natural hazards

    Cards (14)

    • Factors affecting hazard risk - urbanisation
      urbanisation- over 50% of the worlds population live in cities. Some of the worlds largest cities such as Tokyo, and Los Angeles are at risk of earthquakes.
      densely populated areas are at risk of natural events
    • Factors affecting hazard risk - Poverty

      in the poorest areas of the world, poverty may force people to live in areas at risk of natural events (Lima in Peru)
    • Factors affecting Hazard risk - Lima in Peru
      Poverty:
      Lima is at risk of multiple natural events such as Earthquakes, Floods, Tsunamis and Landslides
      In Lima there is a shortage of housing and this has led to people building on unstable slopes which are prone to floods and landslides
    • Factors Affecting Hazard risk - Climate change
      due to the world getting warmer, which leads to increased temperature, it can cause a higher frequency of more intense tropical storms.
      This may cause some areas of the world to become wetter with an increased risk of flooding e.g. monsoon season in Bangledesh
    • Factors Affecting Harvard risk - Farming
      When a river floodlit deposits fertile silt on its floodplain which is excellent for farming.
      But when people choose to live near a floodplain they are putting themselves at risk of flooding. Especially in low lying areas such as south of Bangladesh.
    • what is a tectonic plate and why are they moving?

      where a convection current occurs, plates move towards each other. The movement of the plates and the activity inside the earth, is called the theory of plate tectonics.
    • continental and oceanic plates
      Continental crust- This crust forms the continents that we know today, and it's made of granite making it less dense than the oceanic crust. (can't sink, cannot be renewed or destroyed, older, 1500 million years old)
      Oceanic Crust- This forms under the oceans and is made of basalt and is very dense (denser, sinks, can be renewed or destroyed, igneous rock, basalt, newer, 200 million years old)
    • destructive plate margin
      • found where a continental and oceanic plate are moving towards each other.
      • 1 - oceanic plate descends under the continental plate because it is denser
      • 2- as the plate descends it starts to melt due to the friction caused by the movement of the two plates. This is called subduction. The plate is now magma.
      • 3 - the magma rises through the gaps in the continental plate. If it reaches the surface, it forms a volcano.
    • conservative plate margin
      • 2 plates slide past each other
      • as the plates are not smooth, the friction causes the plates to get caught on each other and pressure builds up.
      • eventually the pressure becomes so great they slip passed each other
      • this releases huge amounts of pressure, so an earthquake happens.
      • the focus (where an earthquake starts) are usually close to the surface
      • earthquakes up to 8.5 on the Richter scale, small tremors almost daily, no volcanos.
    • constructive plate margins
      • 2 plates move apart
      • magma rises up to fill the gap through the cracks. this forms a volcano
      • the crust on each side of the boundary often has cracks called faults in it. since magma can escape easily at the surface the volcano does not erupt with much force
      • if the boundary is under the ocean, the lava cools when it reaches the surface and creates new land. the whole of Iceland was created this way
      • as the plates move apart, friction may cause small earthquakes that do not cause much damage.
    • Primary effects of the Nepal earthquake
      • 9000 people died and a further 20,000 people were injured from the earthquake
      • 3 million people were left homeless after their homes were destroyed
      • electricity, communications and water supplies were effected
      • 1.4 million needed food, shelter and water for weeks after
      • 7000 schools were destroyed and hospitals became overrun
      • overall damage estimated over 5 billion US dollars
    • secondary effects of the Nepal earthquake
      • the ground shaking triggered landslides and avalanches which then blocked roads and hampered relief efforts
      • the avalanches on Mount Everest killed around 19 people
      • a landslide blocked the kali gandaki river, which many people had to evacuate due to flooding
    • immediate responses on the Nepal earthquake
      • india responded within 15mins of the earthquake
      • half a million tents were needed
      • 14 international medical teams sent to Nepal, the UN says, and up to 15 international search and rescue teams
      • helicopter were used to help those on the Himalayas
    • long term responses to the Nepal earthquake
      • quake lakes formed and had to be cleared to stop flood risk
      • 7000 schools need rebuilding
      • June 2015 conference on future risk and support
      • 300,000 migrated from Kathmandu to seek shelter and support
      • social media was used for communication
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