What sort and type of technology is used to find out the different layers of the earth?
Lots of complicated equipment is used, but it’s the most simple equipment which has given us the most information. Seismometers located around the earth which record wave velocities from earthquakes. The rate at which different waves reach different seimographs around the world relative to the epicentre of the earthquake was used to deduce the simple core/mantle/crust structure (and also more complex layering, such as transisitions in the upper mantle and the core-mantle boundary layers).
