Volcano

• Diastrophism


  Horizontal and vertical movement of the crust
• Erosion


  Physical removal of rock due to running water, glacial ice and wind or changes in ground water
• Volcanism


  Phenomenon related to various processes associated with surface discharge of magma or hot water
• Volcano


  An opening in Earth's crust through which molten rock, rock fragments, and hot gases erupt
• Magma


  Liquid rock
• Lava


  Molten rock that has emerged at the surface
• Features of a Volcano

  • Cone
  • Vent
  • Magma chamber
  • Crater
  • Caldera
  • Sills
  • Dikes
  • Conduit
  • Flank
  • Summit
  • Throat
  • Ash cloud
  • Volcanic Bombs/lapilli
  • Tephra fall
  • Pyroclastic flow
  • Lahar
• Plate boundaries


  Where most volcanoes form
• Where volcanoes occur


  • Subduction zones
  • Over hot spots
  • Where plates are pulling apart
• Water Vapor


  More water=bigger explosion
• Trapped gases (water and CO2)

  Easy escape (low pressure)=quiet eruption, Difficult to escape (high pressure)=explosive/violent eruption
• Magma Type


  Basaltic (thin) =quiet eruption, Granitic(Rhyolitic)/Andesitic (thick)=violent eruption
• Pyroclastic flow


  Fast moving current of hot gases and rock traveling downhill from a volcano
• Pahoehoe


  Lava that forms a ropelike structure as it cools
• Aa


  Lava that forms a stiff, slowly moving flow
• Volcanoes with basaltic lava


  • Hawaiian Volcanoes, including Kilauea and Mona Loa
  • Iceland, including Heimaey and Hekla
• Volcanoes with granitic lava


  • Yellowstone Caldera
  • Katmai, Alaska
• If the Yellowstone Caldera had erupted in a populated area, it would have had catastrophic consequences
• Volcanoes with andesitic lava

  • Mount Pelee, Martinique
  • Mayon, Philippines
• Shield Volcano


  Formed by quiet eruptions, slow-moving lava flows, basaltic lava builds up in flat layers, largest with gently sloping sides
• Shield Volcanoes


  • Mauna Loa
  • Mt. Kilauea
• Cinder Cone Volcano


  Caused by explosive eruptions, granitic lava thrown high into the air, lava cools into different sizes of volcanic material called tephra, steep-sided, loose slopes
• Cinder Cone Volcano


  • Parícutin Volcano in Mexico
• Composite Volcano


  A mix of the other two types, can be quiet or violent, can have basaltic or granitic lava, can have steep or gentle slopes, layered of tephra
• Scientists monitor volcanoes to look for warning signs that an eruption may be coming, including earthquakes, changes in ground tilt, rising temperatures, and changes in volcanic gases
• Caldera


  A huge crater formed by the collapse of the volcano when magma rapidly erupts from underneath it
• How volcanic eruptions affect Earth

  • Land: Lava, Landslides (can cause tsunamis), Mudflows
  • Air: Poisonous Gases, Volcanic Ash, Haze
  • Water: Hot Springs, Geysers, Fumaroles, Deep-Sea Vents
• There can be benefits from volcanic eruptions, such as richer farmland and beautiful landscapes
• Yellowstone Park supervolcano eruptions

  2.4 million and 640,000 years ago
• Life Cycle of a Volcano


  • Active
  • Dormant
  • Extinct