Plate boundaries and tectonic hazards (4 marks)

Explain why earthquakes occur at conservative plate boundaries. [4 marks]

Mark scheme (point-marked, 1 mark each, max 4):

• At a conservative boundary, plates move past each other horizontally (parallel). [1]
• There is no subduction, so no magma is generated and no volcanic activity occurs. [1]
• The plates lock together due to friction; pressure builds up over time. [1]
• When the pressure is released suddenly, energy travels as seismic waves causing an earthquake. [1]
• Example: San Andreas Fault (North American and Pacific plates) / Caribbean Plate boundary (Haiti 2010). [1] (bonus context)

Common error: Stating that plates collide head-on — at conservative boundaries they slide laterally, not collide.