Water, water, water! You don't want to survive an earthquake just to die of dehydration! Pack one gallon PER PERSON, PER DAY. Experts say you should pack for SEVEN DAYS. Count any pets as a person.
Canned and non-perishable food. Make sure you've got enough for everybody -- for SEVEN days. If you're going to pack food that needs water added to it, pack extra water IN ADDITION to step one.
A manual can opener. Mine may look like it's electrically-powered but it's just fancy-looking, that's all. Count on having no electricity while packing!
Medicine, a first aid kit, and band-aids. Obviously.
Clothes -- lots of it. Also pack sturdy shoes (there's going to be a lot of rubble!) and rain gear just in case. Don't forget underwear!
Toilet paper, toiletries, and, ahem, "feminine hygiene products". I think you get the drift. If not: PADS. TAMPONS. Now stop blushing and move on to the next step.
Spare house and car keys. I don't think I really need to explain this. Of course, if your house and/or car is wrecked in the earthquake, then ... right. Moving along.
Blankets and/or sleeping bag. I don't know about you, but I'd rather not sleep on concrete, stone, brick, dirt, or whatever dirty place you end up sleeping in.
Portable weather radio and a flashlight. I didn't have one at hand when I made this guide but you definitely should. Excuse me while I smack myself a little and make a quick trip to Walgreens.
Money! Everyone loves money. Keep it on hand to buy whatever odds-and-ends you'll find yourself needing.
Plastic/paper disposable plates, cups, and silverware. You really don't want to be eating off the dirty, dusty ground. (I was too lazy to go downstairs for the plates and stuff so here's a cup.)
Foil. And hey, plastic wrap too. I actually didn't mean to take a picture of the plastic wrap but now that it's visible you should chuck that in too. You never know.
Paper towels! For cleaning stuff up. Try to shove this into the area where somebody else will find it so that they will be the ones to have to clean stuff, not you.
Lighters, candles, and matches. Remember -- count on having no electricity! Also yes, that is a LIGHTER, not some sort of expensive exotic mascara.
String, tape, wire, and/or rope. For obvious reasons.
Plastic bags. Again, for obvious reasons. Can you imagine not having something to just absentmindedly throw stuff into?
Maps. Yes, this is Google Maps. And that blue dot is exactly where I live. Do not make fun of/stalk me please. (You should use paper maps. Obviously.)
Pens, paper, stamps, and envelopes. Kind of self-explanatory.
Books and things to keep you occupied!
And finally, a knife or blade.
Put all of this into a large, durable pack/bag and you're set! Feel free to comment with suggestions to make your kit even better.
Remember to pack things for your pets as well! And write down any important numbers -- just in case you need to call somebody in an emergency. I hope this helped, and be safe!