EARTHQUAKES

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How Earthquakes Shape and Alter the Earth’s Surface

Many things can change the appearance of Earth’s surface. Landforms can be created and altered by landslides, volcanoes,

tsunamis, glaciers, erosion, wind, and earthquakes.

Illustration of different types of landforms

Before we learn about earthquakes, let’s review what we already know about the

layers of the earth.

Earth’s Layers

Earth is made up of different layers. Some of these layers are solid, some are liquid, and some are both.

The outer layer of the earth is called the crust. The crust is the thinnest layer and made mostly of hard rock.

The second of Earth’s layers is the mantle. The mantle is very hot, made mostly of solid rock and about 1,800 miles thick.

The center of the earth is called the core and is the hottest of Earth’s layers. The core is divided into two sections, the outer core and the inner core.

The inner core is made of solid nickel and iron.

The outer core is a liquid layer of melted nickel and iron.

LET’S REVIEWCLICK ON THE BOX OF THE CORRECT ANSWER

The thin outermost layer of the earth is called the _____________________.

outer core

crust

inner core

mantle

SORRY!

Let’s go back to the information to find the answer.

The outer layer of the earth is called the crust. The crust is the thinnest layer and made mostly of hard rock.

The second of Earth’s layers is the mantle. The mantle is very hot, made mostly of solid rock and about 1,800 miles thick.

The center of the earth is called the core and is the hottest of Earth’s layers. The core is divided into two sections, the outer core and the inner core.

Are you ready to try again? Click on the circle to go back to the last question.

FANTASTIC!

Let’s keep going!

t The second of Earth’s layers is called the _____________________.

outer core

crust

inner core

mantle

SORRY !

Let’s go back to the information to find the answer.

The second of Earth’s layers is the mantle. The mantle is very hot, made mostly of solid rock and about 1,800 miles thick.

Are you ready to try again? Click on the yellow circle.

THAT’S CORRECT!!!

You’re doing a great job!

Which layer of the earth is the hottest?

the crust

the mantle

the core

The center of the earth is called the core and is the hottest of Earth’s layers. The core is divided into two sections, the outer core and the inner

core.

Are you ready to try again? Click on the yellow circle.

WAY TO GO!!!

Keep up the good work!

Which of the following statements is true?

The mantle of the earth is made of solid nickel and iron.

The crust of the earth is made of solid nickel and iron.

The inner core is made of solid nickel and iron.

The outer core is a liquid layer of melted nickel and iron.

The inner core is made of solid nickel and iron.

Are you ready to try again? Click on the circle to go back to the last question.

GREAT JOB!

You are now ready to begin learning about earthquakes.

It is estimated that there are approximately 500,000 detectable earthquakes in the world

each year.

Most earthquakes go unfelt but 100,000 of them are strong enough for citizens of an area

to feel.

Only about 100 earthquakes per year are actually strong enough to cause damage.

Fact:

Source: U.S. Geological Survey

What Are Earthquakes?

Earthquakes are the sudden, rapid shaking of the Earth causedby the breaking and shifting of rock beneath the Earth’s surface.

They are Earth’s natural means of releasing stress.

What Causes an Earthquake?

The outside of the Earth is called the crust. This crust is not solid like most people think. It is made up of about 20

different pieces called plates. The Earth’s plates float on a layer of hot, melted rock called magma.

Illustration of the various plates and the directionin which they move,

The place where two plates come together is called a fault line. Most earthquakes occur along a fault line.

This is a picture taken from high in the sky of a fault line where the two plates have smashed together, thrusting the surface of the earth upwards to form a mountain range.

The rocky edges of the plates are jagged and rough and don’t always slide smoothly past each other. When this happens the plates get stuck and stress builds up deep below Earth’s surface. Eventually Earth’s plates break

apart with a huge jerk. This is what causes an earthquake!

LET’S REVIEWCLICK ON THE BOX OF THE CORRECT ANSWER

What are earthquakes?

An imaginary circle around the center of the earth.

The sudden, rapid shaking of the earth.

A cone shaped mountain that sprays out molten rock.

Good GuessBut

Not QuiteLet’s go back to the information to find the answer.

What Are Earthquakes?

Earthquakes are the sudden, rapid shaking of the Earth causedby the breaking and shifting of rock beneath the Earth’s surface.

They are Earth’s natural means of releasing stress.

Are you ready to try again? Click on the circle to go back to the last question.

GREAT JOB!!!

Let’s keep going!

The Earth’s crust is made up of _____________________.

many pieces called plates

hot, melted rock

puzzle pieces

What Causes an Earthquake?

The outside of the Earth is called the crust. This crust is not solid like most people think. It is made up of about 20 different pieces called plates. The Earth’s plates float on a layer of hot,

melted rock called magma.

Are you ready to try again? Click on the circle to go back to the last question.

CORRECT!!!

Let’s try another question

Earth’s plates are always in motion because they float on a layer of hot, melted rock called __________________ .

lava

magma

mantle

Let’s go back to the information to find the answer.

The outside of the Earth is called the crust. This crust is not solid like most people think. It is made up of about 20

different pieces called plates. The Earth’s plates float on a layer of hot, melted rock called magma.

Are you ready to try again? Click on the circle to go back to the last question.

WAY TO GO!!!

Keep up the good work

Where do most earthquakes happen?

On a mountain

Under the ocean

Where two plates meet

The place where two plates come together is called a fault line. Most earthquakes occur along a fault line.

Are you ready to try again? Click on the circle to go back to the last question.

YOU ROCK!!!

You’re doing a great job

The place where two plates come together is called_________________________ .

the equator

a fault line

tectonic plates

Are you ready to try again? Click on the circle to go back to the last question.

VERY GOOD!!!

You’re doing a great job

LET’S STOP AND WATCH A VIDEO

This is a very good video about earthquakes from YouTube.

Click on the big to be taken to the video. When the video ends, minimize the YouTube screen to come back to this page.

http://www.youtube.com/watch?v=wNig4aqGVHs

Wasn’t that a great video?

Let’s continue with our last two sections.

Although earthquakes occur all over the world, most take place along an earthquake belt. There are three large areas or zones on our planet where the majority

of destructive earthquakes occur.

Where Do Most Earthquakes

Occur?

The Pacific Ring of Fire

The Pacific Ring of Fire is a major earthquake belt around the PacificOcean. 90% of all earthquakes occur in this region. The western coast

line of North America lies along this belt.

Runs along thecoast of California, Washington, and Alaska

The Alpide Belt

The Alpide Belt is the region with the second most frequently occurring earthquakes. This is the zone which

extends through the Himalayan Mountains in Asia.

The Mid-Atlantic Ridge

The Mid-Atlantic Ridge runs down the center of the Atlantic Oceanand is an extensive underwater mountain range.

LET’S REVIEWCLICK ON THE BOX OF THE CORRECT ANSWER

Earthquakes can occur __________________________ .

only along an earthquake belt

only in the ocean

only on land

anywhere

Where Do MostEarthquakes Occur?

Although earthquakes occur all over the world, most take place along an earthquake belt. There are three large areas or zones

on our planet where the majority of destructive earthquakes

occur.

Are you ready to try again? Click on the circle to go back to the last question.

WAY TO GO!!!

Which of the following statements is true?

The Alpide Belt is the name of the earthquake zone that runs along the coast line of the U.S.

The Pacific Ring of Fire is the name of the earthquake zone that runs along the coast line of the U.S.

The Mid-Atlantic Ridge is the name of the earthquake zone that runs along the coast line of the U.S.

The Pacific Ring of Fire

Runs along thecoast of California, Washington, and Alaska

The Pacific Ring of Fire is a major earthquake belt around the PacificOcean. 90% of all earthquakes occur in this region. The western coast

line of North America lies along this belt.

Are you ready to try again? Click on the circle to go back to the last question.

AWESOME!!!

Are There Different Types of Earthquakes?

Scientists still can not predict exactly when an earthquake might occur. As the stress builds up between the plates in the Earth, the rock must eventually give.

Divergent, Convergent, Transformational

The two plates under stress could shift or slide in several different ways. This creates many different types of earthquakes. To help study earthquakes, scientists have classified the various types of earthquakes into three categories depending on the direction in which the two plates move.

Example of transformational motion:the San Andreas Fault in California

Example of convergent motion:the Himalayan Mountains

Divergent Motion: Moving Apart

This is when the two plates separate and move away from each other, opening a large gash in the earth. This type of plate movement happens often on the ocean floor. When the plates separate, a new seafloor is created. This type of earthquake can occur on land as well. The Mid-Atlantic Ridge is the best example of divergent plate movement in the ocean.

Click on the picture to see an exampleof divergent motion. When finished, “X” out of the page to return.

Convergent Motion: Coming Together

This happens when the two plates move toward each other. When Earth’s rock gives way under the built up stress below, one plate will slide over top of the other plate. This top plate is often thrust upwards and mountains and volcanoes will often result. The Himalayan Mountain Range is a spectacular example of convergent motion.

Click on the picture to see an example of convergent motion. When finished, “X” out of the page to return.

Transformational Motion:Sliding Past

Transformational plate motion occurs when two plates slide laterally past one another. The resulting earthquakes are usually shallow and volcanic activity is not normally present. The San Andreas Fault which runs through California is an example of transformational plate movement.

Click on the picture to see an example of transformational motion. When finished, “X” out of the page to return.

What type of plate movement is this?

Transformational

Convergent Divergent

LET’S REVIEWCLICK ON THE BOX OF THE CORRECT ANSWER

Sorry!

Try Again

AWESOME!!!

Nice job!!!

What type of plate movement is this?

Transformational

Convergent

Divergent

WAY TO GO!!!

Another correct answer

What type of plate movement is this?

Transformational

Convergent

Divergent

That’s the way

You did it!

Congratulations

You have successfully completedthis lesson.

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