"Keith Willshaw" wrote in message ...

The same source states

"Nearly everything was heavily damaged up to a radius of
3 miles from the blast and beyond this distance damage,
although comparatively light, extended for several more miles."

Clearly the area affected was much more than that within
a radius of 2 kms


Heavy damage usually refers to something like that caused by a 3 PSI
overpressure, which will destroy internal walls of a house and leave
the contents of the house all piled up against the far wall, but
doesn't destroy the exterior frame of the house.

I think the estimate probably was considering the area where most
structures were completely destroyed.

I concede that "affected area" was a poor choice of words on my part.
"Area razed to the ground" would be more appropriate.