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GCSE: Plate tectonics

GCSE: Plate tectonics. Convection currents. Internal structure.

vernon-wiggins
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GCSE: Plate tectonics

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  1. GCSE: Plate tectonics

  2. Convection currents

  3. Internal structure

  4. Millions of years ago there was one large continental land mass called Pangaea. As the plates drifted apart this split into two. The northerly one was called Laurasia and the southern one Gondwanaland. The plates moved through the power of the convection currents operating in the upper mantle. Today the plates have formed a pattern which was very different to the past. For example the white cliffs of Dover were formed in tropical seas, as at one time Dover was in the tropics!

  5. Continental Drift > Alfred Wegner’s theory • Evidence: • Jigsaw Theory – Brazil’s east coast fits into western Africa- this was because at one time they were part of the same supercontinent – Gondwanaland • Fossil evidence – the same fossils have been found in Antarctica and South Africa – because they were once connected • White cliffs of Dover – are made of chalk which was laid down in a tropical sea – so at one time the UK was once in the tropics! • Alternating magnetic bandings in the North Atlantic

  6. Magnetic banding

  7. EARTHQUAKES

  8. Plate margins

  9. P10 Q2C/D Summary As the strength of an earthquake increases so does the risk of death There are exceptions however: LEDC’s are less able to cope with earthquakes - the buildings are often made of poorly constructed materials (eg Turkey) MEDC’s are better able to cope with earthquakes - they have the money to invest in making sure that the buildings are strong (eg San Fransisco, USA) Mankind is getting better at predicting and preparing for earthquakes - which explains why so many people died in the Japan quake of 1923 (156,000)

  10. A3 Sheet - Earthquakes • Causes • Where 2 plate boundaries collide • Friction, heat and pressure builds up • This is released in sudden jerking movements • The centre of an earthquake = Focus • Above the focus on the ground = Epicentre • Measured on the Richter Scale

  11. A3 Sheet - Earthquakes - Effects • People are made homeless - refugees • Bridges collapse • Looting of buildings after the earrthquake • Millions of £ of damage is caused • Insurance companies struggle to pay the costs of rebuilding • People trapped in buildings and cars • People die • Fires start - eg Kobe Earthquake 1995 • Burst gas and water pipes • Electricity wires are damaged - therefore no power

  12. A3 Sheet - Earthquakes - Prediction • Strange animal behaviour - eg dogs, Japanese Cat Fish, cows • Monitoring stations - Richter Scale eg Parkfield, California • Scientists place monitoring equipment in the ground - eg Seismometers • Richter Scale results • Record previous earthquakes - see if there is a pattern

  13. A3 Sheet - Earthquakes - Protection • Stay in open! • Earthquake practice drills - eg Japan • Reinforce the foundation of buildings • Put in rubber shock absorbers under the buildings • Steel rods to strengthen the building • Make a safety kit / survival kit / 1st Aid • Avoid cars and lifts

  14. A3 Sheet - Earthquakes • Prevention • Putting water into fissures has been tried but to no avail!

  15. A3 Sheet - Earthquakes • Why People live there • 1. People have no where else to go • 2. Job opportunities - eg Los Angeles • 3. Cheap housing • 4. Feel safe - “it won’t happen to me - not in my lifetime” • 5. High standard of living there • 6. Good climate - eg California • 7. Houses are constructed very safely - eg reinforced foundations

  16. Types of Margins Types of margins

  17. 1. Constructive Boundaries

  18. Magnetic banding

  19. (I) Constructive Ocean+Ocean Plate eg Mid Atlantic Ridge(North American + Eurasian Plate)

  20. Iceland rift

  21. Thingvellir, Iceland

  22. (II) Continental+Continental Plate Eg East African Rift Valley(African and Indian Plate)

  23. 2. Destructive Boundaries

  24. Pacific Ring of Fire

  25. (I) Ocean+Continental Plates - eg Peru, Andes(eg Nazca and South American Plates)

  26. Andes

  27. (ii)Ocean + Ocean Plates Eg. Marianus Trench(Pacific and Philippine Plates)

  28. (iii) Continental+ContinentalEg Himalayas, Nepal(Indian+Eurasian Plates)

  29. Tibetan plateau

  30. 3. Transform Boundaries

  31. Eg. The San Andreas Fault, California, USA

  32. Off-set Highway on the San Andreas Fault

  33. Valleys along the fault line

  34. Gap theory

  35. CASE STUDY SAN FRANSISCO

  36. SAN FRANSISCO ENCARTA VIDEO

  37. 1906 Earthquake

  38. San Andreas Fault

  39. 17th October 1989 7.1 Richter Scale Causes: San Andreas Fault - Transform Boundary Building in Marina District - this was poor quality land - unsuitable for houses

  40. Effects • US$6Bn damage • Fires • 62 died • Gas mains broken • Homeless people / Refugees • Motorways / Roads collapsing

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