Tectonics

• Pyroclastic flows- Fast-moving current of hot gas and volcanic matter moving away from the volcano that can reach speeds of 700km/h.
• Lahars- A destructive mudflow on the slopes of the volcano.
• Volcanic gases- Toxic gases that are emitted into the atmosphere.
• Landslides- Large masses of wet or dry rock and soil that fall, slide and move very rapidly due to the force of gravity.
• Lava flow- Streams of molten rocks that ooze or flow from an erupting vent.

  • Andesitic- Sticky
  • Basaltic- Runny
• Ash clouds- Consists of fragments of pulverised rock, minerals and volcanic glass measuring less than 2mm diameter.
• Ground shaking/ displacement- The primary cause of an earthquake. Can cause damage to man-made structures.
• Fires- Ruptured gas lines and arcing electrical wires are the main source of ignition.
• Tsunami- A long, high sea wave caused by an earthquake or another disturbance.
• Liquefaction- A phenomena whereby a saturated or partially saturated soil substantially loses strength from the shaking which causes it to behave as a liquid.
• The inner core-

  • Made of solid iron
  • 6000C
• The outer core-

  • Semi-molten
  • Made of iron and nickel
  • 4500C - 6000C
• The mantle-

  • The widest layer of the Earth
  • Upper part is solid and lower part is semi-molten
  • Semi-molten rocks form the asthenosphere on which tectonic plates float
• The crust-

  • Forms the outer shell of the Earth.
• Oceanic-

  • Younger- less than 200 million years
  • 5-10km thick
  • Denser
• Continental-

  • Older- Most over 1500 years
  • 25 - 100km thick
  • Less dense
  • Cannot be renewed or destroyed
• Convection currents-

  Magma is heated by the inner core causing it to rise towards the crust but then it cools, hardens and sinks back down for the process to repeat.
• Constructive- Two oceanic plates move away from eachother.
• Destructive- An oceanic and continental plate collides and the oceanic plate is forced under the continental plate.
• Conservative- Two plates rub against each other. Friction.
• Collision- Two continental plates move together and the mass moves upwards.
• People live in hazardous regions because-

  1. Volcanoes can bring benefits such as fertile soil, hot water (Hot water in 90% of Icelands buildings is supplied by hot water within the crust.)
  2. Better building designs to withstand earthquakes.
  3. Better warnings.
  4. Fault lines allow water to reach the surface which can be useful in desert regions.
  5. Uneducated/ unaware of the risks.
  6. People living in poverty have other priorities.
  7. Rare.