Natural hazards

• Earthquake Case Study: Chile
• Location of Chile

  • South America
  • South west coast of South America
  • Southern hemisphere
  • West of Argentina
• Causes and Info

  • Destructive plate margin
  • Nazca and South American plates
• • 27 February 2010
  • Richter scale: 8.8
  • Caused a tsunami
  • Winds at 800km/h
• Why live near tectonic hazards?

  • Don't want to leave
  • Jobs
  • Family
  • Fertile soil for farming
  • Tourism provides jobs
• Monitoring

  • Earthquakes: Can't be Monitoring the Earth's movement
  • Volcanoes: Small earthquakes, Escaping gas, Change in the volcano's shape
• Planning

  1. Earthquakes: Buildings with shock absorbancy, Automatic shut off switches to prevent fires

  2. Volcanoes: Strengthen buildings, Trenches and barriers
• • Can't afford to move
  • Doesn't happen very often
• Prediction

  • Earthquakes: Can't be reliably predicted
  • Volcanoes: Can be predicted by monitoring the volcano
• Protection


  1. Earthquakes: Avoid high risk areas, Prepared emergency services, Educate locals, Practice evacuation drills, Emergency supplies

  2. Volcanoes: Can't be protected
• Tropical Storms Case Study: Typhoon Haiyan
• • Made landfall in the Philippines on 8th November 2013
  • The most affected areas were Tacloban and Cebu
  • Up to 280 mm of rain
  • Up to 314 km/hour winds
  • Storm surge with 2.3m waves
  • One of the most powerful storms recorded
• Disasters also have significant economic impacts, including damage to infrastructure, loss of productivity, increased healthcare costs, and decreased tourism revenue.
• In addition to these immediate effects, disasters often lead to long-term consequences such as displacement, poverty, and social unrest.
• Natural Hazard

  A natural process which could cause death, injury or disruption to humans or destroy property and possessions
• Two Main Types of Natural Hazard

  • Geological Hazards
  • Meteorological Hazards
• Geological Hazards

  Caused by land and tectonic processes, including volcanoes and earthquakes, landslides and avalanches
• Meteorological Hazards

  Caused by weather and climate, including tropical storms and other extreme weather (e.g. heatwaves and cold spells)
• Hazard Risk

  The probability of people being affected by a hazard in a particular area
• Factors Affecting Hazard Risk

  • Vulnerability - the more people in an area exposed to natural hazards, the greater the probability they will be affected
  • Capacity to Cope - the better a population can cope with an extreme event, the lower the risk of them being severely affected
• Factors Affecting Hazard Risk

  • Type - the risk from some hazards is greater than others (e.g. tropical storms can be predicted and monitored, but earthquakes happen suddenly with no warning)
  • Frequency - natural hazards that occur more often may carry a higher risk
  • Magnitude - more severe natural hazards tend to have the greatest effects
• Natural hazards are extreme events that pose a threat to people
• Tectonic plates are constantly moving and the Earth's surface is separated into these plates
• Continental Crust

  Thicker (30-50 km) and less dense
• Oceanic Crust

  Thinner (5-10 km) and more dense
• Plates are moving because of convection currents in the mantle
• Three Types of Plate Margin

  • Destructive Margins
  • Constructive Margins
  • Conservative Margins
• Destructive Margins


  1. Oceanic plate is subducted (forced down into the mantle) and destroyed, creating gas-rich magma, volcanoes and ocean trenches

  2. Where continental plates meet, the ground is folded upwards, creating fold mountains
• Constructive Margins


  Magma rises from the mantle to fill the gap and cools, creating new crust
• Conservative Margins

  Crust isn't created or destroyed, plates move sideways past each other or in the same direction at different speeds
• Volcanoes at Destructive Margins

  Denser oceanic plate moves down into the mantle, melts, and magma rises through cracks in the crust to form a volcano
• Volcanoes at Constructive Margins

  Magma rises up into the gap created by the plates moving apart, forming a volcano
• Volcanic Eruptions

  Volcanoes emit lava and gases, and some erupt lots of ash which can cover land, block out the sun, and cause pyroclastic flows
• Earthquakes

  1. Caused by the tension that builds up at all three types of plate margin as the plates move

  2. The plates eventually jerk past each other, sending out shock waves which are the earthquake
• Focus

  The point in the Earth where the earthquake starts
• Epicentre

  The point on the Earth's surface straight above the focus
• Moment Magnitude Scale

  • Measures the amount of energy released by an earthquake (magnitude)
  • A logarithmic scale, so a magnitude 7 earthquake causes 10 times as much ground shaking as a magnitude 6
• Earthquakes of magnitude 6 and below normally only cause slight damage, while those of magnitude 7 and above can cause major damage and deaths
• Global Atmospheric Circulation


  The overall movement of air between the equator and the poles that affects the Earth's climate
• Global Atmospheric Circulation


  1. Air moves due to differences in air pressure, creating high and low pressure belts and cells

  2. Air rises at the equator, sinks at 30° and 60° north/south, and moves back towards the equator or poles