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

For all IRIS NSTA activities Go to: NSTA 2007

Earthquake Prediction: Precursory Events Ex/ 1989 Loma Prieta Earthquake

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

Earthquake Prediction: Animal Behavior??

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

Seismic “Gap” Hypothesis Another Approach: Forecasting

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

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

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

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

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

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

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.

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

In , 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]

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

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 ?

“Seismologists have predicted a 40-60% chance of a devastating earthquake 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 catastrophic New Madrid quake dictates that we approach the preparedness on a regional basis"  Unjustified given geologic evidence

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

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). More reasonable assessment, based upon actual seismicity

Earthquakes occur where earthquakes occur Earthquakes occur where seismometers exist

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

o Historical o Instrumental 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.

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

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

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

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