1. Time-independent hazard-random process in time: used for building design, planning, insurance, probability Time-dependent hazard-a degree of predictability, enable authorities to prepare for an event-false alarms- loss of public confidence, China- shut down of public services during false alarms The Idea of Earthquake Prediction

2. Earthquake Predictions The 1960’s- descriptions of physical changes 1970’s- 1975, successful prediction; 1976, 250,000- people died in Tangshen, China 1980s- Jim Berkland, fluctuations of missing dogs in local newspapers, increase number of calls to satellite TV companies Greek scientists, electrical signals

3. Haichen, China, 1975 An evacuation warning was issued the day before The local rural population was educated and aided in the monitoring changes in land elevation and ground water reports of peculiar animal behavior- snakes coming out of the ground in January, livestock not going into their barns an increase in small earthquakes

4. 1977- National Earthquake Hazards Reduction Program (NEHRP) 1. Precursor detection instruments at the site 2. Detect and recognize precursors 3. Get colleagues to agree, accept and put out a warning The Idea of Earthquake Prediction or Forecasting

5. Earthquake forecasting- some connection between the level of chance between observation and event; probabilities and errors involved Scientists cannot predict earthquakes –Evacuation before an event since 1975 has not occurred Earthquake Forecasts

6. Long-term Forecasts Retrofitting Building codes Legislation Insurance Emergency plans Education to the public Preparedness

7. Long-term Forecasting Methods

8. Identify fault trace Trench Analyze sedimentary layers and offsets Date organic material Paleoseismicity

9. Large Bay Area earthquakes are more frequent at some times more than others 1836-1911; 1911-1979 (68 years of no events) Historical Seismicity Patterns

10. Parkfield Seismic Area 1988-90% probability for a M6 earthquake 1901 1922: 21 years 1934: 12 years 1966: 32 years 2004: 38 years Statistical Method of historic earthquakes Shortest interval: Longest interval: Average: 25.5 years Problems with this method? Recurrence Interval

11. Paleoseismology and recurrence interval Pallet Creek offset 1857 1745: 112 years 1470: 275 years 1245: 225 years 1190: 55 years 965: 225 years 865: 100 years 545: 320 years Shortest interval? Longest interval? Average? –187 years Strengths of this method: Shortcomings?

12. Seismic Gaps -areas on a larger fault system that lack seismicity

13. Bay Area faults belong to the San Andreas fault system Movement varies Right-lateral strike-slip faults 1868- Hayward fault 1906-San Andreas fault 1989-San Andreas fault Variation of average movement on known faults

14. Bay Area faults move at different rates to accommodate the total amount of slip of the San Andreas fault system Total+ 34 mm/year SAF 19 mm/yr Hayward fault 9 mm/yr Variation of average movement on known faults

15. Each vector represents the amount of movement on each fault Variations may indicate an imminent earthquake Earthquake Prediction and Probability Variation of average movement on known faults

16. Pattern of Seismicity

17. Working Group on California Earthquake Probabilities Group of 100 geologists, engineers, government officials evaluated all information Came up with a probability of a magnitude 7 or greater in the next 30 years 1988. 1999, 2003, 2008 Earthquake Forecasting and Probability

18. Assumes a random distribution of earthquakes In the Bay Area, 5 earthquakes greater or equal to M 6.75 occur approximately every 30 years 50% probability-just as likely to happen as not to happen

20. Loma Prieta- 30% probability in 1988- eq, 1989 Parkfield -90% probability in 1988-eq, 2004 Landers, Northridge, Kobe- earthquake on a little known fault The Idea of Earthquake Forecasting

21. Short-term Prediction based on precursors

22. All the described precursors sometimes occur but as of yet do not occur in a manner that successfully predict earthquakes

23. What should be expected? A reasonable time period The location- fault or fault segment Magnitude or amount of energy released

24. Ground deformation Preceding the 1906 earthquake in Marin County-elastic rebound theory The Palmdale bulge- monitoring began in the 1960’s, associated with the SAF Ground Deformations

25. Radon emission- a radioactive gas that sometimes shows an increase preceding an earthquake- There was a ten-fold increase 30 kilometers away from the epicenter 9 days preceding the earthquake. Problem with this method? Radon Gas Emissions

26. Parkfield Experiment Examining precursors or those events that sometimes occur before a main event Changes in physical properties in close proximity to the fault

27. Parkfield experiment Magnitude 6 earthquake occurred on average every 22 years from 1857-2004 Similar location Similar seismic wave pattern recorded Hopes of documenting an earthquake before, during, and after the main shock in order to produce a short-term prediction technique.

28. Precursors expected to observe Foreshocks Ground deformation Surface cracks associated with the 2004 earthquake

29. San Andreas Fault Observatory at Depth: 2004 Examining physical changes to the rocks at depth

30. Animal Prediction Unusual animal behavior prior to a disaster Greece, 373 BC, rats, snakes and weasels deserted days before an earthquake Advanced vibrations? Change in electrical charges? Change in magnetic field? So far, unable to use unusual animal behavior to predict earthquakes

31. Chi Chi Earthquke, Taiwan, 1999 Initial smaller earthquake during the first 4 seconds have higher frequency waves than larger earthquake The warning could be sent Seismic waves travel at about 2 miles per second

32. Early Warning System Detect P-wave arrival Warning system Emergency centers, hospitals, railways Depends on distance to how helpful Japan-March, 2011, M9, Tokyo-stopped trains; cell phone notification; 8-10 minutes tsunami Kobe-fault under city Mexico-11 warnings, M6 or greater

33. Early Warning System: U.S.System $80 dollars over 5 years Arrival of P-waves 3-4 minutes: Cascadia Subduction Zone 1 minute warning for SAF 30 seconds: –doctors stop surgery; –Duck and cover –Trains stop