Describe a scenario leading to a man-made catastrophe that could result in the kind of destruction found in Gathering Blue.

It is important I think that we are never specifically
told what happened to trigger off the Ruin that destroyed our version of humanity and
plunged humans into a kind of dark age where they lost all their technological
sophistication and knowledge. We are given a few tantalising clues, such as in the
beginning of Chapter Three, where we are told about the Ruin
Song:

Most
especially it was frightening when it recalled the Ruin, the end of the civilisation of
the ancestors. Verses told of smoky, poisonous fumes, of great fractures in the earth
itself, of the way huge buildings toppled and were swept away by the
seas.

Later, reference is
made to skyscrapers exploding in flames. I think it is significant that we see humanity
long after the Ruin, and this is enforced by the way that no-one can remember what
precisely happened. However, if we think of what we are told in the above quote, the
reference to huge buildings being knocked down by the sea indicates that an
environmental disaster could have been responsible. The poisonous fumes could easily be
from a nuclear disaster, such as a nuclear reactor being destroyed by the weather, just
as what has recently happened in Japan. However, equally we could argue that the Ruin
was the result of a World War or something like that.