tectonic hazards

• What are the different types of crust?

  Oceanic and Continental
• What is continental crust?

  Thick, lighter and old
• What are tectonic plates?

  A rigid segment of the Earth’s crust which moves across the heavier, semi-molten rock below.
• How does slab pull theory move tectonic plates?

  The denser plate sinks back into the mantle under the influence of gravity. It pulls the rest of the plate along behind it.
• How do convection currents move tectonic plates?

  Heat from the core makes magma in the mantle rise towards the crust. As the hot current nears the crust, it begins to cool and sink back towards the core. As the magma sinks, it drags the plates across the surface of the Earth.
• What is a volcano?

  Large, often cone shaped landforms, fed by molten rocks deep within the mantle.
• What is an earthquake?

  A sudden violent shaking or trembling of the ground caused by the movement of tectonic plates.
• What are the different types of margin?

  Constructive - plates move apart

  Destructive - plates move together

  Conservative - plates slide past each other
• What is happening at a constructive margin?

  Plates move apart

  Volcanoes are formed because as the plates move apart crust rises from the mantle, forming low sloping volcanoes made of new rock

  Earthquakes are formed because new solid rock sometimes fractures as it is moved, causing earthquakes. These shallow earthquakes are usually small and not violent.
• What is happening at a destructive margin?

  Plates move towards each other

  Volcanoes are formed as the oceanic plate subducts under the continental plate as it is more dense.  As the oceanic crust subducts further into the mantle it melts and the magma rises through the continental crust to erupt as explosive stratovolcanoes. 

  Earthquakes take place as during subduction friction between the plates causes pressure to build up. This pressure is released to cause powerful earthquakes.
• What is happening at a conservative margin?

  Plates slide past each other

  No volcanoes as there is no where for magma to rise

  Earthquakes are formed as friction causes them to become stuck. Pressure builds up and up until eventually the rock fractures in an earthquake
• What are primary impacts?

  The initial impact of a natural event on people and property, caused directly by the hazard
• What are secondary impacts?

  The after-effects that occur as indirect impacts of a natural event.
• What are immediate responses?

  The reaction of people as the disaster happens and in the immediate aftermath. 

  About saving lives
• What are long-term responses?

  Later reactions that occur in the weeks, months and years after the event.  About rebuilding
• Why do people live in areas of tectonic hazards?

  • The ash from volcanoes can create fertile soils which is good for high crop yields
  • Rocks from volcanoes create mineral deposits which can be mined providing jobs and a boost to the economy.
  • Earthquake resistant buildings and planning help reduce the risk so people feel safe to live there.
  • Geothermal energy (hot water from the Earth’s crust) provides energy and cheap heating, specifically in Iceland
• What are the management strategies for reducing tectonic hazard risk?

  Monitoring - Recording physical changes to help forecast when and where a natural hazard might strike. 

  Prediction - Attempts to forecast when and where a natural hazard will strike, based on current knowledge

  Protection - Actions taken before a hazard strikes to reduce its impact on property

  Planning - Actions taken to enable communities to respond and recover
• How can we monitor tectonic hazards?

  Volcanoes  

  Changes in volcano shape, levels of gas and surface temperature

  Earthquakes

  Some foreshocks can be monitored.
• How can we predict tectonic hazards?

  Volcanoes

  Based on the monitoring data, hazard predictions can be made to support evacuation

  Earthquakes

  It is very difficult.  We know plate margins are at risk
• How can we protect against tectonic hazards?

  Volcanoes

  Very powerful and hard to block.  Can use embankments (barriers) to stop lava flow

  Earthquakes

  Earthquake resistant buildings - Expensive

  • Shock absorbers in foundations
  • Shutters over windows
  • Counterweights on the roof
  • Walls are reinforced with steel
• How can we plan for tectonic hazards?

  Volcanoes

  Hazard maps have been made, so many places cannot be built on - Exclusion zones

  Earthquakes

  Earthquake drills - national one in Japan 1 Sept

  Earthquake safety checklist, Fastening down furniture, Having emergency kits ready to go