tectonics

• natural hazard: an event that occurs naturally and has a social impact.
• atmospheric hazard: a hazard linked to weather/atmospheric conditions.
• geological hazard: a hazard that occurs on land/ is affected by the movements of the earth.
• flooding hazard: a hazard linked to water.
• risk factors of a natural hazard are urbanisation, poverty, climate change and farming.
• earthquakes happen at all 4 plate boundaries. Volcanoes occur at constructive and destructive plate boundaries as well as hotspots.
• hot spots: areas where the crust is thinner which allows magma to rise through cracks and gaps to form a volcano.
• tectonic plates move due to convection currents in the mantle.
• constructive plate boundary: the two plates move apart leaving a gap for magma to rise. This creates new crust and a volcano. Convection currents also cause a build up of tension and when it is released, an earthquake happens.
• destructive plate boundary: the plates move towards each other and the denser oceanic plate gets subducted. This causes friction which causes an earthquake. The plate melts away and magma rises to the surface, causing a volcanic eruption.
• conservative plate boundary: the two plates slide past each other so no new crust is made. The plates snag, causing a build up of tension resulting in an earthquake.
• collision plate margin: two continental plates crash into each other causing rocks to get pushed up and folded. There is no new crust made. The crash also triggers an earthquake.
• earthquakes are measured using the Mercalli scale (using observations) and the Richter scale (using data).
• Nepal is located in Asia. The capital is Kathmandu and the surrounding countries are India and China. It is also surrounded by the Indo-Australian and Eurasian plate margins.
• Nepal:

  primary effects:

  • 9000 people died
  • 20000 people were injured
  • 3 million people were left homeless.
  • the cost was $5 billion

  secondary effects:

  • landslides were caused
  • an avalanche on mount everest which killed 19 people.
• Nepal:

  Immediate responses:

  • search and rescue
  • half a million tents to provide shelter
  • field hospitals
  • emergency aid from other countries

  long-term responses:

  • roads repaired
  • tourism
  • building rebuilt with improvements
• Chile is located in South America. The capital is Santiago and the surrounding countries are Peru, Bolivia and Argentina. It is surrounded by the Nazca plate and the South American plate.
• The Chile earth quake happened on February 27th 2010 at a destructive plate margin.
• The Nepal earthquake happened on April 25th 2015 at a destructive plate margin.
• Chile:

  primary effects:

  • 500 people died
  • 12000 people injured
  • 220000 homes destroyed
  • a cost of $30 billion

  secondary effects:

  • 1500km of road destroyed
  • coastal towns destroyed by tsunami waves
• Chile:

  immediate responses:

  • search and rescue
  • field hospitals
  • power and water restored

  long-term responses:

  • housing reconstruction plan
  • no foreign aid needed due to a strong economy from copper exports.
• benefits of tectonic activity:

  • money and jobs from tourism
  • volcanic rocks can be used in construction
  • fertile soil for farming
  • in Iceland, geothermal energy provides 25% of electricity.
• the 3 p's:

  • prediction - volcanoes can be predicted using satellites and geophysical movements. Earthquakes can be predicted using seismicity.
  • protection from earthquakes can be through using cross bracing, reinforced steel walls, shock absorbers and shutters.
  • planning - using hazard maps and planning which areas need to be evacuated.
• focus: the point beneath the ground where an earthquake occurs.
• epicentre: the location on earth's surface directly above where the earthquake starts.
• geothermal: energy generated by heat stored deep in the earth.
• seismic waves: energy released when tectonic plates move.
• seismograph: an instrument used to record movement of the earth.