News / Science & Technology

Earthquake Science Still a Shaky Business

Accurate predictions still elude scientists

New Madrid Earthquakes 1811-12. One side of fault trench or "fissure" near banks of St. Francis River, Clay County, Arkansas. 1904.
New Madrid Earthquakes 1811-12. One side of fault trench or "fissure" near banks of St. Francis River, Clay County, Arkansas. 1904.

Multimedia

Audio
TEXT SIZE - +

The magnitude 5.8 earthquake that rattled the East Coast of the United States in August caught everyone - even geologists - by surprise. But even when there's reason to think an earthquake could be around the corner, scientists still can't make good predictions.

It’s been 200 years since big earthquakes rocked the New Madrid Seismic Zone, a fault system that runs down the central U.S. through parts of Illinois, Missouri, Kentucky, Arkansas and Tennessee. The region has had plenty of smaller quakes since then, but no one can really say when the next big one might be.

The New Madrid earthquakes of the winter of 1811 to 1812 have become the stuff of legend. They were so powerful, the story goes, they made the Mississippi River run backwards.

“It was what we call a thrust fault," says Susan Hough of the U.S. Geological Survey in Pasadena, California. "And it came up to the surface beneath the river and actually created a stair step in the river bottom, to where it set up waves that went coursing back upstream.”

According to Hough, much of what we know about those early quakes comes from first-hand accounts, like this one written by future United States president Zachary Taylor, who felt the shaking 370 kilometers away in Louisville, Kentucky.

The sight was truly awful: houses cracking; chimneys falling; men, women and children running in every direction - in their shirts - for safety and a friend of mine was so much alarmed as to jump (out) of a window and was very much hurt.

Hough’s calculations put the largest New Madrid earthquake at about 7.0, the same magnitude as the January 2010 earthquake in Haiti. The official USGS estimate is 7.7.

The problem is, scientists can’t predict when, where, or even if another earthquake will happen.

Northwestern University geophysicist Seth Stein doesn’t expect another big quake at New Madrid anytime soon. He and others have been using GPS technology to measure how the ground moves - or deforms - along active faults.

“Now, normally the way earthquakes work is that you store up energy, the ground deforms before a big earthquake - kind of like stretching a spring - and then it snaps, and you have an earthquake,” Stein says.

That warping of the ground has been measured in California, Alaska, Oregon, and Washington - along every U.S. fault where we think a big earthquake is on the way. So that’s what Stein and his colleagues expected to see when they started taking those same kinds of GPS measurements at New Madrid.

To their complete surprise, they saw absolutely no motion of the ground. Stein says part of the explanation could be that seismic zones in the middle of a continent seem to behave differently from those in places like California, where the huge plates that make up the earth’s surface thrust up against each other.

“Faults in the middle of the continents will be active for short periods of time geologically, maybe a few thousand years, and then they’ll turn off and be inactive for times, and then start up again," he says. "So it looks like we may be seeing the end of one of those cycles.”

But many other geologists don’t agree. Robert Williams of the USGS in Colorado says you can’t ignore the past. The earthquakes 200 years ago liquefied the soil underground, blasting jets of wet sand out onto the surface.

“There’s been some great science done, with geologists digging into these 1811, 1812 sand blows, and then, lo and behold, discovering evidence for older sand blows caused by earthquakes of about the same magnitude as the 1811, 1812 sequence,” Williams says.

They realized that before 1811, there had been quakes in about 1450, and again before that, in 900. Williams says that pattern of very large earthquakes means another big one could be on the way.

“We can’t predict earthquakes. So the geologic record is really the strongest piece of evidence we have to remain concerned about earthquakes there in the New Madrid region.”

Experts hope by the time the next big quake does hit the region, we’ll be ready for it.

You May Like

Analysts Warn of Regional Proxy Conflict in Afghanistan

Analysts warn if Kabul’s neighbors do not start to cooperate, competing desires for influence could deteriorate into a bloody proxy war in the country More

Saudi Intelligence Chief Replaced

Bandar bin Sultan came under criticism for supporting al Qaida, prompting King Abdallah to wrest Syria operations away from him in February, handing them to Interior Minister Prince Mohammed bin Nayef More

Poetry Magazine editor Don Share talks what makes a good poem with VOA's David Byrd

What makes a good poem? And is poetry as viable an art form as it once was? To find out, VOA's David Byrd spoke to Don Share, the editor of Poetry Magazine. More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Google Buys Drone Companyi
|| 0:00:00
...
 
🔇
X
George Putic
April 15, 2014
In its latest purchase of high-tech companies, Google has acquired a manufacturer of solar-powered drones that can stay in the air almost indefinitely, relaying broadband Internet connection to remote areas. It is seen as yet another step in the U.S. based Web giant’s bid to bring Internet to the whole world. VOA’s George Putic reports.
Video

Video Google Buys Drone Company

In its latest purchase of high-tech companies, Google has acquired a manufacturer of solar-powered drones that can stay in the air almost indefinitely, relaying broadband Internet connection to remote areas. It is seen as yet another step in the U.S. based Web giant’s bid to bring Internet to the whole world. VOA’s George Putic reports.
Video

Video Ray Bonneville Sings the Blues and More on New CD

Singer/songwriter Ray Bonneville has released a new CD called “Easy Gone” with music that reflects his musical and personal journey from French-speaking Canada to his current home in Austin,Texas. The eclectic artist’s fan base extends from Texas to various parts of North America and Europe. VOA’s Greg Flakus reports from Austin.
Video

Video Millions Labor in Pakistan's Informal Economy

The World Bank says that in Pakistan, roughly 70 percent work in the so-called informal sector, a part of the economy that is unregulated and untaxed. VOA's Sharon Behn reports from Islamabad on how the informal sector impact's the Pakistani economy.
Video

Video Passover Celebrates Liberation from Bondage

Jewish people around the world are celebrating Passover, a commemoration of their liberation from slavery in Egypt more than 3,300 years ago. According to scripture, God helped the Jews, led by Moses, escape bondage in Egypt and cross the Red Sea into the desert. Zlatica Hoke reports that the story of the Jewish Exodus resonates with other people trying to escape slave-like conditions.
Video

Video Police Pursue Hate Crime Charges Against Kansas Shooting Suspect

Prosecutors are sifting through the evidence in the wake of Sunday’s shootings in a suburb of Kansas City, Missouri that left three people dead. A suspect in the shootings taken into custody is a white supremacist. As VOA’s Kane Farabaugh reports, he was well-known to law enforcement agencies and human rights groups alike.
Video

Video In Eastern Ukraine, Pro-unity Activists Emerge from Shadows

Amid the pro-Russian uprisings in eastern Ukraine, there is a large body of activists who support Ukrainian unity and reject Russian intervention. Their activities have remained largely underground, but they are preparing to take on their pro-Moscow opponents, as Henry Ridgwell reports from the eastern city of Donetsk.
Video

Video Basket Maker’s Skills Have World Reach

A prestigious craft show in the U.S. capital offers one-of-a-kind creations by more than 120 artists working in a variety of media. As VOA’s Julie Taboh reports from Washington, one artist lucky enough to be selected says sharing her skills with women overseas is just as significant.
Video

Video UN Report Urges Speedier Action to Avoid Climate Disaster

A new United Nations report says the world must switch from fossil fuels to cleaner energy sources to control the effects of climate change. The Intergovernmental Panel on Climate Change released the report (Sunday) following a meeting of scientists and government representatives in Berlin. The comprehensive review follows two recent IPCC reports that detail the certainty of climate change, its impacts and in this most recent report what to do about it. VOA’s Rosanne Skirble has the details.
AppleAndroid