1. 1 Can We Predict Earthquakes? Can We Predict Earthquakes? Andrea Nemeth Advisor: Dr. Mark Schilling

2. 2 Earthquake Prediction location time magnitude probability of occurrence reliable accurate The collapse of part of Jefferson Junior High School in Long Beach in 1933. (Photo: Portland Cement Association)

3. 3 Methods Employed In Earthquake Prediction statistical probability physical measurements geochemical observations observations of animal behavior Seismicity of California (USGS)

4. 4 Real Data or Simulated?

5. 5 Popular media statements “the Big One is overdue” “the longer it waits, the bigger it will be” (USGS)

6. 6 Statistical Models time-independent Poisson (exponential) model time-dependent Gaussian gamma log-normal Weibull distributions Brownian Passage Time

7. 7 Poisson Model Weibull Model Magnitudes of EQs and the time intervals between EQs are each assumed to be independently distributed. memoryless The probability of rupture is a function of the accumulated strain.

8. 8 Parkfield and Wrightwood Parkfield area medium-sized EQs occur here fairly regularly Wrightwood area long term data is available LA (USGS)

9. 9 1857, 1881, 1901, 1922, 1934, 1966 USGS prediction: an earthquake of ~M6 would occur in Parkfield between 1983 and 1993 The Experiment

10. 10 So how regular are the recurrence times of these earthquakes? Mean: 24.5 years Standard deviation: 9.25 years. The intervals between these EQs: 24, 20, 21, 12, 32, 38

11. 11 Probability Plots

12. 12 Can we rule out the possibility that even EQs at Parkfield are random in time? Result: 8.8% of all simulated interval sequences had standard deviation less than 9.25. Conclusion: This sequence is somewhat regular, but not extremely unusual. 2473102531 20 2529753 214527205 1213974718 32171632222 381141273912 9.255.7914.5910.6317.7516.93

13. 13 Wrightwood 534, 634, 697, 722, 781, 850, 1016, 1116, 1263, 1360, 1470, 1536, 1610, 1690, 1812, 1857

14. 14 The Recurrence Times of the EQs at Wrightwood The time intervals between successive EQs: 100, 63, 25, 59, 69, 166, 100, 147, 97, 110, 66, 74, 80, 122, and 45 years. mean: 88.2 years standard deviation: 37.8 years.

15. 15 Probability Plots

16. 16 Simulation for the Wrightwood area Result: Only 1.5% of all simulated interval sequences had standard deviation less than 37.8 years. Conclusion: This sequence of 16 EQs at Wrightwood is more regular than the Parkfield sequence.

17. 17 Summary Several factors make EQ prediction difficult: the cycle of EQs is long the fundamental physics of EQ faulting is not yet understood no clearly recognizable precursor has been observed EQ history is short for most faults

18. 18 Potential Future Work Further investigation of the Wrightwood data Analysis of other data sets from the San Andreas Fault Study of other statistical models with our data

19. 19 Acknowledgments This project was sponsored by the NASA/JPL PAIR program. I thank Dr. Carol Shubin for her continuous support, interest and encouragement. I’m very grateful to Dr. Mark Schilling, my advisor, for his comments on the data analysis and preparation, for his valuable insights and observations.