Pearson Edexcel GCSE (9-1) Geography B (1GB0) · Spec 1.7, 1.8 and 1.9
Tectonic hazards
Read the notes, then try the questions. Each one is marked the moment you press Check, and shows the right answer and why.
Key ideas
- The Earth has a crust, a mantle and a core. The crust is the thinnest layer. Oceanic crust is thinner and denser than continental crust.
- Plates move because of convection in the mantle, ridge push and slab pull.
- At a constructive margin plates move apart and magma rises to make new crust. At a destructive margin a denser oceanic plate is subducted and melts, so explosive volcanoes form. At a conservative margin plates slide past each other and cause earthquakes.
- Shield volcanoes have runny lava and gentle slopes. Composite volcanoes have thick, sticky magma, steep slopes and explosive eruptions.
- Impacts and management are needed for a developed country and for a developing or emerging country. A rich country can still be badly hit, for example by a very large earthquake and tsunami.
Key terms
- Subduction
- A denser oceanic plate sinks beneath another plate at a destructive margin.
- Slab pull
- The weight of a sinking plate pulls the rest of the plate along behind it.
- Ridge push
- New crust at a ridge is higher and slides away, pushing the plate.
- Primary effect
- Damage caused directly by the hazard, such as collapsed buildings.
- Secondary effect
- Damage that follows later, such as fires, disease or lost jobs.
Common mistakes
- Saying earthquakes only happen at destructive margins. They also happen at conservative and constructive margins.
- Using a developing country as the example for a developed country. The tier of country matters.
- Saying rich countries are always well protected. Magnitude, location and tsunamis can still cause great harm.
Exam tip
Paper 1 Section A includes a tectonic hazard where you choose volcano or earthquake inside the question, so know both. For an 8-mark Assess or Evaluate, judge how effective the management was, with evidence and a conclusion. If a photograph shows a volcano, name the type (for example composite) instead of describing its shape.
Free practice questions
7 questions, 16 marks. Answer, then press Check. The marking guide explains how the marks are worked out. Nothing is saved.
- Question 1 · True or false[3 marks]
Decide whether each statement about the structure of the Earth and plate margins is true or false.
1. The mantle lies between the crust and the core.
2. New oceanic crust is formed at constructive margins.
3. Earthquakes only happen at destructive plate margins.
- Question 2 · Fill the gaps[2 marks]
At a destructive margin the ___ plate is subducted, and at a ___ margin plates move apart.
Word bank: constructive · oceanic · conservative · continental
- Question 3 · Matching[3 marks]
Match each process to the margin type where it happens.
- Question 4 · Choose more than one[2 marks]
Which TWO describe a constructive plate margin?
Choose 2.
- Question 5 · Put in order[1 mark]
Put these stages of a volcanic eruption at a destructive margin in the correct order.
Use the arrows to put these in the right order, first at the top.
- 1The sinking plate melts to form magma
- 2The oceanic plate moves towards the continental plate
- 3Magma rises through weaknesses in the crust
- 4The denser oceanic plate is subducted
- 5An explosive eruption occurs
- Question 6 · Sort into groups[3 marks]
Sort each feature into the plate margin where it is found.
Gentle eruptions as magma fills a gap
Earthquakes but no volcanoes
Explosive volcanoes above a subducted plate
- Question 7 · Choose more than one[2 marks]
Which TWO factors can reduce the risk from an earthquake?
Choose 2.