Hi, my name is Mr. Lawledge and I'm so excited to be learning with you today.

We are going to have a great time.

Let's get started.

Today's lesson is the causes of Earthquakes from the unit, Earthquakes.

How do they change the world? By the end of the lesson, you will be able to describe and explain what causes an earthquake.

We are going to work really hard together today, but I'm here to help and we can learn together.

The keywords we will be using today are, Earth's crust, tectonic plates, shock waves and plate boundaries.

Earth's crust is the outermost layer of our planet, and today we're going to learn what the other layers are as well.

The huge pieces that's Earth's crust is broken into are known as tectonic plates.

Shock waves.

Shock waves are areas of sudden high pressure or temperature that travel through water, air, or the ground.

The point where two tectonic plates meet is known as a plate boundary.

Our lesson today will be split into two parts.

The first part is, why does the land move? The second part is, what causes earthquakes? So let's begin with our first section.

Why does the land move? To understand the causes of Earthquakes, we must first understand the formation of Earth.

Without this, we won't understand why and how the land moves.

Earth is made up of four main layers.

You may have heard some of these before, but starting with the outermost layer, we have the crust, the mantle, the outer core, and the inner core.

So we have the crust, the mantle, outer core, and inner core.

Let's just stop and check our understanding here.

Can you identify which layers of Earth are these? Pause the video now and have a think about that one.

(no audio) Did you get that correct? Yes.

We have the mantle and the inner core.

Well done if you've got both those answers correct.

Let's look at the layers of Earth in a bit more detail.

The inner core is the layer in the centre of the Earth.

It consists of liquid, iron and nickel.

Incredibly, it is over 5,000 degrees Celsius in temperature.

Wow, that's hot, isn't it? The outer core is the next layer that we are going to look at.

The outer core surrounds the inner core and also consists of liquid iron and nickel.

It is also extremely hot with temperatures similar to the inner core.

Let's pause and check our understanding here.

Which of these is the outermost layer of the Earth? Is it A, the crust, B, the mantle, C, the outer core, or D, the inner core? Pause the video and think carefully here.

(no audio) Were you correct? Well, then if so, it is the crust.

Our next layer is the mantle.

The mantle is sandwiched between the outer core and the crust.

Interestingly, it is the largest layer of Earth.

It is approximately 2,900 kilometres thick.

That's roughly 1,800 miles.

It is mostly made up of semi-molten lava.

Semi-molten lava is extremely hot metal and rock that is in a state between a solid and a liquid.

That's really important for today's learning 'cause that will tell us a bit more about why tectonic plates move.

Temperatures at the mantle are between 1,000 and 3,700 degrees Celsius.

Wow.

Our last layer of the Earth is the layer in which we live on.

It's the crust.

Earth's crust is made up of rocks and minerals, and as you may know, temperature on the outermost part of the crust, which is the part we live on, varies depending on where you live in the world.

The closer you are to the equator, the hotter it will be.

Let's just check our understanding here again.

Which layer of Earth is made up of semi-molten lava? Is it A, the crust, B, the mantle, C, the outer core, or D, the inner core? Pause the video and have a think about that question.

(no audio) Were you correct? Yes.

It is the mantle.

And remember, Earth mantle is the thickest layer of Earth.

Here we have a diagram of Earth's layers, and as you can see, the Earth's mantle is constantly moving, and that's because the heat from the core is melting it and turning it into semi-molten lava.

Remember, semi-molten lava is extremely hot metal and rock that's in a state between a solid and a liquid.

(no audio) Earth's crust is made of huge blocks of land called tectonic plates.

Tectonic plates fit together like a jigsaw, and each one is given a name based on where in the world it is located.

Tectonic plates sit on top of the Earth's mantle, which is constantly moving.

Do you know which tectonic plate the UK is on? Let's see if you can spot it.

(no audio) Did you get that right? It is the Eurasian plate.

Well done if you spotted that.

The movement in the mantle causes the tectonic plates, which are sat on top of the mantle to move very slowly over time.

Tectonic plates can move in different directions.

They can move towards each other.

This in geography terms is known as a convergent plate boundary.

They can also move away from each other.

This in geography terms is called a divergent plate boundary.

We have reached our first task here.

Can you draw a line to label the correct layer of Earth? Got the four options there, the mantle, the inner core, the outer core, and the crust.

When you completed that, do you think you can tell your partner how tectonic plates move? Pause the video now and see if you can complete that first task.

(no audio) Welcome back.

How did you get on? Did you correctly identify the mantle, the inner core, the outer core, and the layer that we live on, which is the crust? Did you tell your partner that tectonic plates move as they sit on top of the mantle? The heat from the core rises and melts the mantle, which moves the tectonic plates.

Well done if you got all that right.

Well done.

You completed the first part of our lesson.

Let's have a look at our second part.

What causes earthquakes? So we're gonna use part of the information that we've just learned to help us with that second question.

First of all, let's define what an earthquake is.

An earthquake is sudden shaking of the ground caused by shock waves through Earth's crust.

Remember, shock waves are areas of sudden high pressure or temperature that travel through water, air, or the ground.

We talked about tectonic plates.

Tectonic plates are huge pieces of Earth's crust that fit together like a jigsaw.

The point where two tectonic plates meet is called a plate boundary, and you can see them there on our world map.

Let's stop and check our understanding here.

Can you point to the plate boundary between the Eurasian plate and the North American plate? So the plate boundary between the Eurasian plate and the North American plate? Pause the video and let's see if you can find it.

(no audio) There it is.

Well done.

If you've got that right.

Where tectonic plates meet at plate boundaries, they move against each other.

Some of the plates slide past each other, which creates friction that builds up.

Some tectonic plates push against each other, which creates pressure that builds up.

When this pressure is released, the energy from the force is released in shock waves causing vibrations in the Earth's crust.

This is an earthquake.

Let's check our understanding here with a true or false.

Tectonic earthquakes are random events, so they occur randomly.

Is that true or false? Pause the video here to think about that question.

(no audio) Well done if you said that was false.

Now let's see if we can justify our answer here.

Is it A, that earthquakes are random events as they occur from the sudden release of friction or pressure between tectonic plates? Or is it B, earthquakes are not random events as they occur from bad weather and storms? Think carefully.

Pause the video now to have a go at that question.

(no audio) Well done if you answered A.

Earthquakes are not random events as they occur from the sudden release of frictional pressure between the tectonic plates.

The biggest earthquakes happen when the tectonic plates are moving side by side.

Here you can see the Pacific plate moves faster than the North American plates.

Here we have a map which shows the location of the world's earthquakes in 2017.

There are a lot, aren't there? The size and colour of the spot shows how big the earthquake was.

So here, red earthquakes are the biggest earthquakes that occurred, and blue earthquakes are the smallest earthquakes.

Red earthquakes have a magnitude of over eight.

Most of the bigger earthquakes were on the Pacific plate boundary, which you can see here.

Although most earthquakes occur due to the movement of tectonic plates, they can also occur due to volcanoes erupting, collapses like mine collapses and explosions.

All of these can make a sudden shaking of the ground.

Let's stop and check our understanding here.

Which of the following can cause earthquakes? I'm gonna give you a clue.

There's more than one option here.

Is it A, tectonic plate movement? B, volcanic eruptions, hurricanes for C and D, underground collapses? Pause the video now and have a think about those questions.

(no audio) Welcome back.

Did you get those right? So tectonic plate movement can cause earthquakes.

The volcanic eruptions can cause earthquakes and underground collapses can cause earthquakes.

Hurricanes cannot cause earthquakes.

Well done if you've got all of those right.

Your second task for today is to draw a flow chart using the pictures to help you to describe how earthquakes occur.

Pause the video now and complete that task.

(no audio) Welcome back.

Did your work include the following information? Tectonic plates are huge blocks of land that fit together like a jigsaw.

Tectonic plates are constantly moving as they sit on top of Earth's molten mantle.

As they move, the tectonic plates can slide or push against each other, curating friction or pressure.

The sudden release of the pressure causes shock waves to be released towards Earth's crust, and this is an earthquake.

Well done if you included all of that information.

That takes us to the end of our lesson.

Let's quickly summarise today's lesson.

We have learned that Earth is composed of four layers.

The crust, the mantle, the outer core, and the inner core.

We've also learned that movement in the tectonic plates that form Earth's crust causes earthquakes, and we've also learned that earthquakes occur at plate boundaries where two tectonic plates meet.

Well done for all your hard work today, and I hope to see you again for some more fantastic geography.

(no audio).