How earthquakes trigger tsunamis - BBC?

An earthquake under the sea can cause a tsunami by pushing water up and down really fast.

Imagine you're in a bathtub full of water. When you jump in, the water gets pushed up, that's like an earthquake. If you jump really hard, it sends waves crashing toward the other side, that's like a tsunami.

When an earthquake happens on the ocean floor, it moves big pieces of Earth around. This movement can push or pull the water above it very quickly. The water starts to rise and fall in big waves, these are the first signs of a tsunami.

If you're far away from where the earthquake happened, these waves might look small at first. But as they travel across the ocean, they get bigger and faster, just like when a tiny ripple in a pond turns into a wave that knocks you over!

When the big waves reach the shore, they can crash onto land with amazing force, kind of like a giant wall of water coming toward you. That's why tsunamis can be so powerful and dangerous.