Seeing Northeast Japan in ruins is a jarring reminder of lives lost to killer waves and storm surge in Louisiana and of past power outages and hurricane damage to industrial plants. Our terrain is less vulnerable to quakes than Japan, but local power-plant operators say, to be on the safe side, they're prepared for bigger tremors than the state has felt so far.
Roy Dokka, Louisiana State University civil and environmental engineering professor and geologist, said small earthquakes occur in southeast Louisiana all the time though the region lacks instruments to detect and monitor them adequately. He is executive director at the LSU Center for GeoInformatics. The state's only seismic monitor is housed at Loyola University in New Orleans.
"The Michoud fault is pretty insignificant," Dokka said. The Michoud geologic structure runs through eastern New Orleans. "However, a bigger, fairly substantial fault lies on the north side of Lake Pontchartrain and cuts across much of the state. That fault's north side is going up and its south side is going down as fast as your fingernails grow." Another structure called the Lake Pontchartrain fault lies in the middle of the lake.
In late July 1987, Irish Bayou, a fishing area southeast of Lake Pontchartrain in Orleans Parish, felt a magnitude 3 quake associated with the lake fault. Faults in that vicinity are unlikely to generate a big quake any time soon, however, Dokka said. "Big earthquakes occur where the earth's plates grind past each other," he noted.
John Lopez, director of the coastal sustainability program at the Lake Pontchartrain Basin Foundation in New Orleans, said "faults crossing Lake Pontchartrain have been associated with magnitude 3 to 4 earthquakes. The Pontchartrain fault has a creeping movement, which is slower and less contained than most major faults." Lopez said faults in Southeast Louisiana aren't very active and aren't considered much of a risk. Earthquakes occur when stress that built up over time is released, he noted.
South Louisiana faults, which run in an east-west direction parallel to the Gulf Coast, are more numerous and active than faults in the northern part of the state, however. A magnitude 4.2 event in Donaldsonville on Oct. 19, 1930 was among the biggest recorded quakes in Louisiana in the last century.
And on Aug. 1 of last year, a magnitude 3 quake felt north of Baton Rouge might have been from groundwater pumping or other causes, Dokka said.
In local earthquakes, oil and gas drilling is sometimes considered a culprit. "Earthquakes can be triggered by any number of factors, including other quakes and man-made influences," Lopez said. "Decades ago, injection of water into the Colorado subsurface caused fault movement and quakes."
Liquid waste injection in a borehole is believed to have caused a damaging, 5.3 quake in the northeast Denver area on Aug. 9, 1967, and it was followed by a magnitude 5.2 event in the region three months later.
Louisiana geologists say the New Madrid fault, a 120-mile-long seismic zone that extends along the Mississippi River from Missouri to Arkansas, is something to keep an eye on longer term. "During a series of New Madrid quakes from 1811 to 1812, dishes flew off shelves in Washington, D.C. and New Orleans, but there wasn't much documentation associated with those events locally," Dokka said.
From 1811 to 1812, four big New Madrid quakes, centered in Arkansas and Missouri, were magnitudes 7 to 8, and were the largest ever recorded in the eastern half of the U.S. Waves ran in the opposite direction in sections of the Mississippi River. The New Madrid fault may be related to an ancient feature under the Mississippi River alluvial plain, known as the Reelfoot Rift.
Dokka cautioned that "several nuclear power plants lie in the region of the New Madrid quakes and are vulnerable to shaking."
Meanwhile, Louisiana gets nearly 20% of its energy from nuclear power, and that compares with 20% for the nation as a whole and Japan's 30%.
Last August, the Nuclear Regulatory Commission released data on 104 nuclear power reactors, using 2008 U.S. Geological Survey maps and new estimates of quake risks in eastern and central states. A MSNBC Television study later used that information to rank plants. With a rank of "one", the riskiest plant on the list was Indian Point 3 in Buchanan, N.Y.--estimated to have a 1 in 10,000 chance yearly of suffering core damage from a quake. River Bend 1, in St. Francisville, La. north of Baton Rouge, ranked thirty-third on the list, with a 1 in 40,000 chance of quake damage yearly. Waterford 3, in Killona, La. in St. Charles parish near New Orleans, ranked forty-first, with a 1 in 50,000 chance each year.
The River Bend and Waterford, La. plants are operated by Entergy, and were ranked as more dangerous than the median, or middle, value of a 1 in 74,176 chance yearly of core damage from a quake for all 104 reactors.
Shares of Entergy Corp., which operates utilities in Louisiana, Mississippi, Arkansas and Texas, sank to an almost two-year low last week. New Orleans-based Entergy owns or manages 12 nuclear plants in the United States, including the Northeast.
Michael Burns, New Orleans-based spokesman for Entergy Corp., said the company's nuclear plants were designed and built to withstand natural disasters, including quakes, certain seismic limits based on historical activity, storm surge and catastrophic flooding.
Japan's recent 9.0 quake was at least 1,000 times greater than anything typically recorded at Entergy plant sites, Burns noted. He said the natural environment surrounding nuclear plants in Japan is very different from areas around Entergy's plants.
U.S. safety rules are strict, Burns said. "The Nuclear Regulatory Commission requires that safety-significant structures, systems and components be designed to take into account the most severe, natural phenomena historically reported for each site and surrounding area," he said. NRC standards account for the possibility that a future event, like an earthquake or flooding, could be more severe than any recorded event. "Systems are designed with multiple, contingent backup systems to provide greater safety margins," he said.
Under NRC regulations, "design for seismic risks varies by region and location, based on tectonic and geological fault line locations," Burns said.
New safeguards and more training have been implemented since the 9-11 terrorist attacks to allow U.S. nuclear operators to cool reactor cores during power outages or failures of backup generators, he said.
Safety programs at nuclear plants are monitored by the NRC, Burns said. Plant programs include risk analysis and design enhancements to address natural and man-made risks; operator training for extreme conditions, along with drills and evaluations by the NRC; and emergency-response plans to protect public health and safety, like those after Katrina. Burns said safety plans are made by operators in cooperation with local, state and federal agencies.
Burns said the global nuclear industry will incorporate lessons learned from the current crisis in Japan in its operations.
Meanwhile, a report released on March 17 by the Union of Concerned Scientists gave the NRC mixed reviews, and said the agency tolerated some known, safety problems. The report titled "The NRC and Nuclear Power Plant Safety in 2010: A Brighter Spotlight Needed," said U.S. nuclear plants released unmonitored amounts of radiation into the environment over the last decade. The report examined fourteen "near-misses" at U.S. nuclear plants and evaluated the NRC's response in each case.
In the report, the Union of Concerned Scientists commended the NRC for some of its actions. In Louisiana, the NRC prevented Entergy's River Bend plant near Baton Rouge from restarting after Hurricane Gustav ripped sheet metal siding from three walls of a turbine building in September 2008. Starting the plant without full walls might have allowed release of radiation, according to the report. Entergy was allowed to restart after the walls were repaired.
David Knox, Houston-based spokesman for NRG Energy, Inc., which runs the coal-fired, Big Cajun II power plant 40 miles north of Baton Rouge near New Roads, said that vicinity is low in seismic activity. But, he said "we take any potential threat to our facilities and operations seriously, and build and operate our units in a way that makes them as safe as possible. The only issue that the Big Cajun II plant faces in the unlikely event of seismic activity would be for the unit, or stand-alone generator, to trip off-line, or shut down." In that event, the unit would shut down safely, he said, and generation would come from other units that were unaffected by seismic activity.
Big Cajun II has three, separate generation units, each capable of providing 615 megawatts of electricity. Together, the three units can supply 1.5 million homes.
Meanwhile, looking out to sea, Dokka said earthquakes occur several hundred miles offshore in the middle of the Gulf of Mexico, generally with a maximum magnitude of 5. He said "we're unprepared for quakes in Southeast Louisiana," in a view that differed from the power plant operators. He added "while that could be a problem, I believe we're better off spending money on protection from hurricanes rather than earthquakes."
Local geologists, of course, are also worried about the rate at which ground is sinking in the region. Lopez said that because of water pumping, the city of Kenner, a suburb of New Orleans, is now lower in elevation than the neighboring LaBranche Wetlands.
"Subsidence in New Orleans is happening fast, and it's not because of global warming," Dokka said. He's writing a paper on subsidence that will be published late in the year.
This article was published in "The Louisiana Weekly" in the March 21, 2011 edition.
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