Book 2, Question 142 · Video
Why Does the Ground Shake?
Sometimes the ground trembles. That is called an earthquake. Giant plates can slip! Most shakes are small. Some places have earthquakes more often than others, mostly near the edge
Read the full answer →What Crafty Clover says in this video
Intro
Hey there, curious minds! I'm Crafty Clover! Let's discover something amazing. Why does the ground shake?
The Big Idea
Sometimes the ground trembles. That is called an earthquake. Giant plates can slip! Earth's crust is broken into plates, and when they slip, the ground can shake. Most shakes are small, and many are too weak to feel. Earthquakes happen every day around the world, but most are too small to notice.
Plates Press
Step one: plates press. Earth's crust is made of giant plates, and they slowly push against each other. They move only about as fast as your fingernails grow. Slow pressure can build for many years before the rock finally gives.
Rock Sticks
Step two: rock sticks. Where two plates meet, the rocks can stick together instead of sliding. Stress builds up, like a bent stick that is about to snap. The waves spread out like ripples in a pond, and the ground jiggles.
Rock Slips
Step three: rock slips. Finally, the stress is stronger than the friction, and the rock slips suddenly. The stored energy is released in an instant. After the slip, the rocks settle into a new position.
A Closer Look
Let's take a closer look at why the ground shakes! First, plates press. Second, rock sticks. Third, rock slips. And fourth, the ground jiggles, because the slip sends waves through the ground.
Quick Facts
Quick facts! Most shakes are small. Some places have earthquakes more often than others, mostly near the edges of plates. Grown-ups have safety plans for bigger ones, like drop, cover, and hold on. Scientists use tools called seismometers to measure shaking. Buildings in shaky places are built to bend, so they stay standing.
Think Like a Scientist
Now, think like a scientist! Rub two blocks of wood together, slowly. Feel how they stick and then suddenly slip. That sudden slip is like an earthquake. Can you explain how friction and stress work in this activity?
Outro
Earth's plates never stop moving, and we can learn to be prepared! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!