Natural Hazards

• natural hazard

  A natural event that threatens people or has the potential to cause damage, destruction and death.
• Hazard risk

  The probability or chance that a natural hazard may take place.
• What factors affect hazard risk?

  - Urbanisation (denser population of people and buildings)

  - HIC's (afford better technology and defences)

  - Climate change (warmer area more chance of greater storms)

  - Farming
• Atmospheric hazards

  Created in the atmosphere by the movement of air and water:example hurricanes,tornadoes.
• Terrestrial Hazards

  created by the movement of Earths tectonic plates: example, earthquakes, volcanoes.
• Water based hazards

  Created by rivers, sea or oceans: example, tsunami ,rivers
• Biological Hazards

  Viruses, bacteria, and other organisms in the environment that harm human health: example, disease such as malaria
• Describe the distribution of volcanoes

  - Generally, found on plate boundaries

  - Specifically, along the west coast of South America

  - There are some anomalies such as the ones in the middle of the pacific ocean
• Destructive boundaries


  Plates that move towards each other
• Constructive boundary

  Where two tectonic plates move away from each other
• Conservative boundary

  where two tectonic plates slide past each other
• How are volcanoes formed at a constructive plate boundary

  - Plates move apart due to convection currents.

  - A gap is created.

  - Magma rises to fill the gap.

  - It then cools and builds up.

  - It then forms a volcano
• How are volcanoes formed at destructive boundaries

  • Plates move towards each other due to convection currents

  • Oceanic crust sinks beneath continental crust because it is denser.

  • This occurs at the subduction zone

  • Friction causes the crust to melt and create magma.

  • Magma rises to the surface forming volcanoes.
• how are earthquakes formed at conservative boundaries

  • Plates move in similar directions at different speeds.

  • Friction causes plates to lock.

  • Pressure builds as the convection currents try to move the plates.

  • Eventually, pressure releases, the plates jerk/jolt.

  • This causes an earthquake.
• How do earthquakes form at destructive plate margins

  • Tension builds when plate gets stuck as moves down past the other into the mantle

  • Plates eventually jerk/jolt

  • Sends out shock waves
• How do earthquakes form at constructive plate margins

  Tension builds along cracks in the plates as they move away from each other
• how to measure earthquakes

  - seismograph

  - ratchet scale
• Why do earthquakes cause more damage in LICs than HICs

  - Weaker infrastructure

  - Less planning and prediction
• Monitoring

  Using scientific equipment to detect warning signs of events such as a volcanic eruption
• prediction

  using historical evidence to make predictions about when and where a tectonic hazard may happen
• protection

  Actions taken before a hazard strikes to reduce its impact, such as educating people or improving building design.
• planning

  identifying and avoiding places most at risk
• Why people live near volcanoes

  • Fertile soil- releases potassium into soil

  - E.g. - Naples, Italy - olives, nuts and fruits growing next to mount Vesuvius

  
  

  • Tourism

  • E.g - Mount Etna attracts thousands of tourists who travel in cable cars providing a wide range of jobs for local people.

  
  

  • Minerals: Lots of minerals (copper, gold, silver, lead)

  - E.g. Yanacocha gold mine in Peru
• How can monitoring reduce the effects of tectonic hazards?

  Monitoring tectonic activity using equipment may help predict and identify major events so that people can evacuate
• How can planning reduce the effects of tectonic hazards?

  - volcanoes - risk assessment and hazard mapping to identify areas to practise evacuation or restrict building

  
  

  - earthquakes - risk assessment and hazard mapping to identify areas to protect buildings and infrastructure
• How can prediction reduce the effects of tectonic hazards?

  Prediction can forecast which areas should be prepared for one to occur. It gives people time to evacuate — this reduces the number of injuries and deaths.
• building features to help withstand an earthquake

  - Shock absorbers- absorb ground shaking

  - Rolling weights on the roof- balance the building when it starts to sway

  - Shutters- protect people from falling glass
• How do we plan to reduce earthquakes damage

  Making hazard maps, which restricts certain land use

  Education, people know how to prepare

  Emergency Services, always prepared
• How to predict volcanic eruptions

  Earthquakes, gas output( sulphur dioxide) ground swelling, increased temperature, and strange animal behavior.
• Describe the distribution of earthquakes

  - Generally, found at plate boundaries

  - Specifically, West coast of America

  - There are anomalies e.g the earthquake South East of Africa