I hold my breath and pray everytime I drive thru the Caldecott tunnel in SF's Eastbay. It sits right over the Hayward fault.
I hold my breath and pray then too. If you can manage it, the ferry from Vallejo to downtown San Francisco is a nice alternative.
Certainly not all jobs can be done at home, or at a remote office, but a lot can be.
At one time it made sense to have "cities", transportation was difficult. But today when a good portion of a work force lives twenty or more miles from the office, why not have small satillite offices out in the suburbs.
High speed network connections would allow both telephones and computer networks to work anywhere, and instead of having a bunch of people driving in, have them go to a small office in the suburbs for most of their day by day work, and if need for face to face make the trip two or three times a month rather then daily.
Again, I understand some jobs require everyone to work next to each other, but I suspect most office jobs do not.
There are answers to this problem other then digging tunnels.