It has been my general observation that if the infrastructure is collapsing under its own weight, then that city is going to take a big hit, come earthquake time. I had outlined this in Urban Seismic Risk, but it is not generally know that New York City, is at very high risk of damage and loss of life, if an earthquake would hit.
In fact, New York is one of the very few cities where an earthquake scenario has been laid out (along with some cheesy movies!). The city area has had quite a few historical earthquakes, and is tied with Boston as the city most likely to crumble with a bit of shaking.
The whole east coast is on a 'passive margin'. I think it's somewhat unfair that this bit of tectonics is the most unstudied zone ever. I mean who wants to do their research on something passive? No money, and no tenure!
But, take away the rest of the world, then our passive margin is quite exciting. It used to be in the central hub of action, when the giant Gondwana broke up, possibly adding to the woes of dinosaurs when all that cold ocean water started to circulate. Since then our passive margins have been sinking for millions of years, brought down by the cold oceanic crust that wants to soon join its maker. This tug brings about some big earthquakes, notably the 1857 Charleston earthquake.
So, nothing makes a city more unfit for an earthquake than crumbling infrastructure. All those nice 100 year old steampipes (that are doing a 'splendid job'), will do what old steampipes do. The brick brownstones don't have much of a chance. A lot of Manhattan is on solid rock, but there is a lot of filled swamp around (which will get amplifications of over 100 times).
Of course, it's a battle of who gets it first! I'm rooting for Toronto, who hasn't even got an earthquake scenario! The innocent always get whacked.