Book 5, Question 59 · Video
Shake, Rattle and Roll! Why Does Earth Have Earthquakes?
Earth's outer layer is broken into big pieces called plates that move very slowly. Sometimes the edges get stuck, and then they suddenly slip. That sudden slip sends out shaking wa
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What Crafty Clover says in this video
Intro
Hi! I'm Crafty Clover! Let's discover something amazing. Why does Earth have earthquakes?
The Big Idea
Sometimes the ground shakes. That's an earthquake! Earth's outer shell is broken into giant pieces called plates. They move very, very slowly, and they can get stuck against each other. Plates lock, stress builds, then rock slips! Let's see how.
Step 1
Step one: plates get stuck. Earth's plates keep pushing past each other. But where rock blocks meet, at a crack called a fault, they can lock together. The rock is rough, so it doesn't slide smoothly.
Step 2
Step two: stress builds up. The plates keep pushing, even though the rock is stuck. So the rock slowly bends and stores up energy. It's like bending a ruler, more and more.
Step 3
Step three: the rock slips! When the stress is too much, the rock breaks and slips. All that stored energy is let go at once. Then the shaking energy spreads out in all directions.
A Closer Look
Let's look at how an earthquake spreads. The rock slips at the spot underground called the focus. The place on the ground straight above it is the epicenter. From there, seismic waves spread out and shake the ground.
Quick Facts
Quick facts! There are millions of earthquakes every year, but most are so small that people can't feel them. Scientists use a machine called a seismograph to record shaking. Most earthquakes happen along the edges of plates, like the Ring of Fire around the Pacific Ocean. Grown-up note: practice Drop, Cover, and Hold On. Get under a sturdy table and hold on.
Think Like a Scientist
Now, think like a scientist! Try this with a grown-up. Hold a thin ruler at both ends, and bend it slowly. Bend it more, until it snaps or springs back. How is that like rock building up stress?
Outro
So earthquakes happen when stuck rock finally slips and sends out waves. Amazing, right? Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!