Physical Processes at Plate Margins

• What happens at a conservative plate margin?


  Two plates move in the same direction at different speeds. The friction between the plates builds stresses and trigger earthquakes when they slip.
• There are no volcanoes at conservative plate margins as theres no magma.
• Why do people live near tectonic hazards?

  • Poorer people have no choice - family, food, money seen as more important.
  • Volcanoes bring benefits - fertile soils (the Carribean) and hot water.
  • Earthquake resistant designs which reduce risk of great damage.
  • Earthquakes / volcanic eruptions are seen as rare, therefore less people see the risk.
• What happens when two continental plates meet?


  When two continental plates meet, there is no subduction so no magma to form volcanoes, e.g the Himalayas. Instead, powerful earthquakes are triggered.
• What factors increase hazard risk?

  • Climate change: leads to increased intensity of extreme weather events.
  • Urbanisation: densely populated areas are more at risk
  • Poverty: lack of good quality hazard resistant materials increases risk.
• What are the tectonic theories?

  Convection currents, ridge push and slab pull.
• Convection currents: Heat from the core causes magma to rise in the mantle towards the crust and sink towards the core as it cools, this cycle is repeated which moves the plates along.
• How do constructive plate margins lead to earthquakes?

  oving apart, magama is forcing it's way to the surface. As magma breaks through the voerlying crust it causes earthquakes.
• How do constructive plate margins lead to volcanoes?

  At this margins, two plates move apart and magma rises to the surface, this magma is very hot and fluid. The lava erupting from a volcano will flow a long way before cooling, resulting in typically broad and flat shield volcanoes.
• What volcanoes form at constructive plate margins?

  Broad, flat shield volcanoes.
• How do destructive plate margins lead to earthquakes?

  Two plates are moving towards eachother, the denser plate is subducted beneath the less dense plate. The friction causes strong earthquakes.
• How do destructive plate margins lead to volcanoes?

  When two plates come together the denser coeanic plate is subducted under the less dense continental plate. The subduction creates sticky, gas-rich magma. This causes steep-sided, composite volcanoes which erupt violently
• What happens when two continental plates meet at a destructive boundary?

  When two continental plates meet, there is no subduction as they are both equally dense, because there's no magma, volcanoes can't be formed. Strong earthquakes are still triggered.
• Mid Atlantic Ridge: Iceland.

  • Geothermal energy generates 25% of Icelands electricity.
  • Volcanic rocks are used in road and building construction.
  • Dramatic landscapes - volcanoes, geysers, hot springs, waterfalls, etc - support a huge tourism industry.
  • Naturally ocurring hot water provides central heating for 90% buildings.