When (Not If, When) Will the Big Earthquake Hit the Midwest?
by www.SixWise.com

When the next "big one" will hit is the million-dollar question among earthquake enthusiasts. But perhaps an even more appropriate question isn't when the next big one will hit, but where.

Though California is often regarded as the earthquake epicenter of the nation, there is another major fault line that most people are not aware of. It runs right through the heart of the "American breadbasket," and when it has its (next) big break, experts say the impact could be far worse than anything the West Coast has experienced in modern times.

The New Madrid Fault System spans a 120-mile stretch from Charleston, Missouri and Cairo, Illinois, down Interstate 55 to end up in Marked Tree, Arkansas. The massive zone crosses five state lines and cuts across the Mississippi River in three places and the Ohio River in two.

It's true that the greatest risk of earthquakes in the United States is definitely along the West Coast ... but, although the tremors may not be as frequent, when they do occur along the New Madrid Fault Line, the damage covers more than 20 times the area.

When Will the Next "Big One" Hit the Midwest?

We say the "next" big one because a major earthquake event did hit this region in the past. The Great New Madrid Earthquake of 1811-1812 describes a series of over 2,000 shocks that spanned a five-month period, destroying farmland and causing great destruction.

Although the Richter Magnitude Scale that we use to measure earthquakes today wasn't available at this time, it's estimated that five of these "shocks" measured 8.0 or higher, and it's said that 18 were strong enough to ring church bells all the way on the East Coast.

The New Madrid Fault Zone is currently active, and has more than 200 measured shocks (over 1.0 on the Richter scale) each year. The St. Charles County (Missouri) Division of Emergency Management (EMD) reports the following activity in the zone:

• Tremors large enough to be felt (2.5 - 3.0 on the Richter scale) are noted annually.

• Every 18 months, the fault releases a shock of 4.0 or more, capable of local minor damage.

• A shock of 4.3 occurred along the New Madrid Fault on Thanksgiving 1996, which was felt by people in the states of Missouri, Arkansas, Tennessee, Kentucky, Illinois and Mississippi.

• A magnitude of 5.0 or greater, occurring about once per decade, can do significant damage, and be felt in several states.

Further, a damaging earthquake (6.0 or greater) occurs about once every 80 years, the last one being in 1895. This, says the EMD, would cause serious damage to buildings from Memphis to St. Louis.

A major earthquake (7.5 or greater) happens once every 200-300 years, with the last one in 1812. According to EMD, there is a 25 percent chance of an earthquake of this magnitude occurring along the New Madrid Fault Line by 2040.

A quake this size, they say, " ... would be felt throughout half the United States and damage 20 states or more. Missouri alone could anticipate losses of at least $6 billion from such an event."

How about another event like the series of quakes felt in 1811-1812?

Researchers predict that these types of events occur only once every 500-600 years, which means they don't expect another for 100 years or more. However, experts including emergency planners, engineers and seismologists have given the event a 3 percent chance of occurring by the year 2040.

Can Earthquakes Really be Predicted?

While no one can predict an earthquake with utmost certainty, scientists do "forecast" future earthquakes using the best methods currently available.

According to the U.S. Geological Survey (USGS) and the Center for Earthquake Research and Information of the University of Memphis, it's estimated that in the next 50 years along the New Madrid Fault Zone:

• There's a 7 percent to 10 percent chance of a magnitude 7.5-8.0 earthquake occurring in this region.

• There's a 25 percent to 40 percent chance of a magnitude 6.0 or larger earthquake occurring.

The EMD has given it an even greater chance, saying there's a 90 percent chance that a 6.0 earthquake will be felt in this region by the year 2040. They say it's events of this size (6.0-7.6) that concern them the most, since they are the ones most likely to occur within the lifetimes of our children, and have the potential to cause great damage.

Joan Gomberg, of the U.S. Geological Survey earthquake hazard program in Memphis, agreed. "If a major earthquake were to hit southern Illinois, the damage could be great," she said. "If it's a six, it depends upon where it hits. If it hits next to an urban area, it could do a lot of damage. But if it occurs in the boondocks, it won't be nearly as damaging."

If an Earthquake Hits the Midwest ... Are They Prepared?

According to an investigation by the St. Louis Post-Dispatch, "Repeated recommendations from all levels of government in an eight-state region of the central United States have been largely ignored on how to best brace for an event that scientists expect will kill thousands and cause widespread chaos."

"We are entirely unprepared," said Amr Elnashai, who runs the Mid-America Earthquake Center at the University of Illinois. "It is really amazing -- really amazing. How can a country as rich and prosperous as the U.S. leave itself in peril this way?"

The Post-Dispatch investigation, in a review of studies and reports and interviews with more than 150 government officials, researchers and preparedness advocates, found:

• Many government agencies haven't estimated what kind of damage a major earthquake will cause to their emergency facilities, which could cripple response efforts.

• No plan is in place to renovate older schools to more up-to-date, stricter building codes or even to use low-cost fixes to strengthen them.

• Utilities are not required to report on hazardous material spills and other problems that could occur during an earthquake, nor their plans to remedy them.

• Key bridges are vulnerable to earthquake damage, and some states have no programs in place to fix them.

• Over 80 percent of counties across the region are late to file required plans on how they will prepare for earthquakes and other natural disasters.

• Some communities haven't held earthquake drills in more than a decade.

However, some progress is being made. Government research has identified key danger zones and risks of earthquakes, and, with all of the terrorism response training in recent years, earthquake response will also improve. Further, some areas have received grants to strengthen vulnerable facilities. 

Recommended Reading

Earthquakes: They're Happening in MOST U.S. States; When is the Next "Big One?"

The Six Most Feared but Least Likely Causes of Death

Sources

Daily Egyptian December 7, 2005

St. Louis Post-Dispatch: Our Region is Ill-Prepared for the Next 'Big One'

St. Charles County Division of Emergency Management

Richter Magnitude Scale