Plate Tectonics and Volcanoes

Plate Tectonics and Volcanoes

• Volcanoes are closely linked to plate tectonics, which is the movement of the Earth's lithosphere (outer layer)
• There are three main types of plate boundaries:
  • Divergent: where plates move apart, new crust is formed, and volcanoes are common (e.g. mid-ocean ridges)
  • Convergent: where plates move towards each other, subduction occurs, and volcanoes are also common (e.g. Andean mountain building)
  • Transform: where plates slide past each other, few volcanoes occur (e.g. San Andreas Fault)

Types of Eruptions

• Volcanic eruptions can be classified into several types based on the intensity and style of eruption:
  • Explosive eruptions: violent, sudden release of gases and rock, often producing pyroclastic flows and ash clouds (e.g. Mount St. Helens)
  • Effusive eruptions: gentle, continuous flow of lava from a volcano, often producing shield volcanoes (e.g. Hawaiian Islands)
  • Vulcanian eruptions: moderate-sized eruptions with a mix of explosive and effusive characteristics
  • Phreatomagmatic eruptions: interaction between magma and water, producing a violent explosion (e.g. Krakatau)

Volcanic Rocks

• Volcanic rocks are formed from the cooling and solidification of magma or lava:
  • Igneous rocks: classified as intrusive (formed below the surface) or extrusive (formed above the surface)
  • Common types of volcanic rocks:
    • Basalt: dark-colored, fine-grained, and common in shield volcanoes
    • Andesite: intermediate-colored, medium-grained, and common in stratovolcanoes
    • Rhyolite: light-colored, coarse-grained, and common in continental volcanoes

Volcanic Hazards

• Volcanic eruptions can pose several hazards to humans and the environment:
  • Pyroclastic flows: fast-moving, hot clouds of ash, gas, and rock that can be deadly and destructive
  • Lahars: mudflows or landslides caused by volcanic activity, often deadly and destructive
  • Ash fall: ash particles can affect air travel, agriculture, and human health
  • Lava flows: can cause damage to infrastructure and property
  • Volcanic gases: can be toxic and affect human health and the environment

Plate Tectonics and Volcanoes

• The Earth's lithosphere is broken into several large plates that move relative to each other, resulting in plate boundaries.
• There are three main types of plate boundaries: divergent, convergent, and transform.

Divergent Plate Boundaries

• Characterized by plates moving apart, resulting in the formation of new crust.
• Common features include mid-ocean ridges, volcanic activity, and the creation of shield volcanoes.

Convergent Plate Boundaries

• Characterized by plates moving towards each other, resulting in subduction and volcanic activity.
• Examples include Andean mountain building and the formation of stratovolcanoes.

Transform Plate Boundaries

• Characterized by plates sliding past each other, resulting in minimal volcanic activity.
• Examples include the San Andreas Fault.

Types of Volcanic Eruptions

• Explosive eruptions: characterized by a violent, sudden release of gases and rock, producing pyroclastic flows and ash clouds.
• Effusive eruptions: characterized by a gentle, continuous flow of lava from a volcano, producing shield volcanoes.
• Vulcanian eruptions: characterized by a mix of explosive and effusive characteristics.
• Phreatomagmatic eruptions: characterized by the interaction between magma and water, producing a violent explosion.

Volcanic Rocks

• Formed from the cooling and solidification of magma or lava.
• Classified as intrusive (formed below the surface) or extrusive (formed above the surface).

Types of Volcanic Rocks

• Basalt: dark-colored, fine-grained, and common in shield volcanoes.
• Andesite: intermediate-colored, medium-grained, and common in stratovolcanoes.
• Rhyolite: light-colored, coarse-grained, and common in continental volcanoes.

Volcanic Hazards

• Pyroclastic flows: fast-moving, hot clouds of ash, gas, and rock that can be deadly and destructive.
• Lahars: mudflows or landslides caused by volcanic activity, often deadly and destructive.
• Ash fall: ash particles can affect air travel, agriculture, and human health.
• Lava flows: can cause damage to infrastructure and property.
• Volcanic gases: can be toxic and affect human health and the environment.