What are underwater earthquakes?

Underwater earthquakes are like when the floor of the ocean suddenly shifts, just like when you move a table and things on it fall over.

Imagine the ocean floor is like a giant puzzle made of big pieces called plates. These plates slowly slide past each other or crash into each other deep under the sea. Sometimes, they get stuck and then suddenly let go, snap!, that's an underwater earthquake.

If you were swimming near where the earthquake happened, it might feel like someone gave the water a big push. This push can make waves travel across the ocean really fast. If those waves are strong enough, they can become tsunamis, which are like giant ocean hills that come rushing toward the shore.

In 2011, a huge underwater earthquake happened near Japan. It was so powerful it made the whole ocean shake and created tsunamis that hit the coast, some of those waves were taller than buildings!