natural hazards

• Natural hazards


  Pose major risks to people and property
• Natural hazards


  • Meteorological hazards - created in atmosphere, movement of air and water, linked to weather
  • Geophysical hazards - created by movement of the Earth's tectonic plates and by surface rock and soils
  • Hydrological hazards - created by river, lack of water
• Where natural hazards occur

  • Japan
  • Philippines
  • Indonesia
• Factors affecting chance of a place being affected by a natural event

  • Magnitude - size of a hazard event
  • Frequency - how often it occurs
  • Population density - number of people in an area and how close they are
  • Level of development - how much money is available for preparation and prediction
• Tectonic plate theory


  The land we live on is made up of tectonic plates
• Layers of the Earth

  • Crust - thin
  • Mantle - 2950 km thick, thicker than crust
  • Outer core - 2300 km thick, high pressure, liquid
  • Inner core - solid, very hot
• Oceanic crust


  10 km thick, made of iron, magnesium, silicon and oxygen, green in colour, younger
• Continental crust


  Thicker than oceanic crust, less dense, older
• How tectonic plates move

  1. Constructive - plates move apart

  2. Destructive - one plate moves over another

  3. Conservative - plates slide past each other
• Destructive plate boundaries


  Cause volcanoes and earthquakes
• Volcanoes and earthquakes occur in lines, concentrated on the edges of tectonic plates
• Constructive plate boundaries - plates move away from each other, pressure decreases, magma rises between cracks
• Destructive plate boundaries - denser oceanic plate is pushed under lighter continental plate, causing volcanoes and earthquakes
• Conservative plate boundaries - plates slide past each other, can cause earthquakes
• Types of volcanoes


  • Shield volcanoes - gentle sloping sides, runny lava
  • Composite volcanoes - steep sides, explosive, viscous lava
• Volcanic hazards


  Major cause of death, include pyroclastic flows, lava flows, lahars (mudflows)
• Earthquakes


  Shaking of the Earth's surface, caused by movement at tectonic plate boundaries
• Earthquake features


  • Focus - point where earthquake occurs underground
  • Epicentre - point on surface directly above focus
  • Moment magnitude - reliable measure of earthquake size
• Primary and secondary earthquake effects

  • Primary - people killed/injured, homes destroyed, cables broken
  • Secondary - tsunamis, landslides, contamination, disease, transport disruption, fires
• GPS movement in the ground.
• protection:


  1. designing buildings and strengraoning reads (mitigation expensive)

  2. ensure people are not injured or it.
• What does prediction in the context of volcanoes refer to?

  It refers to attempts to forecast when and where a disaster will strike.
• Why is it easier to predict volcanic eruptions than earthquakes?

  Because there are more observable signs and changes in volcanoes.
• What tools are used to monitor changes in a volcano's surface?

  Satellites and meters are used to monitor changes.
• What do seismometers measure?

  Seismometers measure small earthquakes.
• How do thermal heat sensors contribute to volcanic prediction?

  They detect changes in temperature around the volcano.
• What is the purpose of measuring the temperature of water in streams and rivers near volcanoes?

  To see if the temperature is increasing, indicating volcanic activity.
• What does preparation involve in the context of disaster management?

  Actions taken to get ready for a disaster.
• What is the goal of community preparation for disasters?

  To enable communities to respond and recover from disasters.
• What are some actions taken to prepare emergency services for disasters?

  Preparing shelters, food, and evacuation strategies.
• What is the purpose of tsunami warnings in coastal areas?

  To prevent unnecessary injuries by alerting people of danger.
• What are protective actions taken before a hazard strikes?

  Actions taken to reduce the impact of the hazard.
• What are some design features of buildings to protect against volcanic eruptions?

  Air-tight seals on windows and doors, flame-resistant materials, and reinforced roofs.
• How do lahar channels help in volcanic protection?

  They redirect the flow of lahar to minimize damage.
• What is the prediction of earthquakes generally like?

  It is extremely difficult to predict the date, exact location, and time.
• What is the role of radon detection devices in earthquake prediction?

  They measure radon gas levels, which can indicate seismic activity.
• How do sensitive seismometers contribute to earthquake prediction?

  They measure tremors that may indicate an impending earthquake.
• How does GPS technology assist in predicting earthquakes?

  It measures movement in the ground that may indicate seismic activity.
• What unusual behavior in animals might indicate an upcoming earthquake?

  Animals may act strangely before an earthquake occurs.
• What are some protective measures designed for buildings against earthquakes?

  Designing buildings to be stronger and ensuring they do not collapse.