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NEPEC (The National Earthquake Prediction Evaluation Council) was formed more than 30 years ago to provide the director of the USGS with advice and recommendations on earthquake predictions and related scientific research.
Last week, in advance of this weeks Great Central U.S. Shakeout and next month’s National Level Exercise (NLE 2011) (see The Great Central U.S. Shakeout), NEPEC issued a 26-page report on their assessment of the hazards presented by the New Madrid and associated fault lines:
Cover letter accompanying report from NEPEC Chair Terry Tullis to USGS Director Marcia McNutt.
The report is the result of a independent panel of experts, chaired by Professor John Vidale of the University of Washington.
It finds that while many uncertainties exist, the panel believes that the New Madrid Seismic Zone represents a significant hazard for large earthquakes with the potential to cause widespread damage
Which falls in line with the thinking by FEMA and many other agencies, who believe that the interior of the country is at risk of a major seismic disaster.
Hence this year’s NLE 2011 scenario of a major Midwest earthquake.
Not everyone agrees, however.
In recent years there has been much discussion over just how big a threat the New Madrid fault poses in the foreseeable future.
In the Bulletin of the Seismological Society of America in 2002, titled The Earthquake Potential of the New Madrid Seismic Zone, Martitia P. Tuttle, Eugene S. Schweig, John D. Sims, Robert H. Lafferty, Lorraine W. Wolf and Marion L. Haynes wrote:
The fault system responsible for New Madrid seismicity has generated temporally clustered very large earthquakes in A.D. 900 ± 100 years and A.D. 1450 ± 150 years as well as in 1811–1812. Given the uncertainties in dating liquefaction features, the time between the past three New Madrid events may be as short as 200 years and as long as 800 years, with an average of 500 years.
In 2009 Northwestern University geophysicist Seth Stein and Purdue University geophysicist Eric Calais published what many consider to be a controversial paper in the Journal Science that claimed the New Madrid fault zone was “shutting down”, and that it posed little danger.
In March of 2009 Purdue University published the following press release:
New Madrid fault system may be shutting down
WEST LAFAYETTE, Ind.The New Madrid fault system does not behave as earthquake hazard models assume and may be in the process of shutting down, a new study shows.
A team from Purdue and Northwestern universities analyzed the fault motion for eight years using global positioning system measurements and found that it is much less than expected given the 500- to 1,000-year repeat cycle for major earthquakes on that fault. The last large earthquakes in the New Madrid seismic zone were magnitude 7-7.5 events in 1811 and 1812.
This most recent NEPEC report, however, calls their conclusions into question.
As far as which position is correct?
We’ll either have to wait through decades without serious seismic activity on the New Madrid fault line, or endure a violent and destructive Midwest earthquake, before we can know the answer to that question.
In the meantime, the best advice I can give when faced with an uncertain future is to plan for the worst, and hope for the best.
So if you live in any of the 8 states (Alabama, Arkansas, Kentucky, Illinois, Indiana, Mississippi, Missouri, and Tennessee) that will be participating in this year’s Great Central U.S. Shakeout, I would encourage you to take part.
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