Unit 5 volcaneos

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Cheetah13
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296320
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Unit 5 volcaneos
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2015-02-19 17:15:28
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geology volcaneos
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Test 2
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geo
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  1. Most volcanic activity occurs at what plate boundaries?
    subduction zones and divergent boundaries
  2. What is intraplate volcanic activity?
    occurs far from plate boundaries and is the result of plates moving over mantle hot spots
  3. Name 2 examples of intraplate volcanic activity (one oceanic and one continental)
    • *Hawaiian islands is an oceanic plate over hotspot
    • *Yellowstone is a continental plate over hotspot
  4. Define volcano
    a hill or mountain formed around a vent as a result of eruption of lava and pyroclastic material
  5. Define volcanism
    the process whereby magma and its associated gases arise through the crust and are extruded onto the surface or into the atomosphere
  6. Define volcanic ash
    pyroclastic materials (particles) that measure less then 2mm
  7. Name the types of volcanic activity
    • *Fissure eruptions
    • *central point eruptions
  8. What are fissure eruptions?
    lava pours out of an elongated fissures, flooding large areas (e.g. mid ocean ridges)
  9. What causes fissure eruptions?
    stretching of the athenosphere
  10. What are central point eruptions?
    magma comes out of centralized areas, materials piles up around this area to form a cone shaped volcano
  11. What is a flood basalt?
    lava flows that pours out of fissures (low silica basalt magma) forms thick layers of basalt rock can cause waterfalls
  12. What is a basalt plateau?
    large area covered with flood basalts can cause waterfalls
  13. What are lava flows?
    Lava flows are relatively quiescent movement of magma over land surface
  14. What are the two types of eruptive styles for volcanoes?
    • *lava flows
    • *explosive eruption
  15. What does eruptive style depend on?
    • *composition
    • *temperature
    • *gas content
  16. increase in temperature results in ____ viscosity of the magma
    low
  17. A decrease in temperature results in ____ viscosity of the magma
    high
  18. If magma is low in silca it can glow more readily causing _________
    Lava flows
  19. If higher silca magma are sticky and do NOT flow readily gases are trapped in magma chamber building pressure untili an ______ occurs.
    explosive eruption
  20. If higher siilca magma are sticky and do not flow readily gases are trapped in magma chamber building pressure until an explosive eruption occurs.

    True or False
    True
  21. If higher siilca magma are sticky and do flow readily gases are trapped in magma chamber building pressure until an explosive eruption occurs.
    False
  22. Name 2 types of high silica magma
    Andesite or Rhyolite
  23. Name a low silica magma
    Basalt
  24. Name 2 types of Lava flow textures
    Pahoehoe and Aa
  25. What is pahoehoe?
    a type of lava flow with a smooth ropy surface
  26. How does pahoehoe form?
    as lava flows the top of the flow cools off forming a crust that gets rumpled as lava below continues to flow
  27. What is Aa?
    a type of lava flow with a surface of rough, angular blocks and fragments
  28. How does aa form?
    If chunks cool and drop from flow they create a surface covered by jagged blocks
  29. what does pyrcolastic mean?
    materials blown out of a volcano
  30. Name the types of textures  of volcanic rocks
    Lava flow texture and Pyroclastic texture
  31. Name two types of pyroclastic textures
    Tephra and tuff
  32. What is tephra?
    accumulations of pyroclastic material (ash, cinders, bombs)
  33. What is tuff?
    lithified air-tephra (rock with pyroclastic texture)
  34. Name the types of volcanoes
    • Shield volcanoes
    • Composite volcanoes
    • cinder cones
  35. How are volcanoes classified?
    by size and shape
  36. How can volcanoes affect climate?
    In order for climate to be affected a large eruption of volcanic ash (particles) must aerosoal going straight up to earth's atmosphere blocking solar radiation cooling the earth for 1-2 years. (e.g mt. st. helens)
  37. Fissure eruptions happen at __________ and sometimes on flanks of _______ volcanoes and on hot-spots occasionally.

    A) divergent boundaries; shield 
    B) divergent boundaries; composite
    C) convergent boundaries; composite
    D) convergent boundaries; shield
    A) divergent boundaries; shield
    (this multiple choice question has been scrambled)
  38. What is the shape of a volcano dependent on?
    Shape is dependent on whether cone is built from lava flows, pyroclastic material or both
  39. What is a shield volcano?
    a dome shaped volcano with low, rounded profile built up mostly by overlapping basalt lava flows
  40. If a volcano showed characteristics of lava flow, low silica magma, and a big Arial extent what kind of volcano would it be

    A) composite
    B) shield
    C) cinder cone
    d) any of the above
    B) shield
    (this multiple choice question has been scrambled)
  41. What is a composite volcano?
    A volcano composed of lava flows & pyroclastic layers, typically of intermediate composition and mudflows
  42. If a volcano showed characteristics of steep sides, andesitic to rhyolitic magma, and has evidence of lava flows and pyroclastic deposits

    A) composite
    B) cinder cone
    C) shield
    d) any of the above
    A) composite
    (this multiple choice question has been scrambled)
  43. Name an example of a shield volcano
    Hawaiian Island volcaneos are shield volcanoes
  44. Name an example of a composite volcano
    Mt hood- cascade is an example of a composite volcano
  45. What are cinder cones?
    A cinder cone is a small, steep sided volcano made up of pyroclastic materials resembling cinders that accumulate around a vent
  46. If a volcano showed characteristics of small steep sided made entirely of pyroclastic deposits and formed on a flank 

    A) shield
    B) cinder cone
    C) composite
    d) any of the above
    B) cinder cone
    (this multiple choice question has been scrambled)
  47. Name an example of cinder cones
    Mt Kilauea Lki eruption in 1959
  48. In what plate tectonic settings will we find composite volcanoes?
    Most composite volcanoes are going to be at convergent sub-duction zones
  49. In what plate tectonic settings will we find shield volcanoes?
    Most shield volcanoes are a result of hotspot volcanism
  50. In what plate tectonic settings will we find lava plains?
    Most lava plains are most common at divergent boundaries
  51. what are calderas?
    depressions formed by explosive collapse of volcano
  52. What is a geyser?
    water & steam shoot out due to build up of pressure from steam
  53. What is a hot spring?
    hot groundwater discharged at surface
  54. Name an example where one can find geysers and hot springs
    Yellowstones "Old Faithful"
  55. how are geysers and hot springs related to volcanic activity?
    Magma is so close to underground water that the resultant boiling of the pressurized water reaches a point of exploding
  56. how does lava flow happen and what threats do they pose to people or property?
    Lava flows occur during an eruption and are slow but can burn people, land and destroy property
  57. how does pyroclastic flows happen and what threats do they pose to people or property?
    Pyroclastic flow is a mixture of hot gas & ash that can flow rapidly down sides of volcano up to 60+ mph and can be very deadly
  58. how does ash fall happen and what threats do they pose to people or property?
    Ash fall happens during an eruption and can cause breathing problems and difficulty seeing.
  59. how does lahars (mudflows) happen and what threats do they pose to people or property?
    Lahars are the result of melting snow moving with fine grains creating a mudflow can bury people alive and destroy homes
  60. how does earthquakes happen and what threats do they pose to people or property?
    Earth activity occurs as magma shifts at the subsurface and are a warning sign of the volcano. Can destroy property if earthquake is deep enough
  61. how does poisonous gases happen and what threats do they pose to people or property?
    Poisonous gases may seep to surface as a warning sign and contaminate water/air with hyrdomonoxide, sulfer, and even hydrodioxide usually a warning signing of eruption
  62. Can volcanic eruptions always be predicted?
    NO
  63. Can eruptions and associated phenomena be controlled?
    Protecting life and property requires accurate forecasting of eruption and adhering to warning signs

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