It maytake two years to prove McCracken isn't even in the New Madrid Fault zone, in time to help bring a new centrifuge plant.
By Joe Walker email@example.com
"What we're really trying to do is define the northern end of the New Madrid zone," said John Kiefer, a member of a team studying seismic conditions in the Paducah area. "Right now there is a lot of debate whether Paducah sits on the northern end or is actually some distance from the northern end."
The New Madrid zone runs through Alabama, Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee.
Kiefer said the team hopes data from newly installed equipment will provide answers within two years, in time to help Paducah's efforts to persuade USEC Inc. to build a 500-job uranium enrichment plant here rather than in Piketon, Ohio. Because Paducah currently is considered in the New Madrid zone, the cost of building the gas centrifuge plant here is considerably higher than in Piketon.
Seismic codes also mean expensive bracing for homes and commercial buildings that have large windows and other irregularities. The problem has bogged the building-permit process in Paducah and McCracken County.
"We have equipment in the ground and have gotten some excellent readings from the recent earthquake in Evansville, Ind.," said Kiefer, vice chairman of the Kentucky Governorís Council for Earthquake Risk Reduction. "We hope to get a few more quakes into the data, but everything so far pretty much confirms what we were saying. The risk in terms of Paducah is overstated."
Kiefer said experts once thought there was a 90 percent probability that a moderate earthquake ó defined as about 6.0 on the Richter scale ó will occur in the fault zone in the next 50 years. That probability is now believed to be only 7 to 10 percent, but a tremor of that magnitude would still cause major damage to poorly constructed buildings and possibly injuries and deaths, he said.
The projections are very loose because the last major quake ó defined as one of at least 7.5 in magnitude ó took place in the New Madrid zone in the early 1800s, he said, adding that he hopes the new tests will provide more accurate information.
"The bottom line is our information in the New Madrid region is based on a lot of speculation and guesswork ... with a huge margin for error," Kiefer said. "In California, their work is based on a lot of real information because they have earthquakes, and some pretty big ones, almost daily."
Stricter building codes adopted by Kentucky and other states rely on the most conservative U.S. Geological Survey based on a 10 percent probability that a moderate quake will reoccur in 50 years. That compares with older maps based on a 2 percent probability. A few counties, such as McCracken, now have much tougher codes because they are in high-risk areas.
But Kiefer says the maps donít take into account characteristics specific to areas such as the New Madrid Fault zone. His group wants the state to revise codes using a third set of USGS maps based on a 5 percent probability.
Joan Gomberg, a USGS geophysicist based at the University of Memphis in Tennessee, said the probabilities that were most widely used previously were devised in 1985. "We didnít have accurate data," she said. "The principal reason the probabilities have changed is that weíve learned a lot since then."
She said probabilities were figured within about a 50-year window and donít specify a particular spot.
Gomberg said advanced technology has allowed researchers to examine historic and geologic records to unravel the faultís seismic past. The result is a complete account of earthquake activity throughout the region.
Kiefer said the 7 to 10 percent probability was in place in 2002 when Kentucky survey members began urging the USGS and other scientists to reconsider the maps. "In the long run, I would hope it would have some impact on the Paducah situation and make this a little more realistic," he said.
The seismic study is being funded by the new Kentucky Consortium for Energy and the Environment, an outgrowth of the state's New Economy initiate. Consortium Director Dick Schmidt, based in Paducah, plans to meet with Kiefer and others Tuesday in Lexington to go over the latest results.
"We anticipate this whole process will help better define what the seismic risk is, particularly near the potential site of the new centrifuge plant," said consortium member Ken Wheeler of Paducah. "But it will take a year or two."
The Associated Press contributed to this report.