Wow, you could program that now. I like that event because it is all reactionary and whether or not there is actually a UFO is irrelevant. Bouts of hysteria about strange events have happened, so I'm cool with it.
I just want to know why somebody wants a meteor event to wipe out most of the world. Randomly. Seriously, do you remember when they were playtesting the event that instantly destroyed a city, and the playtesters demanded they take that out because they hated it? Now you want to do that to most of the planet?
A meteor has never actually wiped out the world according to history books. Why would you want an event of a city being destroyed by an asteroid if it hasn't even occurred. Only the atomic bomb has been used to destroy a city.