Earthquakes, and the Earth Structure

Earthquake and Seismic Waves

P and S waves

Pulses of Compression in Solid and Liquid

P-waves

Shear Distortions in Solid but NOT Liquid

S-waves

P-waves move through liquid: S-waves don’t

Earthquakes and Seismic Waves

Seismograph

Seismogram

Travel-Time curves

Reflection and Refraction

Refraction: “bending” of waves as the wave passes from one medium to another

Laser light source Laser path in air

Laser path in water

Laser source

Reflected Laser path in water

Refraction and Head Waves

“Head Wave”: Refracted Laser path along air/water interface

Man Made Earthquakes

Refraction in the Earth

Head Waves

Finding the Mantle Finding the

Mantle

Finding the Mantle Finding

the Mantle

Earthquakes and shadow zones

P- and S-wave

Shadow Zone

Finding the Core

S-wave

Shadow Zone

Outer core is Liquid

Compositional Layers of Earth

Seismic Velocity

structure of Earth

Seismic Velocity outer 1000 km

Today’s structure

of the Earth

Crust vs Whole Earth

Composition

Evolution of the Universe

Big-Bang to Solar System

Earth grows and rounds

Earth Grows and Rounds Out

Earlier

Later

4.5 to 4.4 Ga: Differentiation

The Iron

Catastrophe

Earth’s Early Structure

Compositional layers of the Earth