahars. Get ready to delve into the mesmerizing realm of volcanoes!

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VOLCANOES!

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  1. VOLCANOES!

  2. What is a volcano? • When magma reaches the Earth’s surface, causing an explosion of lava and ash, it is called a volcano. Magma = underground Lava = above the surface

  3. What causes volcanic eruptions? • Magma rises through cracks in Earth’s crust. • It can seep out or build up pressure, causing a volcanic eruption.

  4. Where do they occur? • Volcanoes occur at plate boundaries. The movement of the plates releases pressure, allowing magma to reach the surface.

  5. Where do they occur? • Volcanoes can occur where plates spread apart, such as at mid-ocean ridges.

  6. Where do they occur? • Volcanoes can occur where plates crash into each other, such as at subduction zones.

  7. Where do they occur? • Volcanoes can also occur above “hot spots” in the mantle.

  8. Island Building Demonstration

  9. The Ring of Fire

  10. Cascade Eruptions

  11. Types of Volcanoes • There are two important factors that affect volcanic eruptions: • Lava viscosity • Gas pressure

  12. Viscosity • Viscosity is a material’s resistance to flow. • Honey, for example, has high viscosity.

  13. Magma Composition • MAFIC • Rich in iron • Lower melting point • Runny lava • FELSIC • Rich in silica • Higher melting point • Thick, sticky lava

  14. Magma Composition • MAFIC: Basalt • INTERMEDIATE: Andesite • FELSIC: Rhyolite

  15. Viscosity Demonstration

  16. Gas Pressure Demonstration

  17. Flood Basalts • Really runny lava seeps out from cracks and spreads out • Builds up in layers over time, forming columnar basalt

  18. Flood Basalt Demo

  19. Shield Volcano • Liquid lava emitted from a central vent • Builds up in layers over time, forming a gently sloping “shield” shape

  20. https://www.youtube.com/watch?v=G3ZWAgN3Wzc

  21. Cinder Cone • Explosive liquid lava emitted from a central vent • Relatively small • Can build up over time to become a shield volcano

  22. https://www.youtube.com/watch?v=CNJc_6Xm1_4 https://www.youtube.com/watch?v=q2VLIbU6rh4

  23. Stratovolcano • More viscous lava • Explosive eruptions • The most well-known type of volcano

  24. Lava Dome • Very viscous lava • Builds up quickly in a mound • Relatively small • Often found in craters of stratovolcanoes

  25. https://www.youtube.com/watch?v=h6B1myUKAS4

  26. Caldera • Very viscous lava • Huge, explosive eruptions • Collapses once the magma chamber is empty, leaving behind a giant crater

  27. https://www.youtube.com/watch?v=BBGmXsZHInw

  28. Summary https://www.youtube.com/watch?v=mdeFHaZHjYw

  29. Volcanic Hazards • Toxic fumes • Tephra • Ash • Acid rain • Pyroclastic flow • Landslides • Lahars

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