Cambridge IGCSE Environmental Management: Natural Hazards — Revision Notes

Topic 6 of Cambridge IGCSE Environmental Management (0680) covers four hazards: earthquakes and volcanoes, tropical cyclones, flooding and drought. For each you must describe where and why it happens, its impacts on people and the environment, and strategies for managing it before, during and after the event, with their benefits and limitations. Volcanoes and floods also bring opportunities, which the syllabus asks you to explain.

For full explanations see the natural hazards study guide; then try the natural hazards practice questions.

Syllabus coverage (0680, 2027-2029)

Ref	Learning outcomes
6.1.1-6.1.10	Earth’s structure; continents; distribution; plate boundaries; earthquake and eruption features; impacts; management; opportunities from volcanoes
6.2.1-6.2.4	Formation conditions; impacts; management of tropical cyclones
6.3.1-6.3.5	Causes, impacts, management and opportunities of flooding
6.4.1-6.4.5	Definition, causes, impacts and management of drought

Earthquakes and volcanoes (6.1)

Structure of the Earth: crust (thin, solid outer layer) → mantle (hot, slowly moving rock) → core.

Continents (7): Africa, Antarctica, Asia, Europe, North America, Oceania, South America.

Distribution: most earthquakes and volcanoes lie along plate boundaries, such as the ring around the Pacific Ocean; some volcanoes form over hotspots away from boundaries, such as Hawaii.

Convection currents in the mantle move the plates:

Boundary	Movement	Hazards
Divergent (constructive)	Plates move apart	Volcanic activity and earthquakes
Convergent (destructive)	One plate subducts beneath another	Earthquakes and a line of volcanoes
Conservative	Plates slide past each other	Earthquakes only

Earthquake features: sudden release of energy; focus (point underground where it starts); epicentre (point on the surface directly above); magnitude measured on the Moment Magnitude Scale.

Eruption features: magma rises and reaches the surface as lava; ash; gases (water vapour, carbon dioxide, sulfur dioxide); acid rain; volcanic bombs; pyroclastic flows (fast, hot clouds of gas and rock).

Impacts: damage to buildings and infrastructure; loss of crops, livestock and habitats; evacuation; fire; tsunamis; landslides; contaminated drinking water; water-related disease; financial losses; human health.

Opportunities from volcanoes: fertile soils; mineral extraction; building materials; geothermal power; tourism.

Tropical cyclones (6.2)

• Called storms, hurricanes or typhoons depending on region.
• Form between 5° and 30° north or south of the Equator, over oceans at least 27 °C and at least 60 m deep.
• Impacts: buildings and infrastructure damaged; crops, livestock and habitats lost; evacuation; flooding; landslides; contaminated water and water-related disease; financial losses; health.

Flooding (6.3)

Causes: land relief (low-lying land); saturated, compacted or eroded soil; deforestation, agricultural practices and urbanisation (less infiltration, more run-off); climate change (sea-level rise, more extreme weather); storm surges and tsunamis.

Opportunities: nutrient-rich silt deposited on farmland; recharge of surface water and ground water stores.

Drought (6.4)

Drought = a period of dry weather that is longer or more severe than normal.

• Causes: lack of rain; climate change (higher global temperatures, more extreme weather).
• Impacts: water sources dry up; loss of crops, livestock and habitats; soil erosion; desertification; death of organisms; famine; more wildfires; poorer air quality; financial losses; human health.
• Strategies: monitoring and warning; emergency water supplies; water conservation; increasing supply (dams and reservoirs, aquifers and wells, desalination, rainwater harvesting); international aid.

How are hazard impacts managed? (before, during, after)

Stage	Strategy	Benefit	Limitation
Before	Monitoring and warning (seismometers, satellites, rainfall gauges)	Time to evacuate	Earthquakes cannot be predicted precisely; warnings must reach remote areas
Before	Land use zoning (earthquakes, floods)	Keeps homes off the most dangerous land	Hard to enforce where land is scarce
Before	Building structure (cross-bracing, deep foundations, raised floors, cyclone-proof roofs)	Fewer collapses and deaths	Expensive to build or retrofit
Before	Disaster preparation (plans, drills, supplies, rescue teams)	People know what to do	Needs funding and regular practice
During	Evacuation and shelters	Saves lives	People may refuse to leave homes and livestock
After	Rebuilding damaged areas	Restores homes and services	Slow and costly; may rebuild in the same risk zone
After	International aid	Quick supplies, money and expertise	May not reach those most in need; can create dependency

Worked example: can a tropical cyclone form here?

A source gives data for three ocean areas. Test each against all three conditions.

Area	Latitude	Sea temperature	Depth	Cyclone possible?
A	15° N	28 °C	3 000 m	Yes - all three conditions met
B	2° S	29 °C	4 000 m	No - too close to the Equator (below 5°)
C	22° S	24 °C	2 500 m	No - water cooler than 27 °C

Exam tip: say which condition fails, quoting the figure, rather than just “no”.

Common mistakes and exam traps

• Confusing focus and epicentre: the focus is underground; the epicentre is on the surface.
• Saying volcanoes occur at conservative boundaries.
• Forgetting the three cyclone thresholds: 5-30° latitude, 27 °C, 60 m depth.
• Giving “evacuation” as a “before” strategy for earthquakes, which give little or no warning.
• Listing impacts without saying whether they affect people or the environment when asked for both.

Frequently asked questions

Why are some volcanoes far from plate boundaries? They form over hotspots, where hot mantle material rises beneath the middle of a plate.

What makes a strong “discuss” answer for hazard management? Name the strategy and the stage (before, during or after), give a benefit, give a limitation and finish with a judgement.

Can floods be good for people? Yes. The syllabus names two opportunities: nutrient-rich silt on farmland and recharge of surface and ground water stores.

Official syllabus

Cambridge IGCSE Environmental Management (0680) syllabus for 2027, 2028 and 2029 - official syllabus PDF, Topic 6.