Earthquakes are the only major natural disaster with no warning — no Watch, no Warning, no time to act before shaking begins. All earthquake preparation must be done in advance. The most critical difference between survivable and unsurvivable earthquake outcomes is the combination of where you are when it hits, what you do in the first 10 seconds, and how your building is constructed. This guide covers the specific preparedness actions that matter.
Drop, Cover, Hold On: The Only Correct Action During Shaking
The outdated “triangle of life” advice (crouch next to furniture rather than under it) is not supported by structural collapse data and has been repudiated by FEMA, USGS, and the American Red Cross. The correct protocol:
- Drop: Get on your hands and knees immediately. This protects you from being knocked down while allowing movement.
- Cover: Get under a sturdy desk or table if one is nearby. If no table is available: move to an interior wall away from windows and cover your head and neck with your arms. The most important thing to protect is your head and neck — not your whole body under furniture.
- Hold On: Hold onto the table leg if under a table. If no table: stay in place with head covered until shaking stops. The major risk is from objects falling — staying in one place prevents walking into falling debris.
Do not run outside during shaking: Most injuries occur when people attempt to move during shaking. Building facades, exterior walls, and parapets are likely to fall. The exterior of a building during an earthquake is one of the most dangerous locations.
Building Type Risk Assessment
| Building type | Risk level | Failure mode | Action |
|---|---|---|---|
| Wood-frame house (post-1980) | Low-Medium | Shifting off foundation; interior damage | Bolt house to foundation if not done |
| Wood-frame house (pre-1960) | Medium | Cripple wall collapse; foundation failure | Cripple wall bracing retrofit ($3,000–8,000) |
| Unreinforced masonry (brick/stone) | Very High | Wall failure, ceiling collapse | Seismic retrofit or evacuate during major event |
| Soft-story apartment (first floor garage) | Very High | First-floor collapse; pancaking | Many cities now require mandatory retrofit |
| Reinforced concrete (post-1980) | Low | Generally survives most earthquakes | Standard preparation |
| Mobile home | High | Slides off piers; gas line rupture | Tie-down systems; exterior gas shutoff knowledge |
Gas Shutoff Procedure
After an earthquake, a broken gas line is a serious fire and explosion risk — but do not shut off your gas unless you smell gas, hear it hissing, or see a broken line. Gas shutoff requires a utility worker to restore service — if you shut it off unnecessarily, you may be without heat and hot water for days during a utility-swamped post-disaster period.
When to shut off gas:
- You smell natural gas inside or outside the building
- You hear a hissing sound near gas appliances or the meter
- You see a broken or visibly damaged gas line
Shutoff procedure: The main gas shutoff is at the gas meter, on the pipe entering the meter. Use an adjustable wrench or a dedicated gas shutoff tool (a 4-inch crescent wrench stored near the meter in a visible location). Turn the valve 1/4 turn — the valve is off when the slot is perpendicular to the pipe.
Important: Only PG&E or your gas utility can restore service after shutoff. Call the gas company first, not a plumber, for service restoration.
Aftershock Sequencing
Aftershocks follow the main earthquake in a predictable decay sequence (Omori’s Law):
- After an M6.0 earthquake: expect 10+ aftershocks of M5.0, diminishing over days to weeks.
- After an M7.0: expect aftershocks up to M6.0 or higher. These can cause building collapse that was not triggered by the main event.
- The largest aftershock is typically 1.2 magnitude units smaller than the main quake (Bath’s Law). After an M7.5, expect at least one aftershock near M6.3.
Do not return to a damaged building until it has been inspected — aftershocks can collapse structures weakened but not destroyed by the main event.
Household Preparation: Pre-Event
Structural Mitigation
- Water heater strapping: A falling water heater breaks the gas line. The fix: two metal straps attached to the wall studs at the upper and lower thirds of the tank. Code-required in California; recommended everywhere. Cost: $15–30 in materials, 30 minutes to install.
- Secure tall furniture: Bookshelves, refrigerators, and wardrobes topple during shaking. L-brackets attached to wall studs prevent toppling. Cost: $3–5 per piece of furniture.
- Cabinet latches: Spring-loaded cabinet latches prevent cabinet doors from swinging open and contents spilling during shaking. Relevant for chemicals stored under sinks.
72-Hour Supply Kit (Earthquake-Specific)
- Water: 1 gallon per person per day × 3 days minimum (municipal water may be contaminated or off)
- Water filter (Sawyer Squeeze): For sourcing water if municipal supply is interrupted longer than 72 hours
- Food for 72 hours: No-cook shelf-stable items — utilities may be off
- Shoes stored by the bed: Broken glass and debris on floors — bare feet are a serious injury risk
- Adjustable wrench: Gas shutoff tool, stored near the gas meter
- Dust masks (N95): Demolished unreinforced masonry buildings generate concrete dust containing silica — lung hazard
- Portable battery charger + NOAA weather radio
Where to Go Next
Water storage for the post-earthquake period — tank sizing and chemical treatment — is in long-term water storage: tank sizing, rotation protocol, and chemical treatment. Emergency power for utility outages after earthquakes is in emergency power: generators, solar panels, and battery banks.
