Sure it's cool to destroy New York, but it's even cooler to destroy Los Angeles. That's why Omega Man, the 1970s version of I Am Legend, took place in Los Angeles. Viral decimation is only one of the many ways LA has been crushed, according to a 1998 book by Mike Davis, Ecology of Fear, in which the irascible social critic gives us a helpful list of how LA is destroyed in 145 scifi/disaster novels. Of course nukes top the list, with a whopping 49 books wiping out LA in a big blast. But you'll be surprised by some of the lesser-known forms of LA-elimination.
Here is Davis' list of ways LA is destroyed in literature, with number of occurrences, for your contemplation:
Hordes (invasion), 10
Bermuda grass, 1
Global warming, 1
Needless to say, Davis moved out of LA to Hawaii several years ago.