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Scientists Fear Bigger Quake in Midwest

By Robin Lloyd,
Posted: 2008-04-21 06:54:32
Filed Under: Nation News, Science News
LiveScience.com


(April 20) - The magnitude 5.2 earthquake that rocked the Midwest on Friday was felt from Kansas to Georgia, and aftershocks could continue for months at this strange seismic zone at the nation's center and even trigger another big quake, a geophysicist said.

Photo Gallery

David Falconer, AP

Top 10 States
For Earthquakes

1 of 10    

Oregon
Ranking: 10
Earthquakes Between 1974-2003: 73
Percent of total in the U.S.: 0.3

The quake occurred on a northern extension of the New Madrid fault, about 6 miles north of Mt. Carmel, Ill. The New Madrid fault was responsible for devastating quakes in the Mississippi Valley in 1811 and 1812. So the Friday quake and its aftershocks likely are raising the blood pressure of some residents and scientists.

For decades, scientists have debated whether and when the underlying fault could generate another temblor of similar and deadly strength.

"I think we saw a window to this possibility today in the Wabash Valley," said geophysicist Allessandro Forte of the Université du Québec à Montréal, who has studied the region's seismicity. "It's to the north of the New Madrid seismic zone, but given the strength of crust, the stress can be distributed great distances. It's not clear if we could see something in the next few years or even next few months, I would say."

The last earthquake in the region to approach the severity of Friday's temblor was a 5.0 magnitude quake that shook a nearby area in 2002, according to the U.S. Geological Survey.

Photo Gallery

Damian Dovarganes, AP

Earthquake Outlook
For California

1 of 7    

There is a 99.7 percent chance that a strong earthquake will strike California in the next 30 years, according to the first forecast to look at earthquake probabilities for the entire state. Southern California faces a 97 percent chance of such a tremor, the forecast said.

An event actually surpassing today's magnitude last occurred in 1968, a magnitude 5.3 quake that was felt in 23 states, said Forte. The magnitude scale is logarithmic so a change of 0.1 or 0.2 makes a big difference in terms of energy output. The 1968 event was felt in Ontario and Boston.

"The $64,000 question is what this earthquake portends for the future," Forte said. "The answer is I'm afraid it can go either way."

Stress relief or hair trigger?

One scenario predicts that some stress is relieved on the local faults where this earthquake occurred and will cool things down for a few decades. The other scenario is not so happy.

"There is the possibility, and we can only see over next few months what will happen, that the redistribution of stress on neighboring faults might trigger further earthquakes, and we can only guess as to whether they'll be equally large as (Friday's) earthquake," Forte said.

Aftershocks from the Friday quake will continue for several weeks, maybe months, he said. Already, there have been many, of magnitudes in the range of 2 and 3, radiating outward from the epicenter.

"If we are seeing a propagation outward of stress changes after today's 5.2, which was a big one, and those stress changes finally come up on a fault which is on a hair trigger and ready to go, those small changes are sufficient to generate another big one on a fault which is locked and ready to go," Forte said.

How much risk?

Recent estimates have downgraded the risk of a large earthquake on the New Madrid fault.

In the 1980s, scientists said there was a 90 percent chance of a magnitude 6 or 7 temblor occurring in this area within the next 50 years.

Natural Disasters

When a 6.9-magnitude earthquake hit San Francisco on Oct. 17, 1989, which major sporting event was underway at the same time?

  • NBA finals
  • World Series
  • World Cup

Under what body of water was the epicenter of the earthquake that spawned the Asian tsunami in 2004?

  • Red Sea
  • Indian Ocean
  • Pacific Ocean

Eighty-one people were reported to have been killed by tornadoes in the U.S. in 2007. How do most tornado deaths happen?

  • Lightning spawned by the tornado
  • Being swept up in the tornado
  • Flying or falling debris

Hurricane Katrina, the Category 5 storm that ravaged New Orleans, first made landfall in which state?

  • Louisiana
  • Texas
  • Florida

In 1996, a blizzard crippled cities across the Northeast U.S. for days. What's the minimum wind speed required for a snowstorm to be classified as a blizzard?

  • 15
  • 25
  • 35

According to the U.S. Geological Survey, a 1964 earthquake in the U.S. was the largest ever recorded in the nation. Where did it happen?

  • San Francisco
  • Prince William Sound, Alaska
  • Portland, Ore.

How many Houston-area residents fled Hurricane Rita, a Category 5 storm, as it approached the city in September 2005?

  • 100,000
  • 500,000
  • More than 1 million

The "Great Flood of 1993" inundated dozens of towns across nine states in the Midwest. How many acres of land were left underwater?

  • About 10 million
  • About 20 million
  • About 50 million
A 2007 USGS fact sheet, however, said there is only a 25 percent to 40 percent chance of a magnitude 6 or larger there in the next 50 years.

However, a team that includes Michael Ellis of the University of Memphis estimated in 2005 that the odds of another 8.0 event in the region within 50 years are between 7 and 10 percent.

These debates about the New Madrid fault are far from resolved, Forte said, with some saying the accumulated stress in area faults is weakening while others say it is not going to dissipate any time soon. "This is not exactly a well-defined science as yet," he said.

Forte is part of the latter camp, based on his research on an ancient, giant slab of Earth called the Farallon slab that started its descent under the West Coast 70 million years ago and now is causing mayhem and deep mantle flow 360 miles beneath the Mississippi Valley, where it effectively pulls the crust down an entire kilometer (.62 miles).

"The stresses from the sinking Farallon slab are not going to disappear any time soon," he said.

So, apparently, is J. David Rogers in the latter camp. The geological engineer at Missouri University of Science and Technology says Midwestern earthquakes are potentially more powerful than California quakes.

Shakier situation

More News From LiveScience.com

Unique geology in the Midwest increases the shaking intensity of earthquakes because seismic energy moves through the dense bedrock at very high speeds, then becomes trapped in soft sediments filling river channels and valleys, Rogers said.

Rogers and some of his graduate students have been modeling synthetic seismic events in the New Madrid region. Most of their scenarios are modeled after an 1895 earthquake with a magnitude of 6.4 that was centered in Charleston, Mo.

The preliminary results are sobering, said Rogers. Data indicates ground shaking would be magnified about 600 percent within the flood plain of the Missouri River, a development that would cause most of Missouri’s existing long-span bridges to collapse.

"You don't even need a really big earthquake to do significant damage in Missouri," Rogers says. "It could happen tomorrow."

The relative quake risk of the New Madrid seismic zone is a great debate that might be driven in part by competition for grant money, Forte said. Those scientists who work on West Coast quakes have an incentive to claim that the research money should be spent on that region, while the central continent-focused researchers obviously are more invested in funds coming their way.

Overall, there are many more earthquakes out West. Of all earthquakes with a magnitude of 3.5 or greater from 1974-2003, Alaska had more than 57 percent, according to the U.S. Geological Survey. That was followed by California at 23 percent and Hawaii at 7 percent. These other states ranked four through ten: Nevada, Washington, Idaho, Wyoming, Montana, Utah and Oregon.

2008-04-20 17:11:07
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917 comments

delmer6523 02:54:51 PM May 04 2008

Report This!

1983 buffalo ny had a Earthquake i told my mom and she did not beleve me until she heard it on the news so we can to get them

black2deep 02:51:09 AM Apr 23 2008

Report This!

mixgrl1986 12:59:32 AM Apr 22 2008

Report This! hey, you got money to buy $100 dollar sneakers for your spoiled kids, you can pay $10 a gallon for gas..........or ride a bicycle.
---------------------------------------------------------------------------
What world do you live in? I have a hard time just buying a $10 dollar pair of shoes, much less waste it on a $100 dollar pair of shoes. I suppose if you live in the 90210 distric you can, but they are the exception to the American economy not the rule.

theoracle7 07:33:19 PM Apr 22 2008

Report This!

Earthquake to level the New Madrid area and send towns like Poplar Bluff under water? Hmmmm.....
Wonder if Al Quida will get it started with a stolen Pakistani nuke - they will sooner or later.....somewhere.

cjayabee 01:17:22 PM Apr 22 2008

Report This!

cjayabee writes: Since creationism and intelligent design are touted as being one and the same, then you are wrong, there is no scientific evidence whatsoever of any intelligent design. Bones that break, organs that become cancerous, eyes that go blind, stillborn births, birth defects, aids, etc., etc. No intelligent design there. How did we get here? No one knows. Some thing, some energy force could have created us. That's more believable than the creation/god myth which doesn't even remotely make any sense. Some people need to believe, some people don't. I just enjoy my very real life on this earth and try to be kind and compassionate to my fellow humans. That's all that matters.
>>>>>>>

cjayabee to patriotpix - You merely choose to believe in some god.
------------------------------------------------------------------------
black2deep writes: Actually, there is quite a large amount of scientific evidence that there is some kind of intellagent design behin

beckycoke 02:22:19 AM Apr 22 2008

Report This!

I'm not that far from the New Madrid fault line. I hope it doesn't do what they think it will. 100 miles isn't that far when all hell is breaking loose.

mixgrl1986 12:59:32 AM Apr 22 2008

Report This!

hey, you got money to buy $100 dollar sneakers for your spoiled kids, you can pay $10 a gallon for gas..........or ride a bicycle.

rowanntn 12:23:24 AM Apr 22 2008

Report This!

consdiering where and how severe it was id say we can look for more.

healnghanz 11:43:13 PM Apr 21 2008

Report This!

i am not afraid of an earthquake in the mid west. i hope the whole midwest sinks into the ogallalla aquifer, and takes all the christian fundamentalists whith it.

qwertyjim 11:12:10 PM Apr 21 2008

Report This!

When H is elected in November he will put an end to earthquakes. I mean W probably plotted with his rich oil buddies to make this earthquake so they would get rich. H will put an end to corruption like this he is for Hope and change. Vote for H in 08'. Vote for H in 08'

black2deep 07:26:07 PM Apr 21 2008

Report This!

cjayabee 01:38:25 PM Apr 21 2008

Report This! to patriotpix - You merely choose to believe in some god.
------------------------------------------------------------------------
Actually, there is quite a large amount of scientific evidence that there is some kind of intellagent design behind the universe. Even Stephen Hawkins has stated that at the very basic core of everything is pure thought. There is a difference between an intellagent creator and religious prattle. The religious community is even more worride that God will be proven to exist than even the athiest are. It means that they have to really review what it is they are preaching. It is one thing to believe in a God and a totally different matter to know that there is one.

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