-I would expect the authorities to prepare for such an eventuality; however, I can also understand the need to keep this low-key - way too many would take the fact that the government prepared for such an event would mean either that they feared one was imminent or more sinister still - planned one.
Which interestingly means that although we all agree we should pretty much panic and react accordingly in the event of such an emergency, it's best for people not to anticipate such panic until absolutely necessary. And this implies we ought to trust others to come up with contingency plan for us, since we ourselves shouldn't think about it for now.
Much better to just keep quiet about it.