Every year more than 1000 tornadoes across the nation kill more than 70 people and injure 1500 more with billions of dollars in damage. Northern Iowa and
Southern Minnesota have a rich history of tornadoes. Our viewing area is right on the edge of Tornado Alley. Tornado Alley is the part of the
Midwest that typically sees the most tornadoes. It reaches from Texas up to Southern Minnesota and back down through Iowa into Missouri and
Arkansas .
Over a 45 year period the area has seen more than 100 tornadoes. Some of the twisters were among the strongest tornadoes possible. These tornadoes include the
Rochester tornado in 1883 that led to with the formation of the Mayo Clinic. More recent tornadoes include a 1966 tornado that hit Belmond and one that tore through
Charles
City and Elma in 1968. All three tornadoes were classified as F-5's, the most severe ranking on the tornado scale.
Already parts of the country are seeing some significant tornado damage. This past weekend, tornadoes killed seven people and destroyed or damaged another 400 homes in
Arkansas. But some research at
Iowa
State
University might be able to do something about the damage and maybe even save lives.
According to Dr. Bill Gallus, a professor of meteorology at
Iowa
State
University , “The goal of this project is to improve building designs so that people are safer in the future.”
Most cities in our viewing area have been spared a direct tornado hit. However, the most recent city hit in our area was Glenville and it saw plenty of damage.
Spencer Krier remembers May 1, 2001. "It was scary," he recalls.
That's when a tornado tore through Glenville. Spencer was only six at the time...but he remembers the day well.
"When we came out and I actually saw the thing” said Krier. “It was pure white, it hadn't picked up any dirt or anything."
The storm hit the town and did some major damage. Now
Iowa
State researchers are using a tornado simulator to figure out if some of that damage could have been prevented.In an effort to help improve building codes, researchers are trying to figure out how strong forces inside a tornado are.
“We knew from some prior research that the winds in tornadoes might have a stronger impact on homes than the same strength of straight line winds would have,” Gallus said.
Currently, International Building Code requires buildings to withstand 90 mph straight line winds. 90 mph winds are equivalent to an F1 tornado, the second weakest on the scale. According to Gallus, “One of the main findings that we have had is that the forces on the side walls and the roof of the home depends on how fast the tornado is moving and the angle the tornado is approaching the home. In general, if the tornado is moving slowly toward the house, the walls and the roof are going to experience much stronger forces. If the tornado is fast moving, then current building codes might do a pretty good job telling us what kind of forces the home is going to face. In addition, if the tornado comes directly toward the house or toward the side, the forces are going to be greater than if the tornado hits the home at an angle.”
Since it's impossible to change the direction of a house when a tornado is reported, research shows that there are other areas of a home that can be improved. Gallus and the other researchers at
Iowa
State also learned that the speed of a tornado over the ground impacts its force.
“Now we found out in those cases when the tornado is moving slowly, the forces on the sidewalls could be double what the building code expects. “
Those forces can be three to four times greater on a home's roof -- and that's when problems can get a lot worse and the massive destruction follows.
“Which is why in a tornado you see homes fail because part of the roof would blow off and once the air is able to get into the house, it is able to cause a lot more damage,” said Gallus.
One way you can reinforce new structures as well as some existing structures is with hurricane straps. These clips help to anchor your roof to your house as many houses roofs are just held on by gravity. You will have to check with a building professional to see if they can gain access to the necessary areas of your home to anchor your roof to your walls. It is also a good idea to make sure your walls are anchored to your foundation.
Even if you can't secure your roof and foundation, there are some simple things to minimize the damage from a tornado. Simply clean up items in your yard that can blow around and hit your house during a storm. The research on tornado forces continue and one day could result in big changes in the way homes are built.
"We might find out other things that even the shape of structures should be done differently, and that's research is still on-going,” said Gallus. “We're testing many different orientations of buildings, designs of homes, types of roofs, churches, schools are all part of the grand plan on things that are going to get done over the next year or so. There is a lot I think we have to learn. We might find in the future that you should never build buildings that have a particular shape.”
Until building codes are upgraded and homes are built to withstand stronger winds, you still need to remember some basic safety rules. In the seven years since that May-Day Twister...Spencer has grown up quite a bit. To this day he still knows what to do when storms approach.
“When you hear about a tornado warning or severe thunderstorm, head to the basement and take cover,” said Krier. “Or if you are on the road head into a ditch someplace and wait it out.”
Despite a lot of research into safer buildings, there's little change in how people should stay safe. The best thing you should do is take shelter in the lowest level of your home. A basement is best, but an interior room without windows will do as well. If you are out on the road, don't try to outrun a tornado, but try to drive out of its path. If you can't, don't take shelter under a highway overpass, but abandon your car and lie flat in a ditch.
|
