I had an earthquake kit for years, in the shed. Once we got our
motorhome it became our earthquake kit on wheels (heehee). It took many, many, MANY, hours of planning, shopping, assembling of that shed earthquake kit...I was very thorough in my prep. It actually took me over a month to shop for everything (hardware stores, grocery, pharmacy, etc). Also keep in mind that you must annually check the kit and rotate in new canned food, water, and other items to keep them fresh. It was a pain to accomplish but gave me peace of mind to have the kit on hand, just in case.
There are some great earthquake kit lists on the internet...you can decide how detailed and extensive you want to go, depending on the amount of storage space you have.