Introduction to Earth Sciences I
1.2 Mass of the Earth: Cavendish's Experiment to "Weigh the Earth", continued
The exact density profile of the Earth is not well known, but the best estimates come from seismic studies. Seismic energy from earthquakes penetrates the whole Earth and allows us to determine the internal structure based on the speed of propagation of energy (we will deal with this in a later section). The speed of propagation is related to density in a regular way so that allows the density structure to be deduced.