Magmas and Volcanoes

  1. What are the three types of volcanoes?
    • Shield volcanoes
    • Tephra cones
    • Stratovolcanoes
  2. What does a Shield volcano look like?
    • Broad
    • Dome shaped
    • Gentle slopes
    • HUGE

    Image Upload 1
  3. What composition does a Shield volcano have?
  4. What kind of flow does a shield volcano have?
  5. What does a Stratovolcano look like?
    • Large
    • Steep

    Image Upload 2
  6. What kind of flow does a Stratavolcano have?
    Pyroclastic and Lava
  7. What composition does a Stratovolcano have?
  8. What does a Tephra cone look like?
    • Small
    • formed from pyroclastic debris around a vent
    • magma is gas rich

    Image Upload 3
  9. What composition does a Tephra cone have?
  10. What flow does a Tephra cone have?
  11. What are craters?
    Depressions near summit from which volcanic materials are ejected
  12. What are Lava Domes?
    Late-stage, very viscous lava extruded after most gas exsolved
  13. What are calderas?
    • Circular, steep walled basins >1km in diameter near summit
    • HUGE
  14. What is a Resurgent dome?
    • Due to uplift of caldera
    • also small tephra cones/lava flows
  15. What are Diatremes?
    Volcanic pipes filled with rubble of broken rock
  16. Is all lava erupted from volcanoes?
  17. What are Fissure Eruptions?
    • Extrusion of basaltic lava along elongate fractures
    • Image Upload 4
  18. What are Plateau basalts?
    Wide, flat plains produced by lavas from fissure eruptions
  19. What are Pillow basalts?
    Pillow shaped masses of basalt formed by submarine eruptions
  20. What are Ash Flows?
    • Andesitic or Rhyolitic magma
    • Less common than basalt
  21. What causes Thermal Springs?
    Ground water heated by hot rock in or near old magma bodies
  22. What is a Geyser?
    • Thermal spring that displays intermittent eruptions of water and steam
    • Pressure builds and water reaches above boiling point
  23. What are 5 Volcanic Hazards?
    • Pyroclastic flows
    • Burial and or suffocation from ash
    • Mudflows
    • Tsunami
    • Famine
  24. What is Magma?
    Molten Rock, together with any suspended mineral grains and dissolved gases, that forms by melting of rock in crust and mantle
  25. What is a Volcano?
    Vent from which magma and gases are erupted
  26. What is Lava?
    Magma that reaches earth's surface
  27. What is Magma made out of?
    • Si02¬†always predominant
    • Characterized by high Temperatures
  28. How hot is Magma?
    1000 - 1200 degrees Celsius
  29. What is Viscosity?
    The thickness of lava
  30. Higher temperature lava will have a ________ viscosity.
    • Lower
    • Runny
  31. Low temperature lava will have a _______ viscosity.
    • Higher
    • very viscous
  32. Lava that is High in Si02 will have a ______ viscosity.
    • High¬†
    • Thick
  33. Lava that is Lower in Si02 will have a ______ viscosity.
    • Low
    • Runny
  34. What is Pahoehoe?
    Smooth ropy-surfaced lava formed from very hot fluid lava
  35. What is Aa?
    Rubbly, rough-looking lava formed from cooler, very viscous lava
  36. What does lower density cause in magma?
    Slowly rise
  37. What are some examples of Nonexplosive volcanoes?
    • Lava fountain
    • Spatter cone
    • Lava Tube
    • Vesicles
  38. How does a Lava fountain form?
    Forms when basaltic magma rises so rapidly that gas bubbles from solution
  39. How does a spatter cone form?
    Forms when bits of falling lava pile up beside the vent
  40. What are Lava tubes?
    Subsurface channels in Pahoehoe lava flows
  41. What is a Vesicle?
    • Gas bubble holes preserved in solidified rock
    • produces rocks with vesicular texture
  42. What are Amygdules?
    Vesicles filled by secondary minerals
  43. What type of Magma is explosive?
    Viscous Andesitic and Rhyolitic with high dissolved gas content
  44. What is Pumice?
    Froth of innumerable glass walled bubbles
  45. What is ash?
    Tiny fragments of shattered solidified magma
  46. What is a Eruption Column?
    Mixture of hot gas and tephra rising rapidly into the air
  47. What is Tephra fall?
    Rain of debris particles as eruption cloud drifts with upper winds
  48. What is a Pyroclastic flow?
    • Denser than air
    • mixture of hot gas and ash
    • fast and lethal
  49. What is Ignimbrite?
    Solidified deposit resulting from pyroclastic flow
  50. What is a Lateral Blast?
    Sideways eruption
Card Set
Magmas and Volcanoes
Magmas and Volcanoes