1. 1.) Energy released by an earthquake or explosion travel through the Earth’s interior as waves. 2.) There are 2 types a.) P-waves b.) S-waves 3.) These waves have different properties and behaviors that allow us to “see” inside the Earth. P- and S-Waves *The quickie version

2. P- and S-Waves *The quickie version P-Waves 1.) Travel fastest (primary) 2.) They can travel through solid and liquid 3.) Particles vibrate parallel to propagation 4.) SLINKY DEMO/CD DEMO 5.) They refract to tell us about Earth’s interior

3. S-Waves 1.) Travel slower (secondary) than P-Waves 2.) They can travel through ONLY solid and NOT liquid 3.) Particles vibrate perpendicular to propagation 4.) SLINKY DEMO/CD DEMO P- and S-Waves *The quickie version

4. 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 SO Wave velocity actually increases with speed. POINT: wave travel path bends when they pass from one layer to the next.

5. P- and S-Waves *The quickie version Refraction: