Volcanoes

• Warning Signs 1

  • Earthquakes & landslides- increased movement of magma below ground causes earthquakes. This can occur up to a year before eruption.
  • Ash & steam- this is a sign that magma is rising and is close to the surface. This can be problematic for aeroplanes.
  • Mountains changing shape- magma inside the volcano puts pressure on the inside of the mountain. This is only really helpful in HICs, as they have the required technology to notice it.
• Warning Signs 2

  • Eruptions of gas- the rising magma forces gas (mainly sulphur, which has a distinct smell) to the surface.
  • Raised water temperature- rising magma may slightly heat local water sources. However, this is usually not very noticeable.
• Dangers 1

  • Pyroclastic flow- cloud of very hot ash, which moves at 70-80mph. This can kill instantly and is impossible to outrun. (Primary)
  • Tephra- volcanic bombs which are thrown over 19 miles into the atmosphere and fall to earth as flaming rocks and boulders. They are deadly and destructive, and it's hard to predict where they will land. (Primary)
  • Lahar- mix of water, lava, and mud which flow down the mountain. They are extremely hot and very fast moving, they can completely cover buildings and severely harm people. (Secondary)
• Dangers 2

  • Tsunamis & flooding- fast moving debris falling into the sea can cause a tsunami in distant countries, however this is relatively unlikely. Melting snow (and other factors) can cause flooding. (Secondary)
  • Landslides- displacement of large amounts of land, however these are quite small most of the time. (Secondary)
  • Eruptions of gas- rising magma forces out gas such as sulphur dioxide, may cause choking and acid rain. (Primary)
  • Lava- usually quite viscous so it can easily be outrun, yet causes severe burns. (Primary)
• Protection Methods

  • Trenches and barriers- digging channels is divert lava away from villages and dams to stop flow, e.g Mount Etna, Italy, cost £3 mil but prevented £25 mil damage.
  • Cooling lava- lava is sprayed with water to make it solidify, e.g Iceland 1973
  • Volcanic shelters- built near volcano to protect against tephra and pyroclastic flow, e.g Japan, Mount Asama, 2004 & 2009
  • Evacuation- alerting people to leave as soon as possible, but doesn't protect infrastructure.
  • Dropping bombs- on to the crust as volcano erupts to divert the lava, e.g Mauna Ioa, 1935
• Advantages

  • Geothermal energy- 80% cheaper than fossil fuels, 87% of buildings in Iceland get hot water from geothermal energy
  • Volcanic soil (andosol)- extremely fertile, creates food, jobs, forests which attract tourists. Makes up 1% of soil in the world, has the potential to feed 10% of the population.
  • Tourism- e.g hot springs, lava/magma chamber tours. 10 million people visit volcanoes per year.
  • Mining / minerals- in Indonesia, sulphur is mined from Kawah Ijen, workers make $6 a day, but it can lead to breathing / health issues, e.g in the last 40 years, 74 miners have died.