"Overview: Lessons And Recommendations From The Committee For The Symposium On Practical Lessons From The Loma Prieta Earthquake"
One can expect electrical power outages for a day or three after a significant seismic event -
Lesson 27: Power outages in downtown San Francisco lasted several days following the earthquake due to the need for time-consuming inspections of major buildings for gas leaks and ignition sources prior to energizing the downtown power grid. This was the largest single source of business interruption resulting from the Loma Prieta earthquake.
If the route 'home' compels travel through (rather than across and out of) the area of power failure, any hike longer than a couple of hours is likely to find such small stores closed (and probably defended).