1. Name of School Date Earthquakes and Seismology

2. Plate Tectonics

3. A Century of Earthquakes: 1906-2006

4. Global Seismographic Network

5. 2006 Earthquakes > M5.5 2006 Earthquakes > M5.5 in the world

6. How Many? Earthquake Magnitude and Equivalent Energy Comparisons Source: http://www.iris.edu/edu/onepagers/no3.pdf

7. Earthquakes generate Seismic Waves that travel around the globe and tell us about the Earth’s interior.

9. Simple Seismometer A simple way to measure shaking from earthquakes. To see it in action, watch this 14 sec video http://www.youtube.com/watch?v=DX5VXG mdnAg&NR=1

10. What is an Earthquake? Earthquake: The sudden release of elastic energy by fracture over some area of the earth.

11. What is an Earthquake? Earthquake: The sudden release of elastic energy by fracture over some area of the earth. Earthquake: The sudden slip on a fault (release of elastic energy), and the resulting ground shaking and radiated seismic energy caused by the slip.

12. Fault: A fracture (crack) in the earth, where the two sides move past each other and the relative motion is parallel to the fracture.

13. Typical Plate Boundaries

14. Plate Boundaries & earthquakes

15. Types of Faults

16. A fence built over a fault…

17. 1906 San Francisco Earthquake Fence Offset

18. Offset Stream Channels in Central California

19. Types of Seismic Waves P-wave: Primary Wave. Compressional wave, like a Slinky © being pushed and pulled. S-wave: Secondary Wave. This is a shear wave where particles move perpendicular to the travel direction of the wave. Surface Waves: Both Love and Rayleigh Waves. Only shallow particles are disturbed. Love waves are sideways, Rayleigh are vertical (like ocean waves).

20. Types of Seismic Waves

22. Seismographs HorizontalVertical

23. Distance to quake epicenter P S L Note: P-wave first S-wave second Surface waves last Time lag between p and s- wave arrival is called  t. Fig 3.22

24. Ts=23s Tp=14s Maximum Amplitude = 540 mm

25. Locating Earthquakes Fig. 3.23

26. Locating Earthquakes

28. Earthquake Size Richter Magnitude: Relative Size of an Earthquake (based on seismograph shaking) Seismic Moment/Moment Magnitude: Absolute Size of an Earthquake (based on energy released) Modified Mercalli Intensity: How much I’m shakin’ (based on talking to people)

29. Calculating Richter Magnitude A.K.A Local Magnitude M L = log 10 A - log 10 A o A is the amplitude of the s-wave measured at given station A o is the amplitude of a M R =0 event at the same distance P S

31. Log of the Amplitude for a Magnitude 0 Earthquake

32. M = 4 M = 0

33. Earthquake: The sudden slip on a fault (release of elastic energy), and the resulting ground shaking and radiated seismic energy caused by the slip.

34. Aki ’ s Seismic Moment Formula M o =  s A Where:   is the shear modulus. S is the average slip on the faulted area. A is the area of the fault plane over which slip has occurred. Shear modulus (   can just be thought of as the strength of the faulted material

35. Modified Mercalli Intensity Based on response of humans and structures I (not felt except by few) XII (total destruction) Still useful for comparison with older earthquakes for which there were no instrument records

36. Earthquake Info on the Internet http://earthquakes.usgs.gov/

37. Earthquake Info on the Internet http://earthquakes.usgs.gov/eqcenter/dyfi.php

38. Did You Feel It??? Go online and tell us!

39. Earthquake Info on the Internet http://www.data.scec.org/recenteqs.html

40. Southern California with Faults & the Big Bend

41. Southern California from Space(1)

42. Southern California from Space With a Few Major Faults

43. Historical Earthquakes (1800-1850) Historical Earthquakes (1850-1900)Historical Earthquakes (1900-1950) Historical Earthquakes (1950-2004) Historical Earthquakes (1000-1800) Smith and Sandwell, 2006

44. Thank You for Your Attention Questions?