VOLCANISM

• Volcano: a rupture on the earth's surface where molten rocks, smoke, hot gases, and ashes are ejected
• Crater: a funnel-shaped opening located at the top of the volcano
• Caldera: formed when the wall of the volcano collapses, followed by an explosive eruption
• Classification of Volcanoes:

  • According to record of eruption:
  • Active: volcanoes that erupted 10,000 years ago
  • Inactive: volcanoes with no eruption for the last 10,000 years
  • According to shape of their cone:
  • Shield volcano: known for its low profile, broad and slightly domed structure
  • Cinder cone volcano: characterized by steep slopes and a wide crater
  • Composite Cone Volcano: large and described as having a nearly perfect sloped structure
• Dormant volcano: one type of active volcano which is not erupting but is likely to erupt again
• Magma: extremely hot liquid positioned under the surface of the earth
• Viscosity: liquid resistance to flow

  • High viscosity: lava flows slowly
  • Low viscosity: lava flows faster