Check out the video on this link: http://www.facebook.com/photo.php?v=1817415148842. (Thanks to my friend VIR for sharing the link.) The tragedy is not even due to an earthquake, other natural disasters, nor even a terrorist attack.
My friend ponders, is it the designer's or the contractor's fault?
Actually, sometimes it's also the owner's fault, or the developer's, or one of the sub-contractor's, or the government / regulating body's fault. And sometimes, it's nobody's fault. Sometimes, some things haven't been discovered yet -- classic example is the Tacoma Narrows Bridge collapse. In this case though, it was clearly somebody's fault. Whose it is now is not the point.
It's a very difficult, and broad-ranging topic to discuss, but my quick two cents on this is that new things are being discovered by researchers everyday, and we all shouldn't ever stop learning these new things. I've known people who are still standing by what they know from decades ago which are now established to be unsafe practices. But then there's also the business aspect of it all. Learning requires an investment, people need jobs/projects so they would charge less or settle for lower wages just to get those jobs/projects, and in the end, these people who settle for less don't have the time nor the financial resources to invest in learning.
I've been on both sides of the coin. I can see why industry dislikes research, and why the research community disdains industry. In the end, having a perspective on both is very important. If you're in industry and you belittle research work and expertise, or if you're in research and you ignore the experience of those in industry, you are compromising.
UPDATE: One of my friend's friend commented and said that it could also have been the facilities' fault for accommodating people more than the capacity of the floor. Indeed. Related to what I was saying earlier, the floor wasn't probably also designed for dancing.
UPDATE 2: Learned from another friend that... "Apparently this was a roof deck converted to a regular floor. The floor sagged weeks before this happened and the owners just ignored it." In short, it's not due to faulty construction.