Earthquake Gas Shutoff: When to Turn Off Gas and How to Do It

Fire causes more earthquake loss than shaking does — San Francisco 1906, Kobe 1995, and the Cypress-structure fires after Northridge all started the same way: a cracked gas line met a spark. The fix is ten seconds with the right wrench, but only when the smell tells you to.

The short answer: shut off the gas only if you smell gas (rotten-egg odor), hear a high hissing near the meter or an appliance, or see severe damage to a gas line or the house. Otherwise leave it on — restoring a needlessly shut-off line takes a utility crew and can leave you without heat for days. When you do shut it off, make one 90-degree quarter-turn of the meter valve so the bar sits crosswise to the pipe, and don't try to turn it back on yourself.

If you've walked your home before a quake — anchored furniture, strapped the water heater, cleared exits — this is the same pre-walk. Details for the full setup are in how to prepare your home for an earthquake.

When to shut it off — and when NOT to

California utilities, FEMA, and the USGS agree. Tape this list inside the meter box.

Shut it off if you notice ANY of these after shaking:

• Strong sulfur/rotten-egg odor, inside or outside.
• Hissing near the gas meter, a stove, or the water heater.
• Dead houseplants, white dust, or dust blowing from a line.
• The house has shifted, the foundation is cracked, or a gas appliance has toppled.

Leave it ON if:

• You feel a quake but smell and hear nothing, and the building looks intact. Most quakes at intensity V–VI need no shut-off; a needless one adds a days-long wait for restoration.
• A neighbor says "just turn it off to be safe." Utility guidance is explicit: only the affected building's valve, and only on evidence.
• You can't safely reach the meter because of debris, a leaning wall, or a downed line — evacuate and call from outside instead.

Once you shut the main valve, don't restore it yourself. Gas crews must purge air, relight pilots, and check for leaks.

Find the valve before the quake

In single-family homes the meter is usually on an exterior wall near the street; in apartments it's in a utility closet or basement. Look for a raised cast-iron or brass valve with a flat rectangular bar on the pipe before the meter dial, plus a second valve at each indoor appliance.

Put the wrench where you can reach it without searching in the dark:

• A Prime-Line PH 17106 Gas Shut-Off Wrench (~$11, single-piece steel, fits the standard 1/4-turn bar) zip-tied to the meter pipe or hung on a nail at eye height next to the meter. Don't bury it in a toolbox — aftershocks dust everything and flashlights roll.
• A backup in the garage near the water heater, since a toppled heater is the most common leak source. If you strapped the heater per our home-prep checklist, you're already ahead.

How to turn it off in 10 seconds

Practice once — with gas on and no leak — so the motion lives in your hands. Then leave the valve alone.

1. Smell and listen. Crouch low near the meter. If you detect odor or hiss, proceed.
2. Fit the wrench square on the bar. The Prime-Line PH 17106 Gas Shut-Off Wrench seats on all four flats — no adjustable jaw to slip when your hands shake.
3. Quarter-turn clockwise until the bar sits perpendicular (crosswise) to the pipe. Along the pipe is on; across is off. One firm turn — don't force past 90 degrees.
4. Leave it there. Hang the wrench back on the pipe and get outside.
5. No spark sources. Don't flip switches, unplug appliances, use a phone near the leak, or light a flame. Report from upwind or a neighbor's line.

Apartments and condos: many share a manifold — shutting the building main cuts gas to every unit. If only your unit smells, shut the appliance valve first; if the odor persists or is at the manifold, use the main and alert the manager.

What about automatic shut-off valves?

Seismic excess-flow valves (EFVs) trip on a big flow surge. Useful, but not a substitute: they can trip on a strong aftershock with no leak (a false shut-off you still need a tech to reset), and they can miss a slow crack that fills a crawl space over hours. Older meters often lack one — check your meter's tag. Think of an EFV as a seatbelt and the wrench as the steering wheel.

The first 10 minutes after any shake

1. Drop, cover, and hold on until shaking fully stops (full drill in what to do during and after an earthquake).
2. Shoes on, radio on — a Midland ER310 Emergency Radio tells you whether to stay or evacuate before cell towers jam.
3. Smell for gas, listen for hiss, glance at the water heater — shut off only on evidence.
4. If you shut off, kill small fires with what you have, but get out if smoke is beyond a wastebasket.
5. Text family (texts queue better than calls when networks congest); check on neighbors who may not smell mercaptan.

Power, light, and water when gas stays off

A shut-off means no stove, no furnace, and sometimes no hot water until the utility clears you.

• Light: A solar lantern like BioLite Luci Emergency Lantern charges by day and runs all night without fuel.
• Power: The EcoFlow RIVER 3 Portable Power Station (245 Wh) keeps phones and radio going for days.
• Water: A Reliance Aqua-Tainer 7 Gallon Water Container (7 gal) covers the days when the water utility also runs slow after a seismic event.

Common mistakes

• Shutting off "just in case" after every felt quake — then waiting 2–5 days for a tech like thousands of neighbors who did the same.
• Storing the wrench indoors. The meter is outside — the tool belongs outside.
• Using pliers or an adjustable wrench that rounds the bar. A fitted wrench costs ~$11 and doesn't slip.
• Trying to relight pilots yourself. Leave restoration to the crew.

Quick recommendations

• First buy: Prime-Line PH 17106 Gas Shut-Off Wrench — ~$11, lives on the meter
• Stay informed: Midland ER310 Emergency Radio — NOAA alerts when phones fail
• See at night: BioLite Luci Emergency Lantern — solar light, no fuel
• Backup power: EcoFlow RIVER 3 Portable Power Station — phones and radio for days

Walk out tonight, find the meter, fit the wrench, picture the quarter-turn. That 60-second rehearsal is the whole skill.

Sources: FEMA Ready.gov gas-shutoff guidance, USGS earthquake safety handbooks, SoCalGas and PG&E shut-off instructions (2024–2026). Confirm your valve type with your local gas utility — shapes vary by region.