Looking at the photos, it's interesting that some buildings survived. Makes you realize the most important thing in earthquake research is engineering.

I remember after 921 there was talk of 'unlucky' 12 story buildings collapsing. It was later learned that that height allowed for a resonance of the seismic wave to be hit (not sure what the proper term is). The height allowed the wave to be amplified or at least it did not interrupt the wave. It all had to do with physics more so than construction quality. Buildings a floor or two different of the same quality stayed standing.

They learned that they could place weights on certain floors to counter this effect.

I saw a video today in which the commentator was standing behind a twelve story building that had just collapsed. (Can't find it now. I think it was BBC.) Same effect?