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Volcanoes

A volcano is an opening in the Earth's crust that is formed when magma rises from inside the Earth and erupts through the Earth's crust. Volcanoes can be formed at constructive plate margins and destructive plate margins.

Destructive plate margins

Destructive plate margins

  • The denser oceanic plate is forced under the continental plate at destructive margins.
  • The friction and pressure cause cracks (vents) to form in the continental plate. The magma rises to the surface of the Earth through the cracks in the continental plate.
  • This usually creates highly explosive volcanoes (e.g. Mount Vesuvius in Italy) that produce a lot of gas and lava (magma above the surface).
Constructive plate margins

Constructive plate margins

  • At constructive plate margins:
    • Tectonic plates move apart (diverge) because the convection currents in the mantle diverge, creating outward pressure.
  • Magma bubbles up to fill the gap between the plates, creating a volcano.
  • This kind of volcano is common in Iceland.
Hotspots

Hotspots

  • Hotspots do not happen at plate boundaries. But they still count as volcanic activity.
  • Hotspots happen on parts of the Earth's crust over hotter parts of the Earth's mantle.
  • The rising hot air weakens the Earth's crust and magma can reach the surface, bubbling up through the weakness in the crust.
  • The Hawaiian islands all formed as a result of a mid-Pacific hotspot.
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The Challenge of Natural Hazards

1.1

Natural Hazards

1.2

Tectonic Hazards

1.3

Weather Hazards

1.4

Climate Change

2

The Living World

2.1

Ecosystems

2.2

Tropical Rainforests

2.3

Hot Deserts

2.4

Tundra & Polar Environments

3

Physical Landscapes in the UK

3.1

The UK Physical Landscape

3.2

Coastal Landscapes in the UK

3.3

River Landscapes in the UK

3.4

Glacial Landscapes in the UK

4

Urban Issues & Challenges

5

The Changing Economic World

5.1

The Changing Economic World

5.2

Economic Development in the UK

6

The Challenge of Resource Management

6.1

Resource Management

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Food

6.3

Water

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Energy

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