Water supply is critical. And often the issue that causes the most problems during a major disaster. As mentioned, start with a supply of bottled water. There are many sources for water, but few, if any, you can trust during a major disaster. A large supply of fuel to boil water and cook food may also become a problem over time. The last layer of water survival preparedness would be a hand operated water filtration pump. Even the small filtration pumps backpackers use can keep you alive for weeks.
Time to buy MRE's, Check out Steve1989 on UTube . Whatever you do, never buy Chinese rations. He liked British, Canadian, US, French, Italian,Portugese and Russian products.
Also Most common injury during earthquakes are from glass. Have slippers or shoes by your bed. Keeping family together is most important, choose an A, B and C location to meet. Duct tape, sewing kit, zip ties and superglue are very handy too. Emergency blankets (the reflective ones) are cheap and useful. Contractor bags are great for keeping gear dry, makeshift shelters, water storage and much more but they are light weight and affordable. I keep them in my car, garage, pantry and emergency kit. Used from my car when last year when I needed to put chains on when it unexpectedly snows on a vacation. Kept me dry. Booze or weed. Whatever your fancy, nice to take the edge off after a day or so of stress. Also tradable If you have extra antibiotics great, otherwise tell your doctor you will be traveling somewhere remote and need a precautionary prescription. Don’t tell them somewhere that will require other shots or medications. Store in a cool, dry place. Those are a few additional items.
Being prepared for a big earthquake and several days or even weeks of massive chaos is not the same as preparing for the Zombie Apocalypse. Although having a firearm won’t hurt, it most likely won’t be necessary. However, many of us do have forearms. A massive earthquake will not mean the end of society, just immediate devastation. FEMA, the national guard and many private organizations will come to our aid and the rule of law will matter.
I double checked the expiration on my Mountain house packages and many are good until 2043-2047! Kind of crazy to think I’ll almost be 60 years old when they expire!! I started out by buying ~10 of them when they were on sale, and continued to buy a few here and there whenever I saw them on sale.