You may not be wrong....I lived in SoCal for many years - in my youth, before I got smarter and got out - and I think I remember reading of some studies having to do with the release of methane gas prior to a quake. Or it could just be the tipping point of refried beans being the predominant meal choice.
(just funnin’ with ya) :D
The problem with that theory is that the methane released from the ground wouldn’t smell like rotten eggs. Natural methane is odorless, they have to put the “rotten egg” smell into it with an additive, otherwise nobody would notice if they had a gas leak.