What tier would an explosion be big enough to require maps to be redrawn?

[ByArrow]

-So what kind of damage are we talking about?

-Rand and McNally will
have to redraw their maps.

What tier would that be?

 

[Flashlight237]

Maps are representative of the locations they're made for. There is no specific tier for this. If we're talking about Earth, our maps typically come with these bar things called "scales":

If you have a Rand McNally world atlas like I do (although mine is made in 1986, so it thinks Yugoslavia and the USSR exist), I'd see about using that as a reference. Ideally you'd have to grab a ruler or pixel-scale the bars themselves, then use whatever reference measurement you got to measure the crater or whatever the explosion caused.

If it's a fictional world, on the other hand... Well, you're kinda screwed.

 

[ByArrow]

The moment the explosion occurs, the characters travel to the past, so the destruction or crater caused by the explosion is not visible.

 

[Flashlight237]

The moment the explosion occurs, the characters travel to the past, so the destruction or crater caused by the explosion is not visible.

In that case, I don't think the explosion is calculable.