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Hazards and disasters

Hazards and disasters

Hazard Hurricane2


Environmental hazards exist at the interface between physical geography and human geography. Natural hazard events are often exacerbated by human actions, although conversely, human‑induced hazard events are also affected by natural environmental conditions. The principles involved in studying natural hazards are identical to those involved in studying human‑induced hazards.

Hazard ss-110425-chernobyl-004_ss_full


The focus of this optional theme is on the full range of human adjustments and responses to hazards and disasters at a variety of scales. The term “natural disaster” is deliberately avoided in this theme because it is not considered to be an accurate reflection of the multitude of underlying reasons that expose people to risk and subsequently create the pre‑conditions necessary for a disaster to occur.

In studying this theme, students are expected to examine the following four hazards.

  • Either earthquakes or volcanoes
  • Hurricanes (tropical cyclones, typhoons)
  • Droughts
  • Any one recent human‑induced (technological) hazard resulting in an explosion or escape of hazardous material

At least one case study of a hazard event (or disaster) is required for each of the four hazard types.

1 Characteristics of hazards (7 hours)

Explain the characteristics and spatial distribution of the following hazards.

hazards IB 1

  • Either earthquake or volcanoes 
  • Hurricanes (tropical cyclones, typhoons)
  • Droughts
  • Any one recent human-induced (technological) hazard (explosion or escape of hazardous material)

Distinguish between the chosen hazards in terms of their spatial extent, predictability, frequency, magnitude, duration, speed of onset and effects.

2 Vulnerability

hazards IB 2

Vulnerable Populations (1 hour)

Explain the reasons why people live in hazardous areas.

Vulnerability (3 hours)

Discuss vulnerability as a function of demographic and socio‑economic factors, and of a community’s preparedness and ability to deal with a hazard event when it occurs.

hazrds IB 3Natural-Disaster-Preparedness-DVD-mth

3 Analysis of risk (3 hours)

Examine the relationships between the degree of risk posed by a hazard and the probability of a hazard event occurring, the predicted losses and a community’s preparedness for it.
Explain the reasons why individuals and communities often underestimate the probability of hazard events occurring.
Discuss the factors that determine an individual’s perception of the risk posed by hazards.

Hazard event prediction (3 hours)

Examine the methods used to make estimates (predictions) of the probability (in time and space) of hazard events occurring, and of their potential impact on lives and property.
Discuss these methods by examining case studies relating to two different hazard types.

4 Disasters

hazards IB 4 natural-disasters

Definition (1 hours)

Distinguish between a hazard event and a disaster. Explain why this distinction is not always completely objective.

Measuring disasters (3 hours)

Describe the methods used to quantify the spatial extent and intensity of disasters.
Explain the causes and impacts of any one disaster resulting from a natural hazard.
Explain the causes and impacts of any one recent human‑induced hazard event or disaster.
Examine the ways in which the intensity and impacts of disasters vary in space and have changed over time.

5 Adjustments and responses to hazards and disasters

Responses to the risk of hazard events (2.5 hours)

Discuss the usefulness of assessing risk before deciding the strategies of adjustment and response to a hazard.
Describe attempts that have been made to reduce vulnerability by spreading the risk (aid, insurance) and by land-use planning (zoning).

Before the event (1.5 hours)

Describe strategies designed to limit the damage from potential hazard events and disasters.

Short-term, mid-term and long term responses after the event (5 hours)

Describe the range of responses, at the community, national and international levels, during and after a hazard event or disaster.
Distinguish between rescue, rehabilitation and reconstruction responses.
Explain how these responses are affected by individual and community perceptions.
Examine the factors that affected the choice of adjustments before, and responses to, actual hazard events or disasters.
Discuss the importance of re‑assessing risk, and re‑examining vulnerability, following any major hazard event or disaster.


1 Characteristics of hazards 

1.1  Earthquakes –  are caused by sudden releases in energy from the earth’s crust, resulting in seismic waves.



An earthquake (also known as a quake or tremor) is the perceptible shaking of the surface of the Earth, which can be violent enough to destroy major buildings and kill thousands of people. The severity of the shaking can range from barely felt to violent enough to toss people around. Earthquakes have destroyed whole cities. They result from the sudden release of energy in the Earth’s crust that creates seismic waves. The seismicity or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

Kathmandu, Nepal

Kathmandu, Nepal

Key Earthquake Terminology

Epicentre: The location on the earth’s surface directly above the hypocentre.
Hypocentre (focus): The actual site/location that an earthquake takes place.

hazards IB 5
Aftershock: A smaller earthquake that takes place in the coming hours, days and weeks after the main earthquake.
Seismic Waves: These are waves of energy that travel through the earth as a result of an earthquake. There are two types of waves; body waves that travel through the earth and can be divided into p-waves (more longitudinal) and s-waves (more transverse) and surface waves that travel across the surface.
Tremor: A tremor is another name for an earthquake, but is all sometimes the name given to a lesser earthquake or the felt effects of a big earthquake by people living further from the epicentre.



1.2 Tropical cyclones (hurricanes) – they are intense low pressure systems that develop over warm tropical seas. 

hazards IB 8 5203526_orig

Hurricanes: A tropical storm is a large low pressure system characterised by high winds and heavy rain. They are also known as typhoons in East and South-east Asia and cyclones around the Indian Ocean. To be classified as a tropical storm, winds must exceed 119km/hr (74 mph). Small low pressure systems are called tropical storms (63-118km/hr) and tropical depressions (0-62km/hr).

hazards IB 9 Global_tropical_cyclone_tracks-edit2


1.3 Droughts – prolonged period of months and years where supply of water falls below demand.

hazards IB 12 photos-of-the-severe-drought-thats-devastating-crops-in-the-midwest

Causes of drought

1. Variations in the movement of the ITCZ

drought 1

The high pressure over the Azores spreads and in some years spreads across North Africa. This is a blocking high pressure preventing the ITCZ northward migration of the ITCZ over west Africa in the northern hemispheres summer. This often occurs over the Sahel region.

drought 2

East Africa Drought (2011)

East Africa (or the area sometimes referred to the Horn of Africa) started suffering from a severe drought from mid-July in 2011. It is believed to be the worst drought in over 60 years and covers areas in Somalia, Kenya, Ethiopia, Eritrea, Djibouti and Sudan (now South Sudan). The drought was primarily caused by failing rains. The area received 30% less rain than the average between the years 1995-2010. In some areas the rains failed completely. The drought has been blamed on the deaths of between 50,000 and 100,000 people.

The drought has caused numerous problems including:

  • Crop failures and livestock deaths leading to rising food prices and food shortages (famine)
  • Over 920,000 refugees being forced to leave Somalia
  • An increase in measles outbreaks in refugee camps
  • An increased risk of malaria due to people living outside and in tents
  • An increase in sexual violence committed against refugees along with an associated risk of contracting HIV

From the outbreak of the drought the UN estimated that about 12 million individuals need food aid and requested $2.5 billion in humanitarian assistance. A large shortfall and a slow response are blamed on thousands of deaths. The reluctance of Al Shabab (an Islamist group) to allow aid groups to work in Southern Somalia is also blamed on a large number of deaths.

2. El Nino – The warming up of sea-temperatures in the eastern Pacific and its effect upon atmospheric circulations can bring major changes to rainfall patterns. Causes drought in – Australia, Indonesia, USA, eastern Brazil and South Africa.


drought 4

3. Changes in the track of the mid-latitude depressions: in temperate regions, depressions bring certain areas a large amount of their total rainfall. If anti-cyclonic depressions will track north and south of their usual areas resulting in drought. The UK has often been affected by the blocking anticyclones.

Article from the Guardian (below) discusses the 2012 drought in the SE UK

Drought in SE England

Human causes of drought:

Deforestation: Cutting down trees which not only means the land will be receiving less nutrients and be less stable, but it can also mean reduced transpiration rates and reduced rainfall.

Overpopulation: As the world population continues to grow (now about 7 billion) the demand for water, for domestic use increases.

Industrial and Agricultural Demand: As the world’s population grows bigger, more food is needed and more commodities demanded. Both of these increase the demand for water.

Economic Development: As countries develop and individuals get richer, they tend to use more water e.g. showers, toilets, gardens, cars, etc.

Physical causes of drought:

Rising Temperatures: As global temperatures increase more water is needed to grow crops and more water is lost through evaporation.

Falling Rainfall: The reduction in rainfall significantly reduces the supply of available water

Key Terminology and Hazards

Arid: Arid means extremely dry, lack of moisture.
Desert: An arid area with very low levels of precipitation, making it impossible to support large amounts of vegetation, animals or people. Antarctica is technically a desert because of its low precipitation rates. The Sahara Desert is the largest traditional desert.
Water stress: When the demand for water exceeds the supply of water and shortages exist.
Physical Water Scarcity: When the supply of rainfall is lower than the demand of water.
Economic Water Scarcity: When water supplies exist, but the local population can not access them because of pollution, lack of technology, etc.

Hazards and Problems

Famine: Drought can lead to crop failures and livestock deaths that can lead to undernourishment and famine (food shortages).
Biodiversity Loss: Drought can cause plants and animals to die. Animals that drink large quantities of water like elephants can be some of the first to die.
Conflict: As water supplies begin to reduce then conflict over the remaining sources intensifies. This can be particular severe if resources are shared between countries or tribes.
Refugees: Because of the shortage of water and potential famine, people are forced to leave their home and often country to try and find food and water.
Desertification: A shortage of water can cause the land to start to degrade. Eventually this may lead to desertification (the land turning to desert).
Economic Loss: If a country is having to support refugees while at the same time seeing a decline in its exports (primary agricultural products) then the economy may decline.
Dependency: It is often poor countries that suffer from drought and it is these countries that find it hardest to cope, so often become dependent upon charities and international aid.
Education: As people suffer from undernourishment they often become weaker and are unable to teach and or go to school. Also during times of drought people (students and teachers) have to walk further to find water. All of these things would lead to a decline in the quality and quantity of education.

hazards IB 11 drought-severity-world

1.4 Human induced – hazards can be manmade as well as natural.

hazards IB 13

Probably the most famous manmade disaster is the Chernobyl Nuclear accident in 1986.

The 2010 Gulf of Mexico Oil Spill: Causes and Consequences

In 2010 the Deepwater Horizon drilling rig exploded in the Gulf of Mexico causing an environmental disaster. This article provides a contemporary case study on the impacts of energy production, a key issue at A-level, exploring why the disaster occurred and the full range of its consequences.

On 20th April 2010 a disaster took place some sixty kilometres off the Louisiana coast. An explosion occurred aboard the Deepwater Horizon drilling rig; the burning rig sank two days later. Some 1500m underwater, the well being drilled by the Deepwater Horizon was now spewing crude oil into the Gulf of Mexico at a rate of around 8,000 barrels – or 1.3 million litres – per day. This would become the largest oil spill in the world and greatest environmental disaster in US history.

The subsequent focus for politicians and the media was on the environmental impact on the Gulf Coast and the social and economic impacts on the population. With the high costs of the disaster – in terms of economic losses and environmental clean-up – much effort was also spent apportioning the blame for the disaster on the companies involved. This process of assigning responsibility became international as the main company involved, BP, was seen as foreign owing to its British origins.

This article firstly provides some background on oil production in the Gulf of Mexico; it then examines the consequences of the oil spill – both environmental and human – before considering why the risks of drilling for oil in the Gulf of Mexico were and continue to be taken. Through identifying the connections between the different aspects of the disaster – the environmental, economic and political – a better understanding can be gained. Also, whilst the local impacts of the oil spill may be most obvious, it is also important to study the national and international scales where consequences of the disaster can be traced.

The US Gulf Coast

Companies have been drilling for oil in the Gulf of Mexico since 1938. Today the oil industry dominates the economy of the Gulf Coast. The industry involves $124 billion of economic activity every year, which is about 53% of the region’s total. There are currently around 4,000 oil rigs in the Gulf of Mexico with new wells being drilled every year. With an estimated 140 million barrels of oil lying under the Gulf of Mexico, the industry’s importance is not likely to diminish.

The second largest industry on the Gulf Coast is tourism, generating around $100 billion per year. Fishing and shipping, whilst both large employers, make up only around 1% of the region’s economy. As both the tourism and fishing industries rely heavily on the natural environment – for its attractive landscapes and wildlife – there could be conflict with the oil industry, even without an oil spill.

The natural environment of the Gulf Coast is incredibly diverse and ecologically sensitive. It includes marshes, deltas, mangroves and oyster reefs. The habitats of the Gulf Coast provide for approximately 17,500 species, many of which are unique to the Gulf Coast. In light of this environmental diversity, the presence of the oil and gas industry can be viewed as a major risk to the natural environment, as well as a source of conflict for other industries in the region.

Environmental impacts of the oil spill

Following the incident in April, 4.9 million barrels of oil is estimated to have spilt into the Gulf of Mexico before the damaged well was eventually sealed (see Table 1 for a timeline of events). Not all of this oil reached the shoreline, some was burnt off or dispersed at sea and an unknown quantity is still circulating the underwater currents of the Gulf. Of the oil that did reach the Gulf Coast, the consequences were severe. Over 7,000 dead animals were collected in the months after the spill and several coral reefs were destroyed. The potential for longer-term damage to animal life came from an increased number of aquatic microbes that would reduce oxygen levels in the water. The animal food chain was affected by the spilt oil and the chemicals used in the spill response. With the potential to enter human food, this posed a health risk to people.

In response to the oil spill, BP organised the largest peacetime maritime force including some 46,000 people, nearly 7,000 vessels and over 120 aircraft. A range of chemicals was used both on and under the surface to try and break down the oil. Much of the oil that reached the surface was gathered together and burnt off. The main benefit of this approach was a reduction in the amount of oil that reached the shoreline. Subsequently, thousands of volunteers patrolled beaches collecting any oil that came ashore and bathing any animals that had come into contact with oil.

Human impacts

To explore the human impacts of the 2010 Gulf of Mexico oil spill – economic, social and political – it is useful to think about the local, national and international scales where those impacts happen. At the local scale, along the Gulf Coast, the oil spill had, and continues to have, an impact on other industries – mainly fishing and tourism. With many beaches affected by oil, tourists were deterred from visiting. This led to a loss of income predicted to be about $23 billion over three years. For the fishing industry, the health risks of oil and other chemicals entering the food chain meant that income and jobs were lost. The time required for the food chain to recover will be decades. For some parts of the Gulf Coast not badly affected or quickly restored, many potential visitors were not aware of this and so those areas still suffered a loss of income. To help individuals and businesses who had been affected by the oil spill, BP created a $20 billion relief fund which locals could apply to. BP were perhaps faster to accept responsibility and provide compensation in the USA than some oil companies have been in other parts of the world, such as Shell in Nigeria.

Just as other industries suffered a loss of income and jobs, the oil industry itself also suffered. In the aftermath of the oil spill, all oil drilling was banned in the USA; when the ban was lifted the regulations were much tighter. This led to less drilling activity and therefore fewer jobs for people in the oil industry, which had been a large and high-paying employer.

At a national level, there was pressure on President Obama and the US Congress to hold BP to account. This pressure was heightened by the Congressional elections to be held later in 2010. One aspect of the media coverage – and politician’s language – was reference to BP as ‘British Petroleum’, a name that BP had not used since the late 1990s. This repeated reference, with the suggestion of foreign responsibility for the disaster, helps to illustrate the international consequences of the oil spill.

Whilst BP is an international (multinational) company, it was founded and is headquartered in the UK. Furthermore, £1 out of every £6 held by UK pension companies was invested in BP at the time. This meant that any financial losses suffered by BP would significantly affect pensions in the UK. As such, there were calls for the British government to step in and limit the damage to BP’s finances and reputation. This posed a particular challenge as the oil spill happened shortly before the new Prime Minister David Cameron was elected. Cameron said very little publically on the oil spill or the treatment of BP, perhaps not wishing for a difficult relationship with the US government. Four years on, BP’s share price still hasn’t recovered from its substantial fall after the spill.

Conclusion: why was there an oil spill in the Gulf of Mexico?

The 2010 oil spill in the Gulf of Mexico may have been the largest recorded, but it was not necessarily the worst in terms of either environmental or human impact. It did, however, cost billions of dollars and lead to job losses, businesses closing and even UK pension funds struggling. The environmental impact was perhaps greater because of the ecological diversity and sensitivity of the Gulf Coast. In light of the consequences that have been seen over the subsequent years, it is important to ask the question of whether drilling that oil well was worth the risk – for both BP and the USA.

Whilst not the deepest well, it was nevertheless pushing technological boundaries. Furthermore, the Gulf of Mexico provides a domestic energy supply rather than needing to import oil, thus providing energy security for the USA. As drilling moves further out into the Gulf of Mexico, deeper waters and deeper oil and gas sources mean that the limits of technology are being continuously pushed. The expense of researching new technology and drilling more expensive wells is made possible by a historically increasing oil price which makes companies a profit. The price increase of the past 4 decades has been the result of an ever-increasing demand for oil, with the US still the highest consumer of oil in the world. So one argument suggests the risk of drilling the well is acceptable for BP because of the reward available, both in terms of profit and supplying the energy demand. The recent dramatic fall in the international price of oil over the past two years, to less than half its June 2014 price per barrel, puts a question mark over the economics of expensive production wells.

Other arguments might suggest the US should consider reducing its demand for oil, either by improving energy efficiency or increasing renewable energy production. Alternatively, oil can be extracted from tar sands and gas from shale, therefore reducing some of the demand on the Gulf of Mexico.

In taking a geographical perspective, this article has hopefully proven the complexity of the issues involved with energy production. This complexity makes decisions difficult and can also lead to conflict with those that do not agree with the decisions made. Taking the same perspective can reveal similar complexity in energy issues around the world.


  • There are a range of impacts of oil spills, not just on the environment but also on people.
  • The impacts of energy production do not just occur at the local, but also the national and international scales.
  • Meeting the demand for energy must be judged against the risks of energy production, especially where technological boundaries are being pushed

Points for discussion

  • Should companies drill for oil in ecologically important areas such as the Gulf of Mexico?
  • Looking at human and environmental issues, at a number of scales, what are the merits and possible problems with gas fracking in the UK?


Well: hole drilled down into the seabed and into a store of oil and/or gas so it can be extracted to the surface.

Drilling rig: vessel used to drill a well.

Energy security: political concern for how a country meets its energy demands in terms of where energy is supplied from. A related concern is whether a country can meet its energy needs through domestic supplies, in other words, from its own resources, or whether it must import energy from other countries which might lead to dependency on those countries.

Further reading

BBC News – Deepwater Horizon

BBC News – Surviving the oil spill (interactive video)

National Geographic Education – Oil spills

2 Vulnerability

Vulnerable pop 1 haiyan-typhoon

Super-Typhoon Haiyan

Vulnerable populations

People either choose or are forced to live near potential hazards for a number of reasons. Those reasons include:
Poverty: In many countries people are simply to poor, not to live in hazardous areas. This is especially true for newly arrived migrants who may be forced to build on marginal land e.g. a steep hill that is vulnerable to landslides or a river or coastline that is vulnerable to flooding.
Fertile soil: The minerals released during volcanic eruptions make the soil extremely fertile and ideal for agriculture. In countries like Indonesia, Philippines and El Salvador you will find people farming up very steep volcanic slopes, often building terraces to make farming easier.
Geothermal Energy: Where there is volcanic activity, it is normally possible to source the renewable energy of geothermal power (basically using the heat of the land to generate electricity). El Salvador has a geothermal power plant and countries like Iceland use geothermal power to generate electricity and heat water.
Tourism: Volcanoes often become very popular tourists attractions. People like to look at them, climb them and hopefully view stunning volcanic lakes or possibly lava. In Central America there are a whole series of volcanoes that have become popular tourist attractions ranging from Pacaya and Agua in Guatemala, to Santa Ana and El Boqueron in El Salvador, Masaya in Nicaragua and Arenal in Costa Rica. Mount Fuji (a volcano) National Park in Japan is the most visited national park in the world. Also volcanic areas often have natural thermal springs, Japan is famous for its onsen and Iceland is famous for its Blue Lagoon.
Resources: Some minerals like sulphur are located on the slopes of volcanoes. But also other minerals like the huge deposits of copper in the Atacama Desert, Chile are located near tectonically active areas and attract large numbers of people.
Beauty: Volcanoes can be extremely beautiful to look at. Mount Fuji is a perfect volcano and stunning to look at so many people chose to live near it. When Mount St. Helen’s volcano erupted some of the victims were people that refused to leave their houses because they loved the area so much.
Friends and family (inertia): Some families have lived in hazardous locations for generations. Their family homes and business are located in the area and people simply don’t want to leave or possibly can’t afford to leave.
Employment: Some hazardous areas offer good employment opportunities. For example many of the best tourist and fishing locations are found in coastal areas in the tropics e.g. the Caribbean, the Philippines and the Maldives. All three of these places are extremely vulnerable to hurricanes and flooding.
Ignorance: Some people are simply unaware that they are living in a hazardous area. If an earthquake or hurricane has not hit somewhere in recent history or a volcano has not erupted for many hundreds of years, then people forget or are unaware that they live near a potentially dangerous hazard.
Prediction: More and more people are prepared to live in hazardous ares because they trust scientific prediction. They believe scientists will be able to predict flood events, volcanoes and hurricane and give them adequate warning to protect themselves and their property.
Preparation: Most countries now prepare their citizens much better for hazards. People are educated about how to protect their home, how to evacuate, etc. This preparation gives people the reassurance to live in hazardous areas.
Hazard Recurrence: If some hazards don’t occur very often, or certainly hazards of high magnitude don’t happen very often then people will be prepared to take the risk. For example, on average only one supervolcano erupts every 10,000 years, so people are going to be happy to live near one, because the chances of it erupting during their lifetime is very low.
Building Design: Because of improved building design people now feel more confident of living in hazardous areas. Buildings are now designed to withstand earthquakes, hurricanes, etc. Most countries also have pretty strict regulations when building new structures.
Defences: Many countries and regions have built defences to protect from hazards e.g. levees on rivers and sea walls along the coast. These defences give people greater confidence to live and work in known hazard zones.
Hazard Mapping: Many countries now map their countries in terms of potential risk and exposure to hazards. Because people have been told to live in relatively safer (not totally safe) areas they are more confident about living near hazards.

Human Factors

Physical Factors

Increasing Risk and Vulnerability

  • Overcrowding and high housing/population density e.g. Mexico City
  • Areas with large amounts of informal housing e.g. Guatemala City
  • Areas that have been deforested e.g. large parts of Central America, the Philippines and Indonesia
  • Populations that live in remote inaccessible areas e.g. Himalayas
  • Countries with poor transport and communications e.g. Afghanistan
  • Poor or heavily indebted countries that rely on international aid e.g. Ethiopia
  • Countries with poor medical care e.g. Haiti
  • Hazard hotspots e.g. El Salvador and the Philippines
  • Low coastal countries e.g. Bangladesh
  • Countries with large rivers e.g. the Yangtse and Yellow Rivers in China
  • Areas in between the tropics that suffer from hurricanes e.g. the Caribbean
  • Areas that lie in tectonically active areas e.g. Chile
  • Arid areas that may suffer from drought e.g. the Sahel

Decreasing Risk and Vulnerability

  • Areas that have been hazard mapped so populations live in safer areas e.g. Wellington in New Zealand.
  • Areas that have early warning systems e.g. Pacific countries benefit from the tsunami early warning system
  • Areas with trained search and rescue teams and good medical care e.g. Japan
  • Countries with earthquake proof building design e.g. US
  • Countries that have educated populations in hazard management e.g. Japan
  • Countries that have developed sea defences and shelters e.g. the UK
  • Areas that have low frequency of hazards e.g. the UK
  • Areas that only suffer from relatively low magnitude hazards e.g. Europe
  • Areas that have a steady climate (not too hot, too cold, too wet or too dry)
  • Areas that only suffer from one major hazards

The influencing factors

Demographic Factors
1. Size of vulnerable population, 2. Population Density

Socio Economic Factors
3. A Country’s level of development,  4. An Individuals Wealth

Community Preparedness
5. Public Education, 6. Recent Hazard Events,
7. Early Warning Systems, 8. Building Codes

A community’s ability to deal with a hazard event. 
9. Governance, 10. Effective Lines of Communication, 11. Emergency Personnel, 12. Insurance Cover.


HAZARD (physical and human): This mean hazards that could potential or do hit a country or region. VULNERABILITY: This means how at risk populations are to natural or human hazards. CAPACITY – This means how able a country or region is able to react and recover to a natural hazard.

  • Earthquakes
  • Volcanoes
  • Floods
  • Hurricanes
  • Landslides
  • Tsunami
  • Tornadoes
  • Famine
  • Drought
  • Avalanches


  • Nuclear accident
  • Chemical leak
  • Population density
  • Poverty
  • Marginal land
  • Building design
  • Proximity to factories/industry
  • Proximity to hazardous areas
  • Hazard hotspots
  • Defences
  • Education level
  • Accessibility and Communication
  • Evacuation routes and practiced safety procedures
  • Deforestation
  • Drainage
  • Prediction
  • Hazard mapping
  • Fertility of soil
  • Relief of land
  • Age, sex, health
  • Search teams
  • Medical care
  • Search equipment (sniffer dogs or heating seeking equipment)
  • Helicopters and boats
  • Communication links (mobile phones or satellite phones)
  • Water and food
  • Tents and blankets
  • Wealth
  • Aid

BBC News article – Counting disaster: Who’s dying where?

BBC News article – Access to technology ‘aids survival in natural disaster’

Read the above article.


3 Risk and risk assessment

Analysis of risk

Risk is an interesting phenomenon. Even though the probability of something happening might remain constant, human actions can either increase or decrease the risk of something happening.

Risk: The probability of a hazard event causing harmful consequences.

People’s perception of risk or affected by a number of variables including:

  • Personal experience e.g. never experienced a hazard or know friends that have been killed
  • Personality e.g. risk taker, timid, careful
  • Knowledge e.g. do you know there is a risk or are you naive
  • Economic Status e.g. live in a strong house with the money to afford to escape a hazard or living in an informal settlement

Factors Increasing Risk Perception

Factors Decreasing Risk Perception

Involuntary Hazard: If you have no control over a hazard or being exposed to a hazard e.g. earthquake or chemical explosion then you are likely to have greater respect and an increased fear.
Many Fatalities: Where hazards cause widespread death e.g. strong earthquake or tsunami then people are normally more fearful.
Unfamiliar or Not understood: Hazards that people don’t understand like a tsunami or nuclear accident tend top cause a greater amount of fear.
Uncontrollable Hazard: Most physical hazards can not be controlled fully, especially large natural hazards like hurricanes and tsunamis. These uncontrollable hazards often cause more fear.
Awareness: If people are repeatedly warned about an impending hazard e.g. a hurricane about to hit then people will become more fearful.
Large scale, fast impact and high magnitude: Hazards that cover large areas, happen quickly and have a high magnitude tend to cause greater fear e.g. tsunami.
Voluntary Hazard: If people have chosen to carry out something hazardous, they have measured the risk and decided that the risk is acceptable.
Few Fatalities: Where casualties are often few e.g. British flood or avalanche is the Alps people view the risk as less because they believe that they will not be affected.
Familiar and Understood: Hazards that people hear about regularly and understand cause less e.g. floods.
Controllable Hazard: Some hazards can be controlled more e.g. immunisations for diseases or the icing of roads to reduce traffic accidents. These types of hazards are often perceived as less dangerous.
Lack of Awareness: If people don’t know about a hazard e.g. pollutants in water or the atmosphere they can obviously not perceive the risk.
Small scale, slow impact and low magnitude: If a hazard is only small-scale e.g. flood, takes a while to happen e.g. drought and weak then people are less fearful.

Risk assessments usually look at a number of variables, including:

  • Potential Hazard: Looks at the potential hazards, for a country this might be natural hazards like earthquakes and hurricanes, for a school it might be hazards like sun stroke, traffic accidents or getting lost.
  • Likelihood of Hazard: Look at the frequency of the hazard happening. Again for a country this might how frequent floods happen or for a school the chances of someone running into a road or tripping down some stairs
  • Likely Impact: What problems the hazard will cause. This might be damage to property, death and injury for a tsunami or cuts and bruises for falling down stairs.
  • People at Risk: Who will be affected. Will it be a whole country or just an individual e.g. a drought might affect a whole country, but getting lost might be just one person.
  • Mitigation: How the threat of the hazard can be reduced e.g. building defences to protect from floods or warning students to wear hats and use sunscreen.

Countries and organisations often have to assess the risk of a certain situation however the risk posed by hazards are often underestimated. The reasons for this include:

  • Hazard happens infrequently e.g. supervolcano
  • Hazard happens frequently so people know the affects and know how to prepare and react and therefore may underestimate the potential affects e.g. hurricanes in the Caribbean.
  • Risk of hazard unknown e.g. intraplate earthquake or nuclear leak
  • Belief that they will not be affected e.g. live in a safe area in a strong house
  • Belief that they will be given adequate warning e.g. prediction and notification e.g. tsunami warning system in the Pacific Ocean
  • Belief that they are protected against the hazard e.g. Japan protected against tsunamis and earthquakes
  • Government tries to play down affect of hazard e.g. Chernobyl accident in USSR (now the Ukraine) or Cyclone Nargis
  • Low magnitude hazards e.g. drought in UK
  • Little media attention or poor communication meaning you have not properly been informed e.g. Cyclone Nargis in Myanmar (Burma)
  • Voluntarily put at risk e.g. free climbing
  • Hazard normally affects few people e.g. UK flood
  • Underestimate secondary hazards e.g. the tsunami after the Japanese earthquake or disease after the Haiti earthquake.
tsunami 2004

Tsunami 2004

Occasionally underestimating a hazard can have catastrophic consequences. The governments surrounding the Indian Ocean knew that there was a risk from tsunamis in the area. However, they did not believe that the risk was big enough to spend money on fitting an expensive tsunami warning system. The result was that on 26th December 2004 people had no warning of the impending tsunami and close to 250,000 people died. The governments surrounding the Indian Ocean have now fitted a tsunami warning system.



Probability: The frequency that something is likely to happen. Probability is normally expressed as the ratio between the number of occurrences and the total number of possible occurrences. In geography the probability of hazard events are usually looked at in terms of there normal return interval e.g. once every ten years. Calculating probabilities can be very complicated and inaccurate. Some methods used to calculate probabilities include:

Location: By looking at the location of a settlement it is possible to make some estimates at the probability of a settlement suffering from a hazard. If a settlement is by a river, on a fault line, by the coast, in the hurricane belt or on a steep hill it obviously has a higher probability of suffering from some type of hazard. However, even when you know if a settlement is in a hazardous area it is then much harder to calculate when and how often the settlement will suffer from hazards.

Historical records: To try and calculate probability of any major hazards it is possible to look back through historical records and attempt to calculate the return interval of hazards. For example on average El Salvador suffers from a major earthquake every 10 to 12 years. This is OK for calculating long-term probability but useless for predicting the exact time or location of a hazard.

Gap (or seismic) Theory: This theory states that any displacement in one section of a fault line should be equal to displacement in other sections. Therefore areas along a fault that have not recently experienced quakes are more likely to suffer quakes in the future.


Why is it important to predict hazards?

  • Reduce the risk of death and injury.
  • Reduce damage to property and land
  • To protect agriculture e.g. move cattle to higher land during a flood or cover vulnerable crops during frosts
  • To give warning to citizens in order to give them time to evacuate and/or prepare
  • To prepare emergency services e.g. cancel non-emergency medical procedures, call up rescue teams, etc.
  • Cancel all non-essential travel e.g. flights and shipping to reduce the chance of accidents
  • Seek international assistance
  • Give warnings to vulnerable industries e.g. recall fishing boats during hurricanes or close mines during flooding.

Despite improvements in predictions, evacuation warnings are not always made or made very late. Some of the reasons for the delay in evacuation notices include:

  • Governments don’t want to cause panic. A panic may cause more deaths than the hazard.
  • The cost of ordering an evacuation (both in physically moving people and closed businesses)
  • Unpredictable warnings. People may actually be evacuated into a more dangerous area.
  • Late predictions. If a warning comes late it maybe safer for people to stay in their homes, rather than attempting to move away.
  • Some old, young and sick people are unable to travel
  • Some people don’t hear evacuation warnings or can’t afford to evacuate (no car, no where to go, etc.)
  • Some people don’t want to leave their home, business, pets, etc. unattended
  • People believe they are safe in their homes and can defend against the hazard.

Predicting earthquakes

Of all the world’s major natural hazards, earthquakes are probably the hardest to predict. Unlike most hazards there is no build up of magnitude e.g. droughts and floods (they tend to get progressively worse, whereas the strongest part of the earthquake is normally the first quake), there are no warning signs e.g. volcanoes (changes in shape, heat, etc.) and the hazard does not move towards land e.g. hurricanes and even tsunamis (so you can prepare for its arrival).

Even though it is still impossible to predict the exact location, strength and time of an earthquake, seismologists have made some advances in predicting earthquakes.

Read the following articles (below):

The Guardian – Is it finally possible to predict earthquakes?

The Guardian – Predicting earthquakes: Why seismologists have a mountain to climb.

BBC – Can we predict when and where quakes will strike?

BBC – Predicting quakes and saving lives with smartphones. 

How do seismologists predict earthquakes?

  1. Foreshocks: An increase in the frequency of small earthquakes (foreshocks) have been used to predict large earthquakes. Probably the most famous example was the prediction of the 1975 Haicheng earthquake which measured 7.2 on the Richter scale. However, only about 5% of foreshocks lead to bigger earthquakes so there can be a lot of false alarms. (USGS – Haicheng earthquake prediction)
  1. Seismic History: Seismologists can study the seismic history of earthquakes and try and make predictions of when future earthquakes are likely to happen. For example El Salvador has a major earthquake roughly once every ten to twenty years. However, at best this can only give a rough time frame and can certainly not pinpoint the time or location of an earthquake.
  1. Animal behaviour: Some scientists believe that small animals e.g. cats, toads and dogs are able to detect pre-seismic activity and alert people to an imminent earthquake. Some scientists believe that it is low frequency electromagnetic signals that they are responding to. It is believed that toads en mass hopping across the road in Taizhou, China two days before a major earthquake that killed 10,000 people was actually a warning sign that local authorities should have acted upon.
  1. Plate boundaries: Most earthquakes are found along plate boundaries so scientists can alert countries and populations to the risk of earthquakes. However, even knowing the potential location certainly does not help predicting the time of a quake. Also some earthquakes happen along old and unknown plate boundaries and faults or actually happen with plate boundaries e.g. intra-plate earthquakes. Because these earthquakes are almost impossible to predict that they can cause a lot of damage because populations are not prepared.
  1. Radon: The release of radon has been studied as a precursor to a major earthquake. However, all studies have proved inconclusive, but what scientist claimed that he did predict the recent L’Aquila earthquake in Italy using this technique.
  1. Geological Changes: Scientists believe that small-scale uplift, tilt or subsidence of the ground can be precursor to major earthquakes. However, it would be almost impossible to try and monitor all geological changes around the world to try and predict earthquakes.
  1. Rock stress: Scientists also believe that changes in the stress of rocks can also be a sign of imminent earthquakes. Some research done along the San Andres fault suggested changes in rock stress 2 hours before an earthquake. Again though it would be almost impossible to monitor all plate boundaries look for changes in stress.


Predicting hurricanes


Hurricane prediction – a not so exact science.


Although hurricanes are very hard to predict and track, scientists gaining a better understanding so can never give more accurate warnings. To begin with scientists know the conditions necessary for hurricanes to form, namely warm water. Therefore they know that hurricanes are likely to form in tropical areas towards the end of summer e.g. in the Caribbean between June and November. They also know that hurricanes normally move westwards (because of easterly winds) and slightly towards the poles (see map to the right). Even though scientists can not say exactly when a hurricane will form, because they form at sea they can make attempts to predict the path of hurricanes so that they can predict landfall and therefore warn communities. Hurricane tracks are predicted in a number of ways, by attempting to measure; temperature (air and sea), pressure, wind speed/direction and moisture:

Satellites: Satellites are now much more sophisticated and can measure the size of hurricanes, the direction they are travelling, but also cloud structure and ocean temperatures.

Weather radar: The US has a total of 155 radars constantly scanning the skies over the US and its surrounds. They are capable of recording wind and precipitation data.

Aircraft: The US Air Force uses aircraft to drop sensors into hurricanes to measure wind speed, wind direction, pressure, etc.

Buoys and floats: These can measure water and air temperature, wave height and the direction and speed of wind.

Computer models: All the information that is collected from the four methods above is then fed into computers to try and predict future movements and changes of hurricanes. However, even with improved data, models can often pick very varied courses and changes of hurricanes. To the right is a map showing the different computer predictions for Hurricane Katrina – you can see the predicted tracks are very varied.

Before Hurricane Katrina the following prediction was made – watch the YouTube clip below.


4 Disasters

“A disaster is a sudden, calamitous event that causes serious disruption of the functioning of a community or a society causing widespread human, material, economic and/or environmental losses which exceed the ability of the affected community or society to cope using its own level of resources.” (geography blog)

For a disaster to be entered into the database of the UN’s International Strategy for Disaster Reduction, at least one of the following criteria must be met:
  1. a report of 10 or more people killed
  2. a report of 100 people affected
  3. a declaration of a state of emergency by the relevant government
  4. a request by the national government for international assistance                               (

Natural Process or Event: A physical process that takes place, but poses no threats to humans or their property e.g. a volcano on an uninhabited island.
Natural Hazard: A natural process or event that has the potential to cause loss of life or injury or damage to property. You can also get manmade hazards like nuclear accidents or chemical spills.
Natural Disaster: The realisation of a major hazard that has caused significant loss of life/injury and/or damage to property.
Hazards can also be classified by some of their major characteristics. These characteristics can determine how severe the hazards are.

The following characteristics can determine how severe the hazards are:

Duration: The length of time that a hazard lasts for. As a general rule the longer the hazard the more severe it is likely to be. For example and earthquake that lasts 1 minute is likely to be more severe than one that last two seconds and a drought that lasts ten years is likely to be more severe than one that last three months.
Magnitude: This is the strength of a hazard. Most hazards are measured on a scale e.g. the Richter scale or the volcanic explosivity index (VEI). Generally speaking, the stronger the hazard the more severe the hazard is.
Predictability: Some hazards are easier to predict than others. For example, volcanoes normally give warning signs before they erupt and tropical storms can be tracked from development to landfall. However, others like earthquakes are much harder to predict. Generally speaking hazards that hit with no warning are going to be more serious.
Regularity: If hazards happen often and in quick succession e.g. a earthquake followed by multiple aftershocks then then the severity is likely to be greater. During hurricane seasons, countries can be hit by repeated storms each causing greater damage because it has not been possible to recover from previous damage.
Frequency: The return interval of hazards of certain sizes. For example earthquakes with a magnitude of over 8.0 happen on average once a year, but earthquakes of only 3 or 4 happen many times a day. If the hazard is a less frequent strong event, then it is going to have a bigger impact.
Speed of onset: If the peak of the hazard arrives first or arrives quickly e.g. an earthquake, then the affects are likely to be worse than one that arrives slowly e.g. a drought.
Spatial concentration: Where hazards are located or centred. For example earthquakes tended to be focused along plate boundaries, whereas tropical storms tend to be located in coastal areas in the tropics. Hazards that are located in known areas can be better prepared for and managed better.
Areal extent: If a hazard covers a large area e.g. a drought covering the whole of East Africa, then the severity of the hazard is likely to be more severe, than a flood hitting just one village.
Number of hazards: If a location is hit by multiple hazards that the affects can be more severe. For example hazard hotspots like Indonesia can be hit by earthquakes, volcanoes, landslides and flooding all simultaneously.

As a general rule as the magnitude of a hazard increases, the frequency of the hazard happening actually decreases.



5 Adjustments and responses to hazards and disasters

There are many methods available to dealing with hazards but they tend to fall into 3 categories:

  • Preparation – governments might consider how they can educate and prepare their populations for a disaster, so that they know what to do in a hazardous event. Also, governments can put into place laws and building codes to govern what can be built and to what standard, so that hazard impacts from hurricanes, earthquakes etc can be reduced.
  • Prediction – this is basically the mechanism by which we try to forecast when and where a hazard will occur. There are a huge range of prediction methods now for a huge range of hazards, think about the Avalanche risk charts you may have seen whilst skiing.  We can use satellites, river flow meters, sulphur dioxide meters, tilt meters etc to predict different hazards. We are better at predicting some hazards such as flooding, than we are others, such as earthquakes, because some of the warning signs are clearer and because of the amount of response time to each hazard.
  • Prevention – these are the methods that we can put into place as human beings to either prevent the hazard entirely or prevent some of the negative impacts of a hazard.  Some hazards such as forest fires can be prevented, by using fire breaks and prescribed (deliberate fires) major forest fires can be stopped.  Other hazards cannot be prevented, such as Hurricanes.  However, we can prevent some of the flooding during hurricanes by having correct drainage systems and coastal defences.

Reducing vulnerability – preparation

Aid – Aid can be used as an adjustment before potential hazards strike or after hazards strike. Aid before hazards strike will take the form of development aid and may include:

  • The building of wells to reduce drought and disease
  • The improvement of irrigation and the introduction of GM crops to reduce famine
  • The building of dams to reduce the risk of flooding and droughts
  • The building of roads and mobile networks to improve transport and communication throughout a country
  • The building of schools to improve education about hazards
  • The building of hospitals to reduce hazards like disease and treat people injured in hazards


Elementary school children take cover under their desks as part of a nationwide earthquake drill.
Aid given after a hazard or during a hazard is more emergency aid. Emergency aid may include:

  • The sending of rescue teams to search for victims
  • The provision of medicine or doctors to help injured
  • The provision of food and clean water
  • The provision of tents and blankets, etc.

Aid may also be given at a later date to help rebuild after a disaster e.g. rebuilding homes, roads, schools, hospitals and electricity supply.


Insurance is the act of insuring (protecting) property, people, businesses, etc. against the risk of something happening e.g. a person dying or being injured, or property being flooded or burnt down. In order to insure something it is necessary to pay a premium appropriate to the likelihood of something happening e.g. a 80 year old person is likely to die fairly soon, so any premium will be high, but the likelihood of a 25 year old dieing in the near future is much less so the insurance premium will be much less. Normally insurance policies are taken out with private companies, but if the risk of insuring is too high, then private companies may refuse insurance. In these circumstances governments will sometimes offer insurance. For example the New Zealand government has a national insurance policy protecting all houses in New Zealand against earthquake damage. There are a number of advantages and disadvantages to insurance including:


  • People can rebuild if homes and/or property are damaged by hazards
  • People can receive money for lost income if their job or business is impacted by a hazard


  • Not everyone can afford insurance
  • Insurance is offered in all areas in all countries
  • Insurance may be denied if the risk is too great
  • People maybe less willing to spend money on protection, if they know insurance will pay for repairs.

Hazard mapping


Crater Lake, Oregon simplified hazards map showing potential impact area for ground-based hazards

Hazard maps are created by calculating the vulnerability of different areas to natural hazards. Hazard maps are often made to calculate populations vulnerability to hazards like earthquakes, hurricanes, volcanoes and floods. Once potential hazards are known then appropriate adjustments can be taken. Adjustments may include:

  • Creating zones where building is not permitted because it is too dangerous
  • Creating zones where only low value uses are permitted e.g. farming
  • Protecting areas that are vulnerable to hazards with the use of defences
  • Evacuating vulnerable areas (and possibly allowing managed retreat in coastal areas)
  • Rebuilding vulnerable areas to new building standards

When creating a hazard map a number of variables will be considered. For example scientists creating an earthquake hazard map will look at the following:

  • Proximity to plate boundary or known fault
  • Seismic history (frequency and magnitude)
  • Geology (bedrock is much more stable than alluvial deposits which are vulnerable to liquefaction)
  • Gradient (flatter ground is generally more stable than steep land)
  • Possible secondary hazards (proximity to coast for things like tsunami, but also hills for landslides (forested/deforested))

Although hazard maps allow people and governments to prepare for hazards and enforcing zoning and planning regulations, it might also create difficulties for other people. For example in the UK the Environment Agency has just produced a flood risk map. This has helped communities prepare defenses, but it has also meant that some people have seen the value of their property reduce and prevented them from getting insurance.

Responses to a hazard

Short-term response: A response in the days and weeks immediately after a disaster has happened. Short-term responses mainly involve search and rescue and helping the injured.

Mid-term response: Responses in the weeks and months following a disaster. Mid-term responses involve re-opening transport links and getting electricity and water supplies operational again. It might also involve establishing longer-term refugee camps where there has been large-scale destruction.

Long-term response: Responses that go on for months and years after a disaster. It involves rebuilding destroyed houses, schools, hospitals, etc. It also involves kick-starting the local economy.

These can also be referred to as the 3R’s:

  • Rescue (Short-term)
  • Rehabilitation (Mid-term)
  • Reconstruction (Long-term)


  • Countries search and rescue teams
  • Countries providing helicopters and boats in search effort
  • Countries and NGOs donating food, tents and water (water purification)
  • Countries and NGOs sending medical teams
  • Providing aid money
  • Burying the dead to stop spread of diseases (recovery of bodies)


  • Re-connection of water and electricity supplies
  • Ongoing medical rehabilitation and possible counselling
  • Rebuilding of homes or creation of more permanent temporary structures
  • Re-connection of communication links (internet, phone masts)
  • Rebuilding of transport links (roads, railways, airports, ports)
  • Clearing away damaged buildings
  • Re-open schools and hospitals
  • Cancelling of debt (also long-term


  • Countries providing long-term aid (donations) to a region or country
  • Countries creating enterprise zones to encourage investment
  • Improvement in warning systems (tsunami warning system)
  • Countries investing in effected areas (FDI)
  • Improved education of hazard risks
  • Create new shelters and evacuation routes. Build new defences.
  • Help return of refugees and homing of orphanages

Psychology of disaster – click on the image below.


How has New Orleans recovered in the nine years since Hurricane Katrina?

Using named examples discuss the effectiveness of planning for a disaster [15].




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