1 / 32

8.2 Volcanic Eruptions

8.2 Volcanic Eruptions. Where the rock cycle begins. Learning Targets. Compare the types of volcanic eruptions Describe a method for predicting volcanic eruptions. Volcanic Eruption. Magma collects in magma chamber Hot magma expands  creates pressure

lyneth
Télécharger la présentation

8.2 Volcanic Eruptions

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. 8.2 Volcanic Eruptions Where the rock cycle begins

  2. Learning Targets • Compare the types of volcanic eruptions • Describe a method for predicting volcanic eruptions

  3. Volcanic Eruption • Magma collects in magma chamber • Hot magma expands creates pressure • Vent: crack in the earth’s surface • Magma moving through vent = eruption

  4. How do volcanoes erupt? • Types of eruptions: • Explosive • Non-explosive; effusive

  5. Explosive Eruptions • Can be 1000 times more powerful than atomic bomb • Pressure builds as gases in magma expand

  6. Explosive Eruptions • Explosion shoots ash and gas high in the air • Heavy debris falls; light debris may float around for years • Why is ash and gas in the air important? • Blocks sunlight, produces poisonous gas, mixes with water to form acid, global climate change

  7. Explosive Eruptions • Some magma crystallizes in the air • Called pyroclastic material: ash, lapilli, bomb • Can come down miles from the volcano

  8. Non-explosive eruptions • Another name for non-explosive eruptions • Effusive eruptions • Different mix of mineralsin magma • No gas build up • Less dangerous but lava flows are consistent and unstoppable

  9. Magma Formation • What causes magma to form • High heat • Hot Spots; effusive • Decreased pressure • Divergent boundaries; effusive • Increased water content • Subduction zones; explosive

  10. Lava - Viscosity • Viscosity: Resistance to flow • Honey, ketchup, water • High viscosity • High silica content • Explosiveeruptions  pressure • Low viscosity • Low silica content • Effusiveeruptions  no pressure

  11. Lava formations • Explosivelava  Pyroclastic material • Pyroclast – lava solidifies in the atmosphere • Pyroclastic flow – fast moving current of superheated gas and rock • Can move hundreds of miles per hour • Effusivelava • A’a: jagged, gravelly texture • Pahoehoe: smooth, even lava flow • Pillow lava: cools underwater forms rounded lobes

  12. Predicting Eruptions • History of eruption • Active, dormant, extinct • Earthquakes • Pressureof magma causes earthquakes • Slope deformation • Plastic deformation due to pressure • Gas emissions • Gas escapes before magma

  13. 5. Remote Monitoring

More Related