earthquake!!
DESCRIPTION
A presentation that I used to introduce my year four students to the topic of earthquakes.TRANSCRIPT
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//