Wind Speed Estimation from Asphalt Damage by a Tornado

A road paved with asphalt was damaged by a tornado at Mashiko town in Tochigi prefecture on May 6, 2012. The asphalt with a size of 4m width, 30m length and 50mm thick was peeled off and scattered. Fujita-scale of this tornado was determined from F1 to F2 by Japan Meteorological Agency. If the evaluation is correct, then a lot of damage like this should have been observed more in the past. However, no example that a normal road was damaged by a tornado like this has been observed in Japan. In this paper, the wind speed was estimated from this damage by considering the flying debris and the pressure drop by a tornado. As the result of this estimation, it was clarified that the wind speed reached to 100m/s.