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Volcanic Hazards

Volcanic Hazards. Lava or Pyroclasts. Magma. Hotter. T=1,020°C. T=1,100°C. SOLIDUS. T=1,180°C. T=1,210°C. LIQUIDUS. T=1,020°C. Subduction zone. Transform Boundary. ???. Divergent Boundary. Volcanoes occur:. Above subduction zones At divergent boundaries At hot spots.

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Volcanic Hazards

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  1. Volcanic Hazards

  2. Lava or Pyroclasts Magma

  3. Hotter T=1,020°C T=1,100°C SOLIDUS T=1,180°C T=1,210°C LIQUIDUS

  4. T=1,020°C

  5. Subduction zone Transform Boundary ??? Divergent Boundary

  6. Volcanoes occur: • Above subduction zones • At divergent boundaries • At hot spots

  7. Decompression melting

  8. Hydration melting Subduction Zone Ice  WaterIce + Salt  Salty water

  9. Olivine + H2O  Serpentine Serpentine  Olivine + H2O

  10. Insert subduction zone melting cross-section here

  11. Main ways to melt rock: • Decompression melting • Hydration melting

  12. All 3 ways rocks melt: • Decompression melting • Hydration melting • Heat transfer melting

  13. Heat-transfer melting

  14. Hydration melting Subduction Zone Decompression melting

  15. Heat-transfer melting

  16. Magma Chamber

  17. Eruption depends on: • Volatiles • Viscosity of Magma

  18. Oversaturated Saturated Undersaturated

  19. Bubble Formation:

  20. Fate of Bubbles • Ability to expand • Ability to rise

  21. Boyle’s Law:P × V = Constant

  22. Stokes Law:velocity depends on 1/μ

  23. Eruption depends on: • Volatiles • Viscosity of Magma

  24. Three controls on viscosity: • Temperature • Si concentration • (Volatiles)

  25. Mt. Pinatubo, Phillipines, 1991 Mt. Etna, 2002

  26. Kilauea, Hawaii, 1983 Mt. Etna, 2006

  27. Mauna Loa, Hawaii, 1960 Mt. Etna, 2006

  28. Mt. Unzen, Japan, 1990 Oozing lava

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