P-Waves & S-Waves

Push and shake

An interactive lesson with 7 steps, about 6 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• P-waves: compressional and fast (about 6 km/s in the crust).
• S-waves: shear, slower (about 3.5 km/s), and unable to cross liquids.
• The S–P time gap grows with distance from the quake.

Steps

1. Two kinds of wave
2. Push or shake
3. Through liquids
4. The lag
5. The speed ratio
6. Feeling it twice
7. The rolling ground