ELI5: What causes earthquakes?

Imagine you have a big, bumpy rug on the floor – that's like the Earth's surface, made of tectonic plates. These plates are gigantic puzzle pieces, but they're not still! They're always slowly moving around, bumping into each other, sliding past each other, or even pushing under each other.

Think of it like this:

• Pushing: Imagine pushing two toy cars together on a carpet. They might get stuck, and the carpet wrinkles up. That's like plates pushing together.
• Sliding: Imagine two books sliding past each other on a table. Sometimes they slide smoothly, but sometimes they get caught and then suddenly slip. That's like plates sliding past each other.
• Going Under: Imagine pushing a cracker into soft butter. The cracker goes under the butter. That's like one plate going under another.

This sudden movement releases all that built-up energy as seismic waves. These waves are like ripples in a pond, but instead of water, they travel through the Earth. When these waves reach the surface, they shake the ground, causing an earthquake.

So, in simple terms, earthquakes happen when:

• Giant puzzle pieces (tectonic plates) on Earth are constantly moving.
• These pieces get stuck and build up pressure.
• The pressure becomes too much, and the pieces suddenly slip or break, releasing energy.
• This energy travels as waves, shaking the ground and causing an earthquake.