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Tectonic Hazards

This topic covers tectonic plates and how they move, the three types of plate margin (destructive, constructive and conservative), how volcanoes and earthquakes form, the effects of tectonic hazards in countries of contrasting wealth (New Zealand 2016 and Nepal 2015), why people live in hazardous areas, and how tectonic hazards can be managed through monitoring, prediction, protection and planning.

The Earth's surface is made of huge floating plates that are constantly moving. Rock on. The Earth's Surface is Separated into Tectonic Plates: 1) The Earth's crust (its outer layer) is divided into slabs called tectonic plates that float on the mantle (a layer of semi-molten rock). 2) Plates are made of 2 types of crust: - Continental crust is thicker (30-50 km) and less dense. - Oceanic crust is thinner (5-10 km) and more dense. 3) The plates are moving because of convection currents in the mantle. 4) The places where plates meet are called plate margins or plate boundaries.

Key Terms

Tectonic plates — Slabs of the Earth's crust that float on the mantle and are constantly moving.
Continental crust — Thicker (30-50 km) and less dense type of crust.
Oceanic crust — Thinner (5-10 km) and more dense type of crust.
Convection currents — Currents in the mantle that cause the tectonic plates to move.
Plate margins — The places where tectonic plates meet, also called plate boundaries.

World Map of Tectonic Plates

North AmericanPlateSouth AmericanPlateEurasian PlateAfrican PlateIndo-AustralianAntarctic PlatePacificPlateNazcaPlatePlate boundariesPlate movement

Case Studies

Exam Tips

  • •Make sure you understand tectonic plates and the different boundaries that they can create, or you'll really struggle to work constructively through the rest of the section. Sketching diagrams can be useful.
  • •Explain how volcanoes form at destructive plate margins. [3 marks]
  • •Whether you've studied earthquakes or volcanic eruptions, make sure you know the effects and responses for both a wealthier and a less wealthy country.
  • •It wasn't just lack of wealth that made Nepal more vulnerable than New Zealand -- it also has a much higher population density, so the risk was higher. Whichever examples you've studied, learn them well.
  • •Make sure you know how monitoring, prediction, protection and planning can help to reduce the risks from earthquakes and volcanoes. It's easy to get them muddled up, so try writing out a few points from each box.