Natural hazards

• Natural hazard


  A natural process which could cause injury or disruption to humans and damage or destroy property
• A natural disaster is a natural hazard
• Extreme events which do not pose any hazards are not counted as natural hazards
• Types of natural hazards

  • Geological (caused by land and tectonic activity, e.g. volcanoes, earthquakes, landslides, avalanches)
  • Meteorological (caused by weather and climate, e.g. tropical storms, heatwaves, cold spells)
• Factors affecting hazard risk

  • Hazard risk - the probability that a natural hazard occurs
  • Vulnerability - the more people in areas exposed to natural hazards, the greater the probability they'll be affected
  • Capacity to cope - the better a population can cope with an extreme event, the lower the threat
• Nature of natural hazards

  • Type - some hazards can be monitored and predicted, others happen unexpectedly
  • Frequency - some hazards occur more often than others, increasing hazard risk
  • Magnitude - more severe natural hazards cause greater effects than less severe
• Tectonic plates


  The Earth's surface is made up of moving tectonic plates
• Plate margins


  1. Destructive - plates move towards each other, one plate is forced under the other

  2. Constructive - plates move away from each other, creating a gap filled by magma

  3. Conservative - plates move past each other, grinding along fault lines
• Volcanoes


  1. Magma and gases are forced out of the Earth's interior

  2. Explosive eruptions occur when magma interacts with water
• Earthquakes


  1. Tension builds along plate boundaries as they move, eventually causing the plates to jerk past each other, releasing energy in the form of seismic waves

  2. The epicentre is the point on the surface directly above where the earthquake starts

  3. Magnitude measures the amount of energy released
• Primary effects of earthquakes

  • Buildings and people are damaged or killed by collapsing structures
• Secondary effects of earthquakes

  • Landslides and tsunamis can cause further damage and casualties
  • Fires can break out due to ruptured gas and electricity lines
  • Damage to infrastructure like roads, pipes and communications
• Earthquake response


  1. Immediate - rescue injured, put out fires, provide supplies

  2. Long-term - rebuild damaged buildings and infrastructure, resettle displaced people, promote economic recovery
• Reasons why people live in areas with tectonic hazards

  • Employment and family ties
  • Government support
  • Fertile volcanic soil
  • Tourism opportunities
• Tectonic hazard management strategies

  • Monitoring - use scientific instruments to detect warning signs
  • Protection - build earthquake-resistant structures, reinforce infrastructure
  • Prediction - use scientific data to forecast when hazards may occur
  • Planning - train emergency services, educate public, plan evacuations