Where did we get our evidence about the Earth's structure?

1 Answer
Jul 29, 2017


From p waves and s waves


P waves and S waves are types of siesmic waves generated by the movement of techtonic plates.They can also be artificialy generated by exploding bombs.These waves have different properties.For example. p waves can pass through all mediums: solids,liquids and semi solids while s waves cannot pass through liquids.Thus they create certain 'shadow zones' where no siesmic waves are found.

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They also are different in their method of propogation and shape.

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Thus by knowing the rate of slowing down of the waves in materials tested on earth, the composition can be known by doing a direct comparision.

Also by knowing the angles of p and s wave shadow zones and then doing a little complicated geometry, the radius of each of the layer and thus the thickness can be found