Volcanoes - PowerPoint PPT Presentation

volcanoes n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Volcanoes PowerPoint Presentation
play fullscreen
1 / 35
Volcanoes
257 Views
Download Presentation
soo
Download Presentation

Volcanoes

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Volcanoes

  2. View From Space - Klyuchevskaya, Russia

  3. Shiveluch, Russia

  4. Cleveland Volcano, Alaska

  5. Mount Etna From Space

  6. Mount Etna From Space

  7. Mount Etna From Space

  8. Mount Etna

  9. Magma – molten rock beneath the surfaceLava – molten rock on the surface

  10. Where Does Magma Come From? • Earth’s interior is hot (25 C/km near surface = 1000 C at 40 km) • Pressure inhibits melting • Mantle is solid • Never far below melting point • Volcanoes fed by small pockets 0-100 km deep • Rising hot material may melt • Water can lower melting point

  11. Why Igneous Rock Classification Matters • Silica Content = Viscosity • Silica Content Governs Violence of Eruptions • Silica Poor (Basalt): Fluid lavas, generally little explosive activity • Intermediate Lavas (Andesite): Pasty lavas, explosive eruptions common • Silica-Rich Lavas (Rhyolite): Extremely viscous lava and explosive eruptions

  12. Types of Volcanoes

  13. Bowen's Series and Volcanoes Volcanic Rocks (Rare)  Basalt   Andesite                 Rhyolite Plutonic Rocks Dunite  Gabbro   Diorite                   Granite Fluid               Lava Is...                 Viscous Mild                Eruptions                 Violent Type of Volcano Shield Volcano     Stratovolcano    Plug Dome

  14. A Cinder Cone:Wizard Island, Crater Lake, Oregon

  15. Anatomy of a Cinder Cone, Hawaii

  16. Shield Volcano: Haleakala, Hawaii

  17. Eyjafjallajokull, Iceland

  18. Stratovolcano: Mount Shasta, California

  19. Lava Dome, California

  20. Products of Eruptions Lava Flows Pyroclastic Debris • Bombs • Lapilli • Ash Mudflows Landslides Gases • Steam • Carbon Dioxide • H2S • SO2 • HCl • HF

  21. Environmental Hazards of Volcanoes Pollution • SO2, HCl in Water Lava Flows Falling Ejecta Ash Falls • Building Collapse • Crop Destruction Mudflows • Direct Damage (Colombia, 1985) • Floods (Several Types) Blast (Mt. St. Helens, 1980) Pyroclastic Flow (St. Pierre, 1902) Gas (Lake Nyos, Cameroon, 1986)

  22. Pyroclastic Flow or Nuee Ardente (French: Fiery Cloud)

  23. How Calderas Form

  24. Crater Lake, Oregon

  25. The Stump of Mount Mazama

  26. Supervolcanoes? • Magma Chamber Collapse (Yellowstone?) • Destruction of crops • Destruction of high technology • Economic Disruption • Climatic Effects • Flood Basalts • Climatic Effects • Toxicity

  27. Jemez Caldera, New Mexico

  28. Jemez Caldera, New Mexico

  29. Collapsing Volcanoes – Mount Rainier

  30. Collapsing Volcanoes - Hawaii

  31. Landslide, Mount Saint Helens

  32. Shastina and Landslide Deposit

  33. Mount Shasta and Landslide Deposit

  34. Evolution of Volcanoes An active volcanic landscape

  35. Evolution of Volcanoes A volcanic landscape after a million years or so