HISTORIC buildings would crumble, highway overpasses would collapse, houses would be jarred off their foundations and dams, including possibly Lake Hefner's, would burst, sending walls of floodwater surging across the landscape.
A recent swarm of minor earthquakes has left Oklahomans unsettled, and while experts say the chances of a large, devastating quake happening here are remote, a big one is not out of the question. For the past several weeks, the state has felt an average of 12 quakes a day, many in the Oklahoma City area.
“It's rare for swarms to produce a large earthquake, but it's hard to say anything is for certain,” said Austin Holland, of the Oklahoma Geological Survey.
In November 2011, a 5.6 magnitude quake near Prague buckled U.S. 62 in several places, damaged 14 homes and collapsed a tower on Benedictine Hall at St. Gregory's University in Shawnee.
The quake was the largest recorded in state history, matching the April 9, 1952, El Reno earthquake that toppled chimneys and smokestacks, cracked and loosened bricks on buildings, broke windows and dishes and produced a 49-foot crack in the state Capitol in Oklahoma City. Damage from the 1952 quake was reported as far away as Iowa, Nebraska, Missouri and Texas.
By Oklahoma's own measure, any seismic event measuring 5.5 magnitude or greater is considered a severe earthquake. At that strength, home foundations can crack and large church bells ring on their own, according to the state's hazard mitigation plan.
An earthquake between magnitude 6.2 and 6.5 would partially collapse buildings, make cars difficult to steer and possibly alter the temperature and flow of springs and wells.
At magnitude 6.6 or greater, the state plan anticipates widespread destruction and panic. Should there be a breach of the 70-year-old Lake Hefner dam, water would flow northeast, flooding homes, commercial buildings and Mercy Hospital Oklahoma City before reaching the Cimarron River on the north side of Guthrie. Even a small earthquake in the right location could cause a dam to begin leaking and eventually fail, according to the state plan.
Such an earthquake also could cause extensive damage and possibly injuries and death from falling debris. Traffic would probably be disrupted not only for day-to-day needs but also for critical emergency services like police, fire and ambulances. School bus and mail routes also would be affected. Power and water outages could occur, causing food to spoil. Broken sewer lines could create sanitation problems. Schools, hospitals, grocery stores and other economically important facilities likely would be damaged and closed for extended periods. Employment would be affected because of businesses being closed due to the damage and loss of business.
Despite the potential for chaos, emergency response officials acknowledge the state is woefully unprepared.
On its list of disaster priorities, Oklahoma ranks earthquakes at No. 11, behind tornadoes, winter storms, sink holes, flooding, wildfires, high winds, drought, thunderstorms, lightning and extreme heat.
The amount of money the state allocates toward mitigation is based on the list.
“We don't think Oklahoma when we think earthquakes, and that is this uphill challenge that we face,” said Jim Wilkinson, of the Central U.S. Earthquake Consortium, a group dedicated to reducing the number of deaths, injuries, property damage and economic losses resulting from earthquakes. “There is a reason we need to be planning because the scale may not be as high, but nothing is out of the question.”
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