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Science

Seismic waves

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The Earth has a layered structure, including the core, mantle and crust. The crust and upper mantle are cracked into large pieces called tectonic plates. These plates move slowly, but can cause earthquakes and volcanoes where they meet. The seismic waves produced by an earthquake are monitored and tracked.

Structure of the Earth

The outer-most layer is called the crust. The crust surrounds the mantle, which surrounds the core. There are 2 parts to the core - the outer core and the inner core, which is the inner most part of the Earth's structure.

Cross section showing structure of the Earth

The Earth is almost a sphere. These are its main layers, starting with the outermost:

  1. crust - relatively thin and rocky
  2. mantle - has the properties of a solid, but can flow very slowly
  3. outer core - made from liquid nickel and iron
  4. inner core - made from solid nickel and iron

Note that the radius of the core is just over half the radius of the Earth. The core itself consists of a solid inner core and a liquid outer core.

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