Earth Science," when we felt the ground moving, it was an earthquake.

- Okay, but I still don't exactly get it.

Look, the Earth looks solid.

So how can the ground move?

- Good question.

The Earth feels like it's solid, but check this out-- the inside of the Earth is actually not completely solid.

both: It isn't?

- Sydney's right.

See?

The Earth's surface, and the top layer, is called its crust.

And the crust has these big pieces they call plates - Right, about ten big plates cover the Earth's crust.

- You mean like dinner plates?

Oh, I love dinner.

- Nope.

They're rock plates.

And they're floating in, like, a sea of hot, squishy rock.

- Yep, and that hot, squishy rock is called magma.

- Magma?

I love that word!

- Okay, but... how do rock plates floating on "mag-mah" cause earthquakes?

How does it happen?

- We can ask a real expert--my mom.

Come on, to the DSA!

Boo-yah!

- Really great research, kids.

About ten big plates do make up the Earth's crust.

And under them is magma.

So let me explain earthquakes.

- With tomato soup with crackers floating on top?

- [laughs] Yep.

Think of the soup as the hot magma and the crackers as the plates.

- Ooh, what a cool comparison.

[Mindy's stomach grumbling] - And a really yummy one.

- Sean, would you mind helping me with my demonstration?

Now, wherever the plate edges touch, the rocky parts grind together.

And when one plate grinds against another, it can cause earthquakes-- the rumbling and shaking you felt earlier.

- [laughing] - Hmm.

I think I get it now.

So when's the next earthquake gonna happen?

- I don't know, Jet.

In fact, no scientist really does.

But we do know where an earthquake is likely to occur-- places where the plates are grinding together.

- Like under Boxwood Terrace?

- Exactly.

- Thanks for all your help, Mom.

- And thanks for the soup!

[slurping] all: Mmm, mmm!