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.