What is a natural hazard?

A natural hazard is a natural event that threatens life, property or the environment. Tectonic hazards (earthquakes, volcanoes) come from processes inside the Earth. Hazard risk depends on likelihood, vulnerability, level of development and how well-prepared a country is.

Plate tectonics theory

• The Earth's crust is broken into tectonic plates that float on the semi-molten mantle (asthenosphere).
• Convection currents in the mantle, driven by heat from the core, move the plates a few centimetres a year.
• Alfred Wegener proposed continental drift in 1912, using jigsaw-fit coastlines, matching rock strata and fossil evidence (e.g. Mesosaurus found in both South America and Africa). His idea was rejected at first because he could not explain the force that moved continents.
• Seafloor spreading at mid-ocean ridges (evidenced by symmetrical magnetic striping either side of the ridge) later proved plates really do move, supporting his theory.

Plate boundaries (know all four)

• Destructive (convergent): oceanic and continental plates collide; denser oceanic crust subducts, causing deep earthquakes and composite volcanoes, e.g. Nazca Plate under South American Plate.
• Constructive (divergent): plates move apart, magma rises to fill the gap, producing shield volcanoes and shallow earthquakes, e.g. Mid-Atlantic Ridge.
• Conservative: plates slide past each other, no magma so no volcanoes, but huge friction builds up causing powerful, shallow earthquakes, e.g. San Andreas Fault.
• Collision: two continental plates of similar density collide, neither subducts, crust crumples upwards to form fold mountains, e.g. Himalayas (Indian Plate meeting Eurasian Plate).

Volcanoes

• Shield volcanoes: runny basaltic lava, low viscosity, gentle sides, effusive (non-explosive) eruptions, found at constructive boundaries and hotspots (e.g. Hawaii).
• Composite volcanoes: thick andesitic/rhyolitic lava, high viscosity, steep sides, explosive eruptions with pyroclastic flows and ash, found at destructive boundaries (e.g. Mount Fuji).

Managing tectonic hazards

• Monitoring: seismometers, tiltmeters, gas sensors, satellite imagery.
• Prediction: patterns of past activity, animal behaviour, gas emissions — still not exact for earthquakes.
• Protection: building design (cross-bracing, base isolators, flexible materials), lava/lahar diversion channels.
• Planning: evacuation routes, drills, hazard maps, exclusion zones.

Common mistakes to avoid

• Do not muddle destructive and constructive boundaries — destructive = collision/subduction, constructive = plates moving apart.
• Volcanoes do NOT occur at conservative boundaries.
• Always link named case studies to actual facts and figures, not vague description.
• Remember earthquake magnitude is measured on the Richter or moment magnitude scale — bigger number, exponentially bigger energy release.

Weather vs climate

Weather is the day-to-day state of the atmosphere (temperature, rainfall, wind on a given day). Climate is the average weather over 30+ years for a place. Do not mix these up in exam answers.

UK weather hazards

• The UK sits where five air masses meet (Tropical Continental, Tropical Maritime, Polar Maritime, Polar Continental, Arctic Maritime), which is why our weather is so changeable.
• Depressions (low pressure) bring the UK's typical unsettled weather: warm front then cold front, cloud and rain.
• Anticyclones (high pressure) bring settled weather: hot and dry in summer, cold and frosty with fog in winter.
• UK extreme weather events (e.g. named storms, heatwaves, flooding) are increasing in frequency and intensity, linked to climate change.

Tropical storms

• Form over oceans at 27C or warmer, at least 5 degrees from the equator, so the Coriolis effect can make them spin.
• Need low wind shear and pre-existing disturbance to develop.
• Structure: calm eye in the centre, eyewall with strongest winds, spiralling rain bands.
• Cause damage through strong winds, storm surge and heavy rainfall/flooding.
• Common mistake: forgetting tropical storms lose energy and weaken once they move over land or cooler water, because they are cut off from their warm-ocean energy source.

Climate change

• Natural causes include orbital changes (Milankovitch cycles), volcanic activity and solar output changes.
• Human causes: burning fossil fuels, deforestation and agriculture increase greenhouse gases (mainly CO2 and methane), enhancing the greenhouse effect.
• Evidence: ice cores, tree rings, historical/sea level records show rising global temperatures.
• Management splits into mitigation (reducing causes, e.g. renewable energy, carbon capture, planting trees) and adaptation (adjusting to effects, e.g. flood defences, drought-resistant crops).

Ecosystems

• An ecosystem is a community of plants and animals interacting with their non-living environment.
• Small-scale UK ecosystems (e.g. ponds, woodlands) show the same principles as global biomes: producers, consumers, decomposers, food webs and nutrient cycling.
• Global biomes are large-scale ecosystems shaped mainly by climate (temperature and rainfall) — includes tropical rainforest, hot desert, and others depending on the specification.
• Tropical rainforests: nutrient cycle is fast because heat and rainfall speed up decomposition, but soils are actually nutrient-poor because nutrients are stored in the biomass (trees), not the soil.
• Deforestation causes: logging, farming (cattle ranching, subsistence and commercial agriculture), mineral extraction, road building and population growth.
• Impacts of deforestation: soil erosion, loss of biodiversity, increased CO2 (less carbon storage), disruption of the water cycle.
• Sustainable management includes selective logging, replanting, ecotourism, debt-for-nature swaps and international agreements.

Common mistakes

• Saying weather when you mean climate, or vice versa.
• Forgetting tropical storms need a minimum sea temperature of 27C to form.
• Thinking rainforest soils are fertile — they are not, nutrients are locked in vegetation.

River processes

Rivers erode, transport and deposit material as they flow from source to mouth.

Erosion happens in four ways: hydraulic action (force of water), abrasion (load scraping the bed and banks), attrition (rock fragments wearing each other down and becoming smaller and rounder), and solution (chemical dissolving of rock).

Transport happens by traction (large boulders rolled along the bed), saltation (bouncing pebbles), suspension (fine material carried in the flow) and solution (dissolved material).

Deposition occurs when a river loses energy, for example when it enters the sea, floods onto a floodplain, or the gradient reduces.

Long profile and landforms

In the upper course rivers are steep and erode vertically, forming V-shaped valleys, interlocking spurs and waterfalls (a hard rock layer over soft rock causes undercutting, a plunge pool, and gradual retreat).

In the middle and lower course the river erodes laterally, forming meanders (fastest flow and erosion on the outer bend, deposition on the inner bend slip-off slope) and, when a meander neck is cut through, oxbow lakes.

In the lower course look for floodplains, levees and deltas built from deposited sediment.

Flood management

Hard engineering includes dams and reservoirs, channel straightening, and embankments.

Soft engineering includes floodplain zoning, afforestation and river restoration, which work with natural processes and are usually cheaper and more sustainable.

Coastal processes and landforms

The same four erosion processes (hydraulic action, abrasion, attrition, solution) shape coasts too.

Wave-cut platforms form where a wave-cut notch undercuts a cliff until it collapses, leaving a flat rocky platform.

Headlands and bays form where bands of hard and soft rock meet the sea (differential erosion); the softer rock erodes faster, leaving bays with headlands either side.

On a headland, erosion of cracks creates a cave, then an arch, then a stack, and finally a stump.

Longshore drift moves sediment along a beach in a zig-zag pattern, driven by the prevailing wind's swash angle and the backwash pulling straight back down the beach slope.

Coastal management

Hard engineering: sea walls, rock armour (rip-rap), gabions and groynes (groynes trap sediment moving by longshore drift, widening the beach).

Soft engineering: beach nourishment (adding sand/shingle) and dune regeneration.

Managed retreat allows some low-value land to flood or erode naturally, letting new habitats like salt marsh form.

Common mistakes

Don't confuse hydraulic action (force of water) with abrasion (load doing the scraping).

Remember erosion is fastest on the OUTER bend of a meander, deposition on the INNER bend.

Groynes trap sediment but can starve beaches further along the coast of sand, causing increased erosion downdrift.

Urbanisation trends

More than half the world's population now lives in urban areas, and this figure is rising fastest in NEEs (Newly Emerging Economies) like Nigeria and Brazil, not in HICs like the UK, where urban growth has mostly levelled off.

Urbanisation in NEEs is driven by rural-urban migration (push factors: drought, lack of jobs, conflict; pull factors: jobs, healthcare, education) and by natural increase (high birth rates once people arrive, plus better urban healthcare lowering death rates.

UK city case study - Bristol

Bristol shows typical UK urban issues: housing shortages, urban sprawl into the green belt, traffic congestion, and inequality between areas such as inner-city Easton and wealthier Clifton.

Regeneration example: Bristol's Harbourside was transformed from derelict docks into homes, offices and leisure space, boosting the local economy.

Sustainable urban living features: green spaces, recycling schemes, cycle lanes (Bristol was the UK's first Cycling City in 2008), and improved public transport to cut car dependency.

NEE city case study - Rio de Janeiro or Lagos

Squatter settlements (favelas in Rio, or similar in Lagos) form when rapid migration outpaces housing supply. Key features: informal housing, lack of clean water and sanitation, high unemployment.

Managing challenges: self-help schemes (residents given materials/support to improve their own homes), site and service schemes (basic infrastructure laid first, then people build), and top-down urban planning like Rio's Favela-Bairro project.

Common mistakes

• Do not say urbanisation is mainly a UK problem - the exam expects NEE case studies for rapid urban growth.
• Always name your actual case study city (Bristol/Rio/Lagos) and give SPECIFIC named schemes or places, not vague description.
• Remember push AND pull factors - many students only give one side.
• Distinguish urbanisation (growth of urban population) from urban sprawl (outward spread of a city) - these are different terms.
• Sustainable strategies need real named examples (e.g. Freiburg's Vauban district, or Bristol's cycle network) to get top marks.

Key terms

• Urban sprawl: the unplanned outward spread of a city into surrounding rural land.
• Green belt: protected land around a city where building is restricted.
• Counter-urbanisation: people moving from cities to surrounding rural areas.

What is development?

Development means improvements in a country's economy, quality of life and wellbeing.

• Measured with economic indicators like GNI per capita (Gross National Income).
• Measured with social indicators like literacy rate, life expectancy and access to safe water.
• The Human Development Index (HDI) combines income, education (mean/expected years of schooling) and life expectancy into one score from 0 to 1.
• The Demographic Transition Model (DTM) has 5 stages showing how birth rates and death rates change as a country develops.

Classifying countries

• LICs (Low Income Countries) have low GNI per capita, often below around $1,000.
• NEEs (Newly Emerging Economies) like India and Nigeria have fast-growing manufacturing and industry.
• HICs (High Income Countries) have high GNI, strong services sectors and high HDI, usually above 0.8.
• Common mistake: don't call all poorer countries 'Third World' — use LIC or NEE, the terms OCR expects.

Causes of uneven development

• Physical causes: climate (drought/disease like malaria), landlocked location, limited natural resources.
• Historical causes: colonialism stripped resources and left poor infrastructure.
• Economic causes: unfair trade terms, debt repayments to HICs, lack of investment.
• Political causes: conflict, corruption and unstable government slow growth.

Reducing the development gap

• Investment: money put into a country by TNCs (Transnational Corporations) or foreign governments.
• Aid: can be short-term (emergency, after disasters) or long-term (development projects like wells or schools).
• Fair trade: guarantees producers in LICs/NEEs a fair, stable price for goods like coffee and cocoa.
• Debt relief: cancelling or reducing what LICs owe so money goes to services instead of interest.
• Tourism: growing industry that brings jobs and foreign currency, e.g. Kenya or Jamaica case studies.
• Microfinance: small loans that let people start their own small businesses.

UK economic change (a case study)

The UK has shifted from manufacturing (secondary sector) to services (tertiary/quaternary sector) — this is called deindustrialisation.

• Causes: globalisation, cheaper labour abroad, automation, government policy.
• Post-industrial economy: growth in science parks, business parks and finance (quaternary industry).
• Common mistake: quaternary is research/high-tech (e.g. Cambridge Science Park), not the same as tertiary (services like shops and banks).
• The North-South divide describes economic inequality between richer South East England and the North; policies like the 'Northern Powerhouse' try to rebalance this.
• Rural areas also change: some decline as jobs move to cities, others grow through tourism or renewable energy investment.

What is resource management?

Resources are things people need: food, water, energy and minerals. Demand for all of these is rising because of population growth, rising incomes and changing diets and lifestyles. The UK and the world face a challenge balancing supply with demand while protecting the environment.

Food in the UK

• The UK imports about 40-46% of its food (self-sufficiency has fallen since the 1980s).
• Agribusiness, technology (GM crops, irrigation) and organic farming are all strategies to increase food supply.
• Food miles and carbon footprint are key issues: imported food (like Kenyan green beans) travels thousands of miles.
• Local, seasonal food and urban farming reduce food miles and support sustainability.

Water in the UK

• Water surplus areas are the north and west (high relief rainfall); water deficit areas are the south and east (higher population, lower rainfall) - this is the water deficit/surplus contrast.
• Water transfer schemes move water from surplus to deficit areas, but are expensive and can harm ecosystems.
• Rising demand comes from population growth and appliances (dishwashers, power showers).

Energy in the UK

• The UK energy mix is shifting from fossil fuels (coal, oil, gas) to renewables (wind, solar, biomass, nuclear).
• North Sea oil and gas reserves are declining, increasing reliance on imports.
• Fracking (hydraulic fracturing) is controversial - it could boost domestic gas supply but risks water contamination and earthquakes (tremors).
• Renewable energy is more sustainable but has issues like reliability (wind) and visual impact (turbines, pylons).

Fieldwork skills - the geographical enquiry process

Fieldwork always follows the same stages, and OCR expects you to know them in order:

1. Title, aim and hypothesis - a clear, testable question.

2. Location selection - justify why the site was chosen.

3. Risk assessment - identify hazards and how to reduce them.

4. Data collection methods - primary (collected yourself, e.g. questionnaires, environmental quality surveys, pedestrian counts) and secondary (already exists, e.g. census data, maps).

5. Sampling - random, systematic or stratified sampling, each with pros/cons.

6. Presentation - graphs, GIS maps, annotated photos, choropleth maps.

7. Analysis - describing patterns and using statistics.

8. Conclusion - answering the original question, linking back to the hypothesis.

9. Evaluation - limitations of the method and how it could be improved.

Common mistakes

• Confusing primary data (you collect it) with secondary data (someone else collected it) - a huge marks loss if muddled.
• Forgetting to justify sampling method choice, not just naming it.
• Writing generic answers instead of using specific UK figures and named locations from your own fieldwork.
• Not linking the evaluation back to how reliable/valid the conclusion actually is.