On Sep 9, 8:52 pm, Andy Champ  wrote:
> jamie_...@excite.com wrote:
>
> > When steel-framed buildings collapse due to structural failure, they
> > don't collapse straight down into themselves, because straight down is
> > where all the resistance is. Instead they buckle, topple over (as seen
> > after major earthquakes), or parts of them may break away and fall to
> > the ground (as seen in the Madrid example).
>
> Earthquakes are entirely different.  The movement in an earthquake is
> mostly horizontal.  If you move the ground under a skyscraper several
> metres sideways suddenly it's not too surprising if it falls sideways.

And where did the downward movement come from to make the towers fall
downwards?