Pages 157-
How a tornado in Tsukuba City in 2012 attacked a severely-damaged house was investigated. It was indicated that the differences of estimated damage wind speed based on a steady wind flow in some reports were mainly caused by the difference of wind force coefficients and weight assigned to the damaged house. In this paper, by chasing the moment in a time evolution while approaching of tornado based on Rankine's model considering a sudden drop in atmospheric pressure as well as wind force due to a horizontal wind, the overturning wind speed was decided. It was found that a sudden drop of atmospheric pressure caused by a rapidly-moving tornado reduced the damage wind speed.
