1. U.S. Department of the Interior U.S. Geological Survey The Earthquake is Inevitable: The Disaster is Not

2. Earthquake Organizations U.S. Geological Survey –Federal agency in Department of Interior Caltech Seismological Laboratory –Private university Southern California Earthquake Center –Consortium of universities & USGS California Geological Survey –State agency in Department of Conservation Office of Emergency Services –State agency in Homeland Security

3. Today’s speakers Lucy Jones, USGS –Scientist-in-charge for southern California Gary Fuis, USGS –Project chief, Southern California Earthquake Hazards Egill Hauksson, Caltech –Senior Research Associate Ken Hudnut, USGS –Project chief, Southern California Earthquake Hazards Tom Jordan, SCEC –Director, Southern California Earthquake Center

4. U.S. Department of the Interior U.S. Geological Survey The Earthquake is Inevitable: The Disaster is Not

5. What is an earthquake?

6. What is an Earthquake? Sudden slip of one block of rock across another Produces shaking as one of its effects The shaking is what you feel

7. M5 M6 M7 Magnitude Empirical and arbitrary Defined from ground velocity Each unit means 32 times more energy

8. M5 M6 M7 Moment Magnitude Depends on: –Fault area –Amount of slip Each unit means 32 times more energy

9. Every point on the rupture surface releases energy A bigger fault means a bigger earthquake Rupture Surface Hypocenter Hypo- center Epi- center Fault plane Fault

10. Bigger Faults Make Bigger Earthquakes

11. Shaking = damage potential ShakeMap Yorba Linda September 2002 M4.8 Yorba Linda September 2002

12. What Controls the Level of Shaking? Magnitude –More energy released

13. What Controls the Level of Shaking? Magnitude –More energy released Distance –Shaking decays with distance

14. Hector Mine October 16, 1999 M7.1 Northridge January 17, 1994 M6.7

15. What Controls the Level of Shaking? Magnitude –More energy released Distance –Shaking decays with distance Local soils –amplify the shaking

16. Undamaged Buildings on the fault 1906 San Francisco

17. Damage at Great Distance The Bay Bridge 1989 Loma Prieta The Marina District

18. Site Effects

19. Big earthquakes on big faults M7.9 Denali, Alaska November 3, 2002 200+ mile long fault

20. Near people…

21. Magnitude = Time Earthquakes start at hypocenter The rupture moves over a surface ñ Duration of earthquake depends on magnitude

22. Total Slip in the M7.3 Landers Earthquake Distance along the fault plane, 100 km (60 miles) total length

23. e Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length Slip on an earthquake fault: Start

24. Slip on an earthquake fault: Second 2.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

25. Slip on an earthquake fault: Second 4.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

26. Slip on an earthquake fault: Second 6.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

27. Slip on an earthquake fault: Second 8.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

28. Slip on an earthquake fault: Second 10.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

29. Slip on an earthquake fault: Second 12.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

30. Slip on an earthquake fault: Second 14.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

31. Slip on an earthquake fault: Second 16.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

32. Slip on an earthquake fault: Second 18.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

33. Slip on an earthquake fault: Second 20.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

34. Slip on an earthquake fault: Second 22.0 Depth into the earth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

35. Slip on an earthquake fault: Second 24.0 Depth Surface of the earth Distance along the fault plane, 100 km (60 miles) total length

36. Bigger Earthquakes Last a Longer Time

37. The Risk in Southern California 300+ faults One M≥6.7 event per 7 years

38. The Big Bend Los Angeles has the greatest risk in the United States

39. The bottom line: Earthquakes happen Courtesy of California Geological Survey & U. S. Geological Survey National hazards map

40. Scenario ShakeMap for M 7.4 Southern San Andreas Rupture Courtesy of Ned Field, USGS, Pasadena