chapter 5: our restless earth (volcanoes and earthquakes)

• the crust is the outermost layer
• the core is at the center of the planet, it has two parts - solid inner core and liquid outer core
• magma can be found beneath the surface of the Earth, but it becomes lava when it reaches the surface
• the core is at the center of the planet, its solid iron and nickel with a liquid outer core
• plate tectonics are the movement of plates on top of magma chambers
• we live on the earths crust
• the crust is made up of solid rock
• the crust and mantle together is also known as the lithosphere
• the upper mantle is made of semi-rigid rock
• the lower mantle is made of molten rock (magma)
• the outer core is made of molten iron and nickel
• the inner core is made of solid iron and nickel
• the plate movement in which tectonic plates collide with each other


  convergent/destructive movement
• the plate movement in which tectonic plates slide across each other


  transform/conservative movement
• the plate movement in which tectonic plates move away from each other


  divergent/constructive movement
• oceanic crust is heavy and made of basalt
• continental crust is mainly granite
• subduction zones are where an oceanic plate dives under another plate
• in the lower mantle, the rock is solid but not rigid
• in the upper mantle the rock is rigid
• an earthquake is caused by rock suddenly shifting
• sites of earthquakes and volcanoes

  • lie along lines
  • are often found together
  • occur in the ocean as well as land
• the lithosphere is broken into large slabs known as tectonic plates
• the region where two plates meet


  a boundary or margin
• plate movements cause earthquakes and volcanic eruptions
• gravity is the reason plates move
• when tectonic plates move apart, magma rises to the surface from the lower mantle. this creates an underwater volcano. the rock melts and rises as the pressure on it rises and falls.it then hardens to form a new ridge of lithosphere and it turns into a mountain range under water.
• when plates push into each other, their edges sink into ocean trenches. as it jolts downward, earthquakes occur. it carries water with it into the lower mantle, which lowers the melting point of the rock
• the margin in which plates move apart is called a constructive plate margin
• the margin in which plates push into each other is called a destructive plate
• when plates slide past each other, both plates move in the same direction and sometimes they get stuck but jolt free. this can cause earthquakes.
• a margin in which plates slide past each other is called a conservative plate margin
• stored energy from rock pressure


  strain energy
• strain energy released in waves

  seismic waves
• the shaking from the waves

  earthquake
• where the seismic waves started


  focus
• the point directly above the focus on the earths surface

  epicentre
• smaller earthquakes due to the settling of rock in its new position

  aftershocks
• the machines earthquakes are measured with


  seismometers
• the amount of energy an earthquake gives out


  magnitude