Why did so many skyscrapers collapse?

I liked how the Rock and other people were still able to run normally at the same time the earthquake was shaking skyscrapers to the ground 

I've read that a lot of the buildings there are constructed to only minimum codes of being quake-proof (Japan of necessity has learned a tougher lesson than the US has), and they wouldn't survive a major quake in real life. Maybe not to the point of collapsing completely (jeez, you'd hope not!), but I guess they wanted to make it more visually spectacular for the movie.



You might very well think that. I couldn't possibly comment.

You've obviously never been in an earthquake, it's like being on a boat in rough waters, which can easily tear a building apart. It's quite terrifying actually.

And why did they tip over... when everyone knows from 9/11 that's not how skyscrapers fall.

Like when people say sound proof or bullet proof, it's inaccurate, a better term is resistant, because it can withstand a certain amount. Example would be a piece of glass might be designed to stop a .45cal acp, making it bullet resistant, however if someone uses a .50cal sniper rifle it would cut through it like butter.

Skyscrapers in San Francisco have to be built to withstand a certain level of earthquake, but going above that would cause damage or even bring it down, the largest recorded quake in San Fran is 7.9, this was supposedly 9.6. Which according to an online calculator I just used means the quake in the film was 50.118 times bigger, with 354.813 times the amount of energy released.

Actually, I believe skyscrapers would be one of the more safe structures to be in during an earthquake (don't know how they'd fare in a 9.6 quake, though). In SF and LA skyscrapers are built to sway with the shaking, so it would be scary to be in a skyscraper in a quake but they are safer than other structures. The Transamerica Pyramid in SF has huge ball bearings in its foundation so it would roll with a quake.