Since Christchurch had our Big Quake, I have amended my EDC to include cash. When the power goes down, the only means of procuring goods is by cash or barter (plus the kindness of strangers and the likes of the Red Cross). I also learned that a cell phone is pretty useless in this situation for communication, as a) the lines are over-loaded, and b) the back-up power on cell towers is only a couple of hours. A landline or sat phone (ham radio/walkie talkie??) are the only things that can keep you in contact with the outside world in such a case. And trust me, being able to contact friends and family who are far away is important. You can hardly imagine how much they fret when they hear a disaster has struck your area and they don't hear from you for days.
Other than that, a flashlight has got a lot of use in the last two years. I have used it many times when the power goes off during aftershocks. I always have a dynamo-solar radio/flashlight/cell phone charger near by too, but not literally on me at all times. It is good to know in advance which radio stations emergency services use to communicate on too. Likely your local stations will be off air, so find out which stations might be used in nearby areas for updated local information. I would say that, in a real disaster situation, keeping yourself informed of things like evacuation centers, sources of food, water, medical treatment etc may be more important than having a knife or e-reader handy.
But I also live in an area of the world where the weather is unpredictable. I always have a raincoat with me! Quite handy when you have a fire alarm at work and it is pouring outside...
But hey, this has nothing to do with backpacking.