[BeefWellington]

10.0 is firmly in "if it happens nobody's gonna be around to care what it's designated" territory I think. There's a practical point at which the death tolls are going to be sufficiently high that the number probably shouldn't matter.

Though in tornadoes there definitely are EF-4 designated twisters that are hotly contested online as being truly EF-5; often that's down to where damage occurs in the lifetime of a tornado though and it being difficult to prove windspeeds when a system is moving through, e.g.: trailer park vs an industrial park.

[TylerE]

I don't think it's quite as cut and dried as that. A 9.5 hit Chile about 60 years ago, and about 95% of the most directly hit town survived. Which is not to minimize it - there were thousands of fatalities - but it was human scale tragedy, not apocalypse.