Natural disasters are a consequence of natural hazards. A natural hazard is considered a disaster when it has exceeded a given threshold, meaning it has caused significant damage to society or a community, and they can no longer cope using their own resources. Significant damage includes disruptions to human, material or environmental aspects such as loss of life, injuries, and damage to infrastructure.
What are some examples of natural disasters?
Examples of natural disasters include earthquakes, volcanic activity, extreme heat, floods, wildfires, tsunamis and hurricanes.
What are some of the major natural disasters?
Some recent major natural disasters are:
Haiti earthquake (2010)
Hurricane Katrina (2005)
Sichuan earthquake (2008)
Gorkha earthquake (2015)
Mount Merapi eruption (2010)
Tōhoku earthquake and tsunami (2011)
These disasters had significant social, economic and environmental consequences as large areas were affected, and many died. For instance, approximately 3 million people were affected by the Haiti earthquake in 2010. You will learn more about the reasons for the different levels of impact below and in the article impacts of hazards.
What is the threshold for natural hazards turning into natural disasters?
An example of the criteria for the threshold of hazard turning into a disaster is:
How do natural hazards become natural disasters?
Vulnerability, resilience, and risk factors explain when natural hazards become natural disasters.
Vulnerability is the characteristic of the society or community that influences its susceptibility to hazards.
Resilience is how much the society or community can cope with the hazard, recover and remain functioning. They have the tools to reduce the probability of a disaster.
Risk is the probability of a hazard occurring and causing damaging consequences (such as injuries, loss of lives, impact on health, assets and services).
Hazard risk equation
The hazard risk is calculated using the equation:
The Hazard Risk Equation
This means that the type, frequency and magnitude of the hazard proportionally influence the level of risk. For instance, the risk level of a magnitude 9 earthquake will be larger than the risk level of a magnitude 7 earthquake.
As the vulnerability increases, so does the risk. The factors that influence a community’s vulnerability include its population total, density, structure, distance from the hazard, poverty, politics, infrastructure, and education.
Manageability includes implementing emergency evacuation, rescue and relief plans, preparing people to help each other, and infrastructure designed for resistance against hazards. It is influenced by money, access to aid, the country’s international relationships, debt, and the population structure.
The relationship between development and natural disasters
The difference in characteristics between developed and developing countries determines their level of resilience to natural disasters.
Developing countries tend to have high populations, high birth rates, low resources, low access to technology, smaller economies, and unsafe environments. This makes it more difficult to cope with possible natural hazards. In addition, people in developing countries tend to rely on insecure resources for their income.
Developed countries often have lower populations, low birth rates, higher access to technology, bigger economies, and safer environments.
Disasters can further hinder development by damaging livelihoods, production, infrastructure, and the numbers of the working population. They also destroy environments.
Resilience is increased through the following aspects:
- Economic - job opportunities for everyone to improve wealth, and quality of life
- Social - improvement in health, education and housing
- Environmental - designing the environment to reduce the risk of disaster, sustainable resource management and access to safe water
- Political - human rights, political freedom, preventing the exclusion of groups and fairly distributing resources before and after natural hazards.
Age and natural disaster
The age structure of a population can have a significant impact on their resilience. Children and the elderly are less likely to cope with the consequences of hazards and disasters. They are more likely to suffer from injury, loss of life and chronic health problems.
Elderly people are more vulnerable because of their diminishing physical health, age discrimination and poverty. Approximately 56% of the lives lost in the Tohoku earthquake and tsunami in 2011 in Japan were people aged 65 and above.
Where do natural disasters happen?
The Philippines, Japan and Bangladesh are the countries most prone to natural disasters. They have the highest risk of earthquakes, storms, floods, volcanoes and tsunamis. One of the main reasons is their proximity to destructive plate boundaries. Additionally, the risk of natural disasters is increased by the socio-economic situations in the Philippines and Bangladesh and the low elevation of land in Bangladesh.
The following image shows the distribution of natural disaster risks in the world.
Global natural disaster risk Image: SEDACMaps, CC BY 2.0
According to the map, other countries with a very high risk of natural disasters include Chad, Niger and Cameroon, the Pacific island countries, Caribbean countries and Chile. Many of these areas lie near tectonic boundaries.
How often do natural disasters occur?
The frequency of natural disasters has changed over time. According to the Food and Agriculture Organization of the United Nations, natural disasters happen three times more often than they did in the 1970-80s. Currently, about 6800 natural disasters happen every year.
Natural Disasters - Key takeaways
A natural disaster is when a natural hazard has exceeded a given threshold meaning it has caused significant damage to society or a community, and they can no longer cope using their own resources.
An example of the criteria for the threshold of hazard turning into a disaster is ten or more deaths, one hundred or more people affected and one million dollars in economic losses.
Vulnerability is a characteristic of the society or community that influences its susceptibility to hazards.
Resilience is how much the society or community is able to cope with the hazard, recover and remain functioning.
Risk is the probability of a hazard occurring with damaging consequences
The hazard risk is calculated using the equation: Risk = Hazard Vulnerability/Manageability
Developing countries tend to have lower resilience because of high populations, high birth rates, low resources, low access to technology, a smaller economy and unsafe environments.
Children and the elderly are less likely to be able to cope with the consequences of hazards and disasters.
The Philippines, Japan and Bangladesh are the countries most prone to natural disasters.
Images
Global disaster map: https://commons.wikimedia.org/w/index.php?curid=85090449
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