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  • The world around you is just full of things that are on the move.

  • Airplanes in the sky, cars on the road and tons of animals -- including you and me! -- are

  • walking around everywhere.

  • But you know what?

  • It turns out that the ground beneath your feet is moving too!

  • Most of the time, you can't feel it.

  • Because, most of the time, the ground is moving very slowly.

  • But when you do feel the ground move, that's called an earthquake.

  • During an earthquake, the ground shakessometimes a little, and sometimes a lot.

  • It might seem kind of strange that the ground, which holds up houses and skyscrapers and

  • everything else, can actually move.

  • But it doesand it's all because of the way the Earth is made.

  • If you could cut the Earth in half, and look at it like this, you'd see that the Earth

  • isn't a solid ball all the way through.

  • It has layerskind of like a cake!

  • The top, or outside layer of the Earth...what we think of as the ground...is called the

  • crust.

  • Now, even though the crust of the Earth is certainly very strongit's not made of

  • one big piece.

  • The Earth's crust is actually made of many big pieces that fit together.

  • You can think of these pieces as being like the pieces of a giant jigsaw puzzle.

  • And we call these pieces of the crust plates.

  • Now, the edges of these plates aren't smooth along their edges, like the edges of the plates

  • you eat off of

  • These plates are made of very thick layers of rockso their edges are bumpy and ragged,

  • with rocky chunks sticking out of them.

  • And it's these plates that make up the Earth's crust that are always moving.

  • Like I said earlier, you usually can't feel or see them moving, because they move very,

  • very slowly.

  • Most plates just creep along at about one or two centimeters a year.

  • That's slower than your fingernails grow!

  • But how do these moving plates cause earthquakes?

  • Well, if you look at pieces of a puzzle, you'll see there there's a gap between the pieces

  • where they touch.

  • And, there's a line where the plates touch, too.

  • We call that line a fault.

  • Some faults are very thin, and too small to be seen.

  • And some are very deep in the Earth's crust.

  • But some faults are really big, and you can see them right on the Earth's surface.

  • For example, this fault, which runs almost the whole length of the state of California,

  • is more than a thousand kilometers long!

  • And faults are where most earthquakes happen.

  • As the plates of the Earth's crust move past each other at a fault, the pieces of

  • rock that stick out of their sides sometimes bump into one another.

  • And when this happens, the ground above the platesand anything on the groundshakes.

  • But, sometimes the plates do more than just bump into each other.

  • They get stuck!

  • Have you ever tried to open a door that's stuck?

  • You push and push...and then, all of a sudden...it opens really fast and bangs against the wall!

  • Well, sometimes, two different plates can't move past each other...and they get stuck.

  • But they keep trying to move!

  • They push against each other, just like you pushing against that stuck door!

  • When two things push against each other, the force of all of that pushing causes what we

  • call pressure.

  • And if the thing that's being pushed doesn't move, that pressure has nowhere to go.

  • So it just keeps building up.

  • In the case of our plates of crust, the pressure builds up where they're stuck.

  • It builds and builds...until the rocks break...and the plates suddenly move.

  • This causes the ground above the plates to shakesometimes a lot.

  • How much the ground shakes depends on how much pressure has built up between the plates.

  • The more pressure...the bigger the earthquake.

  • So there's a lot of cool stuff happening beneath your feet!

  • Even if -- most of the time -- you can't even feel it!

  • Thanks for joining us on SciShow Kids!

  • We love viewer questions...so if you have a question about something you see, ask a

  • grownup to help you leave a comment down below, or send us an e-mail to kids@scishow.com!

The world around you is just full of things that are on the move.

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A2 初級 美國腔

造成地震的原因(What Causes Earthquakes?)

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    joey joey 發佈於 2021 年 05 月 10 日
影片單字