security against (something)
something that keeps something safe, protection against something
The money in the bank is my security against losing my job in the future.
Fastest Things Known To Man
Technically when we say fastest tornado we are referring to the wind speed, not forward motion. With that said, the fastest wind speed on record was measured in an F5 tornado near Oklahoma City in 1999. The speeds exceeded 300 mph (484 km/h). On the Fujita scale this means it was barely scraping an F6 and no tornado has ever been classified as an F6.