Earth’s Interior

What’s in there?

How do we know its there?

Why do we even care?

Studying the Earth’s Interior

• Seismic Wave Studies• allow the scientists to compare different

regions• measure refraction• measure reflection• measure velocity changes• measure absorption

• P-waves –move parallel to the direction of their propagation like sound waves

• S-waves – move perpendicular to the direction of their propagation

Zones of the Earth

• Crust• outermost layer• solid rock

• Moho• thin interface

• crust/mantle• rocks denser below

• Mantle• mostly solid• thickest zone• 80% of volume

Mantle Pieces

• Lithosphere• crust + rigid mantle• sections - “plates”

• Athenosphere• wave velocity • “plastic”• partially molten• melting point/temperature

intersect• Stiffer Mantle

Core Regions

• Outer Core• liquid

• how waves refract in shadow zones

• how wave reflect off inner core

• Inner Core• solid

• due to great pressure

Inner Core

• note pressure graph

Earth’s Crust

• Continental Crust (20-70 km)• thickest by mountains• less dense (2.7 g/cm3)

• granitic rocks• Oceanic Crust (7-10 km)

• more dense (3.0 g/cm3)• basaltic rocks

Earth’s Interior

• Mantle (1000-3000 km)• less dense (3.3 – 5.5

g/cm3)• Outer Core (3000-5000 km)

• more dense (9.9 – 12.1 g/cm3)

• iron• Inner Core (5000 – 6000 km)

• most dense (12.7 – 13.0 g/cm3)

• iron and nickel