G1: Natural Hazards
Understanding what natural hazards are, how they are classified, and why some places and people are more at risk than others.
π What is a Natural Hazard?
Definition: A natural hazard is a natural process which could cause death, injury or damage to property. A natural hazard becomes a natural disaster when it has a significant impact on people or the built environment.
It is important to distinguish between hazards and disasters:
- A hazard is the potential threat β the natural event itself
- A disaster occurs when the hazard actually causes significant loss of life, injury or damage
- An earthquake in an uninhabited area is a hazard but not a disaster
- The same magnitude earthquake in a densely populated city is both a hazard and a disaster
Key Equation:
Risk = Probability Γ Vulnerability Γ (1 Γ· Capacity to Cope)
Where:
β’ Probability = the likelihood of the hazard occurring
β’ Vulnerability = how exposed and susceptible people are to the hazard
β’ Capacity to cope = how well people can prepare for, respond to, and recover from the hazard
Risk = Probability Γ Vulnerability Γ (1 Γ· Capacity to Cope)
Where:
β’ Probability = the likelihood of the hazard occurring
β’ Vulnerability = how exposed and susceptible people are to the hazard
β’ Capacity to cope = how well people can prepare for, respond to, and recover from the hazard
π Types of Natural Hazards
Natural hazards are classified into two main categories:
Geological Hazards
Caused by land and tectonic processes:
- Earthquakes β caused by the sudden release of energy along a fault line
- Volcanic eruptions β when magma reaches the surface through vents
- Tsunamis β large ocean waves caused by underwater earthquakes or volcanic eruptions
- Landslides β masses of rock and soil moving down a slope
- Avalanches β rapid flow of snow down a mountainside
Meteorological Hazards
Caused by weather and climate processes:
- Tropical storms (hurricanes, typhoons, cyclones) β intense low-pressure weather systems
- Droughts β prolonged periods of abnormally low rainfall
- Floods β overflow of water onto normally dry land
- Heatwaves β prolonged periods of excessively hot weather
- Wildfires β uncontrolled fires in vegetation areas
| Feature | Geological Hazards | Meteorological Hazards |
|---|---|---|
| Cause | Tectonic/land processes | Weather/climate processes |
| Warning time | Usually very short or none | Often some warning possible |
| Prediction | Difficult to predict precisely | Easier to forecast using satellites |
| Duration | Usually short (seconds to days) | Can last days to months |
| Examples | Earthquakes, volcanoes, tsunamis | Hurricanes, floods, droughts |
β οΈ Hazard Risk Factors
The risk of a natural hazard causing a disaster depends on several factors. People are more at risk if they live in an area where hazards occur, and if they are poorly prepared or unable to cope.
1. Probability
Probability refers to the likelihood of a hazard event occurring in a given area. Some locations have a higher probability of certain hazards due to their physical geography β e.g. countries along plate boundaries have a higher probability of earthquakes.
2. Vulnerability
Vulnerability is the degree to which a person, community or area is likely to be affected by a hazard. Vulnerable populations include those who live in poorly constructed buildings, in high-density settlements, or in low-lying coastal areas.
Factors that increase vulnerability:
- Poorly constructed buildings that cannot withstand shaking or wind
- High population density in hazard-prone areas
- Low education levels about hazard risks and responses
- Poverty β people may not be able to afford protective measures
- Isolation β remote communities may be cut off from help
3. Capacity to Cope
Capacity to cope is the ability of a population to deal with a hazard event. Higher-income countries (HICs) generally have a greater capacity to cope than lower-income countries (LICs).
Factors that affect capacity to cope:
- Wealth β richer countries can afford better infrastructure, emergency services and recovery programmes
- Technology β monitoring equipment, early warning systems, and communication networks
- Education β public awareness campaigns, drills and training
- Government β effective emergency planning, building regulations and response coordination
- Infrastructure β hospitals, transport networks, rescue services
Example: Capacity to Cope Comparison
Japan (HIC): Has strict building codes for earthquake resistance, a nationwide early warning system that sends alerts to phones within seconds of detecting an earthquake, well-practised evacuation drills, and a highly trained emergency response force. The 2011 TΕhoku earthquake (magnitude 9.0) caused significant damage, but Japan's capacity to cope saved many lives.
Haiti (LIC): Lacks building codes, has no early warning system, many buildings are poorly constructed, and emergency services are limited. The 2010 earthquake (magnitude 7.0) killed over 220,000 people β far more than the stronger Japanese quake β largely because of Haiti's low capacity to cope.
π Factors Affecting Hazard Risk
| Factor | Increases Risk | Decreases Risk |
|---|---|---|
| Population density | High density β more people affected | Low density β fewer people exposed |
| Wealth | Poverty β can't prepare or recover | Wealth β can invest in protection |
| Education | Lack of awareness of risks | Public education and drills |
| Building quality | Poorly built structures collapse easily | Engineered buildings resist hazards |
| Location | Near plate boundaries, coasts, rivers | Away from hazard zones |
| Technology | No warning systems | Monitoring and early warning |
| Governance | Weak government, no planning | Strong regulations and planning |
πΊοΈ Global Distribution of Hazards
Natural hazards are not distributed evenly across the Earth. Their distribution is linked to tectonic and climatic patterns:
- Earthquakes and volcanoes are concentrated along plate boundaries, especially around the Pacific Ring of Fire
- Tropical storms occur in ocean areas near the equator where sea temperatures exceed 27Β°C
- Droughts are most common in sub-tropical regions (around 20β30Β° north and south)
- Floods can occur almost anywhere but are most devastating in low-lying areas with high rainfall
The Pacific Ring of Fire: A horseshoe-shaped belt around the Pacific Ocean where about 75% of the world's volcanoes and 90% of earthquakes occur. It follows the boundaries of the Pacific Plate and several other tectonic plates.
π Hazard Trends
The number of reported natural disasters has been increasing globally. This is due to a combination of factors:
- Population growth β more people are living in hazard-prone areas
- Urbanisation β more people concentrated in cities, often in vulnerable locations
- Climate change β increasing the frequency and intensity of meteorological hazards
- Better reporting β improved global communication means more events are recorded
- Land use change β deforestation and urbanisation increase flood risk
Important distinction: The number of geophysical hazards (earthquakes, volcanoes) has NOT increased β they occur at roughly the same rate. It is the number of hydrometeorological hazards (floods, storms, droughts) that has increased, largely due to climate change. The number of DISASTERS has increased mainly because more people live in hazardous areas.
β Practice Questions
Q1: Define the term 'natural hazard'. (2 marks)
Q2: Explain the difference between a natural hazard and a natural disaster. (2 marks)
Q3: Describe three factors that affect the risk posed by a natural hazard. (3 marks)
Q4: Explain why the same magnitude earthquake can cause a disaster in one country but not another. (4 marks)
Q5: Compare the characteristics of geological and meteorological hazards. Give named examples of each. (6 marks)
Q6: Explain why the number of natural disasters has been increasing in recent decades. (4 marks)
β Answers
- A natural hazard is a natural process (such as an earthquake or tropical storm) that has the potential to cause death, injury or damage to property.
- A natural hazard is the potential threat from a natural process. A natural disaster occurs when the hazard actually causes significant loss of life, injury or damage to property or the environment.
- Three factors: (1) Probability β the likelihood of the hazard occurring; (2) Vulnerability β how susceptible the population is to being affected; (3) Capacity to cope β the ability of people to prepare for, respond to and recover from the hazard.
- The impact depends on vulnerability and capacity to cope. In a LIC like Haiti, poorly constructed buildings, lack of early warning, limited emergency services and low education about hazards mean more deaths and damage. In a HIC like Japan, earthquake-resistant buildings, early warning systems, trained emergency services and public drills reduce the impact significantly. The 2010 Haiti earthquake (7.0) killed over 220,000 while the 2011 Japan earthquake (9.0) killed around 20,000 despite being far stronger.
- Geological hazards are caused by tectonic processes (e.g. the 2015 Gorkha earthquake in Nepal, the 2010 EyjafjallajΓΆkull eruption in Iceland). They are difficult to predict and usually occur with little warning. Meteorological hazards are caused by weather and climate processes (e.g. Typhoon Haiyan 2013 in the Philippines, the 2014 Somerset Levels floods in the UK). They can often be forecast using satellite technology, giving some warning time. Both types can cause loss of life and property damage, but meteorological hazards are increasing in frequency due to climate change.
- The number of disasters is increasing because: (1) population growth means more people live in hazard-prone areas; (2) urbanisation concentrates people in vulnerable cities; (3) climate change is increasing the frequency and intensity of meteorological hazards like floods and storms; (4) better communication and monitoring means more events are reported globally. Note that geophysical events have NOT increased β the rise is mainly in hydrometeorological disasters.
π― Exam Tips
- Always define key terms at the start of your answer β 'natural hazard' and 'natural disaster' are commonly asked definitions
- Use named examples to support your points β examiners want specific facts, not vague statements
- When explaining risk, make sure you discuss all three factors: probability, vulnerability and capacity to cope
- Compare HICs and LICs when discussing hazard impacts β the same hazard can have very different outcomes
- Remember that increasing disasters β increasing hazards β it's about population exposure
- Use the formula Risk = Probability Γ Vulnerability Γ· Capacity to Cope to structure extended answers
π Exam Technique
Geography Exam Tips:
For 'define' questions, give a clear geographical definition. For 'explain' questions, use cause-and-effect chains. Natural hazard questions often ask you to compare hazard risk between areas β always consider the three risk factors: vulnerability, capacity to cope, and probability of the event.
For 'define' questions, give a clear geographical definition. For 'explain' questions, use cause-and-effect chains. Natural hazard questions often ask you to compare hazard risk between areas β always consider the three risk factors: vulnerability, capacity to cope, and probability of the event.
β οΈ Common Errors
Watch Out!
Students often think Hazards and disasters are the same thing. Wrong: Hazards and disasters are the same thing Correct: A hazard is the physical event (e.g. an earthquake). A disaster occurs when the hazard impacts people and causes significant damage or loss of life. Not all hazards become disasters.
Students often think Natural hazards only affect LICs. Wrong: Natural hazards only affect LICs Correct: HICs also experience natural hazards. The difference is that HICs generally have better capacity to cope through building regulations, warning systems and emergency services, so the impact is usually less severe.
Students often think Hazard risk is only about how often the event happens. Wrong: Hazard risk is only about how often the event happens Correct: Probability is only one factor. Risk also depends on vulnerability (how exposed people are) and capacity to cope (how well a society can respond and recover).
βοΈ Model Answer
Full-Mark Response
6 marks: Explain why some communities are more at risk from natural hazards than others.
Some communities face greater hazard risk due to three key factors. First, vulnerability: communities in LICs often have poorly constructed buildings that cannot withstand hazard events, making them more exposed to harm. For example, in the 2010 Haiti earthquake, over 200,000 died partly because buildings lacked earthquake-resistant design. Second, capacity to cope: HICs like Japan have advanced monitoring systems, strict building codes and well-practised emergency response plans, which reduce the impact of hazards. Japan's 2011 magnitude 9.0 earthquake killed far fewer people than Haiti's magnitude 7.0 because of this greater capacity. Third, probability: some locations are more hazard-prone than others. Communities near plate boundaries or on flood plains experience hazards more frequently, increasing their overall risk regardless of their wealth or preparedness.
Mark scheme: 2 marks for discussing vulnerability with development, 2 marks for capacity to cope with examples, 2 marks for probability of hazard events
π AO Deep Dive
Assessment Objective Analysis
AO1 requires you to know the three risk factors (vulnerability, capacity to cope, probability). AO2 demands understanding of why these factors vary between places. AO3 asks you to analyse and evaluate how risk varies β comparing LICs and HICs is essential for top marks. AO4 may involve interpreting risk maps or data tables. For grade 9, always use specific examples and recognise that risk is the product of all three factors, not just one.
π Exam Questions by Topic
π¬ Video Resources
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