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Some public structures are being retrofitted to withstand an earthquake and newer building codes are in place, yet older buildings, as hospitals, are among the most vulnerable to an earthquake.
By Dacus Thompson, League Staff
An earthquake along the New Madrid Fault that has its southern terminus here in Arkansas once rang church bells in Philadelphia, made the Mississippi River appear to flow backwards and sank nearly 15,000 acres of forestland to create Reelfoot Lake in northwestern Tennessee. Today, the fault poses one of the greatest natural threats in the central United States, and cities and towns in northeastern Arkansas are bracing for an approaching seismic event with the help of federal and state funding and through emergency planning; but why is no one stockpiling Spaghetti-Os? Seismic hazard maps of the United States show high earthquake probability levels with varying shades of red. One pockmark of earthquake probability extends along the Mississippi River from northeastern Arkansas to southern Illinois. The latter area surrounds the New Madrid Fault, which in 1811 and 1812 caused the two strongest (magnitude 8.1 and 8.0, respectively) earthquakes in the conterminous United States. The Dec. 26 quake off the coast of northern Sumatra was magnitude 9.0.
Earthquake-prone area residents don't seem worried. Despite recent earthquakes in the New Madrid seismic zone (from Aug. 16 to Feb. 16, there were 77 minor earthquakes in the area, most under magnitude 2.0), it is better known for its threat of disaster than its actual earthquakes. When Dr. Iben Browning predicted an earthquake of a magnitude 7.0 along the New Madrid Fault in 1990, it resulted in school cancellations, a rise in earthquake insurance and widespread fear, but no earthquake. The zoologist's misguided prescience has since circulated an indifference to earthquakes in residents in the area, and the impending threat has become almost moot. "When Browning said there was going to be an earthquake, people went and got emergency supplies-water, canned goods, shovels, picks-and some people went up in the hills for a month," said Marked Tree Mayor Lawrence Ashlock Jr. "But I haven't heard much about it since then. I really don't think people are worried about it." Caraway Mayor Joe South was in his home in Caraway Feb. 10 when a magnitude 4.1 earthquake began shaking the ground. "The dishes began to rattle and the windows began to vibrate, and it shook just for a few seconds," said South, who has experienced earthquakes in California and Arkansas. "I thought it was either an earthquake or a big truck had hit the house, and I didn't see no big truck coming through so I knew it was an earthquake." South said he feels the municipality is properly prepared and has a good emergency plan for a big earthquake, but that the residents are not. "People strapped in water-heaters and things like that back around 1990 when the prediction was made, but we haven't changed anything recently."
Preparation work can save lives, reduce property losses. Seismologists predict a 40-60 percent probability of a major earthquake, magnitude 6.5 or greater, happening along the New Madrid Fault within 15 years and a 93-98 percent chance in the next 50 years, says a report by the University of Arkansas Little Rock. How exactly a magnitude 7.0 earthquake will affect Arkansas depends heavily on how well it prepares. Armenia and the San Francisco Bay area, which are of similar population size, experienced earthquakes in the late 1980s, magnitudes 6.9 and 7.1, respectively. Both endured tremendous damage; but San Francisco had a superior emergency plan to Armenia and its buildings were more structurally sound, and thus the Bay area curbed its losses hugely: there were 67 deaths and less than $7 billion in property losses in the Bay area, while Armenia suffered more than 25,000 deaths and property losses of more than $20 billion. Arkansas's legislators have recognized that preparation needs to fall on the San Francisco side. In a preventive step, the Arkansas General Assembly in 1999 updated the state's earthquake building code (ACA 12-80-103), re-establishing three seismic zones in Arkansas based on anticipated damage. The code requires adherence to changes in the building codes for new structures built within designated areas. Northeastern Arkansas is considered to be under the greatest threat because of its location and the nature of its soil-mostly mud, sand and silt, which allows seismic energy to pass through easily. In Arkansas, the farther west and south the county, the less risk it has of being affected by an earthquake. "We had to draw the zones on political boundaries, but nature doesn't know anything about politics," said John David McFarland, chair of the Arkansas Earthquake Advisory Council. "So we tried to draw lines that matched with the geological situation and political boundaries as best we could." Randolph, Clay, Greene, Lawrence, Craighead, Mississippi, Jackson, Poinsett, Cross, Woodruff, Crittenden, St. Francis and Lee counties makeup zone three, the highest rated district. Ashlock and South, whose counties are both in this zone, said their municipalities' buildings are being earthquake prepared according to the code.
Existing buildings can be aided by non-structural elements. McFarland said the biggest concern in a seismic disaster is falling structures, such as schools and hospitals, especially those built before the building code. No requirements for retrofitting already standing buildings exist. "There is not a major hospital in northeastern Arkansas that's prepared for a seismic event," McFarland said. "They were all built before there was even recognition of the seismic problem." The Arkansas Hospital Association declined to comment about earthquake preparation at hospitals in northeastern Arkansas. Some hospitals have been retrofitted. "We were granted a grant when the big earthquake scare came and the government gave out grants to retrofit hospitals in case of an earthquake," Judy Thomas, the executive administrative assistant at Crittenden Memorial Hospital at West Memphis, said. "We retrofitted some of our clinics [and] we retrofitted the ER, so we'd know that if we did have an earthquake, which part of the hospital would be standing and be needed." To improve safety in existing buildings, McFarland recommends focusing on the non-structural elements, such as adding chains to light fixtures, installing shatter proof glass in windows and strapping, fastening and bolting anything-bookshelves, water-heaters, televisions-that could topple over. "Earthquakes don't hurt people," McFarland said, reinforcing his point. "Collapsing buildings, falling items and shattered glass hurt people." The Arkansas Department of Emergency Management (ADEM), which handles all state and local government emergency management activities, has retrofit some northeastern Arkansas school and public buildings and waterlines, and has made Poinsett and Clay county schools safer by installing gas shut-off valves. Many cities are making improvements on their own initiative. FEMA aided West Memphis to bolster its water facilities. West Memphis, a city of 27,666, has aggressively pursued grants in preparation for the worst. One of those grants of close to $300,000 was awarded to the Crittenden County city in 2001 by the Federal Emergency Management Agency (FEMA) to provide mitigation to the city's water system. The grant was used to create redundancy in the system by establishing alternative water lines to bypass main tanks in case they are damaged; automatic cutoff valves were installed to close in the wake of a magnitude 6.0 earthquake or greater; and two buildings housing an auxiliary generator for power and an auxiliary pump for water service were retrofitted with wall columns and metal and steel channels to brace the exterior. "Various and sundry things were done around the city," said Philip Sorrell of Sorrell Consulting Engineers, which implemented the grant. "We didn't have enough money to do major structural retrofits, but I believe the city has done a good job preparing itself with what it has."
$72 million in bridge work aims at a magnitude 7.0 quake. A much larger-scale project began in 1992 to retrofit the Hernando De Soto Bridge over the Mississippi River, which connects Memphis and West Memphis. The retrofitting was to improve the bridge's strength, ductility (making it capable of change without breaking) and isolation by easing the stress on key support components of the bridge. By the end of this year, more than $72 million in combined funding from the Federal Highway Administration, the Arkansas State Highway and Transportation Department and the Tennessee Department of Transportation will have been spent to help the bridge withstand an earthquake of magnitude 7.0. Forecasting earthquakes is precarious, untrustworthy and, in the least, an inexact science. But it is certain that a great earthquake in the New Madrid Seismic Zone could strike at anytime; and the likelihood of such an earthquake grows daily as the earth's plates push and shove against each other, building pressure until they rupture and shake the earth. How devastating that earthquake will be is unknown, but how well it is handled depends upon how well the threat is faced.
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