No matter how you get from Northern to Southern California, you have to cross some faults. All of them are active, more or less. But:

* Competent engineers can design things to 1) not fall down in the maximum credible earthquake, and 2) for probable earthquakes, be repairable in fairly short order. Even PB has some competent engineers, though I'd prefer some other firm due to corporate overhead and history.

* Alignments can be laid out, and have been, to cross major faults at grade. That makes the inevitable (on megaproject time scales, with construction and operation lasting 100 years or more) earthquake more manageable.

Geology is not a project killer. It's something to design and plan around. Even Bob2's tunnel has to deal with several faults, but not the S.A. (should be on the surface by then). Will the others move? Maybe; on a geological time scale, certainly, but on a human time scale it's a crapshoot with the odds in favor of a human alive today not experiencing a big one from more than a few sources. There are other tunnels through both the San Gabriel and the Tehachapi (both near Tejon and near Tehachapi/Mojave) mountains, too. With competent engineering and construction, they should survive for a long time unless everything comes up snake-eyes at once (do you feel lucky?). So your job, as a citizen, is to make sure the politicians you think you can influence do what they can to ensure competence in planning, design, and construction. HSR so far has been a bad example of that. Consider it a challenge to make Plan B better. And your job, as an individual living in earthquake country, is to be prepared and carry on with life.