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2007 NSTA: St. Louis, Missouri

2007 NSTA: St. Louis, Missouri Earthquake Prediction and Forecasting: A Case Study of the San Andreas and New Madrid Faults Sponsored by: IRIS (Incorporated Research Institutions for Seismology) NSF (National Science Foundation) Presented by: John Taber, IRIS

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2007 NSTA: St. Louis, Missouri

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  1. 2007 NSTA: St. Louis, Missouri Earthquake Prediction and Forecasting: A Case Study of the San Andreas and New Madrid Faults Sponsored by: IRIS (Incorporated Research Institutions for Seismology) NSF (National Science Foundation) Presented by: John Taber, IRIS Michael Wysession, Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri

  2. For all IRIS NSTA activities www.iris.edu/joomla Go to: NSTA 2007

  3. Earthquake Prediction: Precursory Events Ex/ 1989 Loma Prieta Earthquake

  4. Also: Resistivity, water pressure and well levels, geyser activity, changes in seismicity

  5. Earthquake Prediction: Animal Behavior??

  6. The exception: Feb 4, 1974: Haicheng, China * Almost no details are known of this.

  7. Another Approach:Forecasting Seismic “Gap” Hypothesis

  8. OLD Map of “Seismic Gap” Predictions Parkfield was in correct place, but very late. Northridge, Landers, Joshua Tree and Big Bear Earthquakes were not even on this map!!!  “New York City Bear Gap” Hypothesis

  9. Parkfield, California, showed evidence of the recurrence of similar-sized (M 6.0) earthquakes

  10. In 1985 a 6.0 Parkfield earthquake was predicted with 95% confidence to occur by 1993. Mean = (1966-1857)/5 = 22 years Expected date = 1988

  11. Didn’t occur until 2004 (16 years late!) Was it a success? Right size, right location, wrong date.

  12. Paleoseismology Sieh et al., 1989 Extend earthquake history with geologic record M >7 mean = 132 yr s = 105 yr Estimated probability in 30 yrs 7-51%

  13. The NMFZ (New Madrid Fault Zone) is a region of elevated seismicity at the intersection of Missouri, Arkansas, Tennessee, Kentucky, and Illinois

  14. The NMFZ is associated with the Reelfoot Rift – a failed rift zone that was active 750 million years ago, as the supercontinent Rodinia began to break up.

  15. The Reelfoot Rift is a region of lower elevation (which is why the Mississippi River flows down through it!).

  16. In 1811-1812, swarm of earthquakes occurred. The largest were: 12/16/1811: M7.2 1/23/1812: M7.0 2/07/1812: M7.4 [Hough et al., 2000]

  17. A Magnitude 8 (M8) earthquake is much bigger than a M7 earthquake: Roughly 10x greater displacements Roughly 30x more energy released FAULT LENGTH FAULT WIDTH “the big one”

  18. NMSZ FREQUENCY-MAGNITUDE RELATIONSHIP • For New Madrid, combine instrumental seismology with earlier data to explore large earthquake recurrence • Large paleoearthquakes occurred at • ~ 1450 and 900 AD • (Magnitudes unknown) • Gives a M7 every few thousand years. • Might NEVER get a M8 earthquake ? Stein & Newman, 2004

  19. “Seismologists have predicted a 40-60% chance of a devastatingearthquake in the New Madrid seismic zone in the next ten years. Those odds jump to 90% over the next 50 years. The potential magnitude of a catastrophicNew Madrid quake dictates that we approach the preparedness on a regional basis"  Unjustified given geologic evidence

  20. Are the seismic hazards as great in NMSZ as California? Of course not. 2% chance of shaking within 50 years: = seismic hazard within next 2500 years

  21. More reasonable assessment, based upon actual seismicity The Global Seismic Hazard Assessment Program (GSHAP), with the support of the International Council of Scientific Unions (ICSU), and endorsed as a demonstration program in the framework of the United Nations International Decade for Natural Disaster Reduction (UN/IDNDR).

  22. Earthquakes occur where earthquakes occur Earthquakes occur where seismometers exist

  23. Earthquakes occur where earthquakes occur Earthquakes occur where seismometers exist Almost no seismometers!!

  24. Notice all the earthquakes EAST of the NMSZ! The NMSZ might be finished (for now?). It might be time for a different failed rift to undergo some continental creaking. o Historicalo Instrumental

  25. GPS SITE MOTIONS: Vertical show glacial rebound Horizontal show no pattern

  26. GPS site motions within their ellipse of uncertainty - no motion! DON’T SEE MOTION AT NEW MADRID OR ELSEWHERE IN EASTERN US: If you don’t bend it, you can’t break it No significant or coherent intraplate deformation visible

  27. GPS CONSTRAINTS ON LARGE EARTHQUAKE MAGNITUDE & RECURRENCE GPS data show little or no (< 2 mm/yr) motion Little - or none -accumulating for future earthquakes Newman et al, 1999 Intersection of Paleoseismology and GPS evidence suggests low M7 earthquakes, but larger events would have VERY long recurrence times. GPS

  28. Will we ever have a real-time warning system for St. Louis? Not likely. Not much you can do with 25 seconds! 25 s !!

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