earthquake lesson

Earthquakes

Earth Science 11Ms. McKean

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Objectives

Use the Elastic Rebound Theory to describe how Earthquakes occur.

Identify the epicenter and focus of an Earthquake given a diagram.

Name and describe each of the 4 types of seismic waves including movement, direction, speed, and how they attribute to Earthquake damage.

Describe how Earthquakes are measured and identify which tools are used in this process.

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PART 1What are Earthquakes

What are Earthquakes? The shaking or trembling caused by the

sudden release of potential energy

Usually associated with faulting or breaking loose of locked plates

Continuing adjustment of position results in aftershocks

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Elastic Rebound Theory Explains how energy is

stored in rocks

Forces will cause rocks to bend until a point of deformation

Rocks stay deformed as forces continue until eventually they force breaks

Energy is released from the fault in waves

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The Focus and Epicenter of an Earthquake

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• The point within Earth where faulting begins is the focus

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

Seismic Waves

Response of material to the arrival of energy released by rupture

Two types:

Body waves (P and S)

Surface waves (R and L)

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Body Waves P- waves (Primary Waves)

Fastest moving

Move like sound waves (compression)

Can travel through both solids, liquids & gases

S-waves (Secondary Waves)

Slower than P-waves

Move like a snake

Can only travel through solids (not liquids)

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Body Waves: P and S waves

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Surface Waves: R and L waves

Surface Waves

Rayleigh Waves and Love Waves Travel just below or along the ground’s surface Slower than body waves; rolling and side-to-side

movement Especially damaging to buildings

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Seismic Waves

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Faults

A fault is a fracture in the Earth's crust

3 main fault groups

Faults are classified depending on how they move.

Faults Normal Fault

occur in response to pulling or tension

the overlying block moves down the dip of the fault plane.

Thrust Fault

occur in response to squeezing or compression

the overlying block moves up the dip of the fault plane.

Strike Slip

the blocks move horizontally past one another.

The Normal Fault Strike-Slip Fault

Thrust Fault

Normal Fault

Thrust Fault

Strike Slip Fault

Check your understanding

1. According to the Elastic Rebound Theory, what causes Earthquakes?

2. What is the difference between the focus and the epicentre of an earthquake?

3. What are the 4 types of seismic waves? How do each of them move? (Try and use descriptive examples).

4. What is a fault? Name the 3 types.

PART 2Measuring Earthquakes

Measuring EQs Intensity

The Seismograph The device which records

Earth tremors

The base of the seismograph is anchored to the ground

A pendulum swings when the earth moves

The pen attached to the pendulum records the movement

The Richter Scale

Measures earthquake magnitude

Based on the amplitude of the wave produced on the Seismograph

Each point represents ground vibrations 10 times greater then the point before it


1. What are the two scales used to measure Earthquakes called? What does each measure specifically?

2. What is the difference in strength between a 4 and a 6 force earthquake on the Richter Scale?

3. Describe how a seismograph works.

PART 3Environmental Impacts

Environmental Impacts

Ground Shaking

Amount depends on three factors:

distance from epicentre the area’s geology the size of the Earthquake


Liquefaction

the vibration of seismic waves causes groundwater to rise to the surface

turns solid ground into a liquid-like material

houses, building will sink into the ground


Tsunamis

a very large sea wave produced by an earthquake

earthquake occurs underwater

earthquake happens, ground moves, water moves to fill in change in ocean floor

wave results

1964 Alaskan Earthquake caused a Tsunami to travel down hit places like Port Alberni and even made it to Hawaii


1. Name three impacts Earthquakes have on the environment.

2. Which one do you think is the most destructive and why?

3. What does liquifaction do to the ground? Where in BC where this be a very big problem?

4. What is a tsunami?

Quiz

Now that you have finished the presentation its time test your knowledge.

Be sure to read each question carefully.

At the end let me know your score.

Good Luck!

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What is the name of the theory that describes how earthquakes

occur

Correct - Click anywhere to continue


Incorrect - Click anywhere to continue


You must answer the question before continuing


Submit Clear

A) Focus Theory

B) Elastic Rebound Theory

C) Strike-slip Theory

D) Richter Theory

Where is the focus of an earthquake found?







Submit Clear

A) On the surface of the Earth where the earthquake occursB) In the core of the Earth where the earthquake is generatedC) The location that has the most damage as a result of the earthquake D) The spot within the crust where the earthquate originates

Which of the following are surface waves?







Submit Clear

A) P and S waves

B) S and R waves

C) R and L waves

D) P and L waves

The type of siesmic wave that moves through compressions is

called







Submit Clear

A) a primary wave

B) a secondary wave

C) a rayleigh wave

D) a love wave

Waves that cause the ground to roll and as a result cause lots of

damage are called







Submit Clear

A) Love waves

B) Rayleigh waves

C) Primary waves

D) Secondary waves

How are faults classified?







Submit Clear

A) their size

B) the amount of damage they cause

C) where they occur

D) how they move

Which is NOT a type of fault?







Submit Clear

A) Normal

B) Strike-Slip

C) Thrust

D) Rupture

What does a siesmograph measure?







Submit Clear

A) Intensity

B) Magnitude

C) Amount of Damage

D) Size of possible tsunami

Match the environmental impact on the left to the descriptor on

the right.Column 1 Column 2

A. large wave generated as a result of underwater earthquake

B. causes building to sink

C. amount depends on the distance from the epicenter

B Liquifaction

C Ground Shaking

A Tsunami







Submit Clear

Earthquake Quiz

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earthquake lesson

Documents

earthquake earthquake

s waves

types of seismic waves

vibration of seismic

love waves travel

sound waves compression

earthquake damage

force earthquake