What is the earthquake risk in San Francisco?

San Francisco has the highest urban earthquake risk in the United States. The city sits directly on the San Andreas Fault (which runs through the Peninsula). USGS estimates a 72% probability of a M6.7+ earthquake in the Bay Area within 30 years. The Hayward Fault (east of SF) is also considered capable of M7.0+ and is overdue. The 1906 San Francisco earthquake (M7.9) and Loma Prieta 1989 (M6.9) are the most significant modern events.

What is liquefaction and how does it affect SF property?

Liquefaction occurs when saturated soil temporarily loses strength during shaking and behaves like a liquid. San Francisco has extensive liquefaction hazard zones — particularly in the Marina District, SoMa, Mission Bay, and the Embarcadero — areas built on Bay fill. During Loma Prieta 1989, the Marina District liquefied and numerous buildings collapsed. Liquefaction zones are mapped by CGS and should be checked for any SF property on filled land.

Which SF neighborhoods have highest earthquake risk?

The Marina District and Pacific Heights (built on Bay fill) have the highest liquefaction risk. SoMa, Mission Bay, and Treasure Island are also high-risk fill areas. The Sunset and Richmond Districts on sandy soils also amplify shaking. The safest areas geologically are Nob Hill, Russian Hill, and Twin Peaks — bedrock areas with the least amplification.

Does SF have flood risk in addition to earthquake risk?

Yes. Mission Bay, Treasure Island, and low-lying SOMA areas carry FEMA flood zone designations. Sea level rise projections for the Bay are significant — SFPUC estimates 3-4 feet by 2100 in some scenarios. The combination of liquefaction risk, tsunami potential from Bay area faults, and sea level rise makes risk stacking on SF waterfront properties a significant concern.

What is the 1906 San Francisco earthquake significance for current property buyers?

The 1906 earthquake (estimated M7.9) destroyed 28,000 buildings and killed 3,000+ people. Most of SF was rebuilt after 1906, meaning many pre-WWII buildings exist. These are not seismically designed to modern standards. Any building constructed before the 1973 Uniform Building Code adoption should be assessed for seismic compliance, and pre-1980 soft-story buildings are subject to SF's mandatory soft-story retrofit ordinance.

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Property Risk in San Francisco
The Big One is Overdue

USGS gives a 72% probability of M6.7+ in the Bay Area within 30 years. San Francisco sits on the San Andreas Fault and has 40% of its area on liquefaction-prone fill. The 1906 (M7.9) and 1989 Loma Prieta (M6.9) set the baseline — the next major event will be larger.

⚡ EXTREME SEISMIC · SAN ANDREAS DIRECT · 72% PROBABILITY

72%

Chance M6.7+ Bay Area / 30 yrs

40%

SF on liquefaction-prone fill

M7.9

1906 SF earthquake magnitude

San Francisco Seismic Profile

EXTREME — Highest US Urban Seismic Risk

USGS / CGS / California Building Code

LIVE API

Primary faultSan Andreas — runs through the Peninsula · M7.9 in 1906

Secondary faultHayward Fault — east side · M7.0+ overdue · 1868 last event

Liquefaction risk40% of city on Bay fill — Marina, SoMa, Mission Bay

Last major eventLoma Prieta 1989 — M6.9 · Bay Bridge collapse · Marina fire

Soft-story retrofitSF Mandatory — Ordinance 152-13 · 3,000+ buildings

Flood riskMedium — Mission Bay FEMA AE · Sea level rise Bay exposure

SF Neighborhoods — Risk by Area

Marina District

Extreme — Liquefaction

Built on Bay fill. Liquefied in 1989. Buildings collapsed. Still highest liquefaction zone.

SoMa / Mission Bay

Very High — Fill + FEMA AE

Bay fill + FEMA flood. Tech hub. New construction better, but site risk remains.

The Mission

High — Soft soils

Sandy soils amplify shaking. Many pre-1980 wood-frame buildings. High soft-story backlog.

Nob Hill / Russian Hill

Lower — Bedrock

Bedrock reduces amplification. Premium location. Still seismically active zone — but best geology in SF.

Sunset / Richmond

High — Sand dunes

Built on sand dunes. Significant amplification. Pre-1940 stock common.

Potrero Hill / Bernal Heights

Moderate — Mixed

Partially on bedrock. Better than Marina/SoMa. Post-1990 newer stock in some parts.

Twin Peaks / Glen Park

Lower — Bedrock

Bedrock hills. Less amplification. Lower density. Wildfire interface risk (different hazard).

Treasure Island

Extreme — All fill

Entirely artificial fill. Sea level rise. Liquefaction. Remediation ongoing. Very high long-term risk.

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FAQ — Earthquake Risk in San Francisco

SF has the highest urban earthquake risk in the US. USGS estimates 72% probability of M6.7+ in Bay Area within 30 years. The San Andreas runs through the Peninsula; the Hayward Fault east of the Bay is considered overdue for a M7.0+ event. The 1906 SF earthquake (M7.9) destroyed the city; Loma Prieta 1989 (M6.9) caused $10B damage.

Liquefaction occurs when saturated fill soil loses strength during shaking and behaves like liquid. SF has extensive liquefaction zones — Marina District, SoMa, Mission Bay, and Embarcadero — all built on Bay fill. The Marina liquefied in 1989 and buildings collapsed. CGS maps these zones; always check before purchasing SF waterfront or low-lying properties.

Bedrock areas have the least seismic amplification: Nob Hill, Russian Hill, Twin Peaks, Bernal Heights. Avoid Bay fill areas (Marina, SoMa, Mission Bay) and sandy soil areas (Sunset, Richmond) for lowest risk. There is no zero-risk location in SF — but bedrock neighborhoods perform significantly better in major events.

SF Ordinance 152-13 requires seismic retrofit of wood-frame soft-story buildings (apartments with open parking at ground level). ~3,000 buildings are covered. Deadlines have been phased by building size. Always verify if a pre-1980 soft-story building has completed its mandatory retrofit before purchasing — non-compliant buildings carry structural and insurance risk.

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