Vocabulary and Summary

Vocabulary

  1. active volcano: Volcano that is currently erupting or is just about to erupt.

  2. dormant volcano: Volcano that is not currently erupting but has erupted in the recent past.

  3. extinct volcano: Volcano that has not erupted in recorded history and is unlikely to erupt again.

  4. magma chamber: Region below a volcano where magma and gases collect.

  5. viscosity: Thickness of a liquid; its resistance to flow.

Summary

  • Volcanoes are located along convergent and divergent plate boundaries. They can be found in the middle of plates at hot spots.
  • Magma can be created when temperature rises, pressure lowers, or water is added.
  • Volcanoes may be active, dormant, or extinct. This depends on whether there is the possibility of magma in their magma chambers.
  • Magmas differ in composition, which affects viscosity. Magma composition has a large effect on how a volcano erupts.
  • Felsic lavas are more viscous and erupt explosively or do not erupt. Mafic lavas are less viscous and erupt effusively.
  • Different lava types create different rock types, such as pahoehoe and a'a. Lavas that cool underwater become pillow lavas.

CK-12 Foundation, Earth Science. http://creativecommons.org/licenses/by-nc-sa/3.0/