RESTLESS EARTH GCSE

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  • Created on: 21-05-16 11:00

Supervolcanoes- Case Study

Yellowstone National Park, Wyoming, America

  • The magma chamber is 80km long and 40km wide.
  • It is on a hotspot and is active-has had three eruptions and is due another.
  • It is predicted that 87,000 people would instantly be killed and 10,000m2 of land would instantly be lost.
  • It is predicted that 15cm of ash would cover builidngs and kill 1 in 3. It would also trigger a mini-ice age.
  • The global temp would drop a predicted 15 degrees and would liekly lead to crop failure and starvation.
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Volcanoes

  • A volcano is a vent from which magma (molten rock stored underground in the magma chamber) can escape.
  • A volcano can be formed at a destructive/constructive plate boundry or a hotspot. At a destructive plate boundry, after the more dense plate has been subducted and melts in the mantle, a pool of magma forms and rises through the cracks in the crust (vents) to erupt onto the surfcae. At a constructive plate boundry, magma rises up to fill the gap caused by the plates moving away from each other. At a hotspot, there is a big upwards convection current and a weak spot in the crust so magam is forced through the crust even though it is not near a plate boundry.
  • A volcano can be classed as active (erupted recently and is likely to again), dormant (have erupted in the last 2,000yrs but not recently) or extinct (unlikely to ever erupt again).
  • The two types of volcano are shied and composite.
  • A shield volcanco is low, flat with gentle sloping sides. The magma is thin and runny and the ruptions aren't very dangerous or explosive. The sides are made of layers of solidified lava. E.g Mauna Loa
  • A composite volcano has steep sides and is made of layers of solidified lava and ash. The lava is thicker and often has pyroclastic flows (a mixture of steam, rock, ash and dust). These erupt more violently. E.g Soufiere Hills
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Earthquakes- Case Study

Developed Country: Kobe, Japan, 1995

  • Caused by a destructive plate boundry as the Philippines was subducted by the Eurasian)
  • It was a magnitude 7.2
  • Immediate Impacts: 1km of Hanshin highway collapsed; 5,500 died; liquefaction destroyed large port; 180,000 homes gone.
  • Secondary Impacts: fires; 90% of deaths were traditional house roof tiles falling on them; fire services had no water as supply was down; big businesses had to shut like Mitsubishi and Panasonic.
  • Short Term Response: Rescue; get everyone acess to water, food and shelter.
  • Long Term Response: After a year, Kobe port was 80% functional; better earthquake proof buildings not built on liquefaction zones; better recording devices.
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Tsunami- Case Study

2004 Asian/Boxing Day Tsunami

  • The tsunami hit 14 countires in Asia and was the most destructive natural disaster ever.
  • Cause: An earthquake on a destructive plate boundry measuring 9.1 on the Richter Scale.
  • Primary Impacts: 230,000 were killed or went missing; 1.7 million became homeless; whole villages were lost; approx 5 million people needed emergency supplies; the infrastructure was severely damaged.
  • Secondary Impacts: The fishing industry were affected; tourism declined; salt water meant that many plants couldn't grow; fragile reefs, mangroves and forests were injured.
  • Immediate Responses: Hundreds of millions of pounds were sent from foreign charities, governments and businesses; foreign countires sent ships, planes and soldiers to help rescue.
  • Long Term Responses: Billions of pounds were sent to help rebuild; programmes set up to get people to work and rebuild houses; warning system was set up; disaster management schemes with trained volunteers.
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Volcanoes- Case Study

Soufriere Hills, Monsterrat, Caribbean, 1997

  • The cause was a destructive plate boundry where the North American was subducted under the Caribbean and magma rose up.
  • 4.5 million m3 of rock and gas was released.
  • Immediate Impacts: 19 died; capital (Plymouth) was buried in ash; whole villlages were lost; 2/3 homes were destroyed by pyroclastic flows; farmland was lost; hospitals, aipport and school was destroyed
  • Secondary Impact: fires ruined infrastructure; tourism fell and then rose since then; volcanic ah improved soil fertility; population fell from 12,000 to 4,000.
  • Short Term Response: evacuated people to the North; temporary shelters; local rescue missions; UK sent emergency aid.
  • Long Term Response: exclusion zone was set up in the South; Uk sent money to redevelop; Montserrat Volcano Observatory was set up to predict futur eruptions.  
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Supervolcanoes

  • A supervolcano is different to a regular one as it is huge, flat rather than mountainous and have calderas (rims the volcano) rather than craters.
  • They are formed when magma rises up to form a bulge on the suface, which cracks, creating vents for lava to escape through. As the magma chamber empties, the bulge collapses to form a depression called a caldera.
  • 1,000km3 of material must be emitted before it can be classed as a supervolcano.
  • It is very difficult to predict an eruption (unlike with volcanoes where you can monitor gas emissions. bulges and ground movement) as any of those could just be regular movements of a supervolcano.
  • If there was a supervolcanic eruption, the effects would be felt globally: there would be huge quanitities of rock, ash and lava; clouds of hot gas and ash would destroy everything in a set radius; ash could block out the sun and trigger a mini-ice age so plant couldn't grow; many would starve.
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Earthquake- Case Studies

Developing Country: Kashmir, Pakistan, 2005

  • The earthquake was caused by a collision plate boundry with the Indian and Eurasian plates.
  • It was a magnitude 7.6.
  • Immediate Impacts: 80,000 died; 3.3 million homes were destroyed; houses collapsed by 'pancaking'; whole villages wereThe earth lost.
  • Secondary Impacts: landslidesblocked roads and delayed rescue; diseases like pneumonia and diarrhea spread in the camps and contaminated water
  • Short Term Respnse: rescue; tents, blankets and medicine; international aid sent equipment, helicopters and rescue teams.
  • Long Term Response: 40,000 relocated away from ruined towns; government provied training and rebuilt homes.
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Tsunamis

  • A tsunami is a huge wave caused by unusal actiivty under water
  • It can be caused by plate movement (after an earthquake at a place boundry, huge volumes of water can be displaced above the focus as the sea floor moves) or a landlside/slump (a body of sediement slumps downwards along a continental shelf, displacing huge volumes of water).
  • As the wave gets closer to land, the water gets shallower so the tsunami slows and becomes taller- creating a huge wall of water.
  • The tsunami acts out in all directions from the point of origin.
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Fold Mountains

  • Fold Mountains are formed at collison plate boundires where sedimentary rock has formed huge depressions called geosyclines. Over millions of years, the rock was pushed together, compressed and forced upwards. Some can form overfolds too.
  • An anti-cline is the up of a fold and the syncline is the down.
  • Examples of fold mountains include the Alps, the Andes and the Himalayas.
  • Fold Mountains can be used for mining, generating hydro-electric power, tourism and farming.
  • Farmers can terrace the steep slopes (cut steps into them) to make the terrain easier to farm.
  • The areas are rich in metsl ores for mining.
  • The steep slopes, snow melt and high lakes are useful to generate hydroelectic power.
  • Tourists are attracted to the glaciers, peaks, volcanoes and views.
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Earthquakes

  • An earthquake is a shockwave caused by plate boundry movement.
  • They are created because when plates move past each other, the movement is jerky so friction occurs. This friction causes heat and makes the plates stick slightly to each other, meaning that the plates can get stuck. As the tension builds up, the plates can suddenly move and get un-stuck and an earthquake is formed.
  • The origin of the earthquake is caused the focus and directly above that on land is the epicentre.
  • The earthquakes can be measured in the Richter Scale. This is a logarithmic scale that measures how much energy is released from an earthquake. The magnitde is measured with a seismomenter (a mechanism that has an 'arm' that shows the vibrations of the Earth).
  • The Mercalli Scale can also be used to measure earthquakes but it measures the effect rather than the size. With a range of 1-12, it shows the effect on the people. For example a measurement of 1 is hardly felt and causes no disrruptions but a higher reading would cause infrastructure to be damaged and people to be injured.
  • Earthquakes are nearly impossible to predict as it is not known what is going on under the crust and if the plates will suddenly spring back.
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Fold Mountans- Case Study

Andes, South America

  • The Andes are 7,000km long and 300km wide.
  • Tourism: The tourists got to see the glaciers, lakes and volcanoes; the Inca Trail and Machu Picchu are so popular that limits have to be set on tourists per day.
  • Farming: In Bolivia, farmers terrace the slopes; it is mostly crops like potatoes but a few cash crops like cotton and rice.
  • Mining: In Peru  they mine tin, gold and silver; in Colombia, they mine nickel; mining accounts for half of Peru's exports.
  • HEP: The Yucan Project in north-east Peru dams two rivers for HEP.
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Tectonic Plates

  • The Earth is made up of the inner core, outer core, mantle and crust.
  • Tectonic plates are slabs of crust that move very slowly due to convection currents in the mantle caused by heat from radioactive processes in the core.
  • Oceanic crust is young, dense and thin and is found under the ocean.
  • Continental crust is older, thicker and less desnse and is found on land.
  • The four types of plate boundries are collision (move together), constructive (move apart), destrucive (move together and the more dense is pushed under in the subduction zone) and conservative (move past each other).
  • Collison and/or destructive plate boundries form fold mountains.
  • Constructive and/or destrucive form volcanoes.
  • Constructive and/or destrucive form oceanic ridges.
  • Destructive form oceanic trenches.
  • They can all form earthquakes.
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