This (see page 30) is the "excerpt" you're referring to.
The lack of any author attribution, as well as the lack of a separate copyright on the paper itself strongly leads me to think that this is an original short story by the paper's author, Michael Priestly rather than an excerpt from a larger story or book.
A meteor drove us underground—an enormous rock that hurtled through
space and landed somewhere in the Nevada desert. We knew the meteor
was coming because the scientists had spotted it through their
telescopes, but there was nothing we could do. When the meteor landed,
the climate would change drastically. It would become cold and dark,
and the air would become too dirty to breathe. There was no escape, so
we could only sit by and await our doom. Then, without much time to
spare, someone got the brilliant idea of going underground
This is backed up by the fact that none of the other articles can be found elsewhere, other than in links that lead back different versions of the papers.