Great Central US SHAKEOUT!

Shakeout 2014
The 2014 Great Central US ShakeOut earthquake drill is six months away on October
16 at 10:16 a.m. (ShakeOut is always on the thirdThursday of October).  In 2013 more than 2.4 million participated, and already more than 500,00 people have been registered for 2014.

Register now at ShakeOut.org/centralus!
By registering, you will be counted in the world's largest earthquake drill and have peace of mind that you will know what to do when you feel strong shaking. Practice makes perfect!


Three of the strongest earthquakes in the history of the continental United States occurred far from California - near New Madrid, MO. Although measurements of magnitude vary, the New Madrid earthquakes of 1811-1812 are counted among the top seven, according to the U.S. Geological Survey.

“There were no instruments back in 1811, but we know there were major earthquakes in the past, and there is a lot of evidence it happened then,” said Tim Larson, geophysicist with the Illinois State Geological Survey at the University of Illinois. Evidence also points to serious earthquakes in 950 and 1400 A.D.

“If the recent past is any indication of what might happen in the future, then you start taking it seriously,” Larson said. “It has happened more than once.”

Southern Illinois is included within the New Madrid Seismic Zone, a deeply buried rift in the Earth’s crust beneath the Mississippi River Valley covering parts of five states. Due to the age and condition of the bedrock, ground motions can travel a great distance in the New Madrid Seismic Zone.

“An earthquake in the New Madrid Seismic Zone can affect an area 10-15 times greater than a similar earthquake in California,” said Bob Bauer, an engineering geologist with the Illinois Geological Survey.

New Madrid Facts
  • The New Madrid Seismic Zone is a failed rift, a place where the North American Plate tried to tear itself loose when the continents drifted apart hundreds of millions of years ago.
  • The zone stretches for 150 miles and covers portions of Missouri, Arkansas, Tennessee, Kentucky and southern Illinois.
  • The rift is buried beneath hundreds of feet of sediment, making it hard to study and impossible to see. The San Andreas Fault, by contrast, can be seen at the surface.
  • Because two plates are not colliding or scraping against one another, the New Madrid Seismic Zone does not reload with energy as quickly. Geologists believe sediment removed by erosion over long periods of time took pressure off the rift and allowed it to release energy in the form of an earthquake.
  • Experts believe the zone remains an earthquake threat because stored-up energy is still waiting to be released.

Logistical challenges
Responding to an earthquake in the New Madrid Seismic Zone would require coordination of emergency responders - mergency management agencies, police departments, National Guard units, and others - from several states. “In California, it’s all in one state,” noted Larson.

“There are a lot of things organized by state that need to communicated, like being sure they have the same frequencies on the radio,” he said. A national exercise focusing on the New Madrid Seismic Zone is planned for May.

“A natural disaster usually doesn’t cover eight states,” said Bauer. “This will be the largest exercise ever in the United States.” Every year, emergency managers collaborate on a single catastrophic event and its potential effect on the entire nation. “This year is the first time it is a natural hazard,” Bauer said. “And this one specifically is a New Madrid seismic event.”

Larson said a serious earthquake in the New Madrid Seismic Zone probably would interrupt transportation on the Mississippi River and nearby highways. Pipelines, bridges, the electrical grid and other infrastructure would be at risk.

The challenge for planners is to attempt to predict possible scenarios, such as what might happen if the power grid is damaged. “We do run exercises where the emergency management community practices its ability to react to different scenarios,” Larson said. “There are so many different possibilities it is hard to get to all of them. But you can try to be prepared.”

The New Madrid fault zone
Location
The New Madrid seismic zone lies within the central Mississippi Valley, is 150 miles long, and touches five states. Its northernmost point is in southern Illinois, and it extends southward into eastern Arkansas and west Tennessee.

History
From 1811 to 1812, the New Madrid Fault Zone saw some of the largest earthquakes in North America’s history. During a four-month period, five earthquakes with magnitude estimates of 8.0 or greater were recorded in the zone. These quakes were responsible for causing the Mississippi River to briefly flow backward.

Activity
The New Madrid Fault Zone boasts at least one earthquake a day, though most are too weak to feel. Scientists say the probability of a magnitude 6.0 or larger quake occurring on the New Madrid Fault in the next 50 years is between 25 percent and 40 percent.

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