Volcanism

• Volcanism


  Volcanic processes and phenomena
• Eruptive products

  • Lava
  • Pyroclast
  • Volcanic gases
• Volcano morphology

  • Shield volcano
  • Stratovolcano
  • Monogenetic cones
  • Dome
  • Caldera
• Effusive eruption


  Lava effusively erupted by a volcano
• Explosive eruption

  Pyroclastic (rock & glass fragments) material explosively erupted by a volcano
• Volcanic Explosivity Index (VEI)


  Used to describe the explosivity of an eruption, taking into account observable & measurable parameters such as the amount of tephra ejected and eruption cloud height
• Dense Rock Equivalent (DRE)


  Characterizes the size of an eruption by taking into account the amount of erupted magma, both effusively and explosively, from volume estimates of erupted products (lava and/or tephra)
• Eruption types


  • Magmatic
  • Phreatic
  • Phreatomagmatic
• Magmatic eruption

  Eruption driven by the overpressure created by volcanic gases exsolving from magma
• Phreatic eruption

  Eruption caused when surface/near-surface water is heated by magma, hot rocks, or hot volcanic deposits, resulting in sudden increase in pressure driving the eruption of water vapor, tephra, but no lava
• Phreatomagmatic eruption

  Explosive eruption generated by the interaction of magma with abundant surface water, resulting in the eruption of water vapor, pyroclasts (from magma and/or surrounding rocks) as well as lava
• Lava

  • Lava flows
  • Lava fountains
• Lava types

  • Pahoehoe
  • A'a
  • Pillow
• A volcano is a vent, hill or mountain from which molten or hot rocks with gaseous material have been ejected, and can also be craters, depressions, hills or mountains formed by removal of pre-existing material or by accumulation of ejected materials
• pahoehoe lava -- fluid, rope-like
• A'a lava -- slower, cooler, lava; chunky appearance
• pillow lava -- occurs in underwater eruptions
• shield volcano

  • flat, gentle slope
  • mafic material: fluid, flows faster = flatter shape
• stratovolcano

  • releases alternating types of lava
• monogenetic cones

  • different vents, same origin
• dome

  • releases viscous lava
  • lava gets stuck in the opening, leading to an increase in pressure
• caldera

  • basin-like depression due to collaps of previous volcano