Growing and Breaking

Why tsunamis tower at the coast

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Waves slow and grow taller as water gets shallower (shoaling).
• Green's law: $H \propto d^{-1/4}$.
• Waves break when their height reaches about 0.8 of the depth.

Steps

1. Slowing down, piling up
2. A tsunami arrives
3. Five metres high
4. Where it breaks
5. Green’s law
6. The sea draws back