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Year 8 - Geography

Volcanic hazards

Tectonic hazards: Why is Earth restless?

Unit Summary

This unit teaches pupils about the physical processes that lead to tectonic hazards and investigates the geographical pattern of hazards across the world. Pupils will also learn how tectonic hazards affect people in different places and how people seek to manage hazards.

Lesson Summary

You will learn to explain what pyroclastic flows, ash and lahars are and relate this to real life examples.

Key Notes

  • Volcanic eruptions can lead to a range of hazards, such as pyroclastic flows, ash and lahars.
  • Pyroclastic flows are flows of hot volcanic gases, ash and rock.
  • Ash is made up of tiny pieces of volcanic rock and glass, this can damage lungs, machines, crops and buildings.
  • Lahars are mudflows caused by volcanic material mixed with water.
  • Mount Semeru (Java, Indonesia) erupted in 2021, triggering damaging pyroclastic flows, ashfall and lahars.

Vocabulary To Learn

  • pyroclastic flow: a very hot mix of lava, ash, gases and rock that flows rapidly down the side of the volcano
  • ash: tiny pieces of volcanic rock and glass
  • lahar: a mudflow formed when volcanic ash mixes with water
  • infrastructure: all the basic systems in a country, such as transport and power supply

Common Mistakes To Avoid

  • Lava is the only dangerous aspect to a volcanic eruption and you can just run out of the way.

3 Quick Questions (With Answers)

1. Explain this geography topic using two clear key points.

Volcanic eruptions can lead to a range of hazards, such as pyroclastic flows, ash and lahars. Pyroclastic flows are flows of hot volcanic gases, ash and rock.

2. Define this geography term and use it in an example. 'pyroclastic flow'

a very hot mix of lava, ash, gases and rock that flows rapidly down the side of the volcano.

3. Correct this common geography misunderstanding.

Mistake: Lava is the only dangerous aspect to a volcanic eruption and you can just run out of the way. Correction: Ash, lahars and pyroclastic flows are all extremely dangerous volcanic hazards. Pyroclastic flows can reach speeds of 435 mph, which is faster than a car.

More Lessons In This Unit

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