Based on this crude but honest assessment of the general public's affinity for the common bicarbonate, you'd be surprised by how much survivalists are into it (#2 on the list of "things for preppers to hoard"). They must expect some pretty serious hankerings for tasty leavened baked goods, or they have extensive phobias about the funkiness of their nuke survival backup plans.
Earthquakes, tornadoes, and hurricanes can cause you to leave your home or even be trapped there. Roads could be blocked due to fallen trees, power lines, or even damaged earth from the natural disaster. Rescue crews can not be in all places at once. You may have to wait it out for quite a while before its over. You won't be able to go to the store or to the corner market.