What Causes Earthquakes

Image result for earthThis should look familiar, it is our home. It is the planet Earth. Or it is a model of the planet Earth. And it shows us what we see. We see continents, we see oceans, it shows us that the Earth spins. But there is one thing that this model cannot show us. It cannot show us what is on the inside of the earth. I press on this and it is hollow. But through science we have discovered that the earth is not hollow. Through science we have discovered what is inside the earth. So, what is inside the earth? Well, when I look at my model I see continents and ocean. But what you cannot see is, underneath the continents and ocean is a crust. A crust that covers the whole earth. And underneath the crust is a warmer layer called the mantle. And then underneath the mantle is this hot, inner core right at the center. So let us take a closer look inside the earth. Underneath all the continents and the ocean, there is the crust and it is important to remember that the crust is actually broken into pieces or plates. It is not just the one, there are many pieces or plates. Through science we have discovered that all those pieces and plates actually move. Now, in another video we talked about why those plates move. Today we want to talk about what happens when those plates move. So we are going to zoom in and take a closer look so you can see what happens when those plates move. To do that, to show you that, we are going to use spray cheese to actually be the mantle right under the crust, and then we are going to use graham crackers to be the crust. So first we need to lay down the mantle, the part right under the crust. And to do that, I am just going to spray some of this cheese. It is important to remember that this mantle is hot, and parts of the mantle are moving. And then we have the crust. The crust sits on top of the mantle in pieces or plates. And because parts of the mantle are moving, that means parts of my crust re moving and that is what we want to look at. Remember that continents and oceans are sitting on top of this crust and those plates are moving and one way those plates can move is, those plates can actually move apart. When they move apart, that mantle actually forms new crust. And when the plates move apart, this is happening under the ocean. Actually, new crust is a added as those plates move apart. Right here, as the plates move apart, the mantle cools down and it forms new crust. So we have seen that plates can actually move apart, but let us take a closer look at what happens when plates slide past each other. Okay, so we have zoomed in so we can take a closer look at what happens when the plates slide past each other. Watch what happens as I slide the plates past each other. It is important to remember it is not a smooth ride. It is actually quite bumpy. In fact, that bumpy ride as plates slide past each other, that is what creates earthquakes. So we have talked about what happens when plates move apart and what happens when plates move past each other. Well, what happens when plates bump into each other? So we have zoomed in again to see what happens when one plate collides with another. What happens when the plates come together and collide, one plate goes under and the other platestays on top. Take a look at that plate that is going under the other one. That plate will actually melt because it is so hot in the mantle. So, so far we have taken a look at what happens to the crust when the plates move under the ocean. Well, what happens when those plates move and there is a continent on top of the crust? Okay, we have zoomed in. We have our mantle, we have our crust, let us add some continents. What happens when the plates move together and collide when there is a continent on top? Well, watch what happens. As the plates collide, the continents collide and I am going to push, and what do you see happening? So, what is that? What did we just make? Well actually, this is the way moving plates make mountains. The earth is an amazing place. It is always changing because those plates are moving. Those moving plates make earthquakes happen, they make mountains, they even make volcanoes.

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