Okay, so it looks like my best option is to use a car to store stuff in and to park it on the street instead of in the garage under the condos.

Enough people have suggested off-site rental that I'll look further into that. My initial impression is that there are no self-storage units within reach, but I'll confirm that and reconsider based on location and possible survivabililty. (I'm aware, for example, of a former moving and storage building that's been converted to self-storge, but it's in a three- or four-story building of unreinforced masonry. It's within a long walk, but that building won't be standing.)

On suggestions to hike out, that's another idea I'd discounted but that I'll reconsider. We're on a peninsula, so we're limited to hiking from mid-peninsula towards San Jose. It may be that it's not possible to hike out, given the geographical constraints along with the issues of health and age. A two-day hike for a twenty-something man in an area where the safer destinations could be anywhere in 360 degrees is not going to be a two-day hike for my wife and me, and the only safer destination is south, where it may be no safer there than here. But it still should be on the agenda as a consideration, because we have no clue where the area of destruction will lie, especially if a local fire causes more destruction than the quake itself. (Or that dreaded tsunami washes into the bay against the advice of all those experts.)

It was interesting to note that most of the suggestions were self-referential: people said what they would do in their area at their age and in their health. I didn't even think about my constraints when I stated my problem and asked for suggestions, and it was educational to see how people answered. Fine-tuning what my situation was resulted in several fine-tuned answers, which I appreciate. (My question was just as self-referential, of course - I assumed my area, my age, and my health would be taken into account.)

Many thanks for the time and thought you've all put in - I do have a good answer, and I have good reason to re-think a couple of areas I'd discounted.