Nukes of Hazard (2013)
The article claims that a nine-megaton blast would wipe out "most of the state of Arkansas".  Wikipedia claims the lethal radius on a bomb of that size is about 20 miles for thermal effects (<a href="http://en.wikipedia.org/wiki/B53_nuclear_bomb#Effects" rel="nofollow">http://en.wikipedia.org/wiki/B53_nuclear_bomb#Effects</a> ), which is around 2% of the area of Arkansas; other effects are described as having an even smaller radius.<p>I suspect, but cannot prove, the wikipedia number is more likely to be correct.