This is a list of tornadoes which have been officially or unofficially labeled as F5, EF5, T10-T11, IF5, or an equivalent rating, the highest possible ratings on the various tornado intensity scales. These scales – the Fujita scale, the Enhanced Fujita scale, the International Fujita scale, and the TORRO tornado intensity scale – attempt to estimate the intensity of a tornado by classifying the damage caused to natural features and man-made structures in the tornado's path. Tornadoes are among the most violent known meteorological phenomena. Each year, more than 2,000 tornadoes are recorded worldwide, with the vast majority occurring in North America and Europe. In order to assess the intensity of these events, meteorologist Ted Fujita devised a method to estimate maximum wind speeds within tornadic storms based on the damage caused; this became known as the Fujita scale. The scale ranks tornadoes from F0 to F5, with F0 being the least intense and F5 being the most intense. F5 tornadoes were estimated to have had maximum winds between and . Following two particularly devastating tornadoes in 1997 and 1999, engineers questioned the reliability of the Fujita scale. Ultimately, a new scale was devised that took into account 28 different damage indicators; this became known as the Enhanced Fujita scale. With building design and structural integrity taken more into account, winds in an EF5 tornado were estimated to be in excess of . The Enhanced Fujita scale is used predominantly in North America. Most of Europe, on the other hand, uses the TORRO tornado intensity scale (or T-Scale), which ranks tornado intensity between T0 and T11; F5/EF5 tornadoes are approximately equivalent to T10 to T11 on the T-Scale. In the United States, between 1950 and January 31, 2007, a total of 50 tornadoes were officially rated F5, and since February 1, 2007, a total of nine tornadoes have been officially rated EF5. Since 1950, Canada has had one tornado officially rated an F5. Outside the United States and Canada, six tornadoes have been officially rated F5/EF5/T10+ or equivalent: two each in France, Germany, and one in Italy and Argentina. Several other tornadoes have also been documented as possibly attaining this status, though they are not officially rated as such. The work of tornado expert Thomas P. Grazulis revealed the existence of several dozen likely F5 tornadoes between 1880 and 1995. Grazulis also called into question the ratings of several tornadoes