Bracing for the Big One

By Eric Hand
Of the St. Louis Post-Dispatch

Photo: Highway 40 (Interstate 64) next to the new Busch Stadium is being retrofitted to better withstand earthquake damage.

Two-thirds of the way between St. Louis and Memphis, between the towns of Tiptonville, Tenn., and New Madrid, Mo., the Mississippi River makes an outrageous loop northward, like it's avoiding something.

The river's levees dead-end at a bulge in the landscape. For decades, geologists have studied this gentle swell in the cornfields.

They have a name for it: the Reelfoot fault.

In the winter of 1811-12, this is where two blocks in the earth wrenched apart so savagely - the western block up, the eastern block down - that the Mississippi River pooled backward into the sunken block. The river, cutting and silting away, has done its best to hide the scar.

"The fact that it's there at all means it has been deforming and growing faster than the Mississippi River has been eroding it," said Arch Johnston, director of the Center for Earthquake Research and Information at the University of Memphis.

Research published June 23 in the journal Nature shows that the fault is coiling up like a spring again - at a rate comparable to the San Andreas fault in California. Geologists know that huge New Madrid earthquakes happened in the past. Now, for the first time, they can say the Reelfoot fault is building up a pressure that could make it buckle again.

There are engineers who say St. Louis should prepare by adopting strict building codes and pursuing expensive retrofits. And there are those who'd rather take their chances. They say money is wasted on such an unlikely hazard.

The debate offers two approaches to risk: one precautionary, the other coolly utilitarian.

In the dusty shadows under Highway 40 (Interstate 64) downtown, workmen cinch steel cables around concrete columns that will grow by a foot in a diameter.

The Missouri Department of Transportation has spent $90 million stuffing steel and concrete into the section of highway from 14th Street to the Mississippi River. Illinois is doing a similar retrofit on the first half-mile of Interstate 64 in East St. Louis.

The stacked highways will be 10 times stronger than before and able to resist the shaking of a 1-in-500 year quake.

But newer building codes require engineers to design for a much larger quake, one that happens every 2,500 years. Should MoDOT and IDOT retrofit the retrofits?

Highway 40 rubs shoulders with the smooth brick of the $400 million new Busch Stadium. The stadium was designed to a 1999 building code - current in St. Louis, but one that may be replaced this fall by the 2003 International Building Code.

The 1999 code is based on an outdated U.S. Geological Survey hazard map from 1976. Since then, the Geological Survey has doubled its estimates for ground-shaking from a New Madrid quake. The stadium, like the highway, is designed for the 1-in-500 year earthquake, not the 1-in-2,500 year quake specified by the 2003 International Building Code.

"Coming out of the ground, (new Busch stadium) is obsolete," said Mike Griffin, a scrupulous structural engineer with ABS Consulting in St. Louis.

Griffin is appalled by construction quality in St. Louis.

"Did you see that building?" he asks a colleague in passing. "Those spindly columns were pathetic!"

The century-old, unreinforced brick and masonry buildings of St. Louis would be deathtraps during a major earthquake, he says. He says the sheen of downtown rehabs is superficial. A building's structure is grandfathered during conversions. No retrofits are required.

"Developers are fighting it tooth and nail," he said. "The almighty dollar is driving everything."

St. Louis County adopted the 2003 International Building Code in May. It estimated moving to the code increased construction costs by 1 percent.

But in Memphis, 50 miles closer to New Madrid, the cost of adopting the code is 10 percent to 15 percent more - enough to drive away business, says Joseph Tomasello, an engineer there with the Reaves Firm. Other engineers disagree and say the 2003 code will drive costs up by at most a few percent.

Thanks in part to lobbying by Tomasello, Memphis in August is likely to approve the new code - minus the strict earthquake requirements.

Tomasello and Griffin stand at opposite ends of the risk-tolerance spectrum. Griffin wants action now. Tomasello prefers a wait-and-see approach.

Tomasello cites a strange paradox: With the 2003 code, Memphis engineers would be designing for California-level shaking. Yet no building in Memphis has ever fallen down because of an earthquake.

"Should we drop everything we're doing and spend all the money we have to protect ourselves from a meteorite?" asks Tomasello.

There's a 7 percent to 10 percent chance of a big New Madrid quake striking in the next 50 years, according to current U.S. Geological Survey estimates. Slim, but a lot more likely than a meteorite. Those probabilities, however, have changed over the years.

Especially when geologists go poking in the ground.

U.S. Geological Survey geologist David Russ came to the Reelfoot fault in 1977, armed with trowels, thick-bristled paintbrushes and the new science of paleoseismology.

Big earthquakes turn sandy soils to jelly. Under pressure, the liquefied sand punches through muds and silts and erupts at the surface as a sand blow. Russ looks for the signs of sand shooting upward in stream banks and trench walls.

A sharecropper let him dig a 12-foot trench in his field across the fault. Russ had three hot weeks to do his work - the time between the sharecropper's wheat harvest and his summer soybean planting.

From sunup to sundown, Russ scraped the trench walls. He found younger sand blows cutting up through older sand blows - a sure sign that big New Madrid quakes rocked the region before 1811.

U.S. Geological Survey geologist Buddy Schweig and consulting geologist Tish Tuttle have continued to catalog sand blows, some on the Meramec River and Cahokia Creek. They eventually found enough material with carbon to date the big earthquakes: one in 1450 A.D., another in 900 A.D., a third in 300 A.D. and possibly a fourth around 2350 B.C.

For most of the 20th century, scientists thought the 1811 quakes were a freak occurrence, a one-time deal. Schweig recalled the slow, dawning realization that their work showed big New Madrid quakes exploding again and again, about every 500 years. Earthquake hazard - and the cost of construction and insurance - would increase.

"It scared us. We didn't want to do it," he said. "I realized that millions of dollars - billions and billions -were at stake."

The lower Mississippi Valley has changed since 1811, when log cabins were the main casualty. A major quake now could cripple transportation routes, snap pipelines and snarl supply chains for the entire country.

Three-fourths of the nation's $7 billion exported soybean crop goes down the Mississippi River.

Memphis International Airport, the shipping hub for FedEx, has been the world's largest cargo airport for 11 years running.

The most northeastern county in Arkansas is one of the largest steel-producing counties in the country, with two Nucor mills.

One can imagine the ripple effects of a New Madrid quake across the nation. When four hurricanes hit Florida last year, for instance, the price of tomatoes tripled.

At least Anheuser-Busch is protecting the beer supply. The company learned its lesson in 1994, when it finished a retrofit at its Los Angeles brewery just before the Northridge earthquake hit. Assembly lines rolled three days after the quake. A-B says it averted $300 million in losses. Shortly thereafter, A-B began a retrofit at its St. Louis brewery.

Missouri homeowners don't seem to be following A-B's lead. Fewer have earthquake insurance now than five years ago - perhaps because it's getting so expensive.

There were 5 percent fewer earthquake policies in 2004 than in 1999. In that time, premiums rose 71 percent, from $605 million to more than $1 billion, according to an analysis of Missouri Department of Insurance data. Illinois does not collect earthquake insurance data.

Almost half of Missouri homeowners have earthquake insurance. Most of them are in the St. Louis area and the Bootheel. Rates of those with earthquake policies range as high as 88 percent in Cape Girardeau and 84 percent in Chesterfield to one north St. Louis ZIP code where only a third of homeowners have it.

A New Madrid quake could stretch much farther than St. Louis. The 1811 quakes were felt over an area at least seven times as wide as the great 1906 San Francisco earthquake. That's because seismic waves travel farther and do more damage in the hard rock of the eastern United States than in the busted up rocks of the West.

The three successive shocks - on Dec. 16, 1811; Jan. 23, 1812; and Feb. 7, 1812 - are thought to be around magnitude 7.7. Church bells rang as far away as Boston.

There hasn't been an earthquake greater than magnitude 6.5 since. Today, several times a week, tremors quiver miles down in the earth, detectable only by instruments. On a map, these make a zigzag pattern. The center of the zigzag is the Reelfoot fault.

In California, plate tectonics are the engine for frequent, big earthquakes. The Pacific Ocean plate, a thick slab of the earth's crust, moves almost two inches a year past the North American plate. That motion builds up along the San Andreas - until it's unleashed all at once in an earthquake.

In New Madrid, there are no plates. Scientists don't know what's causing the earthquakes, but University of Memphis geologist Michael Ellis says the Reelfoot fault could be moving toward one.

Five years ago, a truck pulled into a Tennessee state prison north of Tiptonville, less than a mile from the fault. Ellis needed a safe place for an expensive global positioning system. Prison courtyards work well.

The truck pushed a steel beam more than 60 feet into the soft Mississippi muds. Some bridges don't use piles so deep. Yet this pile held up only a GPS station.

Ellis, one of the Nature paper authors, put a second GPS station on the other side of the fault. In four years, they moved closer together by almost a half-inch - a huge amount in geological terms. If the motion continues, stresses will build that will reach the snapping point someday.

But Northwestern University geophysicist Seth Stein has found nothing but muddiness in the muds. His GPS stations have indicated no motion. And without motion, big earthquakes can't happen. Publishing in the journal Science in 1999, Stein said U.S. Geological Survey maps exaggerated the hazard in the New Madrid region.

Ellis says Stein was "irresponsible" to call for reduced seismic hazard, because he relied on shallow, temporary GPS stations that had bigger uncertainties.

There are critics of the current work, too. Earth scientists at Purdue University, the University of Wisconsin and the University of Arkansas have looked at Ellis' data. Like Stein, they can't find any significant motion.

Stein says the debate over the tiny motions is beside the point. Why should a building with a 50- or even 100-year lifetime stand up to a quake that comes along every 2,500 years? That money is better off elsewhere, he says.

"There's no such thing as a free lunch. The money that you spend strengthening the school isn't available to hire teachers. The money you spend strengthening hospitals isn't available to treat patients. And money that strengthens bridges isn't available to hire cops," he said.

Stein cites a 1999 Federal Emergency Management Agency study that shows how St. Louis and Memphis have substantially lower earthquake risk than California.

FEMA estimated the building damage that earthquakes cause in major cities over the long run. FEMA divided the losses by the value of the city's building stock. The ratio is a better way to compare cities, since a billion dollars of earthquake damage affects St. Louis more than a big city like New York.

St. Louis ranks behind 33 other cities in the FEMA list. Las Vegas ranks 29th, with more than twice the risk. Salt Lake City is 25th, with more than three times the risk. San Francisco is number one, with more than 10 times St. Louis' risk.

So St. Louis' risk is a tenth of California's. It also might seem that the hazard (what the engineer has to design for) should be lower. Since 1800, there have been only 13 New Madrid quakes greater than magnitude 5.5; there were 228 California quakes that size in that time.

The problem is, forcing an engineer to consider a colossal 1811-sized earthquake at all makes the medium ones irrelevant. Going to the 1-in-2,500 year design quake of the 2003 International Building Code brings the Big One fully into play.

"It definitely hurt us more than it did the West Coast," said Mark Caldwell, an engineer with Apex Engineering in western Kentucky.

Kentucky has adopted the International Building Code, but only after remapping the state for the 1-in-1,000 year earthquake hazard. That dropped the five westernmost counties into a lower seismic category.

In Illinois and Missouri, where there are no state building codes, the question of which code to adopt is playing out city by city and county by county.

The U.S. Geological Survey recently sponsored a field trip for non-scientists called "Earthquake Insight." FEMA preaches "earthquake awareness."

It seems like earthquake exaggeration to Tomasello.

He sees no coincidence in money flowing from FEMA, which mitigates risks, to the Geological Survey, which sets them.

However, it seems to take an actual earthquake, not just a hyped one, to get a geologist money.

U.S. Geological Survey funding for earthquakes spiked after the 1989 Loma Prieta earthquake, the 1994 Northridge earthquake and the December tsunami in Indonesia. Funding otherwise has stagnated even as inflation and salary increases cut into it.

That leaves less money for things like GPS stations, which the University of Memphis researchers say could end the debate over the Reelfoot fault motions.

Schweig, a practitioner of this dirty, uncertain science, says he's damned if he plays up risks and damned if he plays them down. He's been accused of glossing over uncertainty. He's also been accused of emphasizing uncertainty to nail down more funding.

But he firmly believes that there is a real earthquake threat in New Madrid, and that the USGS "can still get a lot of bang for the buck" by reducing uncertainties. Each new fault or sand blow helps pin down where and how often future New Madrid quakes can occur.

The threat doesn't seem apparent on an overcast June day to a few catfishermen on Reelfoot Lake who lazily let lines drift into the cypress trees. The swampy lake was created by the 1811 quakes, when a creek found itself dammed by the Reelfoot fault.

Six hours earlier, 15 miles south of the lake, a small, magnitude 3.9 earthquake shuddered nine miles down in the earth. Quakes this size tend to be 1-in-1 year sort of events. It is barely felt, but it grabs the attention of news media.

A tall, blond TV reporter meets Schweig at Reelfoot Lake and puts a microphone in his face.

"Does it mean the Big One's coming?" she asks.

Schweig smiles and hides his exasperation.

Some engineers say earthquake risk is exaggerated. Here is a comparison of some annual causes of death:

Heart disease: 696,947
Cancer: 575,909
Motor vehicle accidents: 43,005
Suicide: 31,655
Homicide: 17,638
Drowning: 3,447
Falls from ladders: 406
Animal bites: 118
Lightning: 66
Bee stings: 54
Tornadoes: 54
Earthquakes: 20*

* Average annual deaths from U.S. earthquakes, 1811-2005. The rate would be much lower were it not for the estimated 3,000 that died because of the 1906 San Francisco quake. Just over 4,000 have died in all U.S. quakes since 1811.

Sources: National Center for Health Statistics, 2002; National
Highway Traffic Safety Administration, 2002; National
Safety Council, 2002; Consumer Product Safety Commission,
2003; U.S. Geological Survey.

Eric Hand covers science for the Post-Dispatch.

Quake sitemap

Powered by ShowMe-Net