What causes earthquakes to happen?
Earth's Restless Puzzle
What causes earthquakes to happen?
The ground feels rock-solid, doesn't it? Stand on it, build a city on it, trust it completely. And yet, every now and then, the ground does something rude: it shakes. So what's going on down there? The short answer is that Earth's outer shell is not one smooth piece. It's broken — and the pieces are restless.
Picture Earth as a giant egg that's been gently dropped. The hard outer shell is cracked into enormous slabs called tectonic plates. These plates carry the continents and the ocean floors on their backs. They fit together like puzzle pieces — except this puzzle never quite sits still.
