Hi my name's Shona from Geoscience Australia today we're going to talk a
little about how the earth works I'm going to use this globe to help me.
I'm just going to take this chunk out and have a look at the inside.
There's lots of different layers to the globe but we're going to focus on the outer layer
this one's the crust and you'll see that it sits underneath the ocean
and also it's thicker and forms the land and the continents
and I want you to remember that the crust is made of rocks but when you look outside
that's the top of the crust even if it's got vegetation and buildings on it
it's still the crust. Now I'll pop this piece back and
I want you to now think of the globe or the world as a giant hard-boiled egg with the thin shell
representing the crust and imagine that our shell is actually cracked up it's broken into pieces.
So we're going to swap over now to looking at the world on a flat map
and it's been cut out into the shape of these pieces that we call tectonic plates
This is the first one we're going to have a look at, when you have a look at that shape
I suspect some of you will think it looks like a cat with one leg
or possibly a whale, or maybe even an alpaca
there's other things as well you might have a wonderful imagination.
Now have I think about where this might be in the world
it might not be a shape that you recognize from looking at maps.
It's actually our plate.
We have Australia sitting here but the plate is much bigger continents are parts of plates
and our plate might include India as well but some maps show them as separate
but remember all that rock that's sitting there underneath the ocean it's still part of our plate.
Now you might also know that tectonic plates move
and every plate moves in a different direction at a different speed
while touching the neighboring plates around the edge.
So let's have a think about the direction that our plate moves
you might like to try and point either north south west or east, have a go.
I'll tell you it's North
with a little bit of East but we're mainly moving northwards.
So we're getting closer to the equator and moving further away from Antarctica
Now let's have a think about how fast we're moving. I'll put this down
Can you hold your fingers up to represent a distance that we move in one year.
Could be anything from a millimeter all the way out to a meter - have a go.
All right correct answer about six or seven centimeters every year.
Now some of you are going oh that's not much
but we are really fast compared to some other continents
some of them doing less than two centimeters a year
in fact Australia is currently the fastest moving continent in the world.
That's a big deal think about a lifetime for a human hundred years of life.
The ground will move seven meters in your life that's a lot
Now I'm going to look at another plate one of our neighbors
this is actually faster than Australia.
So I've said Australia's the fastest continent this is the fastest plate it's also the biggest
this is well I call it Pac-Man plate you may or may not know what that means.
it's actually the Pacific plate
this is what's sitting underneath much of the Pacific Ocean
and it's moving to the west at 10 or 11 centimeters a year and it's one of our neighbors.
So let me get this back this is two plates together.
Where plates are pushing into each other
you get lots of earthquakes happening, the rocks scrape past each other in some way
so around the edges of our plate that's where most earthquakes happen.
You might be wondering is Pac-Man eating Australia? No.
What happens is the rocks underneath the ocean come along and then they slide underneath
but that's why we get lots of these earthquakes happening around New Zealand and to the north.
We get lots of earthquakes happening along this edge
as it slides underneath Indonesia up here.
So what about Australia do we get earthquakes?
You might think well no they're all round the edges
but we do we do still get earthquakes not as big
not as many but we do get them because in some way or another
our continent is getting stressed and every now and again those rocks will move.