It's interesting to see several articles about this recently. Ever since I was growing up in the 1970's, they've been talking about "the big one".

Here's the 1979 show "In Seach Of" discussing it:

Leonard Nimoy's narration is top notch as always: https://www.youtube.com/watch?v=148UfHK6pbs

At the time of the video, they said over 15 million people live along the various fault lines.