How Does Tsunamis 101 | National Geographic Work?

A tsunami is like a big wave that travels super fast across the ocean because something really shakey happens under the water.

Imagine you're playing with a bathtub full of water, and you suddenly drop a rock into it, splash! A wave goes out from where the rock hit. That’s kind of what happens with a tsunami. Deep under the ocean, an earthquake or a volcano can cause the water to move really fast, sending waves toward the shore.

How It Travels

These waves are like long, low ripples that go across the whole sea, sometimes they're so far apart you can’t even see them. But as they get closer to land, they start to grow taller and faster, just like when a small ripple in a puddle becomes a big wave when it hits the side.

How It Hits

When a tsunami finally reaches the shore, it might look like a normal wave, but then boom! The water surges up really high, sometimes even going way past your feet, and that’s when it can knock things over or flood places near the coast.

Take the quiz →

Examples

  1. A big earthquake under the sea causes a tsunami, like when you drop a stone in water and ripples spread out.
  2. Tsunamis are like giant waves that crash onto land after an underwater shake.
  3. Imagine a landslide in the ocean making huge waves that travel far away.

Ask a question

See also

Discussion

Recent activity