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

Turkey: No Ransom Paid for Release of Hostages Held by IS Militants

President Erdogan hails release of hostages as diplomatic success but declines to be drawn on whether their release freed Ankara's hand to take more active stance against insurgents More

Audio Sierra Leone Ends Ebola Lockdown

Health ministry says it has reached 75 percent of its target of visiting 1.5 million homes to locate infected, educate population about virus More

US Pivot to Asia Demands Delicate Balancing Act

As tumult in Middle East distracts Obama administration, efforts to shift American focus eastward appear threatened 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.
NASA’s MAVEN Probe Enters Mars Orbiti
X
September 22, 2014 9:20 PM
NASA’s newest Mars probe, called MAVEN, has successfully entered its designated orbit around the Red Planet. Scientists will use its sophisticated instruments to try to learn what happened to the atmosphere Mars had a few billion years ago. VOA’s George Putic has more.
Video

Video NASA’s MAVEN Probe Enters Mars Orbit

NASA’s newest Mars probe, called MAVEN, has successfully entered its designated orbit around the Red Planet. Scientists will use its sophisticated instruments to try to learn what happened to the atmosphere Mars had a few billion years ago. VOA’s George Putic has more.
Video

Video For West Ukraine City, Conflict Far Away Yet Near

The western Ukrainian city of Lviv prides itself on being both physically and culturally close to Western Europe. The Russian-backed separatists in the eastern part of the country are 1,200 kilometers away, and seemingly even farther away in their world view. Still, as VOA’s Al Pessin reports, the war is having an impact in Lviv.
Video

Video Saving Global Fish Stocks Starts in the Kitchen

With an estimated 90 percent of the world’s larger fish populations having already vanished, a growing number of people in the seafood industry are embracing the concept of sustainable fishing and farming practices. One American marine biologist turned restaurateur in Thailand is spreading the word among fellow chefs and customers. VOA Correspondent Steve Herman reports from Bangkok.
Video

Video Chinese Admiral Key in China’s Promotion of Sea Links

China’s President last week wrapped up landmark visits to India, Sri Lanka and Maldives, part of a broader campaign to promote a new “Maritime Silk Road” in Asia. The Chinese government’s promotion efforts rely heavily on the country’s best-known sailor, a 15th century eunuch named Zheng He. VOA's Bill Ide reports from the sailor’s hometown in Yunnan on the effort to promote China’s future by recalling its past.
Video

Video Experts Fear Ebola Outbreak ‘Beyond Our Capability to Contain’

Each day brings with it new warnings about the deadly Ebola outbreak already blamed for killing more than 2,600 people across West Africa. And while countries and international organizations like the United Nations are starting to come through on promises of help for those most affected, the unprecedented speed with which the virus has spread is raising questions about the international response. VOA's Jeff Seldin has more from Washington.
Video

Video Natural Gas Export Plan Divides Maryland Town

A U.S. power company that has been importing natural gas now wants to export it. If approved, its plant in Lusby, Maryland, would likely be the first terminal on the United States East Coast to export liquefied natural gas from American pipelines. While some residents welcome the move because it will create jobs, others oppose it, saying the expansion could be a safety and environmental hazard. VOA’s Deborah Block examines the controversy.
Video

Video Difficult Tactical Battle Ahead Against IS Militants in Syria

The U.S. president has ordered the military to intensify its fight against the Islamic State, including in Syria. But how does the military conduct air strikes in a country that is not a U.S. ally? VOA correspondent Carla Babb reports from the Pentagon.
Video

Video Iran, World Powers Seek Progress in Nuclear Talks

Iran and the five permanent members of the U.N. Security Council plus Germany, known as the P5 + 1, have started a new round of talks on Iran's nuclear program. VOA State Department correspondent Pam Dockins reports that as the negotiations take place in New York, a U.S. envoy is questioning Iran's commitment to peaceful nuclear activity.
Video

Video Migrants Caught in No-Man's Land Called Calais

The deaths of hundreds of migrants in the Mediterranean this week has only recast the spotlight on the perils of reaching Europe. And for those forunate enough to reach a place like Calais, France, only find that their problems aren't over. Lisa Bryant has the story.
Video

Video Westgate Siege Anniversary Brings Back Painful Memories

One year after it happened, the survivors of the terror attack on Nairobi's Westgate Shopping Mall still cannot shake the images of that tragic incident. For VOA, Mohammed Yusuf tells the story of victims still waiting for the answer to the question 'how could this happen?'
Video

Video Whaling Summit Votes to Uphold Ban on Japan Whale Hunt

The International Whaling Commission, meeting in Slovenia, has voted to uphold a court ruling banning Japan from hunting whales in the Antarctic Ocean. Conservationists hailed the ruling as a victory, but Tokyo says it will submit revised plans for a whale hunt in 2015. Henry Ridgwell reports from London.
Video

Video A Dinosaur Fit for Land and Water

Residents and tourists in Washington D.C. can now examine a life-size replica of an unusual dinosaur that lived almost a hundred million years ago in northern Africa. Scientists say studying the behemoth named Spinosaurus helps them better understand how some prehistoric animals adapted to life on land and in water. The Spinosaurus replica is on display at the National Geographic museum. VOA’s George Putic has more.
Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.

AppleAndroid