Tornadoes: Impacts
Tornadoes can leave a wide swath of devastation in their paths. Weak tornadoes typically break trees, cause damage to houses, and may knock over barns (Figure 12-4). Strong tornadoes are capable of demolishing houses from their foundations, leaving only scattered debris in the vicinity (Figure 12-5). Urban tornadoes can leave shattered glass from windows in storefronts and office buildings, along with extensive structural damage to large buildings, such as schools, shopping centers, and warehouses, in their wake. The extent of damage depends not only on wind speed, but also on the mass and surface area of the object being struck. Objects with an extensive surface area are particularly subject to damage when hit head on by tornadic winds. Even a massive locomotive can be toppled, and automobiles can easily be picked up and battered. Mobile homes are no match for a tornado. Secondary impacts of tornado damage result from damage to infrastructure. Downed power and communications transmission lines, coupled with disruptions to surface transportation, create difficulties in reporting and responding to emergencies. Casualties are common. Fortunately, over 90 percent of tornado casualties are injuries. Casualties are most frequently associated with the collapse of buildings, being struck by flying objects, or trying to escape the tornado in a car. A compilation of tornado-related fatalities nationwide from 1985 through 1997 revealed that 38 percent of all fatalities occurred in mobile homes, 27 percent in permanent houses, and 11 percent in automobiles. (Storm Prediction Center, 2001).  Figure 12-4. Damage typtical of an F0 tornado. (Photo Credit: National Weather Service, Birmingham.) Figure 12-5. Damage typical of an F3 tornado, the strongest documented in the Barren River Area. (Photo Credit: Mike Branick/Storm Prediction Center/National Weather Service).
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