OKLAHOMA CITY — Newcomers to Oklahoma have always peppered their Realtors with questions about tornadoes.
The likelihood of experiencing a twister has been of such concern through the years, it usually inspires some of the first questions asked by those moving to the state.
During the past year, however, would-be homebuyers seem less focused on tornadoes and more with near-daily earthquakes, a group of real estate agents agreed at a forum Wednesday in Oklahoma City.
In an odd twist, said one engineer, the state’s preparedness for strong winds that buffet homes during tornadoes has inadvertently helped it withstand earthquakes, as well.
Homes and businesses designed decades ago to bend and shake in 115 mph winds are now able to withstand shaking ground, which is typically less intense, said Christopher Ramseyer, director of the University of Oklahoma’s Fears Structural Engineering Lab.
After speaking to a roomful of Realtors, insurance agents and lawyers, Ramseyer noted during an interview that a house doesn’t know the difference between a tornado and an earthquake.
“It doesn’t care if it’s wind or seismic. We just need it strong enough that it doesn’t fall over,” he said.
Engineers have long known that seismicity is a concern here, given the fault lines sprawling under the state and Oklahoma’s ancient mountain formations.
“We’ve designed for it,” he said. “Most people never thought structural engineers worried about it. But we did.”
Oklahomans were jolted awake Sept. 3 by the strongest earthquake in the state’s recorded history. The temblor measured a 5.8 magnitude, according to the USGS, and injured one person while damaging numerous buildings.
Ramseyer said current codes are designed such that buildings can sustain quite a bit of damage in an earthquake.
The ultimate goal is not to prevent cosmetic cracking, he noted, but to keep buildings from collapsing on people.
“Our life-safety issue for our structural code is working, and that’s what we designed for,” he said. “It does mean that on low-intensity events, you can have sheetrock cracking. On unreinforced masonry, you can have some failures.
“The trick is the people; the occupants have to be able to walk out the door,” he said. “We’re not here to protect the building. We’re not making it so that the building owner has a pristine building because, frankly, if we did, you couldn’t afford to buy it.”
Still, the litany of homeowners across the state complaining about cracks in their homes has increased in recent years, as the number of earthquakes 3.0 magnitude or higher has ticked upward. The earthquake spike is blamed, in part, on the oil and gas industry’s practice of pumping wastewater into underground disposal wells.
In general, Ramseyer said, Oklahoma’s building codes “are adequate.”
In 2000, the state strengthened its codes to marry design practices for wind with the best seismicity practices developed out west. Last year, policymakers quietly updated the state’s seismic codes, to again align with international codes.
Janelle Stecklein covers the Oklahoma Statehouse for CNHI’s newspapers and websites. Reach her at firstname.lastname@example.org.