Seismic Wave Simulator

This simulation lets you follow a small P-wave pulse through the planet, based on PREM, the real speeds and densities measured by seismologists in 1981. The wave bends back toward the surface because speed increases with depth, causing the downgoing edge to travel faster. There are also discontinuities from mineral phase changes, especially in the mineral olivine at 410 and 660 km, which cause reflections to occur. These differences between layers lead to something called the P-wave shadow zone, discussed in this video.