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

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

WHO: Anti-Ebola Efforts Should Focus on West Africa

Official says WHO is 'reasonably confident' countries bordering those hardest hit by the Ebola outbreak are not seeing the virus crossing their borders More

South Sudan Crisis Threatens Development

Economic costs and lost development opportunities in South Sudan have erased what little progress the country has made since independence in 2011 More

Ukrainian PM Warns: Russia May Try to Disrupt Sunday Poll

Arseniy Yatsenyuk orders full security mobilization for parliamentary election to prevent ‘terrorist acts’ from being carried out 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.
After Decades of Pressure, Luxembourg Drops Bank Secrecy Rulesi
X
October 21, 2014 12:20 AM
European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video After Decades of Pressure, Luxembourg Drops Bank Secrecy Rules

European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video Kobani Refugees Welcome, Turkey Criticizes, US Airdrop

Residents of Kobani in northern Syria have welcomed the airdrop of weapons, ammunition and medicine to Kurdish militia who are resisting the seizure of their city by Islamic State militants. The Turkish government, however, has criticized the operation. VOA’s Scott Bobb reports from southeastern Turkey, across the border from Kobani.
Video

Video China Political Meeting Seeks to Improve Rule of Law

China’s communist leaders will host a top level political meeting this week, called the Fourth Plenum, and for the first time in the party’s history, rule of law will be a key item on the agenda. Analysts and Chinese media reports say the meetings could see the approval of long-awaited measures aimed at giving courts more independence and include steps to enhance an already aggressive and high-reaching anti-corruption drive. VOA’s Bill Ide has more from Beijing.
Video

Video US ‘Death Cafes’ Put Focus on the Finale

In contemporary America, death usually is a topic to be avoided. But the growing “death café” movement encourages people to discuss their fears and desires about their final moments. VOA’s Jerome Socolovsky reports.
Video

Video Ebola Orphanage Opens in Sierra Leone

Sierra Leone's first Ebola orphanage has opened in the Kailahun district. Hundreds of children orphaned since the beginning of the Ebola outbreak face stigma and rejection with nobody to care for them. Adam Bailes reports for VOA about a new interim care center that's aimed at helping the growing number of children affected by Ebola.
Video

Video Young Nairobi Tech Innovator on 'Track' in Security Business

A 24-year-old technology innovator in Nairobi has invented a tracking device that monitors and secures cars. He has also come up with what he claims is the most robust audio-visual surveillance system yet. As Lenny Ruvaga reports from the Kenyan capital, his innovations are offering alternative security solutions.
Video

Video Latinas Converting to Islam for Identity, Structure

Latinos are one of the fastest growing groups in the Muslim religion. According to the Pew Research Center, about 6 percent of American Muslims are Latino. And a little more than half of new converts are female. VOA’s Carolyn Presutti travelled to Miami, Florida -- where two out of every three residents is Hispanic -- to learn more.
Video

Video Exclusive: American Joins Kurds' Anti-IS Fight

The United States and other Western nations have expressed alarm about their citizens joining Islamic State forces in Syria and Iraq. In a rare counterpoint to the phenomenon, an American has taken up arms with the militants' Syrian Kurdish opponents. Elizabeth Arrott has more in this exclusive profile by VOA Kurdish reporter Zana Omer in Ras al Ayn, Syria.
Video

Video South Korea Confronts Violence Within Military Ranks

Every able-bodied South Korean male between 18 and 35 must serve for 21 to 36 months in the country’s armed forces, depending upon the specific branch. For many, service is a rite of passage to manhood. But there are growing concerns that bullying and violence come along with the tradition. Reporter Jason Strother has more from Seoul.
Video

Video North Carolina Emerges as Key Election Battleground

U.S. congressional midterm elections will be held on November 4th and most political analysts give Republicans an excellent chance to win a majority in the U.S. Senate, which Democrats now control. So what are the issues driving voters in this congressional election year? VOA National Correspondent Jim Malone traveled to North Carolina, one of the most politically competitive states in the country, to find out.
Video

Video Comanche People Maintain Pride in Their Heritage

The Comanche (Indian nation) once were called the “Lords of the Plains,” with an empire that included half the land area of current day Texas, large parts of Oklahoma, New Mexico, Kansas and Colorado.The fierceness and battle prowess of these warriors on horseback delayed the settlement of most of West Texas for four decades. VOA’s Greg Flakus reports from Lawton, Oklahoma, that while their warrior days are over, the 15,000 members of the Comanche Nation remain a proud people.
Video

Video Turkey Campus Attacks Raise Islamic Radicalization Fears

Concerns are growing in Turkey of Islamic radicalization at some universities, after clashes between supporters of the jihadist group Islamic State (IS) or ISIS, and those opposed to the extremists. Pro-jihadist literature is on sale openly on the streets of Istanbul. Critics accuse the government of turning a blind eye to radicalism at home, while Kurds accuse the president of supporting IS - a charge strongly denied. Henry Ridgwell reports from London.

All About America

AppleAndroid