natural hazards

• The Crust


  Varies in thickness(5-10km) beneath the ocean. Made up of several large plates.
• The Mantle


  Widest layer(2900km thick). The heat and pressure means the rock is in a liquid state that is in a state of convection.
• The Inner and outer Core

  Hottest section (5000 degrees). Mostly made of iron and nickel and is 4x denser than the crust. Inner section is solid whereas outer layer is liquid.
• Convection Currents


  1 Radioactive decay of some of the elements in the core and mantle generate a lot of heat.

  2 When lower parts of the mantle molten rock (Magma) heat up they become less dense and slowly rise.

  3 As they move towards the top they cool down, become more dense and slowly sink.

  4 These circular movements of semi-molten rock are convection currents

  5 Convection currents create drag on the base of the tectonic plates and this causes them to move
• Destructive Plate Margin


  When the denser plate subducts beneath the other, friction causes it to melt and become molten magma. The magma forces its ways up to the surface to form a volcano. This margin is also responsible for devastating earthquakes. Co
• Constructive Plate Margin


  Here two plates are moving apart causing new magma to reach the surface through the gap. Volcanoes formed along this crack cause a submarine mountain range such as those in the Mid Atlantic Ridge.
• Conservative Plate Margin


  A conservative plate boundaryoccurs where plates slide past each other in opposite directions, or in the same direction but at different speeds. This is responsible for earthquakes such as the ones happening along the San Andreas Fault, USA.
• Low Pressure


  Caused by hot air rising. Causes stormy, cloudy weather.
• High Pressure


  Caused by cold air sinking. Causes clear and calm weather.
• Formation of Tropical Storms

  1. The sun's rays heat large areas of ocean in the summer and autumn

  2. Warm, moist air rises over the particular spots

  3. Temperature reaches 27⁰

  4. Low pressure forms

  5. Thunderstorm develops

  6. Air sucked in from trade winds

  7. Thunderstorm starts to spin due to trade winds and Coriolis effect

  8. Storm spins faster than 74mph, becoming a tropical storm

  9. Cool air sinks in the centre, creating the eye of the storm

  10. Tropical storm hits land, loses energy source, and weakens
• Ash cloud


  Small pieces of pulverised rock and glass which are thrown into the atmosphere.
• Gas


  Sulphur dioxide, water vapour and carbon dioxide come out of the volcano
• Lahar


  A volcanic mudflow which usually runs down a valley side on the volcano.
• Pyroclastic flow


  A fast moving current of super-heated gas and ash (1000oC). They travel at 450mph.
• Volcanic bomb


  A thick (viscous) lava fragment that is ejected from the volcano.
• Atmospheric circulation


  e large-scale movement of air by which heat is distributed on the surface of the Earth.
• Hadley cell


  Largest cell which extends from the Equator to between 30° to 40° north & south.
• Ferrel cell


  Middle cell where air flows poleward between 60° & 70° latitude.
• Polar cell


  Smallest & weakness cell that occurs from the poles to the Ferrel cell.
• Haiti Earthquake 2010

  • Low income country

  Causes

  • On a conservative plate margin, involving the Caribbean & North American plates. The magnitude 7.0 earthquake was only 15 miles from the capital Port au Prince. With a very shallow focus of 13km deep.
• Haiti Earthquake 2010 Effects

  230,000 people died and 3 million affected. Many emotionally affected. 250,000 homes collapsed or were damaged. Millions homeless. Rubble blocked roads and shut down ports.
• Haiti Earthquake 2010 Management

  Individuals tried to recover people. Many countries responded with appeals or rescue teams. Heavily relied on international aid, e.g. $330 million from the EU. 98% of rubble remained after 6 months.
• What is a Natural Hazard

  A natural hazard is a natural process which could cause death, injury or disruption to humans, property and possessions.
• Geological Hazard


  These are hazards caused by land and tectonic processes.
• Meteorological Hazard


  These are hazards caused by weather and climate.
• Causes of Earthquakes


  Earthquakes are caused when two plates become locked causing friction to build up. From this stress, the pressure will eventually be released, triggering the plates to move into a new position. This movement causes energy in the form of seismic waves, to travel from the focus towards the epicentre. As a result, the crust vibrates triggering an earthquake.
• EPICENTRE.


  The point directly above the focus, where the seismic waves reach first
• SEISMIC WAVES


  (energy waves) travel out from the focus.
• FOCUS.


  The point at which pressure is released
• Changing pattern of Tropical Storms


  Scientist believe that global warming is having an impact on the frequency and strength of tropical storms. This may be due to an increase in ocean temperatures.
• Management of Tropical Storms

  Protection - Preparing for a tropical storm may involve construction projects that will improve protection.

  Aid - Aid involves assisting after the storm, commonly in LIDs.

  Development - The scale of the impacts depends on the whether the country has the resources cope with the storm.

  Planning - Involves getting people and the emergency services ready to deal with the impacts.

  Prediction - Constant monitoring can help to give advanced warning of a tropical storm

  Education - Teaching people about what to do in a tropical storm.
• Primary Effects of Tropical Storms

  • The intense winds of tropical storms can destroy whole communities, buildings andcommunication networks.
  • As well as their own destructive energy, the winds can generate abnormally high waves called storm surges.
  • Sometimes the most destructive elements of a storm are these subsequent high seas and flooding they cause to coastal areas
• Secondary Effects of Tropical Storms

  • People are left homeless, which can cause distress, poverty and ill health due to lack of shelter.
  • Shortage of clean water and lack of proper sanitation makes it easier for diseases to spread.
  • Businesses are damaged or destroyed causing employment.
  • Shortage of food as crops are damaged.
• Typhoon Haiyan 2013 Cause


  Started as a tropical depression on 2 rd November 2013 and gained strength. Became a Category 5 “super typhoon” and made landfall on the Pacific islands of the Philippines.
• Typhoon Haiyan 2013 Effect

  • Almost 6,500 deaths.
  • 130,000 homes destroyed.
  • Water and sewage systems destroyed had caused diseases.
  • Emotional grief for dead.
• Typhoon Haiyan 2013 Management

  • The UN raised £190m in aid.
  • USA & UK sent helicopter carrier ships deliver aid remote areas.
  • Education on typhoon preparedness.
• Managing Volcanic Eruptions Warning signs

  • Small earthquakes are caused as magma rises up.
  • Temperatures around the volcano rise as activity increases.
  • When a volcano is close to erupting it starts to release gases.
• Managing Volcanic Eruptions Preparation

  • Creating an exclusion zone around the volcano.
  • Being ready and able to evacuate residents.
  • Having an emergency supply of basic provisions, such as food
  • Trained emergency services and a good communication system.
• Managing Volcanic Eruptions Monitoring techniques

  • Seismometers are used to detect earthquakes.
  • Thermal imaging and satellite cameras can be used to detect heat around a volcano.
  • Gas samples may be taken and chemical sensors used to measure sulphur levels.
• Earthquake Management PREDICTING

  • Satellite surveying (tracks changes in the earth’s surface)
  • Laser reflector (surveys movement across fault lines)
  • Radon gas sensor (radon gas is released when plates move so this finds that)
  • Seismometer
  • Water table level (water levels fluctuate before an earthquake).
  • Scientists also use seismic records to predict when the next event will occur.