Earthquakes and volcanoes

G2 Elective Geography: Tectonics - syllabus K229, 2027

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Understand how earthquakes and eruptions happen, where their hazards reach and why people live in volcanic areas.

• Earthquakes and magnitude

  Sudden movement on a fault releases earthquake energy. Magnitude measures the event's size; shaking and damage vary from place to place.

• Magma and eruption styles

  Runny magma lets gas escape more easily. Viscous magma can trap expanding gas and erupt explosively. VEI describes explosivity, not total risk.

• Where earthquakes and volcanoes occur

  Most tectonic hazards cluster near plate boundaries. Hotspots and hazards that travel far from their source create important exceptions.

• Earthquake hazards

  An earthquake can trigger landslides, liquefaction and tsunamis. Damage then spreads through roads, water, power and other essential services.

• Lava, pyroclastic flows and landslides

  Lava, pyroclastic flows and collapsing slopes behave differently. Identify the material and movement before explaining the damage.

• Ash, gases and lahars

  Wind carries ash; water turns loose volcanic debris into lahars. Hazards can continue after the eruption has ended.

• Benefits of volcanic areas

  Volcanic areas can provide fertile soil, minerals, energy and tourism income. These benefits help explain why people stay despite the hazards.