Mama Cass also made a recording of the song, though I don't recall her using the 'Mother Nature's gas' verse.

I didn't know anything about the song, but there was a documentary about the San Andreas Fault on British television many, many years ago, and the song was used throughout. Somehow, I missed the information given in the credits. However, I came across the Mama Cass recording a year or two later (probably paired with something like 'Talking to my Toothbrush'), and was pleased to find that. However, I suspect that the documentary carried the original.

Lhieuish,

Bobby Bob