1. Seismic Waves

2. What do we know? • Energy that travels through the earth caused by the sudden breaking of rock within the earth or an explosion • Examples?

9. Types of Waves • P-waves • The fastest kind of seismic wave • The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. • S-waves • An S wave is slower than a P wave and can only move through solid rock, not through any liquid medium.

10. P-waves It pushes and pulls the rock it moves through

11. S-waves S waves move rock particles up and down, or side-to-side--perpendicular to the direction that the wave is traveling in

12. Earthquakes • Earthquakes and seismic waves? • Think for two minutes with your partner about the relation between earthquakes and seismic waves.

13. Earthquakes cont. • Seismic movement • Intensity (strength) can fluctuate • Usually last a short time • Question: Where does the majority of seismic activity take place?

14. How do we Measure Earthquakes? • Intensity • Based on perceived sensations and effects and measured by the M.S.K. scale. • Magnitude • Measures the amount of energy released by an earthquake. Measured by the Richter scale.

15. Richter Scale

16. Analyze • Where does the earthquake originate? • Where does one feel the earthquake? • Will the epicenter always be directly above the focus?

17. Seismic Risks • The earth’s crust (or land) shifts and moves causing earthquakes and tsunamis (tidal waves).

18. Prevention/Prediction Seismometer: instruments used to measure motions in the ground and the seismic waves generated by earthquakes and volcanic eruptions

19. Review

20. Review cont. • Is this a P or S wave?

21. Review cont. • Is this a P or S wave?

22. Review cont.