1 / 20

VOLCANOES!

VOLCANOES!. Factors Affecting Eruptions. Magma temperature Hotter flows easier… Magma viscosity – determined by temp and composition. High silica = high viscosity (thickness) High viscosity = violent eruptions… Dissolved gases More gasses means more violent eruptions….

Jimmy
Download Presentation

VOLCANOES!

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. VOLCANOES!

  2. Factors Affecting Eruptions • Magma temperature • Hotter flows easier… • Magma viscosity – determined by temp and composition. High silica = high viscosity (thickness) High viscosity = violent eruptions… • Dissolved gases • More gasses means more violent eruptions…

  3. Volcanic Materials- Lava 3 TYPES OF LAVA FLOWS • Aa- rough and jagged 2) Pahoehoe - wrinkly and ropey texture 3) Pillow - forms underwater at boundaries

  4. Aa Pahoehoe Pillow

  5. Volcanic Materials- Gases • Water Vapor, Carbon Dioxide, Nitrogen, Sulfur Dioxide, and Chlorine Kilauea Volcano, Hawai`i From 1986-2000 emitted 1,000-2,000 metric tons of SO2 every day!

  6. Volcanic Materials • Pyroclastic Materials = Ejected fragments Ash – fine material Cinders and lapilli = medium/pebble sized Bombs and blocks (big stuff) block = hard, bombs = lava

  7. Ash Bombs & Blocks Cinders

  8. Volcanic Terms • Crater – steep walled depression at top • Caldera – large depression in a volcano due to collapse of volcano

  9. Volcanic Terms Conduit – pipe connecting magma chamber to the surface Vent – top of the conduit

  10. Volcanic Terms • Lava plateau – raised flat area of lava • Volcanic neck – remnant of eroded volcano

  11. Columbia Lava Plateau- covers parts of Washington, Oregon, and Idaho

  12. Types of Volcanoes Cinder Cone Composite Shield

  13. Shield Volcanoes • broad base with gently sloping sides Huge in size, mild eruptions, mostly flows, ex: Hawaii Mauna Kea, Hawaii

  14. Cinder Cone • Narrow base and steep sides -Small, violent for size, pyroclastic eruptions, ex: Mt. Paricutin, Sunset crater in AZ

  15. Composite Cone • Medium base and moderately sloped size (volcano looking) Medium size, violent eruptions, andesitic lava, combination of flows and pyroclastic eruptions, ex: Mt. St. Helens

  16. Mt. St. Helens Before & After

  17. Igneous Activity • Plutons (intrusive igneous bodies) • Classified by shape, size, and relationship to surrounding rock layers • Sill – horizontal and between rock layers • Dike – vertical and cut across rock layers • Laccolith – dome/mushroom shaped plutons • Batholith – more than 100 km2 of exposed rock • Stock – less than 100 km2 of exposed rock

  18. Volcano Dangers • Pyroclastic flows – hot gases, glowing ash, and larger rock fragments • Very hot (like cook your butt hot) • Can attain 200 km/hr • Lahars – mudflow formed from volcanic ash and water (melted snow or rain) • Eruptions – you’re there one minute and gone the next…can you say vaporized

  19. Origin of Magma • Read pages 291 – 292 • The role of heat • The role of pressure • The role of water

  20. Volcano Locations • Convergent plates • Subducting plate melts and magma rises • Japan and Mt St Helens • Divergent plates • Plate diverge and magma rises through the rift • Mid-ocean ridge • Iceland • East African Rift • Intraplate (hot spots) • Mantle plume rises towards the surface • Hawaii and Yellowstone

More Related