Missed the gas one, but I'll blame the ambiguity of the question.

If one is familiar with the gas plumbing, has checked its status, and found no evidence of a leak, ok - leave it on. If the quake damage is serious, and one hasn't checked everything out, maybe it should be turned off.

Of course, most quakes are aren't devastating, and many people get over-dramatic in their aftermath, so maybe in some statistical way their answer is optimum.