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USGS earthquake hazard maps — when separate earthquake insurance is worth it

Earthquake damage is excluded from every standard US homeowners policy. USGS's National Seismic Hazard Map shows the probabilistic ground-shaking risk per county — and tells you whether the $200-1,500/year for separate earthquake insurance is worth it.

Published 2026-04-25 · Last reviewed 2026-07-03 · methodology

What USGS publishes

The National Seismic Hazard Maps (NSHM) were last updated in 2023. They show the probabilistic peak ground acceleration (PGA) at the 2%-in-50-years return period — basically: 'how strong could an earthquake be at this location every 2,500 years on average.'

Public access: usgs.gov/programs/earthquake-hazards/hazards. Searchable by ZIP. Outputs the PGA value (in %g, fraction of gravity).

PGA <0.1g: trivial risk (most of the central US east of the Rockies). PGA 0.1-0.4g: meaningful risk (parts of TN/MO/AR/SC). PGA >0.4g: significant risk (CA, AK, WA west, OR west, parts of UT, MT, NV).

Why separate insurance

Standard homeowners (HO-3, HO-5) policies EXCLUDE earthquake damage in every state. This is universal — there's no insurer or state where it's bundled by default.

Required: an Earthquake Endorsement OR a separate earthquake-insurance policy. In CA: most policies are written through the California Earthquake Authority (CEA), a public-private pool.

Premium drivers: location PGA (the USGS number), structure type (masonry vs wood-frame), foundation (cripple-wall vs slab), age, retrofit status.

Cost reality

Annual premiums vary 10-100x by zone. CA hillside masonry: $2,000-5,000/year. Inland WA wood-frame newer build: $400-800/year. Central TN moderate-risk: $200-400/year.

Deductibles are HIGH: typically 10-25% of dwelling-coverage value. On a $500k home: a $50,000-125,000 deductible. Earthquake insurance is for catastrophic loss, not minor cracks.

When it's worth it

PGA ≥0.3g + masonry/older home + you'd lose the home if it collapsed = strong case for coverage.

PGA ≤0.1g (most of the central + eastern US, except a strip from TN to SC and MO bootheel) = generally not worth it.

Mortgages don't typically require earthquake insurance even in high-risk zones (unlike flood). But if you're paying cash + own outright in a high-PGA zone, the math depends on your risk tolerance.

What zipradar shows

We don't currently federate USGS earthquake hazard data per ZIP — this is on the Q4 2026 roadmap. For now, USGS direct (usgs.gov/programs/earthquake-hazards) is the authoritative source.

Wildfire + flood + radon are federated; earthquake adds an important fourth natural-hazard dimension when shipped.