Restless Earth

Part of Unit 1: Dynamic Planet 


Exam: 20.01.2011

  • Created by: Aniqa
  • Created on: 13-01-11 23:26

Restless Earth: Dynamic Planet

4 Spheres:

Atmosphere: Layers of gases around us.

Hydrosphere: Layer of water on Earth's crust.

Biosphere: Thin layer of living things on the crust.

Geosphere: Rocks on Earth's crust & deeper towards the core.

- Humans are changing the spheres:

  • Pollution in the atmosphere has risen.
  • Used up fossil fuels in the Geosphere.
  • Deforestation causing extinctions in the Biosphere.
  • Polluting lakes & rivers, damage to the Hydrosphere.
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Inside the Earth: Diagram


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Inside the Earth

Geothermal heat is produced by Radioactive decay.

Inner core is under High pressure. Outer core is under lower pressure, heat rises & creates Convection currents. 

Plumes: where heat moves towards the surface, concentrated zones. Found on surface of constructive plates, form Hot spots.

Magnetosphere: invisible magnetic field surrounding Earth, protects Earth against harmful radiation. Dynamo Effect. 

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Destructive Boundary


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Plate tectonics

Pangea: Supercontinent.

3 types of plate boundaries: where two tectonic plates meet.

  • Constructive plate boundaries: formed when two plates move apart.
  • Destructive plate boundaries: formed when two plates collide.
  • Conservative plate boundaries: formed when two plates slide past each other. 

Subduction 'recycling': oceanic plate sinking back into mantle at destructive plate boundary, it melts back into mantle.

New oceanic crust formation: 

1. Convection currents bring magma up from mantle. 

2. Magma injected between separating plates. 

3. Plates continue moving apart, allowing magma to be injected. 

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Boundary Hazards

Plate Boundaries: cause earthquakes. 

Earthquakes are caused by friction as plates tear apart, [constructive & conservative] . Pressure builds up against friction, when plates snap apart energy is released. [destructive]  

Tectonic hazards: natural events that effect people & property. 


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Volcano: Case Study

Sakurajima, Japan

  • Destructive plate boundary, Pacific plate > Eurasian plate.
  • 40% of land is fertile soil, growing rice & tea.
  • Sheltered bay makes good port, fish is main export. 
  • Hot springs & lava flows, popular tourist attractions. National Park
  • 7000 people live at base. 

Volcanic eruptions can be predicted. Scientists can say when a volcano will erupt, they can warn people to evacuate or take shelter, Japan is an MEDC so it can afford to spend money on monitoring, protection, and evacuation.  

In developed countries, tectonic hazards damage property, (economic cost) but cause less harm to people, (social costs). 

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Volcanic Hazards & Shield Volcano


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Developing world hazards

LEDC's are at greater risk than MEDC's. 

  • They often live in risky locations.
  • Can't afford safe, well built homes.
  • Don't have insurance.
  • Their governments don't have money to provide Aid.
  • Communications are poor, so no warning or evacuation. 

High death tolls in LEDC's 

Relief Effort:  is like aid. Help is given to those facing an emergency. 

Refugees:  people who are forced due to natural hazards or war. 

Aid:  is help. It can be short-term such as food given in emergency, or long-term such as training in health care. 

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An earthquake starts at the focus. The epicentre is the point on the Earth's surface above the focus - first place to shake. It's a sudden release of energy. Pressure is suddenly released along faults (cracks in the crust), this travels as earthquake waves. -  Magnitude: how much the ground shakes. 


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Earthquake! Long-term planning..

  • Earthquake drills.
  • Emergence services practice rescuing people.
  • People keep emergency kits at home, containing water, food, a torch & radio. 
  • (
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Earthquake in the developing world

Tsunami: series of waves produced by an undersea earthquake.

Primary Effects: caused instantly by earthquake. Roads crack, walls collapse & landslides happen

Secondary Effects: hours, days, weeks after earthquake. Fires breakout disease spreads & food and water run short. 

Aftershocks: often occur as the fault 'settles' into it's new position. Often destroy buildings that were weakened by the earthquake. 

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