Question

Scientists have established that some of the layers of Earth are solid, some are liquid, and some are semi-fluid. Explain how the scientists are able to determine the liquid and solid layers.

Answer 1

Answer:

The earth conducts seismic waves-- when an earthquake occurs, stations farther and farther away from the quake see the S and P waves propagated through deeper and deeper layers. By measuring the arrival time of the waves, the velocity of the waves can be found as a function of depth. There is clear evidence for several layers in the earth which both refract the waves and below which the velocities are different. This is a bit like holding a book under your desk while a friend (gently) taps the other end of the desk.

(I Don't know if that's correct)