What is a Natural Hazard?

• Natural hazard - a physical event that has the potential to cause loss of life or injury and damage property and infrastructure

  • livelihoods can be lost and the environment damaged
  • can be short-term events that last a few minutes or long-term events that can happen over several years
• Natural hazards can be classified in a number of different ways

  • geological hazards e.g. earthquakes and volcanic eruptions
  • climatic hazards e.g. droughts, tropical cyclones, floods
  • magnitude or intensity of the event
  • speed at which the event takes place
  • duration of the event
  • frequency of the event
• Natural hazard does not just mean physical events occuring in the natural world

  • people and property need to be put at risk by the physical event for it to be called a natural hazard
  • the natural hazard that occurs the most frequently is flooding
  • the natural hazard that kills the most people is earthquakes
• Supervolcano - a volcano that erupts at least 1000 km^3 of material
• Risk - the probability of a natural hazard occuring and the losses or damage that might result from that natural hazard
• Natural disaster - when a natural hazard causes damage and the people affected are unable to cope

  • involves social, economic and environmental losses or impacts
  • follows a natural hazard
• Natural hazard (e.g. flooding) + factors affecting possible risk (e.g. high population density) = natural disaster (e.g. how many people killed)
• For a disaster to be in the International Strategy for Disaster Reduction, it needs to meet at least one of these conditions:

  • a report of 10 or more people killed
  • a report of 100 or more people affected
  • a state of emergency declared by the government of the affected country
  • a request by the relevant national government for international assistance
• The impact of a natural disaster will depend on the:

  • length of time people are exposed to the natural hazard
  • vulnerability of the people affected
  • people’s ability to cope with the earthquakes
  • Vulnerability - the characteristics and circumstances of people in a community that makes them susceptible to the impacts of a natural hazard
• Vulnerability - the characteristics and circumstances of people in a community that makes them susceptible to the impacts of a natural hazard