[jadedhacker]

I did some research on Operation Crossroads a while back. I'm not sure what the blast effect damage would be, but it would cause radioactive water to wash over the town. Several warships in the exercise were scrapped because they could not be cleaned as certain isotopes stuck to the metal.

EDIT: Of course, how much radiation exposure you're willing to tolerate is a risk assessment call, but it seems pretty unfair to the civilian population to take any significant increased radiological risk.

EDIT2: 100MT is the design yield of the Tsar bomba, the actual detonated yield was 50MT b/c the plane dropping it would not have been able to escape at the design yield. This is a very very big bomb if that capability were actually used. I assume smaller bombs would also be able to be used as well.