Hazards & Tectonics is a core part of A-Level Geography. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Tropical cycloneLow-pressure storm with sustained winds >118 km/h; called hurricane, typhoon or cyclone regionally.
Eye wallRing of intense thunderstorms around calm eye; strongest winds and rain.
Storm surgeSea level rise from low pressure and wind; Hurricane Katrina surge reached 8.5 m.
Subduction zoneConvergent plate boundary where oceanic crust dives beneath; sites of largest earthquakes.
Mercalli scaleEarthquake intensity from felt effects (I-XII); contrast with magnitude scales.
LiquefactionSaturated soil loses strength during shaking; collapsed buildings in Christchurch 2011.
Park's modelThree-phase response curve: relief, rehabilitation, reconstruction.
ReliefImmediate (hours-days) emergency response: search-rescue, medical aid.
RehabilitationWeeks-months: restore services, temporary housing, plan recovery.
ReconstructionMonths-years: rebuild infrastructure better than before.
Build back betterReconstruction stronger and more resilient than pre-disaster state.
Recovery curvePlots quality of life vs time from pre-event baseline through dip and recovery.
HazardNatural event with potential to cause harm to people and property.
RiskProbability of harm; Risk = Hazard x Vulnerability x Exposure / Capacity.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
Why do tropical cyclones only form over warm tropical oceans?✗ Hurricanes form wherever there are strong winds over the sea. ✓ They need sea surface temperatures above ~27 degrees C to a depth of 50m to provide energy through evaporation, plus enough Coriolis effect (away from the equator) to spin.
Why are tropical rainforest soils typically infertile?✗ Because so much vegetation grows there, the soil must be fertile. ✓ Heavy rainfall leaches nutrients, and most nutrients are stored in living biomass and rapidly recycled — the soil itself holds very little.
Why does the tropical rainforest have distinct vertical layers?✗ Rainforest layers exist because different animals live at different heights. ✓ Competition for light: emergents (40m+), canopy (capturing most light), understorey (shade-tolerant) and forest floor (sparse vegetation due to low light) — each adapted to its light level.
Tropical cyclones require sea surface temperatures above:✗ 16.5 degrees C ✓ 26.5 degrees C
Why do earthquakes typically cause more deaths in LICs than HICs?✗ LICs have more earthquake deaths because more earthquakes happen there. ✓ LICs often have poorly enforced building codes, weak emergency response, dense informal housing and limited preparedness — not because the earthquakes are stronger.
Practise Hazards & Tectonics — free games
Test yourself with these quick revision games for this topic:
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