Tornadoes Offer Lessons in Disaster Response and Planning

By | October 5, 2011

In a year marked by a high number of severe and devastating natural catastrophes, one thing is evident — while rare, some situations are not survivable. For instance, if people or structures happen to be located directly in the path of tornado rated EF-5 on the Enhanced Fujita scale, one with the capacity to do the most damage, the tornado to some extent is going to win.

The twister that hit Joplin, Mo., in May was that kind of tornado. Rated an EF-5, it was wide, slow and traveled 22 miles on the ground. It killed at least 159 people and injured more than a thousand when it blasted through a densely populated section of Joplin on May 22. It was the deadliest single tornado in the United States since record-keeping began in 1950, according to the National Oceanic and Atmospheric Administration’s National Weather Service.

While hundreds of tornadoes tear through the United States every year, those that are rated EF-4 or EF-5 are relatively rare.

“The mega tornadoes, the EF-3s, -4s and -5s that hit this spring, comprise a very small percentage of the types of tornadoes we see every year,” said Julie Rochman, president and CEO at the Institute for Business & Home Safety. “Maybe 2 percent to 3 percent of the tornadoes that we see in this country are those really severe ones.”

Rochman, whose organization researches and disseminates information on how to build structures that are better able to withstand nature’s forces, acknowledged that “an EF-5, if it lands right on your house, there’s really not a lot you can do.”

Similarly, Richard Wagenmaker, meteorologist-in-charge of the NWS Detroit Weather Forecast Office, said that in Joplin there were “a number of people who did all the right things, took shelter in the best available place to them, but still found themselves in situations that weren’t survivable.”

Still, it’s unlikely Rochman or Wagenmaker would concede that taking precautionary steps to protect people and property from an extreme weather event is a waste of effort and money.

Individual Response

Wagenmaker led the NWS assessment team that examined the warning systems and forecast messaging that took place in advance of the Joplin tornado and reviewed the public’s response to warning communications. Their goal was to identify what was done correctly, as well as areas for improvement.

They found that while there was significant advance warning of the impending tornado, most people did not immediately respond to the warning sirens.

“The team found that warning response was highly complex on a number of factors, such as risk perception, credibility of the warning and how the warning is communicated,” Wagenmaker said during a conference call hosted by NOAA. “The vast majority of people that we interviewed received their initial warning from the siren system. There are two issues with the siren systems. One, they’re designed for outdoor use, and two, there is an ambiguity regarding the seriousness of the threat. In other words people asked — what does the siren mean how serious should I take it?”

Most people chose to seek or wait for additional information, Wagenmaker said. The perception was that sirens go off all the time, so people preferred to wait and see what was really going on. That delay may have contributed to the high death toll in Joplin, but other factors were also involved, according to Wagenmaker.

“For example, increased urbanization of the population over the past few decades has increased our vulnerability to severe weather across the country,” he said. “And the Joplin tornado unfortunately hit in an area with a relative high population density on a springtime weekend.”

Wagenmaker said the investigation revealed that those who sought shelter in response to the warnings “knew what to do and where to go. The majority of businesses that we interviewed had a plan for receiving warnings and sheltering their patrons. … Education efforts have clearly paid off.”

Keith Stammer, the emergency manager for Jasper County, Mo., agreed that Joplin “is a weather ready community. … We have for years promoted weather radios and shelter in place.”

Stammer, who also participated in the NOAA conference call, said that to increase the effectiveness of advance warning systems, the city is applying to the Federal Emergency Management Agency (FEMA) for funding for 10,000 weather radios to be distributed to Joplin households. It is also seeking FEMA funds for the construction of around 4,000 in-place shelters to be made available to Joplin residents.

“This has been a community wide collaborative effort for recovery and I expect it will be the same thing when it comes to using the assessment and deciding how we’re going to approach severe weather warning,” Stammer said.

Protecting Property

“It’s not a mystery how to engineer and build a structure to withstand Mother Nature’s forces,” IBHS’ Rochman said.

Many times, even in a smaller weather event, “people are injured or killed because the home or the building that they were in came apart when it shouldn’t have. The tragedy is that we typically in this country have built the same way again and again. We put the same pieces back in the same locations the same way they were before,” she said.

A structure needs to be tied together, she said, in order to have a chance at survival. “Strapping all the different structural elements together is critical no matter what kind of windstorm you’re talking about, whether it’s a hurricane, edge of a tornado, or a lower level tornado, or a thunderstorm.”

Unfortunately, that kind of strapping together doesn’t always happen, even in areas that are prone to the kinds of weather events that can tear a building apart.

“In part, it’s because a lot of these areas don’t have building codes, and in part, just the result of tribal knowledge and local building practices over the years, they don’t strap the roof to the walls and the walls to each other and the walls to the foundation,” Rochman said.

“In many places, these roofs are held on by nothing more than gravity. If they have a front porch or a large overhang and a tornado gets some lift under that roof and tears it off, then the rest of the house is going to disintegrate,” she said.

“Once the roof is gone in a severe tornado, the rest of the house is going to come apart in seconds. … The roof comes off and the exterior walls come apart,” Rochman said. But, she added, “if we know how the houses come apart, we can talk about how to keep them together.”

There are a lot of lessons to be learned from the severe weather events that have occurred this year, Rochman said. Any town that has experienced destructive weather events — such as Joplin, Mo., and Tuscaloosa, Ala. — would do well to view those lessons as an “opportunity to do better for their citizens,” Rochman said.

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