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Volcano Notes

Volcano Notes . 1. What is a volcano . A volcano is a weak spot in the earth’s crust where molten material or magma comes to the surface. . 2. What is Magma. Magma is a molten mixture of rock-forming substances, gases, and water from the mantle. . 3. What is Lava.

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Volcano Notes

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  1. Volcano Notes

  2. 1. What is a volcano • A volcano is a weak spot in the earth’s crust where molten material or magma comes to the surface.

  3. 2. What is Magma • Magma is a molten mixture of rock-forming substances, gases, and water from the mantle.

  4. 3. What is Lava • When magma reaches the surface, it is called lava. Lava cools to form solid rock.

  5. http://app.discoveryeducation.com/techbook2:concept/view/guidConceptId/607573de-6480-444f-aaab-209861cd9b7e/guidUnitId/a6581044-b1e8-4f89-b8d0-77c279cfc175#/tab=model-lesson-tab&page=1&subTab=de-resourceshttp://app.discoveryeducation.com/techbook2:concept/view/guidConceptId/607573de-6480-444f-aaab-209861cd9b7e/guidUnitId/a6581044-b1e8-4f89-b8d0-77c279cfc175#/tab=model-lesson-tab&page=1&subTab=de-resources

  6. 4. Where are volcano’s located? • Most volcanoes occur along divergent plate boundaries, such as the mid-ocean ridge, or in subduction zones around the edges of oceans.

  7. Active volcanos

  8. 5. What are Island Arcs? • When 2 oceanic plates collide, one subducts beneath the other, creating a deep ocean trench and a string of islands called island arcs. ( The Aleutians are an examples)

  9. 6. What are hot spots? • An area where magma from deep within the mantle melts through the crust, far from plate boundaries (Hawaii is an example)

  10. Hot spot volcanoes • Mantle plume theory says that fountains of magma from the core erupt through the crust as the tectonic plate drifts over them, leaving volcanic trails such as the Hawaiian Islands

  11. 7. Why do volcanoes erupt? • As magma rises from the mantle, pressure decrases. The dissolved gases begin to separate out forming bubbles. A volcano erupts when an opening develops in weak rock on the surface. During a volcanic eruption, the gases and the magma rush out.

  12. A shaken bottle of Coke reacts the same way. CO2 is dissolved in the liquid. Gases are released explosively when the bottle is opened. (pressure released)

  13. 9. Characteristics of magma • Silica content determines how easily magma flows • High in silica makes light colored lava that is very thick, sticky, and doesn’t move very far • Low in silica makes dark colored lava that flows easily.

  14. 10. Types of eruptions • A. Quiet Eruptions- a volcano erupts quietly if the magma flows easily and the gases bubble gently (Hawaii) • Quiet Eruptions production 2 types of lava. • Pahoehoe: fast moving hot lava • Aa: cooler, slower moving lava

  15. 10. Types of eruptions • B. Explosive: results from thick, sticky magma. Gases build pressure until they explode. • Explosion breaks lava into fragments. Size range from ash to cinders( pebbles) and bombs (baseball to a car) • Pyroclastic flow- an explosive eruption that hurls out ash, cinders, and bombs as well as hot gases.

  16. 11. Stages of a volcano • A. Active or live: a volcano that is erupting or has shown signs that is may erupt in the near future • B. Dormant or sleeping: currently inactive, but may be thousands of years between eruptions • C. Extinct or dead: unlikely to erupt again.

  17. 12. Monitoring volcano's • Scientist use tiltmeters, laser-ranging devices, and other instruments to monitor surface changes. • Seismographs monitor movement of magma into the magma chamber and through the volcano's pipe

  18. 13. Types of volcano’s • A. Shield- Repeated lava flows during quiet eruptions gradually building up a broad, gentle sloping volcanic mountain

  19. 13. Types of volcano’s • B. Cinder Cone: Cinders erupt explosively from a volcanic vent, they pile up around the vent forming the cone shaped hill.

  20. 13. Types of volcano’s • C. Composite: Layers of lava alternate with layers of ash, cinders, and bombs ( has had both quiet and explosive eruptions)

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