New Madrid 7.7 Quake Scenario
What would happen if a "big one" ... we're talking magnitude 7.7... hit the New Madrid Seismic Zone? The Federal Emergency Management Administration (FEMA), with the Mid-America Earthquake (MAE) Center at University of Illinois, released a report in 2008.
Phase two of the report was released in June 2010 which looked at results of
a complete rupture of the entire New Madrid fault, where phase one looked at
possibilities if various segments erupted.
How much highway/bridge damage? How will people get medicine refills when the doctor and pharmacy records may not be available, and transportation/distribution is in chaos? What's the legality of "good samaritan" medical people coming from a different state to help?
Pulling just one line of stats:
Even one magnitude 7.7 quake in the Midwest would have significant implications for the entire country for years. Please read the (phase 1) report, at http://hdl.handle.net/2142/8971 The main report is a 2 megabyte download. The full report is 74 meg.
They've divided the New Madrid zone into THREE PARTS, and estimated a different fault rupture for each state; sort of a "worst case scenario".
Remember that a "big one" on the NMSZ would likely be a series of quakes, over a few months, on different sections of the fault. There are actually about seven sections to the NMSZ.
The maps below show areas of probable worst building damage. The scenario is DIFFERENT for each state's possible damage. Don't "add them together."
These maps show "worst case" estimates for EACH STATE, individually.
State of Kentucky emergency management folks think the West Kentucky risk calculated by others is overblown, based too much on California calculations.
This Tenn. map doesn't look bad, considering Memphis might be significantly hit. Please read the full report. The bedrock in downtown St. Louis is 10 feet below the surface. The bedrock below Memphis is 3,000 feet down.
SW Indiana: left map shows NMSZ susceptibility; second shows Wabash Valley Seismic Zone susceptibility
this single graphic from Eugene Schweig, 2007, assuming rupture on southwest segment of NM fault system
Again: the scenario shown for each state is DIFFERENT, and should not be "added together" among states.
The New Madrid Seismic Zone (NMSZ) involves eight states: Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee.
Regional Social Impact and Economic Loss
Social losses and economic impacts for each state should not be combined. Since each scenario is based on a different hazard, adding impacts together will not reflect one regional scenario.
You ask how much, how soon? Graphic below comes from engineer Greg Hempen, St. Louis. Consider what he believes happened in three eras on three segments of the fault.
Major Quake in U.S. Midwest Might Kill 6,000, Study Estimates
By Brian K. Sullivan [portions cut]
New Madrid Fault poses grave dangers to Missouri and region, FEMA report warns
By Kim McGuire ST. LOUIS POST-DISPATCH 11/24/2008
The outlook for Missouri and Illinois is grim should a catastrophic earthquake erupt on their segment of the New Madrid seismic zone, according to a new report released to the public late last week that's part of a broader federal emergency planning initiative.
The study, backed by the Federal Emergency Management Agency, predicts casualties and damage to homes, hospitals, roads and utilities in six states should a magnitude-7.7 earthquake erupt along the New Madrid seismic zone. Two other seismic zones, which could affect Alabama and Indiana, were also studied.
Conducted by the Mid-America Earthquake Center at the University of Illinois at Urbana-Champaign, the two-year study paints a dire picture for Missouri should a large temblor strike on the central segment of the fault. Among the predictions: 760 fatalities, $37 billion in total economic loss, 879 severely damaged bridges, 80,000 damaged buildings, 15,837 wastewater pipeline breaks and 121,927 displaced residents.
In Illinois, 276 fatalities and a $31 billion economic loss are projected as well as 242 severely damaged bridges, 48,140 damaged buildings, 4,147 wastewater pipeline breaks and 51,381 displaced residents.
Still, those numbers are lower than predictions for Tennessee. An estimated 2,904 people could die and a total economic loss of $56 billion could be incurred should a catastrophic earthquake strike on its segment of the fault.
The study is part of FEMA's national initiative aimed at developing catastrophic earthquake disaster plans in eight Midwestern states. The initiative aims to identify high-risk areas and possible disaster planning shortfalls.
"This initiative has its roots in Hurricane Katrina," said Mary Margaret Walker, a FEMA spokeswoman. "Since then, we've wanted to take a look at the disaster planning going on across the country. This study has a very specific use in that planning process."
The study provided the basis for planning scenarios used in about 30 FEMA-sponsored workshops conducted this year. A second round of workshops are planned next year, focusing on regional impacts of a catastrophic earthquake.
The New Madrid Fault, running from northeast Arkansas through Missouri's Bootheel into Southern Illinois, is considered one of the most dangerous earthquake zones in the United States.
In 1811 and 1812, it let loose with three major quakes that have been estimated to register magnitude 7.5 to 8. The U.S. Geological Survey projects a 7 to 10 percent chance of an equally strong quake within the next 50 years, and a 25 to 40 percent chance of one of at least magnitude 6.
The new study builds upon similar work conducted by the Memphis-based Central United States Earthquake Consortium several years ago. In general, that study predicted fewer casualties and a lesser impact on homes, utilities and the number of people needing shelter in most of the New Madrid states.
Jim Wilkinson, the consortium's director, said the Mid-America study is now the new benchmark for federal emergency responders but predicted some of the scenarios will change as earthquake science continues to evolve.
"I think there's a tendency to look at these kind of studies and see the numbers as absolute," Wilkinson said. "But there's not a model out there that can exactly predict what would happen in the event of a catastrophic earthquake. It's all a guess. Still, you've got to have something to build emergency plans on and that's how these kind of studies are helpful."
In Missouri, the new study is not likely to alter any current state or local earthquake disaster plans, said Steve Besemer, the state Emergency Management Agency's earthquake program director.
"Anytime you get any credible information like this, it's certainly worthwhile to review," Besemer said. "But it's driving FEMA planning more than us."
Earlier this year, Besemer met with 47 county emergency management directors to discuss earthquake plans, and next month, he will meet with officials in the remaining counties in a series of regional meetings.
Susie Stonner, a SEMA spokeswoman, said county emergency responders know that if they are prepared for the worst-case scenarios like those outlined in the new study, they will be prepared for more likely earthquake events like the magnitude-5.2 quake that rattled St. Louis in April.
"They know they're sitting on top of a powder keg," Stonner said. "They're very serious about emergency planning."
kmcguire at post-dispatch.com | 314-340-8250
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