Earthquakes

# Earthquakes

## Earthquakes

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##### Presentation Transcript

1. Earthquakes Liz LaRosa http://www.middleschoolscience.com2009

2. What is an earthquake? • Used to describe both sudden slip on a fault, and the resulting ground shaking and radiated seismic energy caused by the slip • Caused by volcanic or magmatic activity, • Caused by other sudden stress changes in the earth.

3. Three Types of Faults Strike-Slip Thrust Normal

4. What causes earthquakes? • Tectonic plates move past each other causing stress. Stress causes the rock to deform • Plastic deformation – does not cause earthquakes • Elastic deformation – rock stretches then reaches a breaking point, releasing energy.

5. Elastic Rebound – deformed rock goes back to its original shape http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

6. Focus – point inside the Earth where an earthquake beginsEpicenter – point on Earth’s surface above focus

7. How Seismographs Work the pendulum remains fixed as the ground moves beneath it http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

8. Typical Seismogram http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

9. Primary Waves (P Waves) • A type of seismic wave that compresses and expands the ground • The first wave to arrive at an earthquake http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

10. Secondary Waves (S Waves) • A type of seismic wave that moves the ground up and down or side to side http://daphne.meccahosting.com/~a0000e89/insideearth2.htm

11. Comparing Seismic Waves

12. Surface Waves • Move along the Earth’s surface • Produces motion in the upper crust • Motion can be up and down • Motion can be around • Motion can be back and forth • Travel more slowly than S and P waves • More destructive

13. How do scientists calculate how far a location is from the epicenter of an earthquake? • Scientists calculate the difference between arrival times of the P waves and S waves • The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

14. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

15. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

16. Locating Earthquakes http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

17. How are Earthquakes Measured? Richter Scale

18. How are Earthquakes Measured? Mercalli Intensity Scale Click Link for Interactive Demo http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf

19. Earthquake Waves & Earth’s Interior

20. Seismic Waves in the Earth http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

21. Tsunamis http://www.uwgb.edu/dutchs/EarthSC-102VisualsIndex.HTM

22. Formation of a tsunami http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt

23. Tsunami Warning System http://isu.indstate.edu/jspeer/Earth&Sky/EarthCh11.ppt