How do we see inside the Earth?

How do we see inside the Earth?

• What do we use?• __________________________• Seismology• ____________________________• What do we know that produces

seismic waves?

P-waves

“P” or Primary waves– _______________– _______________– _______________ – Travel through all mediums ( solid, liquid

and air)

“S” Waves

• “S” or Secondary waves– _______________– Vibrate ____________/ ____________– _____________ than “P” waves– Only travel through _______________

The Crust• ________ __________• Like an eggshell• ___________• ___________• Can crack• Two regions:

– ______________ (Basalt rock)– ______________ (granite

rock)

• Crust is _______ dense than the mantle

• Like ice on water; the crust _____________ on the mantle

The Mantle

• _____________• Like the crust

– __________– __________

• Iron, magnesium, calcium are heavier elements

• Mantle is ________ dense • How does the Earth’s crust add to the

density of the mantle?• __________ ___________ down on the mantle…

it compresses the minerals, increasing the pressure and squeezing them into rocks.

The Mantle

• Higher temperature • Why?• __________ __________• Decay of radioactive elements

Layers of The Mantle

• Upper mantle• ___________

– Rigid rock upper portion of upper mantle

• ___________– Lies beneath

lithosphere and “__________” like plastic

– It is ________…silly putty

• Lower mantle

The Core• ________ layers: inner and

outer core• ____ Earth’s volume• ____ Earth’s mass• 2x as dense as the Earth’s

mantle• Why?• Made of _____ ______• Inner core is VERY hot!• Some places as hot as the

surface of the sun!

The Inner Core• ______ ______

– How? – __________ from

Earth keeps Iron packed tightly; doesn’t allow it’s atoms to ______

The Outer Core

• Outer Core– _______ Iron– _______ pressure – _____ and _____ as Earth rotates– Creates _______ _________– Affects Earth’s ________– Produces _______ ______– Possibly responsible for Earth’s magnetic

field

Convection Currents

• What are convection currents?

• ________ of heat flows from ______ to ______

• This sets up a convection current in the ________

Effects of Convection Currents

• When the current comes at a weaker part of the ________, for example at a _______, ________ comes above the earth's surface.

• This is called ______ _______. • The movement of these plates goes very

slowly.• The _______ of two tectonic plates causes an

_________. • The ________ _______ along the bottom of the

_______ causes the moving of the tectonic plates.

Continental Drift & Tectonic Plates

• __________ Hypothesis on Continental Drift

• The World’s continents are in ________

• At one time, the continents were ______ together as one…

• This was known as _______• They fit together like a

jigsaw puzzle

Continental Drift

• Wegner’s theory proposed the landmass known as _______ started breaking up

• Separated into two parts: ______ and ________

• Wegner’s theory of the separation of Pangea was supported by ______, _________, _________ and _________ evidence

Seafloor Spreading• Seafloor is not _________• Constantly _________ itself• ____ ________ ______ (longest & tallest mountain range in the world, center

of the ________ Ocean)• Forms ________: Iceland and Azore• There are _______ in the mountains

Plate tectonics

• __________ move because they are _________ in plates

• The plates shuffle or move _____ of the Earth’s surface

• Plates move in _______ _______ and different ______ from each other

• There are ______ large plates and several smaller plates

Plate Boundaries

• _________ Boundaries– Plates move

_____from each other– Comes from rock in

the ______________– Partially melted– The rock partially

melts = _______– It was _____ before it

left the _______ of the Earth

Convergent boundaries

• Plates move _______ each other

Transform fault boundaries• Plates ______ ______ each other

Earthquakes

• Devastating• ______ (force) applied to _____• Stress causes ______• Eventually the rock cannot bend

anymore• It breaks and releases ______ ______• The released energy ( ______ _____)

travel out in all directions

Earthquakes cont• The initiating site of the

seismic wave: _______• The point at Earth’s

surface directly above the focus: ________

• Measured on a _______ _______ ( the increments are _____ fold in magnitude…)

Tsunami• Seismic sea wave• Created by an

__________