Unit 4 Lesson 5 - Earthquakes

Unit 4 Lesson 5

Earthquakes

By the end of this lesson, you should be able to describe the causes of earthquakes and to identify when earthquakes happen.

Why do Earthquakes happen?

Multiple Choice

Each year there are approximately _________ earthquakes detected around the world.

• 50

• 500

• 5000

• 500,000

Multiple Choice

In the United States. the state with the most earthquakes on average is ___________.

• California

• Alaska

• Hawaii

• Oregon

Multiple Choice

Every year, earthquakes cause ___________ dollars of damages in the United States.

• Thousands

• Millions

• Billions

• Trillions

Multiple Choice

Most earthquakes only last for several _________ of time.

• seconds

• minutes

• milliseconds

• hours

​Fault

Deformation

Elastic Rebound

Earthquake

Focus

Epicenter

Tectonic Plate Boundary

Earthquake Vocabulary

-Ground movements when blocks of rock in Earth move suddenly and release energy.

-Energy is released as waves that travel through the ground

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​What is an Earthquake?

Focus - the place within Earth along a fault at which the first motion of an earthquake occurs.

Epicenter - Directly above the focus on the surface.

Fault - A break in Earth's crust along which blocks of rock move.

​

​Key Parts of an Earthquake

Multiple Choice

Which is an earthquake's point of origin on the surface of the Earth?

• focus

• epicenter

• seismic wave

• fault line

Multiple Choice

Which of the following describes the depth underground for the origination of an earthquake?

• focus 

• epicenter

• seismic moment

• fault line

Multiple Choice

Which letter indicates the fault line?

• A

• B

• C

What causes earthquakes?

​Near the boundaries of tectonic plates!

As the plates move they do not slide past each other smoothly - they get caught up (Their edges are not smooth!). Pressure builds up along these faults at the edges of plates until they can not hold on any longer and they snap. This snap is called elastic rebound.

Multiple Choice

ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed.

• kinetic energy

• potential energy

• elasticity

Multiple Choice

Which plate boundary is displayed?

• Convergent

• Divergent

• Transform

• Hot Spot

Multiple Choice

Which plate boundary is displayed?

• Convergent

• Divergent

• Transform

• Hot Spot

Multiple Choice

Which plate boundary is displayed?

• Convergent

• Divergent

• Transform

• Hot Spot

- Most earthquakes occur at or near tectonic plate boundaries.

- Three types of tectonic plate boundaries.

- Divergent / Convergent / Transform

​

Where do earthquakes occur?

-Plates pull apart causing the crust to stretch (tension)

-Earthquakes are shallow

-No more than 20 km deep

-Occur along normal faults

Divergent Boundary

​-Plates collide causing rock to squeeze (compression)

-Causes the formation of reverse faults (subduction)

-Some of the strongest earthquakes

-depths up to 700 km

Convergent Boundary

​-Plates slide past each other horizontally (shear stress)

-Strike slip faults

-Shallow earthquakes in upper 50 km of crust.

-Common along transform boundaries.

Transform Boundary

Multiple Choice

What do the lines on this map represent?

• volcanoes

• easrthquakes

• plate boundaries

• travel routes

Multiple Choice

Which of these natural disasters happen on these plate boundaries?

• earthquakes

• volcanos

• both of these

• none of these

Multiple Choice

Why do so many earthquakes and volcanos happen along plate boundaries?

• bad weather in these areas

• coincidence

• plates move and shift

• none of these

Multiple Choice

A ____________________ is where two or more tectonic plates meet.

• Plate edge

• Plate ridge

• Tectonic plate boundary

• Tectonic plate focus

Many of the earthquakes that occur do not cause any damage - many don't even feel them.

Strong earthquakes can cause billions of dollars in damage, injuries, and loss of life.

​

​What are some effects of earthquakes?