First off there are no earthquakes where I live, two little tremors is all anyone in my living family can remember. Second my primers are split into three locations. 2/3rds at home and 1/3rd at work. All are in OSHA explosion proof fire lockers. Each fire locker has a automatic fire suppression head above it as does my bench. At each end of every bench is a 4.75 pound DuPont FE-36 Clean-Agent fire extinguisher. My powder is split into two locations of which each are also OSHA explosion proof flammables cabinets with automatic fire suppression units overhead. If you put your guns in fire proof vaults, your flammable components should be in an OSHA approved locker.
The four motorcycles in the garage are much more likely to cause fire problems than primers or powder. That said, also a fire suppression system in garage and a 2 pound real Halon extinguisher in each bikes saddle bags along with two additional 9 pound DuPont FE-36 extinguishers mounted on opposite walls. If you park your hot car full of fuel in your garage that is much more dangerous than any amount of my primers. Add to this, the local fire department (as most will) come out once every five years and update my fire plan for both my business and home. You will notice most fire trucks have computers on board now. If you get a free fire plan done, they put a diagram of your structure in the computer with key flammable locations, contents and places persons could likely be found into their system. They know what to look for and where before they show up. I have monitored alarm with fire detectors everywhere and am located four miles from my local fire station. The one time a smoke head went off at the house they were on scene within 8 minutes and actually caught a smoldering electrical short in a bad lamp before it flamed. They were happy to come and glad they had a fire plan to review on the way. It showed them where the exterior electrical disconnect is which is first thing they did. Which door is the only one that is not force entry rated so they didn't waste time entering nor mess up any 800 dollar doors, where the flammables are located and what they are. I arrived five minutes later to see a smoking lamp in the front yard and a bunch of happy fire fighters that had been bored up till they got to kick in my door. Security has multiple components which a good fire plan is as important as your alarms, safes, dogs and guns to fight off invading hoards looking for the primers. haha. When you get home tonight, look around... Where is the closest extinguisher? When was the last time it was inspected? Is it a quality unit? Do you have enough? I bet if a home invader kicks in your door tonight as you sleep you have a gun close at hand. If you wake up surrounded by flames, is the extinguisher as close and does it work? Do you have enough to fight your way to the kids and then fight your way out to safety? Remember extinguishers are just an escape tool in a real fire. YMMV, IMHO and all other disclaimers apply.