Earthquake Risk by Zip Code: How to Check Your Seismic Hazard Level

Over 500,000 detectable earthquakes occur worldwide each year, according to the USGS National Earthquake Information Center. While most are too small to feel, the United States experiences roughly 50 earthquakes per day that are large enough to be recorded — and about 16 per year cause significant damage.

If you live in a seismically active region, your earthquake risk by zip code determines everything from building code requirements to insurance premiums to whether you need earthquake retrofitting. This guide explains how seismic hazard is assessed, where to look up your risk level, and what to do with that information.

How Is Earthquake Risk Measured?

Earthquake risk isn't a single number. Seismologists and engineers evaluate it through several complementary frameworks:

Seismic Hazard Maps

The USGS National Seismic Hazard Model calculates the probability of ground shaking at every location in the US. The model incorporates:

• Fault geometry — known active faults, their length, depth, and slip rate
• Historical seismicity — recorded earthquake catalogs going back centuries
• Geological data — paleoseismic trench studies, tectonic plate movements
• Ground motion models — how seismic waves attenuate with distance from the fault

The result is a map showing the Peak Ground Acceleration (PGA) that has a 2% probability of being exceeded in 50 years — roughly a 1-in-2,500 year event. This is the standard used in building codes.

FEMA National Risk Index

FEMA's National Risk Index (NRI) assigns every US county an earthquake risk score from 0 to 100. This score factors in:

• Expected Annual Loss (EAL) — the dollar value of building and population loss expected per year from earthquakes
• Social Vulnerability — how well a community can prepare for and recover from a disaster
• Community Resilience — the capacity to bounce back after an event

You can check your county's NRI score using ProtectMyZip's environmental risk tool, which pulls FEMA earthquake data alongside other hazard factors.

USGS Seismic Zones: What They Mean

The USGS doesn't assign "zone numbers" to zip codes directly. Instead, it produces probabilistic hazard curves — graphs showing the likelihood of different shaking intensities at each location. However, building codes historically simplified this into seismic design categories:

Category	PGA Range (%g)	Risk Level	Typical Regions
A	< 5	Very Low	Florida, parts of the Midwest
B	5–20	Low	Most of the eastern US
C	20–50	Moderate	Pacific Northwest, Wasatch Front
D	50–100	High	Most of California, Nevada
E/F	> 100	Very High	Southern California faults, New Madrid zone

Note: The International Building Code (IBC) uses Seismic Design Categories (SDC) A through F, which consider both the hazard level and the soil type at the building site. Soft soils amplify shaking, so two buildings with the same PGA but different soil conditions may receive different design categories.

How to Check Earthquake Risk by Zip Code

Method 1: USGS Hazard Map (Free)

The USGS Unified Hazard Tool (earthquake.usgs.gov/hazards) lets you enter coordinates or a location name and retrieve the full seismic hazard curve. You'll see the probability of different shaking levels over 50 years, 100 years, or any custom time period.

Steps:

• Go to earthquake.usgs.gov/hazards
• Click on the interactive map or enter your zip code coordinates
• Select your edition (2023 is current for the conterminous US)
• View the hazard curve — this shows the annual probability of exceeding each PGA level
• Compare against the building code thresholds in the table above

Method 2: ProtectMyZip Risk Report (Free)

Enter your address or zip code on ProtectMyZip's risk report tool for an instant earthquake risk score. The tool aggregates USGS seismic data alongside FEMA hazard assessments and presents a single 0–100 risk score with a breakdown of contributing factors.

Method 3: State Geological Survey

Many states have their own geological surveys with more detailed local earthquake maps. These are especially valuable in:

• California — The California Geological Survey publishes Alquist-Priolo Earthquake Fault Zone maps showing where surface fault rupture is likely. Check California risk data.
• Washington — The Washington Geological Survey maps Cascadia Subduction Zone hazards and liquefaction susceptibility.
• Utah — The Utah Geological Survey provides detailed Wasatch Fault maps and liquefaction potential maps.
• Tennessee — The Tennessee Geological Survey monitors the New Madrid Seismic Zone, which produced the largest earthquakes in US history in 1811–1812.

Major US Earthquake Zones

West Coast

The San Andreas Fault system in California generates the highest-profile earthquake risk in the US. The southern segment, near Los Angeles, has a 60% probability of a magnitude 6.7+ earthquake in the next 30 years according to the USGS Uniform California Earthquake Rupture Forecast (UCERF3).

The Cascadia Subduction Zone off the coast of Washington, Oregon, and Northern California can produce magnitude 9.0+ earthquakes. The last one, in January 1700, generated a tsunami that reached Japan. Geologic evidence shows these events recur roughly every 250–500 years.

New Madrid Seismic Zone

Centered near the Missouri-Tennessee-Arkansas border, the New Madrid zone produced three magnitude 7.5–8.0 earthquakes in the winter of 1811–1812. These quakes rang church bells in Boston and collapsed buildings in St. Louis. The USGS estimates a 25–40% chance of a magnitude 6.0+ earthquake in the zone by 2050.

Eastern Tennessee Seismic Zone

The second most active seismic zone east of the Rockies, stretching from northeastern Alabama through eastern Tennessee into southwestern Virginia. Earthquakes here tend to be smaller (typically magnitude 2–4) but occur frequently.

Wasatch Fault Zone

Stretching 240 miles along Utah's Wasatch Range, this fault poses significant risk to the Salt Lake City metropolitan area. The Utah Geological Survey estimates a 57% probability of a magnitude 6.0+ earthquake on the Wasatch Fault in the next 50 years.

What Your Earthquake Risk Means for Your Home

Building Code Requirements

If you live in Seismic Design Category C or higher, your local building code requires earthquake-resistant construction for new buildings. This includes:

• Bolted foundations — sill plates anchored to the concrete foundation with expansion bolts
• Cripple wall bracing — plywood shear panels on the short walls between foundation and first floor
• Soft-story reinforcement — steel frames or shear walls on ground floors with large openings (garage doors, storefronts)
• Water heater strapping — securing water heaters to prevent gas leaks and fires

Earthquake Insurance

Standard homeowner's insurance does not cover earthquake damage. You need a separate earthquake insurance policy or endorsement. Key facts:

• Average premium in California: $800–$2,500/year depending on construction and proximity to faults
• Typical deductible: 10–25% of the coverage amount (not a flat dollar amount)
• Covers: structural damage, personal property, additional living expenses
• Does not cover: flood damage from tsunamis or dam failures (requires separate flood insurance)

In San Francisco and other high-risk Bay Area cities, earthquake insurance premiums can exceed $5,000/year for older unreinforced homes.

Retrofitting Older Homes

If your home was built before 1980 in a seismically active area, it likely lacks modern earthquake-resistant features. A basic seismic retrofit costs $3,000–$7,000 and includes foundation bolting and cripple wall bracing. More extensive retrofits for soft-story buildings can run $20,000–$60,000.

FEMA's Hazard Mitigation Grant Program provides federal funding for earthquake retrofitting in qualifying communities. Check with your local emergency management agency for available programs.

Real-Time Earthquake Monitoring

The USGS operates the Advanced National Seismic System (ANSS), a network of over 7,000 seismic stations nationwide. Earthquakes are detected and reported automatically, usually within 2–5 minutes of occurrence. You can monitor real-time activity at earthquake.usgs.gov.

The ShakeAlert earthquake early warning system, operational on the West Coast since 2021, can send alerts to your phone seconds before strong shaking arrives. The system uses the speed difference between P-waves (fast, less damaging) and S-waves (slow, destructive) to give advance warning.

Preparing for Earthquakes

Regardless of your zip code's risk level, the FEMA Ready campaign recommends:

• Secure heavy furniture and appliances to wall studs
• Store emergency supplies: water (1 gallon per person per day for 3 days), non-perishable food, first aid kit, flashlight, battery-powered radio
• Know how to shut off gas, water, and electricity
• Practice "Drop, Cover, and Hold On" drills
• Identify safe spots in every room: under sturdy desks, against interior walls

For a complete earthquake preparedness checklist, visit FEMA's Ready.gov/earthquakes. To check your specific location's risk score now, enter your address in ProtectMyZip and get a free environmental risk report.