Analysis of risk


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

Risk is a very interesting phenomenon. Even though the probability of something happening might remain constant, human actions can either increase or decrease the risk of something happening. For example the probability of catching skin cancer in the UK is roughly 100, 000 (non-melanoma skin cancer) per 62 million people 1 in 620 per year. However, you can reduce your personal risk by using sun cream, avoiding midday sun, not using sunbeds, etc.

People's perception of risk can also vary. Look at the two videos below, to most people the activities would appear very dangerous and very risky. However, to the individuals involved who have spent hours training and practicing may perceive the risk as very small.

In this section we will look at the factors that can affect both risk and the perception of risk.



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

The following knowledge or lack of knowledge about hazards can increase or decrease individual's perception of risk.

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: Just like the two clips above, 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.
Ideas taken from Geography Course Companion - Garrett Nagle and Briony Cooke

Risk Assessment


Risk assessment: Calculating the likely risk of a hazard happening. People make constant risk assessments all the time e.g. is it safe to cross the road. However, organisations like schools have to make more formal risk assessments. They have to calculate the possible risks of things like school trips e.g. exposure to sun, risk of accident, possibility of drowning. If the risk is deemed too high then the trip can not take place. For example many schools in the UK will now not go on school trips to rivers or the coast because of the risks involved. More formal risk assessments have to be carried out on paper, often on set proforma.

Example of Risk Assessment
Example of Risk Assessment

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.

Scores are often applied to the potential of the hazard, its likelihood and impact. If the score of the potential hazard is too high, then the risk will not be taken. Below is an example of half complete risk assessment. The risk assessment is looking at the potential hazards on a school trip. In the attached risk assessment, if the risk is over 10 then the hazard must be avoided.

In summary it is very important for countries and organisations to make assess risk, but in reality the risks 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.

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.

A Map of Death - Popular Science

Indonesia concerned about cost of tsunami warning system - People's Daily

Burma hits out at cyclone reports - BBC article

Japan nuclear plant data error was unacceptable - BBC article

Haiti children facing ongoing disease and trauma - BBC article

Probability


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.

Big Tokyo Earthquake Likely in the Next 30 Years - BBC article

Volcano Warning - Australian Eruption Overdue - ABC News

Using prediction methods it maybe possible to calculate more short-term probabilities. Prediction methods are talked in more detail later (Hazard event prediction), but a summary is given below.

Earthquakes: Earthquakes are very hard to predict. Looking at historical records and following gap theory may give you a long term probability and possible locations, but they are very inaccurate when predicting exact date/time. Short-term predictions are also very unreliable, all the scientists in Tokyo believe that chance of a major quake has increased because of the large number of earth tremors. Animal behaviour and release of radon may help give warnings, but the science has not been proven to make accurate predictions nor to make reliable probabilities of events occurring.

Volcanoes: Again with volcanoes it is possible to look at historical records, but unlike earthquakes volcanoes tend to give warnings which short-term probabilities can be based on. An increase in tremors, gas release or temperature signal that the probability of a volcano in the near future is much higher. Also changes in the temperature and chemical composition of water as well as changes in the volcano shape can signal that a volcano is likely in the near future.

Droughts: It has possible to calculate the probability of droughts occurring months and sometimes years in advance. By studying weather phenomenon like El Nino and La Nina the amount of likely rain as well as likely temperatures can be ascertained. Also by looking at demand (population growth, industry and agriculture) predictions can be made where water stress is likely to happen. The physical location of countries is also important e.g. are they located in arid areas. In addition historical rainfall and temperature records can be studied to predict future weather and the probability of drought.

Flooding: Like with droughts weather phenomenon, weather patterns and historical data can be studied to calculate the probability of flood events happening in the future. Short-term probabilities can also be based on approaching storms and current ground conditions. Most countries have flood warnings that are issued if the probability of flood is sufficiently high.

Wildfires: The probability of wildfires can also be calculated on rainfall totals, condition of vegetation e.g. wet or dry, topography, wind speed, etc.

Even though short-term probabilities are more accurate than long, it does mean that the hazard will happen, probabilities just state the chance of the hazard happening. Volcanoes may return to a dormant state, storms can change cause and rainfall can reduce risk of droughts and wildfires.

Likely Impacts


There are numerous factors that need to be looked at, when individuals, communities, countries and organisations are assessing the likely impacts of hazard events. These factors include:
Frequency and magnitude of hazard: Obviously if an areas suffers from strong hazards and if the hazards are frequent and varied in nature then the impacts are likely to be greater. For example countries like El Salvador are hazard hotspots and can suffer from hazards like hurricanes, volcanoes, earthquakes, floods and landslides all at the same time. The greater the number and magnitude of hazards the the greater the impacts.
Defences: If a community or country is well defended e.g. levees or sea walls then the impacts of the hazard is likely to be less, unless the magnitude of the hazard is greater than what the defences are designed for e.g. Hurricane Katrina in New Orleans and the tsunami in Japan (2011).
Prediction/Warning and Evacuation: Countries like the US that have good prediction technology and are able to warn there populations of upcoming hazards are likely to experience smaller impacts. As well as prediction and warnings it is also important that citizens are trained in evacuation and there are evacuation routes in place.
Building design: Countries with good building codes and enforced building codes are going to suffer lesser impacts from hazards. Japan and California in the US have very strict enforced codes which mean most buildings withstand even the strongest quakes.
Hazard Mapping: Countries that have comprehensive, accurate and enforced hazard mapping are likely to suffer less from the impacts of hazards e.g. Wellington in New Zealand and San Fransisco in California. Areas that don't hazard map and have large numbers of people living on marginal land are likely to suffer greater impacts from hazards because there are more people living in vulnerable areas e.g. Medellin in Columbia.
Topography and Geology: Areas that are relatively flat and are situated on solid bedrock tend to suffer less impacts from hazards. However areas that are hilly are much more vulnerable to secondary hazards like landslides and areas on unstable bedrock or even alluvial deposits like Christchurch are going to be vulnerable to processes like liquefaction and suffer greater impacts.
Transport and communications: Countries that have good communication e.g. mobile networks and the internet can better warn there population of impending hazards are less likely to suffer severe impacts from hazards because their populations can prepare. As well as good communications it is also necessary to have good transport links so populations can escape prior to hazards and rescuers can get in after hazards has happened.
Medical services: Countries with good medical care are going to suffer less impacts because they can treat the injured and reduce secondary hazards like disease. In countries like Haiti where medical care is limited, just as many people died from the secondary hazard of disease greatly increasing the impact of hazards.
Education: In countries with high literacy rates people tend to have a better understanding of the potential hazards the region may suffer from and also have a better understanding of how to prepare for hazard and how to react after one. All these things help reduce the impacts of hazards. In countries with poor education people may not even know that they are vulnerable to hazards and therefore the impacts are much greater.
Emergency services: In countries with rescue teams and good emergency services (police, ambulance and fire) the impacts of hazards are likely to be reduced. Not only can they rescue victims, but they can also help keep calm and distribute aid to the needy.
Money and Insurance: Areas that are relatively affluent are better able to prepare for hazards and recover after hazards. In addition individuals with insurance are better able to recover from hazards. Both these reduce the impacts of secondary hazards and the impacts of future primary hazards.
Vulnerability and likely impacts may be mapped by GIS (geographical information systems). GIS simply refers to the collection, storage, presentation, manipulation, analyse and management of geographical information. The data/information is shown spatially so is normally overlaid on a base map. The GIS map below has used different information e.g. geology, altitude, topography, building design, defences, etc. to create a hazard map.

GIS_HAZARD_MAP.gif