Environment

• Volcano

  Cone-shaped mountain formed by eruptions of lava at the surface of the Earth
• Crater

  A depression on the surface of a volcano, formed by volcanic activity, often circular in shape with steep sides
• Vent

  The natural pipe or fissure that links the magma chamber to the crater or opening on the Earth's surface through which lava, ash and gases flow
• Lava

  Magma that has escaped from beneath the Earth's crust and has flowed onto the surface
• Tectonic plates

  Huge pieces of the Earth's crust that float and move on top of the much denser mantle below them
• Constructive/divergent plate boundary

  Where two plates move apart, allowing magma to come to the surface as lava
• Magma

  Molten rock found beneath the Earth's crust
• Apart from lava, the magma may come out onto the Earth's crust in two other ways: it may explode out as fragments of molten rock, or it may appear as very hot, pulverised solid lava (ash)
• How earthquakes happen

  1. Tension released from inside crust

  2. Plates get stuck

  3. Pressure builds up

  4. Pressure released
• Features of earthquakes

  • Focus: point of earthquake
  • Epicenter: point directly above the focus, on the ground
  • Seismic waves
• Effects of earthquakes

  • Large number of deaths
  • Fires breaking out
  • Water pipes burst
  • Water contamination
  • Shaking ground
  • Subduction zone causes destruction
  • Accessibility cut off
  • Building damage
  • Tsunami can follow
  • Reconstruction costs
• Reduce impacts of earthquakes

  • Prediction
  • Measure earth pressure, and release of gas
  • Use maps and facts to identify high risk areas
  • Unusual animal behaviour
  • Richter scale
  • Preparation
  • Build earthquake proof buildings
  • Train emergency services
  • Set up warning system
  • Create evacuation plan
  • Emergency food supply
  • Prepare earthquake kits
• Earthquake proof buildings

  • Automated weights on roof to reduce movement
  • Rubber shock-absorbers between foundations
  • Foundation sunk deep into bedrock avoiding clay
  • Automatic shutters come down over the windows
  • Interlocking steel frames which can sway during earth movements
• Volcano

  A vent in the earth's surface where magma, gas or ash escapes onto the earth's surface or into the atmosphere
• How do volcanoes form?

  1. Magma rises through cracks of the Earth's crust

  2. Pressure builds up inside Earth

  3. Pressure released-plate movement

  4. Magma explodes to surface causing eruption

  5. Lava cools and forms new crust

  6. Over time, rock builds up and volcano formed
• Impacts/hazards of volcanoes

  • Pyroclastic flows
  • Lava flow
  • Ash clouds
  • Landslides
• Causes of eruptions

  • Fertile soil for crops
  • Tourism
  • Restaurants
  • Science research
  • Mining
  • Geothermal energy
• Constructive margin

  Where plates move away from each other, magma rises to fill the gap
• Destructive margin

  Where oceanic crust moves from friction and heat from mantle, newly formed magma lighter so it rises to surface
• Stages of volcanoes

  • Active: has erupted recently
  • Dormant: has not erupted recently but may in future
  • Extinct: unlikely to ever erupt again, no magma inside
• Shield volcano

  • Low viscosity (runny) lava
  • Low in height, gentle sloping sides with wide base
  • Low silica content (covers long distance)
  • Frequent eruptions but low in magnitude
  • High temperature
  • Low gas content
  • Little build up pressure
• Composite volcano

  • Viscous, thick and sticky lava
  • High in height, steep sided volcanic cones
  • High silica content (covers short distance)
  • Infrequent but high magnitude eruptions
  • Low temperature
  • High gas content
  • Enormous build up pressure
• Where earthquakes occur and volcanoes form is governed by plate tectonics
• Oceanic crust is younger, heavier, can sink and is constantly being destroyed and replaced
• Continental crust is older, lighter, cannot sink and is permanent
• Plate movement is caused by convection currents in the mantle
• Distribution of earthquakes and volcanoes

  • Encircle the whole of the Pacific Ocean
  • Extend down entire length of the mid-Atlantic Ocean
  • Stretch across southern Europe and Asia
• Magma chamber

  A large natural underground chamber of magma found within the surface of the Earth beneath a volcano
• Destructive/convergent plate boundary

  Where two plates move towards each other, and one plate sinks below the other (subduction)
• Hot spot

  A central part of the Earth's crust where plumes of magma rise to the surface
• lazca


  South American plate
• Pacific Ring of Fire


  Region where many earthquakes and volcanoes occur
• earthquake: a sudden and often violent shift in the rocks forming the Earth's crust, which is felt at the surface
• fault line: a fracture or break in the Earth's surface along which rocks have moved alongside each other
• focus


  The location of the actual source of an earthquake below the ground surface; also called the origin
• conservative plate boundary


  Where two plates are sliding alongside each other
• epicentre


  The location on the surface of the Earth above the focus or origin of the earthquake
• Earthquakes and volcanoes


  • Encircle the whole of the Pacific Ocean
  • Extend down entire length of the mid-Atlantic Ocean
  • Stretch across southern Europe and Asia
• Volcanoes


  • Encircle the whole of the Pacific Ocean (known as the Ring of Fire)
  • Extend down entire length of the mid-Atlantic Ocean
  • Some in southern Europe, the Caribbean & east Africa
• Plate Boundaries


  • Collision
  • Constructive
  • Conservative
  • Destructive