Earthquakes

​Understanding Earthquakes

​Why does the Earth shake?

​Review - Plate Boundaries

• Earth's crust is cracked into 12 plates.

• The plates meet at boundaries.

• Scientists study plate boundaries because changes in the geosphere happen there.

• They classify plate boundaries into:

  • Convergent

  • Divergent

  • Transform

• A transform boundary is a place where plates ru​b against each other.

  ​

Multiple Select

Which two facts help to explain why the plates move?

(Pick 2!)

• The plates in the crust are liquid.

• The plates in the crust are solid.

• The mantle below is solid.

• The mantle below is liquid.

Match

Match the plate boundary to its definition.

• Plates spread apart

• Plates come together

• Plates rub against each other

Divergent

Convergent

Transform

• Divergent

• Convergent

• Transform

Match

Match the plate boundary to its diagram.

Divergent

Convergent

Transform

• Divergent

• Convergent

• Transform

What is an earthquake?

• An earthquake is the movement of Earth’s crust resulting from the release of built-up potential energy between two stuck lithospheric plates

Parts of an earthquake

• The point below the surface where the rock breaks is called the earthquake focus

•  As soon as the rock breaks, there is movement along the broken surface causing a split in the surface called a fault

• The epicenter is the point on the surface right above the focus

Parts of an earthquake

• We are going to draw this earthquake diagram in our notebook.

Seismic waves

• Waves that carry energy of an earthquake away from the focus

• Seismic waves that travel through Earth’s interior are called body waves. The two main kinds of body waves are P-waves and S-waves

• Waves on the surface, or body waves that reach the surface, are called surface waves

• P-waves travel through solids and liquids, compressing and expanding the materials they pass through.

• S-waves only travel through solids and temporarly change the shape.

•  Surface waves reach the surface. They are slower than body waves, but they are the waves that cause the most damage.

Multiple Choice

A point on Earth’s surface right above the focus of an earthquake.

• Epicenter

• Heliocenter

• Hipocenter

• Staples center

Multiple Choice

A region on Earth’s surface that is split into two pieces.

• Fail

• Fault

• Fake

Multiple Choice

Which type of seismic waves cause the most damage?

• P-waves

• S-waves

• Surface waves

• Tsunami waves

Where do earthquakes occur?

• Earthquakes commonly occur at the boundaries of lithospheric plates. Earthquakes occur less commonly at faults that are inside plate boundaries

• Millions of earthquakes happen every year. Not all of them are recorded because most are too weak to be felt.

Measuring earthquakes

• Seismometer - device that measures intensity of earthquakes. Intensity is the strength of the shaking motion

• There are two related measurements taken during and after an earthquake—the energy released and the damage caused.

•  The Richter scale rates earthquakes according to the size of the seismic waves recorded on a seismograph

• Aproximately 15 earthquakes in the magnitude 7 range and one earthquake magnitude 8.0 or greater are expected each year

The Mercalli Intensity scale has 12 descriptive categories. Each category is a rating of the damage suffered by buildings, the ground, and people. 

Open Ended

At what category do you notice the buildings start to collapse?

Let's add the Richter scale and the Mercalli scale to our notes

Multiple Choice

How is energy transferred from the focus underground

to the epicenter on the surface?

• By waves

• By teleporters

• By gravity

Multiple Choice

During an Earthquake, ____ rises from underground to the surface.

• Energy

• Magma

• An alien

Dropdown

During an Earthquake, energy is transferred by a ​

Select answer

from the ​ ​

Select answer

underground to the ​

Select answer

on the surface.

Match

Match the following.

• Focus

• Epicenter

• Wave

Energy starts here.

Energy ends here.

Transfers the energy.

• Energy starts here.

• Energy ends here.

• Transfers the energy.

Match

Match the magnitude of the earthquake

to its impact.

• People cannot feel it, but a seismograph can.

• Materials in your house might shake a little.

• Buildings that were poorly made might get damaged,

• Most buildings will get damaged.

• Extreme destruction and death.

1

3

5

7

9

• 1

• 3

• 5

• 7

• 9