Washington, DC - The May 22, 2011, tornado in Joplin, Missouri, rated an EF-5 the most powerful ranking on the Enhanced Fujita tornado intensity scale. It caused 161 fatalities and more than 1,000 injuries, making it the deadliest single tornado in the U.S. since we began keeping official records in 1950. With losses approaching $3 billion, it was also the costliest tornado on record. All told, the tornado damaged 553 business structures and nearly 7,500 residential structures. Over 3,000 of those residences were heavily damaged or completely destroyed.
I was among a small, but highly skilled team of engineers and a sociologist dispatched to the scene two days later to collect data on how well the buildings and emergency communications systems had performed during the storm.
I had come to NIST just three months earlier from Louisiana State University to lead R&D efforts under the National Windstorm Impact Reduction Program. As an engineering professor and director of the LSU Hurricane Center, I had conducted a number of investigations following tropical cyclones. Living in southeast Louisiana for nearly 20 years, my family and I had experienced many of these hurricanes directly, including some of the most infamous storms of the past few decades: Andrew, Katrina, Rita, Gustav, and Ike.
Growing up in Dallas and going to school at Texas Tech in Lubbock, I’ve had a few close calls with tornadoes as well. Coincidentally, as my colleague Erica Kuligowski and I were driving to Joplin to get our first look at the 2011 tornado’s impact, we had a pretty harrowing run-in with an EF-2 tornado. We had to race to the small town of Marshall, Mo., where we ended up huddling alongside some students in the basement of the Missouri Valley College science building.
Only after that tornado, which damaged parts of Sedalia, Mo., had passed, were we able to get back on the road.
As part of my work, I had seen the damage that tornadoes and other severe types of weather can cause, but you never really get used to it. And I had never experienced the aftermath of an EF-5, so Joplin was a first. One hundred sixty-one lives lost, 3,000 residences heavily damaged or completely destroyed; the devastation was overwhelming.
Track of the tornado through Joplin, showing locations of some of the facilities surveyed by NIST as well as estimated building damage levels. Aerial image © 2011 GeoEye. Building footprint data Pictometry®. Used with permission. Enhancements by NIST.
Erica and my other colleagues, Long Phan and Frank Lombardo, fanned out across the city to survey the damage and conduct interviews. We went to inspect St. John’s Regional Medical Center, but could only look at it from afar. The building, a vital resource for the community especially after a weather event as severe as this, had been rendered both unsafe and a biohazard site.
We came away from our reconnaissance of Joplin with a sense that we had to do something to ensure that our communities, the buildings that make them up, and the people who live work, and play there, are safer and more resilient.
St. John’s Medical Center after the storm. Credit: NIST
Did you know that, with the exception of provisions governing the design of storm shelters, the word “tornado” isn’t even in our building codes? Is it any wonder that our buildings fail? We design for other hazards, but tornadoes haven’t been part of that calculation because they are perceived as being too rare, which is strange because we record over 1,200 of them annually.
It’s true that they are smaller events and impact less area than say, a hurricane or an earthquake, but tornadoes are much more common and significantly more intense than we have understood in the past. Tornadoes are also more deadly, causing more U.S. fatalities per year than hurricanes and earthquakes combined.
We need to make a paradigm shift in how we consider tornadoes in the built environment. Not every building needs to be able to withstand an EF-5, but critical facilities like hospitals and 911 call centers must be designed to remain operational following these events so they can continue to serve their communities after the storm.
Many people sought shelter in the Joplin Home Depot. Unfortunately, six people lost their lives when the building collapsed. Credit: NIST
The people of Joplin took the damage of the 2011 tornado into account as they were rebuilding their community and made changes to their building code that improved tornado resistance. While the hospital was eventually torn down, construction on a new, stronger successor was completed in 2015. The community rebuilt schools with storm shelters and added storm shelters to schools that weren’t even damaged. These shelters were different though. Not only can they accommodate the entire population of the school, but also all of the residents within quarter- to a half-mile radius around the school.
They’ve made these shelters available year-round with an automatic unlocking system that activates as soon as a tornado watch is issued.
Joplin has also worked with neighboring communities to develop a regional activation policy for outdoor storm sirens. This is special because no national standard currently exists for such a system. Prior to the touchdown of the 2011 tornado, the people of Joplin heard the sirens go off for a storm on the northern edge of the city that did not produce a tornado. Twenty-seven minutes later, the sirens sounded again, but this time some residents didn’t know what to do, some even thought it indicated an all-clear. While that may be the case in other places, the second siren in Joplin was to alert residents that there was a tornado on the ground. Now, Joplin has standardized these warnings and educated the population on this new siren policy.
The innovative, potentially life-saving changes made in Joplin can serve as a model for other tornado-prone communities.
For our part, my colleagues and I at NIST are working to better measure the properties and impacts of tornadoes and use that knowledge to develop new model building codes, standards, and best practices for more tornado resilient construction and for emergency communications at the national level (PDF).
Jersey barriers tossed aside by a tornado in Arkansas. Common indicators like this give us a good idea of the tornado’s true strength. Credit: NOAA
For instance, we’ve been working on new technologies to estimate wind speeds in tornadoes. The EF Scale is currently based on expert judgement of what wind speeds it would take to cause common types of damage, like lift the roof off a building. But estimating wind speeds this way is subjective and varies greatly with the type of construction. We are developing new damage indicators by measuring, for example, the wind speed necessary to topple common things like Jersey barriers, the moveable concrete walls you see along road construction zones and in parking lots. Jersey barriers are all about the same size and weight, and wind tunnel tests have revealed that they turn over at wind speeds of about 175 mph. Indicators such as these will provide much more accurate information than we have now about winds near ground level. Such information will help to improve engineering designs for tornado resistance of buildings and the consistency of tornado ratings in the national tornado database, which is critical for developing better tornado hazard maps in the future.
At present, we are busy developing a new generation of these maps using the existing tornado database. These maps will be a key element of a performance-based design standard. Although this standard will certainly include guidance for those who want to design for the worst case, it won’t require that all buildings be able to resist an EF-5 tornado. Instead, it will provide a range of ways to optimize life safety and property protection for different probabilities or intensities of tornado strikes. This new standard will allow building owners, working with their architects and engineers, to make informed decisions about how well they want their building to perform, given its role in the community, then design and construct it accordingly.
A safe room that survived when the house it served and surrounding neighborhood were destroyed. Credit: FEMA MAT
Another thing we did was to work closely with FEMA to improve guidance for planning, design, and operation of storm shelters (called safe rooms in FEMA terminology). We included some of the innovations that Joplin made as best practices in FEMA’s recently updated guidelines on the subject.
And, as the misunderstood Joplin warning sirens and our own near run-in with a tornado dramatically illustrated, we also need to improve communications during an emergency. We are working on a project with the Fire Protection Research Foundation to provide guidance to communities on outdoor siren systems. We have also recommended the development of “push” technology, like the amber alerts you get on your phone, that would go to all people in a hazard zone and tell them what to do in a clear, concise, and actionable way. NOAA’s National Severe Storms Laboratory is developing the next-generation forecasting tools required to enable these new products.
I’m proud and inspired by the resilience of the people of Joplin. In the five years since this terrible tragedy, they have pulled together as a community to rebuild, taken a thoughtful look at what this event could teach them, and put that information to good use. In doing so, they have not only made their city stronger and safer, but also made their community an example that others in tornado-prone areas can follow.
I hope that the work we are doing at NIST helps save lives and property from future tornadoes by making every community more resilient.
It’s why we do what we do.