SAN FRANCISCO · CALIFORNIA · USA · SEISMIC RISK INTELLIGENCE

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

D
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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