GCSE Geography Volcanoes
- Created by: Jonafon
- Created on: 22-03-16 19:54
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- Volcanoes
- They are found at Destructive and Constructive Plate Margins
- Destructive
- Constructive
- The magma rises up into the gap created by the plates moving apart, forming a volcano
- Some volcanoes also form over parts of the mantle which are really hot (hotspots) e.g Hawaii
- 3 Different types of Volcanoes
- Composite volcanoes (Mount Fuji, Japan)
- Made up of ash and lava that's erupted, cooled and hardened to layers
- Lava flows slowly and is thick
- It hardens quickly to form a steep-sided volcano
- Shield volcanoes (Mauna Loa on the Hawaiian islands)
- Made up of only lava
- Lava is runny, flows quickly and spreads over a wide area
- Forms a low, flat volcano
- Dome volcanoes (Mount Pelée in Caribbean)
- Made up of only lava
- Lava is thick. Flows slowly and hardens quickly
- Forms a steep-sided volcano
- Composite volcanoes (Mount Fuji, Japan)
- Volcanoes and Earthquiakes are Tectonic Hazards
- Tectonic hazards are natural hazards caused by the movement of tectonic plates
- Natural hazard is a naturally occurring event that has the potential to affect people's lives or property
- When they do affect peoples lives or property, they are called Natural Disasters
- Natural hazard is a naturally occurring event that has the potential to affect people's lives or property
- Tectonic hazards are natural hazards caused by the movement of tectonic plates
- Impacts of volcaoes
- Reasons why people live close to volcanoes
- Soil around volcanoes is fertile because its full of minerals from volcanic ash and lava. Its good for growing crops, this attracts farmers
- Volcanoes are tourist attractions. Many people live near volcanoes to work in tourist industry
- Volcanoes are a source of geothermal energy, used to generate electricity. People live around them to work at power stations
- Reasons why people live close to volcanoes
- Impacts of volcanic eurptions
- Primary
- Buildings and roads are destroyed by lava flows and pyroclastic flows. Buildings collapse if enough ash falls on them
- People and animals are injured or killed mainly by pyroclastic flow but also by lava flows and falling rocks
- Crops are damaged and water supplies are contaminated when ash falls on them
- People, animals and plants are suffocated by carbon dioxide
- Secondary
- Lahars (mudflows) form where volcanic material mixes with water (snow melt). This causes more destruction, injuries and deaths
- Fires are started by lava flows and pyroclastic flows, which then spread
- People may suffer psychological problems if they knew people who died or lose their homes
- People are left homeless
- Shortage of food because crops are damaged
- Shortage of clean water
- Roads are blocked so emergency vehicles and aid cant get through
- Sulfur dioxide released causing acid rain
- Business are damaged or destroyed which causes unemployment
- Impacts are more severe in LEDCs than MEDCs
- low quality of housing, less stable, easier destroyed by earthquakes
- Poor quality of roads make it harder for emergency services to reach injured people so more deaths
- Not enough money to earthquiake proof buildings or have resources to react straight away so more people are effected by secondary impacts
- Healthcare is worse so they dont have enough supplies to deal with lots of casualties so people die from treatable injuries
- Primary
- Reducing impacts of Volcanoes
- Prediction
- Scientists can monitor signs before an eruption
- tiny earthquakes, escaping gas and changes in shape of volcano mean an eruption is likely
- Gives people time to evacuate, reduces deaths and injuries
- Planning
- Future developments can be planned to be built in areas of low risk from eruption
- Firebreaks reduce fire and emergency services can train and prepare
- Evacuation routes can be carefully planned if it was to happen
- Building techniques
- Buildings can be strengthened to withstand falling ash
- Lava diverted using barriers
- Education
- Government educate what to do if an eruption happens, how to get out
- people can be told how to make a survival kit
- Aid
- Receive aid like food, water, money and people (doctors)
- Help reduces impacts (stops people going hungry)
- Prediction
- Supervolcano
- They develop at destructive plate margins or Hotspots
- Hotspots
- Magma rises up through the cracks in the crust to form a large magma basin
- This pressure of the magma causes a circular bulge on the surface (several kilmoetres wide)
- The bulge cracks, creating vents for lava to escape. Lava erupts out of vents causing earthquakes and sends gigantic plumes of ash and rock
- as magma basin empties, bulge is no longer supported so it collapses spewing more lava
- When the eruption is finished, a Caldera (big crater) is left where the bulge collapsed. These get filled with water to form a large lake
- as magma basin empties, bulge is no longer supported so it collapses spewing more lava
- The bulge cracks, creating vents for lava to escape. Lava erupts out of vents causing earthquakes and sends gigantic plumes of ash and rock
- This pressure of the magma causes a circular bulge on the surface (several kilmoetres wide)
- Magma rises up through the cracks in the crust to form a large magma basin
- Hotspots
- They are flat, cover a large area (much bigger rthan normal volcanoes) and have a Caldera (crater at the top)
- Ash shoots kilometres in the air, blocking out daylight over continents, causing mini ice ages as less heat energy from the sun gets to earth
- They develop at destructive plate margins or Hotspots
- They are found at Destructive and Constructive Plate Margins
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