What is megathrust?

A megathrust is like a giant sliding puzzle that can shake the whole Earth when it moves suddenly.

Imagine you're playing with two big slabs of clay, one on top of the other, and they’re stuck together in some places but slippery in others. That’s kind of what happens deep under the ocean, where tectonic plates meet. A megathrust is a special kind of fault line between these giant plates. When the bottom plate pushes up against the top one, it can get stuck for a long time, like when you try to move your toy car but it gets jammed in the rug.

Think about trying to push a couch across a room. At first, it doesn’t move, it’s stuck. But then you give it a big shove, and whoosh! It slides all at once. That sudden movement is like what happens during an earthquake caused by a megathrust.

Sometimes, this giant slide can send waves through the ocean, making really big tsunamis, like when you drop your toy into a bathtub and it makes a splash that goes everywhere!