Earthquake!!Year Four

http://www.youtube.com/watch?v=4Y-62Ti5_6s

Today’s Lesson

What you will learn: The structure of the Earth What this has to do with earthquakes How and why earthquakes form How earthquakes move How an earthquake damages land and

structures How earthquakes are measured

http://www.ucmp.berkeley.edu/geology/tectonics.html

What did you see happening in the animation?

Tectonic Plates

Tectonic plates form part of one of the earth’s layers.

They are like pieces of a jigsaw They are constantly being pushed

around, bumping and grinding into each other - when this happens, an earthquake usually occurs

Tectonic plates move continents at approx 50-100mm each year notes

!

Now lets watch it again……

http://www.ucmp.berkeley.edu/geology/tectonics.html

Australian Earthquakes?

Where do you think the most earthquakes would occur?

Do we get earthquakes in Australia?

http://www.ga.gov.au/bin/drawquake_foyer.plhttp://www.ga.gov.au/bin/listQuakes

The Layers of the Earth

Does anyone know any of the names of the layers of the Earth?

http://earthquakesyearfour.blogspot.com/

The Inner Core

Hottest part of the Earth

Possibly as hot as the Sun

Solid sphere 2500km across – the distance from Sydney to Cairns!

http://earthquakesyearfour.blogspot.com/ Outer Core

notes!

The Outer Core

Liquid layer which is 2200km thick

Temperature approximately 5000 degrees

Made up of hot, molten lava

http://earthquakesyearfour.blogspot.com/ Mantle

notes!

The Lower and Upper Mantle Lithosphere

Lower – made from solid rock

Upper - also known as the lithosphere

200km thick Broken into the tectonic

plates – oceanic and continental

http://earthquakesyearfour.blogspot.com/ Crust

notes!

The Crust

25km of loose rock Makes up less than 1%

of the Earth We live on the top of

the crust This is the part of the

Earth that gets broken and split in an earthquake

notes!

Blanket Activity

Two helpers needed Each to push the ends of the blanket

towards each other What happens? What is this representing?

A bridge across a tectonic plate

that has divided

How did this happen?

How?

So how does an earthquake happen?

Using all of this new knowledge – you tell me!

notes!

Faults Fault- an area or line along

a tectonic plate that the released energy from an earthquake travels along. The earth’s crust is pushed up or down, or over or under when this happens, creating different size faults – like scars on rock or even mountains! notes

!

http://earthquake.usgs.gov/learning/animations/animation.php?flash_title=Normal+Fault&flash_file=normalfault&flash_width=220&flash_height=320

Focus and Epicenter

The underground starting point of the earthquake is called the focus

The above ground starting point of an earthquake is called the epicentre

notes!

Seismic Waves Waves of force that start from the focus

and travel outwards There are primary (p-waves) and

secondary waves (s-waves) p-waves occur first, then s-waves Seismic waves are what causes the

shaking and splitting of the earth Watch this animation to see how they

can travel ALL over the world!

http://www.pbs.org/wnet/savageearth/animations/earthquakes/index.html

notes!

Richter Scale Earthquake strength is classified on the Richter

ScaleMagnitude Description of Effect less than 3.4 Usually felt by only a few people near the

epicentre

3.5-4.2 Felt by people who are indoors and some outdoors; vibrations similar to a passing truck.

4.3-4.8 Felt by many people; windows rattle, dishes disturbed, standing cars rock.

4.9-5.4 Felt by everyone; dishes break and doors swing, unstable objects overturn.

5.5-6.1 Some damage to buildings; plaster cracks, bricks fall, chimneys damaged.

6.2-6.9 Much building damage; houses move on their foundations, chimneys fall, furniture moves.

7.0-7.3 Serious damage to buildings; bridges twist, walls fracture, many masonry buildings collapse.

7.4-7.9 Causes great damage; most buildings collapse.

8.0 or higher Causes extensive damage; waves seen on the ground surface, objects thrown into the air.

Guess the Magnitude

5.4

Guess the Magnitude

6.9

Guess the Magnitude

8.0

2004 Earthquake On Boxing Day, 2004, a 9.3 earthquake

occurred along Sumartra’s west coast This was one of the deadliest natural

disasters of all time – but not because of the earthquake

The focus was on an oceanic tectonic plate, which caused a deadly tsunami that hit Indonesia, Sri Lanka, India and Thailand the hardest

http://en.wikipedia.org/wiki/File:2004_Indonesia_Tsunami_Complete.gif

Questions?

Check the question chart – have we answered everything?

http://earthquake.usgs.gov/learning/kids//