Shutting Off Your Gas
If you smell gas or see your gas meter spinning rapidly, you need to shut off your gas valve.
If you do not smell gas and your gas meter is not spinning rapidly, then you should not shut off your gas valve.
If you shut off your gas valve unnecessarily, then your pilot lights go out. If you then turn your valve on again, your pilot lights are unlit — and if they remain unlit the gas from them becomes a fire hazard.
Be sure that every adult resident of your house knows how and when to shut off your gas valve.
Most homes have a manual gas shutoff valve in the gas line next to the outside gas meter. Manual valves look like this:
If your valve is manual, store a wrench suitable for switching the valve next to it.
If you are concerned that someone may take your gas valve wrench, you may wish to bury it just underneath the gas meter.
Some homes have an automatic gas shutoff valve which shuts off in case of a significant ground motion. If your valve is automatic, be sure you know how to manually switch it off and on.
If you want to change your valve from manual to automatic, one source is the Vanguard Earthquake safety valve. Ehret plumbing in Berkeley installed this kind of valves for a number of ECR residents in 2002.