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VOLCANOES PowerPoint Presentation

VOLCANOES

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VOLCANOES

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  1. VOLCANOES

  2. Formation • Magma is forced upward flows out of an opening in crust

  3. Parts of a Volcano

  4. Parts • Vents –areas from which lava flows • Crater – bowl shaped dent where vent is located

  5. Parts Gas- most common steam, carbon dioxide, sulfur dioxide Lava- molten rock on surface Ash- VERY small rock , minerals, volcanic glass less than 2 mm

  6. Parts • Conduit - a pipe that extends from magma chamber to vent • Magma chamber – area where magma is stored until it erupts

  7. LOCATION • Divergent boundaries • Convergent boundaries • Hot spots

  8. Divergent Boundaries • Plates move apart forming rifts • Lava flows forms rifts & cools quickly by seawater • Keeps building until it rises above sea level

  9. Iceland

  10. Surtsey

  11. Convergent Boundaries • Plates move together (collide) • Oceanic slide under continental • Older oceanic under younger oceanic • Plate melts down to form magma • Then forced upward

  12. Andes Mountains Chile Ecuador

  13. Cascade Mountains Mt. Rainier Mt. St. Helens

  14. Hot Spots • Magma burns through crust • NOT near a boundary

  15. Hawaiian Shield Volcano

  16. Lava Flowing Into the Pacific

  17. Galapagos Islands-Shield Volcanoes

  18. Factors that control type of eruption • Trapped gases • water vapor, carbon dioxide, sulfur dioxide • Composition of Magma

  19. Factors that control type of eruption Trapped gases (water vapor, carbon dioxide, sulfur dioxide Composition of Magma Low silica basaltic magma quiet eruption • Gases can escape easily less pressure quiet eruption

  20. Factors that control type of eruption Trapped gases (water vapor, carbon dioxide, sulfur dioxide Silica rich rhyolitic magma explosive eruption Composition of Magma • Gases build up to high pressure explosive eruptions

  21. Eruption Products Pyroclasts

  22. Eruption Products • Pyroclastics (broken pieces of volcanic rock)- tephra Ash Bombs Cinders Blocks

  23. Eruption Products Pahoehoe • Lava Aa Pillow

  24. Eruption Products • Gases • Water • Carbon dioxide • Sulfur dioxide

  25. Types of Volcanoes • Shield volcano • Quiet eruptions • Basaltic magma • Fast moving lava • Very large • Broad gentle slope • Can erupt hundreds of feet into air  fountains • Kilauea

  26. Types of Volcanoes • Composite (Stratovolcanoes) • Explosive eruptions • Andesitic or rhyolitic magma • Can switch from quiet to explosive forming layers of tephra and lava • Steep sided • Tall • Mt. St. Helens

  27. Types of Volcanoes • Cinder cone volcano • Explosive eruptions • Small in size • Steep sided loosely packed • Short lived • Paricutin

  28. Classification of volcanoes • Active- currently active or erupted in recorded history Kilauea

  29. Classification of volcanoes • Dormant –“resting“ not currently erupting but likely to do so Mt. Hood, Oregon

  30. Classification of volcanoes • Extinct –not erupted in recorded history and are not expected to erupt again Mount Kilimanjaro

  31. Kinds of Volcanic Eruptions • Hawaiian • Quiet • Very fluid lava • Little explosive activity

  32. Kinds of Volcanic Eruptions • Strombolian • small amounts of lava in very short bursts • impressive booming sounds, but the eruptions are relatively small • tephra

  33. Kinds of Volcanic Eruptions • Vulcanian • short, violent, small explosion • tephra, ash clouds, and pyroclastic flows Santiaguito volcano in Guatemala

  34. Kinds of Volcanic Eruptions • Pelean • large quantity of gas, dust, ash and lava fragments • pyroclastic flows • one of the most dangerous - tremendous destruction Mont Pelee

  35. Kinds of Volcanic Eruptions • Plinian • largest and most violent • propels pyroclastic material as high as 30 miles • huge amount of tephra • extremely fast moving lava Mt. St. Helens

  36. Effects of Eruptions • Lava • Destroys whatever is in its path • Usually not harmful to humans

  37. Effects of Eruptions • Gas • Some are poisonous • Acid rain

  38. CAMEROONS… Africa carbon dioxide poisoning Sulfur banks

  39. Effects of Eruptions • Pyroclastics • Collapse buildings • Breathing problems • Kills vegetation • Suffocates and buries animals & people

  40. Effects of Eruptions • Pyroclastic flow • Superheated gas and debris rush down side of volcano • faster than 700 km/hour, higher than 1000 degrees C