One was "Ground Zero" which cropped up with reference to the 9/11 twin towers , I for one had never heard that expression before .
Ground Zero was the point in Hiroshima which was directly below the point
at which Fat Man exploded in 1945. Apparently, just as in Tunguska, all the
debris and wreckage was blown out in a "quasi radial" manner, which allowed
observers to discern a point from which the blast was construed to have emanated.
I hope this explanation is satisfactory. The photographs, which I first saw as a
lad, are truly "iconic". Some structures remained standing but, most housing
being of wood, it was just vapourised and the outer regions were set on fire.
My reading on this matter has led me to some disturbing conclusions. One,
that atomic bomb production was by this time highly mechanised at Oak Ridge
and Los Alamos.
This was truly a notifiable event, if not notable