Experience is a good teacher. We all learned a whole lot about what we needed in our earthquake kit after the Northridge quake in 1994. Each of us were probably the best prepared locally we certainly didn't get everything right. - survival gear
The length of time: You will need a minimum of three days worth of food, water along with other necessities in your kit. When it is a big quake you will need two weeks worth. You will need to make sure your kit is one place which there is a good chance it will be possible to get the kit following the ground stops moving. In most areas that would be outside, which can open up a lot of other conditions.
Food and Water: Be careful everything you include. If you don't prefer to eat it, don't use it in the kit. Look for large amounts of sodium, not really much because it's unhealthy but as it can make you more thirsty. Contain canned goods if you possess the space. This can often take into account some of the fluid intake needed. Soups are great because they can be mixed with many other things to come up with a tasty change from other kit food.
In terms of water, again make certain it's something you will drink. Whether or not this isn't, add some form of instant (or even tea bag) things that will turn it into something you will drink.
Ways of Food Prep: A camp stove may be useful but they make sure that there isn't a gas leak before using any fire. For the evening meal after the Northridge quake some people got out portable barbecues so we had a neighborhood cookout. This served many purposes, including helping those still in shock conquer the trauma.
Medical Needs: You will want a really good, family first aid kit. You can build it yourself but acquiring one and keeping it stocked with fresh stuff could be better. They usually have a first aid book that will help you care for any injuries. Don't forget to pack any prescriptions as well as an extra pair of glasses for those who need them.
Tools: Whatever you decide to need depends partly on the severity of the quake. You will need a means of switching off the gas meter in the event it is leaking. Some water supplies also need a wrench for this reason. Rope, duct tape, a shovel and buckets may be handy.
Stuff to complete: The power came on prior to cable did. Despite the power on, we was without a lot of light because every light bulb had gone bad due to the shaking. We were bored and scared because the aftershocks kept coming. We'd one video that we'd never seen before. I'd meant it as a gift but we ended up watching it anyway. It turned out a comedy plus it helped.
Now the kit has stuff for people to do. There are books and DVDs. There are a couple of games. If the power is out we have a generator to help make sure there's light enough (and power) to use them.
Our kit can also be outside. We have a small travel trailer that is certainly where we maintain kit. As long as nothing hits it, we will be equipped to handle up to two weeks and help the neighbors besides. - survival gear