S-waves (S stands for secondary) are shear earthquake waves that pass through the interior of the Earth. S-waves don't change the volume of the material through which they propagate, they shear it.

When a quake or impact occurs, it generates P-waves (primary waves) and S-waves (secondary waves) that travel through different layers at varying speeds. By analyzing how these waves reflect ...

Traveling through the interior of the Earth, body waves arrive before the surface waves emitted by an earthquake. These waves are higher frequency than surface waves. P waves are also known as ...

This helps the system to more quickly identify trains that should be stopped before the arrival of S waves, or secondary waves, which are much more powerful and destructive. It took an average of ...