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Hazards and Disasters


Hazard: A threat (whether natural or human) that has the potential to cause loss of life, injury, property damage, socio-economic disruption or environmental degradation.

Hazard Event: the occurrence (realization) of a hazard, the effects of which change demographic, economic and/or environmental conditions.

IB Geography, hazard characteristics
Figure D1: Hazard Characteristics



IB Geography, Volcano locations
Figure D2: Volcanic location map
Video D1: Tectonic plate boundaries

Case Study: Soufriere Hills volcano, Montserrat

Montserrat is a Caribbean island that suffered significant environmental and economuc damage when the Suffriere Hills volcano started to erupt.

The capital city Plymouth has been abandoned leading to to forced migration within the island but also to the UK.

Watch the videos apposite and use the links below to complete this case study worksheet.

IB Geography, hazards, motserrat map & timeline
Video D2: Plymouth destroyed
Video D3: Plymouth


Hurricanes are low pressure systems that bring strong winds, large waves and heavy rain. They are formed over seas/oceans with a temperature of 27o or more down to a depth of 60m. Their specific requiremenst mean that they occur in distinct areas of the planet.

Originating as tropical storms, it is the Coriolos force that starts the spinning motion that characterises them. For this to occur they must be 5o or more from the equator.

Hurricane characteristics outline sheet

IB Geography, Hazards, Hurricane paths
Figure: Hurricane paths

Case Study: Hurricane Katrina

Hurricane Katrina reached Category 5 strength while out at sea. By the time it hit New Orleans it had weakened to a Category 3 hurricane but still caused considerable damage and shone the spotlight on Americas ability to deal with a severe hazard event and the emergency response in the aftermath.

Use the information below and in the videos to complete the Case Study worksheet.

Hurricane Katrina information pdf

Katrina Case Study outline sheet

Video: Hurricane Katrina



Human Induced Hazard

Case Study: Chernobyl, Ukraine

Chernobyl (National Geographic)


Vulnerability: the susceptibility of a community to a hazard or to the impacts of a hazard event.

Why do people live in dangerous places?

People choose to live in dangerous locations around the world for various reasons, but in doing so they increase their vulnerability to hazards.

Other factors such linked to development can play a major role - infrastructure quality, technology for prediction of hazard events.


  • fertile soil for farming
  • flat land (building, transport & trade)
  • Navigable river sections
  • Leisure opportunities
  • Scenic & desirable views and landscapes
  • Flooding may infrequent

Volcanic locations

  • fertile soils for farming
  • minerals that can be mined and sold
  • reliable freshwater supply
  • jobs and income linked to tourism

Hurricane prone locations

  • warm climate due to the latitude
  • coastal locations are desirable places to live
  • recreational activities (water sport, coral reefs etc)
  • Trade routes (ports, harbours, markets)

Factors affecting Vulnerability

Population density:

  • high densities make evacuations more difficult. They also require greater emergency medical capacity and the ability to quickly distribute essential supplies (water, food).
  • Disease spreads more quickly in densely populated areas and can rapidly become a major issue.


  • Well designed infrastructure (roads, utilities, communication networks) are more likely to withstand hazard events and greatly speed up emergency procedures after an event.

Insurance cover

  • Socioeconomic groups able to afford comprehensive insurance for property and medical care are able to recover from a disaster much more rapidly.

Availability & preparedness of emergency services

  • Trained rescue teams are more effective & efficient in locating & helping casualties.
  • Emergency plans/procedures that have been practised by the emergency services and local populations can make evacuations much faster & rescues much more effective.
  • Specialist rescue equipment is expensive but speeds up disaster response efforts.
  • Reserve supplies of medicines and bottled water can significantly reduce the spread of disease.


Risk: The probability of a hazard event causing harmful consequences(expected losses in terms of deaths, injuries, property damage, economy and environment).

Risk Perception Factors

Degree of control

If there is a degree of control over the risk (white water rafting, rock climbing) the perception of the risk decreases. If there is no control (earthquakes) the risk perception increases.

Understanding of the Hazard

Understanding the hazard (hurricanes) prompt a lower risk perception than not understanding it (nuclear accidents).

Loss of Life

Disasters that have a large number of fatalities (Asian Tsunami 2004) increase the perception of risk in comparison to low fatality events such as floods.

Media Coverage

High media coverage increase the perception of the risk (Japan earthquake and tsunami 2011).

Frequency of onset

Disasters with immediate effects (earthquakes/tsunamis) increase the risk perception, Slow onsets such as droughts have a lower risk perception.

2014 10 Riskiest Cities in the World





Disaster: A major hazard event that causes widespread disruption to a community or region that the affected community is unable to deal with adequately without outside help.


How have the intensity and impact of disaster events changed over space and time?

  1. Look at Figure D follow the links. Answer/discuss the subsequent questions:
  2. Describe the trends in disaster frequency (total disasters & types of disasters)
  3. Offer explanations as to why you think there are increasing numbers of disasters & why specific ones are increasing. (You should consider issues such as: increasing populations, urban areas, climate change, agricultural practises & deforestation).
  4. How can the risks of disasters be reduced?
  5. Follow this link (UN disaster risk reduction) & explain what you think the statement means:
  6. "There is no such thing as a 'natural' disaster, only natural hazards."
Disaster occurance frequency
Figure D :Frequency of disaster occurance


Importance of Risk Analysis


  • Preparation efforts can be more targeted at the people who are most vulnerable.
  • Appropriate levels of resources can be committed to preparing for the hazard event (there is an opportunity cost if too many resources are allocated).
  • Vulnerable populations can be educated about the risks involved which allows them to plan for it (insurance, building design, emergency supplies).
  • Infrastructure can be modified to withstand the hazard event.

Action to take before the event

  • Building Design: planning regulation about building structures & materials used (shatterproof, fireproof etc).
  • Land use control: zones identified as high risk may have planning restrictions (floodplains, volcanic slopes etc).
  • Infrastructure:
    • Important utilities should be away from known risk areas (water treatment plants/ power stations)
    • Power lines suspended rather than underground in earthquake zones.
    • Defences (levees, sea walls, lava diversion channels) checked and strengthened to meet risk rating.
    • Emergency shelter structures identified & people informed (New Orleans Superdome).

During the Hazard Event

  • Communication between agencies/services should be more effective.
  • Populations & emergency service teams should be aware of evacuation plans/procedures.
  • There should be clear directives about actions to take relating to the severity of the hazard event.
  • Emergency response times should be quicker & efforts more specifically tartgeted.

Responses to Hazard Events

Short Term Responses

  • Emergency rescue services to find people.
  • Issuing emergency supplies (water, food, shelter, medicines).
  • Dealing with dead people/animals to limit the spread of disease.
  • Cleaning debris from key roads and transport routes.
  • Re-connecting vital services (water & power).

Medium Term Responses

  • Re-connecting other services (phone and internet lines, local authority departments).
  • Getting people back in their houses.
  • Loss analysis of damage by insurance companies to speed up payments.
  • Clearance of debris on secondary routes of transportation.
  • Coordination of aid delivery and projects.

Long Term Responses

  • Completion of major rebuilding projects
  • Infrastructure upgrades
  • Completion of any insurance claims still outstanding

The Importance of Insurance

Insurance cover for property and posessions is an option that people often choose to pay for since it means that in the case of a disaster (or fire/theft etc) the insurance company will pay the bill for repairs and replacements.

In areas that are vulnerable to natural hazards it obviously makes a lot of sense to insure valuable possesions. Unfortunately in areas of higher risk the cost of insurance is also higher, which means that less people can afford to be comprehensively covered.

It is often the poorest sectors of society that lack adequate insurance, and these are the people that can least afford to replace their posessions or rebuild their properties after a hazard event.


Watch the videos opposite and answer the following:

  1. Explain why having appropriate insurance cover is so important in high risk areas.
  2. Why do so many people not have it?
  3. Why cannot you not leave it unitl the last minute to get insurance cover?

Chile Vs Haiti Earthquakes

Haiti Vs Chile earthquake: Comparison in terms of magnitude and effects


  1. Read this article (the week).
  2. Make notes about the magnitude & effects of the 2 earthqaukes. Explain the importance of wealth, regulation and preperation in reducing the risk of a natural hazard becoming a disaster.
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