In other words, hidden damage from the previous quake.

A thought I've been having is if it's simply not due to the style of the buildings altogether. In the pics I have seen there seems to be a lot of older style (un-reinforced?) brick construction. Northridge was not as devastating as the construction was simply not as susceptible, either due to quake codes and/or simply due to construction and architectural styles.

Although it is well known that NZ has large quakes, they may simply not have had the history California or Japan has to really show that you can't build certain ways. Much like many knew of the potential for a devastating tsunami in the Indian Ocean, the infrequency of the events were enough to keep it out of the collective memory, and therefore not be acted upon.

At the same time, it's a shame not only for the lives lost, but NZ has some wonderful architecture. (at least that I've seen via Google street view)

Brian