other

• natural hazard is a threat of a naturally occurring event that will have a negative effect on people
• there are 3 types of natural hazard:

  Atmospheric

  Geological

  hydrological
• Factors affecting risk of a natural hazard:

  poverty

  farming

  climate change

  urbanization
• 4 layers of the earth:

  inner core - solid iron and nickel

  outer core - hot liquid iron and nickel

  mantle - semi molten and flows a bit like treacle

  crust - thinnest top layer of the earth
• 2 types of crust : oceanic and continental
• oceanic:

  newer, less than 200 years old

  can sink

  denser

  can be renewed/destroyed

  made from basalt
• continental:

  older, over 1500 million years old

  cannot be renewed or destroyed

  less dense, cannot sink

  made from granite
• slab pull - the weight of the subducting plate pulls the rest of the plate down into the subduction zone due to gravity
• plate tectonic theory - suggest that the earth is made up of several plates that sit on magma that move due to convection currents, the plates have slowly moved overtime and continents were created.

  Oldest country was called Pangaea
• continental drift theory - the super continent Pangaea is what the world looked like when all the continents were joined as one. Evidence for this is coal deposits found in Antarctica, but these can only form in warmer climates, so Antarctica must have been in a different part of the world
• Jigsaw fit - the continents used to fit together like a jigsaw
• Fossil evidence - different continents with oceans in between have found the same species f animals fossils in them, proving that once they must have been closer together and have since moved apart
• 3 types of plate boundaries:

  destructive plate boundary

  constructive plate boundary

  conservative plate boundary
• destructive plate boundary:

  oceanic and continental plates pulling together

  oceanic plate sinks as it is more dense into the subduction zone

  slab pull pulls it even further down

  the plate melt into a magma reservoir

  as pressure rises it bursts, forming a composite cone volcano

  can also cause a earthquake or fold mountains
• constructive plate boundary:

  plates are moving away from each other

  magma rises from the gap and cools and solidifies when it reaches the surface

  magma isn't rising under pressure so any volcanic eruptions are more gentle

  causes earthquakes and shield volcanoes
• conservative plate boundary:

  plates scrape past each-other as they go side by side

  friction builds up between the plates as they become stuck

  sends out a lot of energy, resulting in an earthquake
• 2 types of volcano:

  composite cone

  shield
• composite cone volcano:

  narrow base and steep sides

  destructive plate margins

  more violent eruptions

  alternate layers of ash and lava

  sticky, viscous lava that doesn't flow far
• shield volcano:

  wide base and gently sloping sides

  constructive late margin

  more frequent but less violent erruptions

  runny, flowing lava
• volcanic structure

  A) ash cloud

  B) volcanic bombs

  C) secondary cone

  D) secondary vent

  E) lava flow

  F) crater

  G) pyroclastic flow

  H) main vent

  I) magma chamber

  
• threats from volcanoes:

  lava flow

  volcanic bombs

  mudflows

  ash cloud

  toxic gases
• Volcanic effects: lava flow - can damage and destroy property which causes homelessness. Can also damage crops leading to food shortages and loss of income to farmers
• volcanic effects: volcanic bombs - can destroy buildings, bring down electricity wires and cause loss of life
• volcanic effects: mudflows - blocks roads, reducing ability for emergency services to help, destruction of farmland
• volcanic effects: Ash cloud - flights disrupted, breathing problems, suffocation reduces global temperatures
• volcanic effects: toxic gases - loss of life, breathing difficulties
• short term responses - responses provided straight away to help people at risk and stop immediate danger
• secondary effects - effects that happen due to the primary effects
• primary effects - effects that happen as a direct result of the volcanic activity
• long term responses - responses over a longer period of time and aim to help get back to normal
• benefits of living near a volcano:

  geothermal energy

  mineral extraction

  tourism

  emotional attachment

  fertile soils
• benefits of a volcano: geothermal energy - heat energy produced by the earth. the heat from underground steam is used to turn turbines and produce electricity

  2 thirds of Icelands electricity is through geothermal energy
• benefits from a volcano: mineral extraction - lava deep within the earth is full of minerals that can be mined once the lava cools down
• benefits from a volcano: tourism - attract millions of visitors every year, this is a big economic boost for the area and local economies can make a lot of profit
• benefits from a volcano: emotional attachment - some people that have grow up in an area surrounding a volcano would rather just die with the area than start anew
• benefits of a volcano: fertile soils - lava and other materials form nutrient rich soils that produce healthy crops, provide food for those t hat live near it and income for farmers
• 4 ways of reducing the risk:

  planning

  protection

  prediction

  monitoring
• planning - identifying and avoiding the places most at risk. Can also involve having drills ready for when a hazard occurs
• monitoring - using scientific equipment to detect signs of an event
• protection - designing buildings that will withstand tectonic hazards