1.) Energy released by an earthquake or explosiontravel through the Earth’s interior as waves.

2.) There are 2 typesa.) P-wavesb.) S-waves

3.) These waves have different properties andbehaviors that allow us to “see” inside the Earth.

P- and S-Waves*The quickie version

P- and S-Waves*The quickie version

P-Waves1.) Travel fastest (primary)2.) They can travel through

solid and liquid3.) Particles vibrate parallel

to propagation4.) SLINKY DEMO/CD DEMO5.) They refract to tell us

about Earth’s interior

S-Waves1.) Travel slower (secondary)

than P-Waves2.) They can travel through

ONLY solid and NOT liquid

3.) Particles vibrate perpendicular

to propagation4.) SLINKY DEMO/CD DEMO

P- and S-Waves*The quickie version

P- and S-Waves*The quickie version

Refraction: When a wave hits a boundary (discontinuity) it “bends”because of the different properties of the different materials.

1.) High density=low wave speed.

2.) BUT elasticity of materials increases faster than density SOWave velocity actually increases with speed.

POINT: wave travel path bends when they pass fromone layer to the next.

P- and S-Waves*The quickie version

Refraction: