Fault Lines in the United States
See the major U.S. earthquake faults below — and check the seismic risk, design category, and nearest fault lines for any address, free, using USGS data.
Major Fault Lines in the United States
The USGS Quaternary Fault and Fold Database catalogs more than 100,000 fault sections across the country. These are the major fault lines and seismic zones that drive earthquake risk in the United States — enter an address above to see the faults nearest you.
San Andreas Fault
The ~800-mile transform boundary between the Pacific and North American plates, running nearly the length of California. Source of the 1906 San Francisco (M7.9) and 1857 Fort Tejon earthquakes. California →
Hayward Fault
A right-lateral strike-slip fault through the densely populated East Bay (Oakland, Berkeley, Hayward). It last ruptured in 1868 and is considered one of the most dangerous urban faults in the country. California →
Cascadia Subduction Zone
A roughly 700-mile offshore megathrust running from Northern California to British Columbia, capable of magnitude-9 earthquakes. Its last full rupture was in 1700. Washington → · Oregon →
New Madrid Seismic Zone
The most active seismic zone in the central U.S., spanning Missouri, Arkansas, Tennessee and Kentucky. It produced the powerful 1811–1812 earthquake sequence. Missouri →
Wasatch Fault
A ~240-mile normal fault along the western base of Utah's Wasatch Range, running directly through the Salt Lake City corridor. Utah →
San Jacinto Fault Zone
One of the most seismically active fault systems in Southern California, branching southeast from the San Andreas through the Inland Empire. California →
Denali Fault
A major strike-slip fault arcing across interior Alaska. It ruptured in the 2002 magnitude-7.9 Denali earthquake, one of the largest on land in North America. Alaska →
Newport–Inglewood Fault
A fault zone running through the Los Angeles basin that produced the destructive 1933 Long Beach earthquake (M6.4). California →
What you'll learn
Seismic Hazard Level
Peak ground acceleration, seismic design category, and what it means for your property in plain English.
Recent Earthquakes
Earthquakes within 100 km of your location in the past year, with magnitudes and distances.
Building Code Impact
ASCE 7-22 seismic design parameters that determine construction requirements in your area.
Browse by State
Frequently Asked Questions
How do I know if my house is in an earthquake zone?
Enter your address in the search box above. We'll query USGS seismic hazard data and show your location's Peak Ground Acceleration (PGA), Seismic Design Category, and any recent earthquakes nearby. Every location in the US has some level of seismic hazard — the question is how much.
What is Peak Ground Acceleration (PGA)?
PGA measures the maximum ground shaking expected at a site during a design-level earthquake, expressed as a fraction of gravity (g). A PGA of 0.10g means the ground could accelerate at 10% of gravity. Higher PGA means stronger expected shaking and more stringent building requirements.
What is a Seismic Design Category?
Seismic Design Categories (A through F) are assigned by building codes based on ground shaking intensity and soil conditions. Category A has minimal requirements, while Categories D through F require increasingly stringent structural design to resist earthquake forces. Most of California is Category D or higher.
Do I need earthquake insurance?
Standard homeowner insurance does not cover earthquake damage. Whether you need a separate earthquake policy depends on your location's risk level, your home's age and construction type, and your financial situation. Locations with PGA above 0.20g should strongly consider it. Our reports can help you assess your risk level.
Where does this data come from?
All data comes from the United States Geological Survey (USGS). Seismic hazard parameters use the ASCE 7-22 Seismic Design Maps API. Earthquake events come from the USGS FDSN earthquake catalog. We query USGS in real time — nothing is modified or interpreted beyond plain-English explanations.
Understanding Your Earthquake Risk
Every location in the United States has some level of earthquake risk. The USGS maps seismic hazard across the country using decades of earthquake records, fault studies, and ground motion models. FaultLineMap.com makes this data accessible by turning complex engineering parameters into plain-English risk reports for any US address.
Earthquake risk depends on more than just proximity to a fault line. Soil conditions, building age, construction type, and local geology all affect how much damage an earthquake can cause. A moderate earthquake on soft river sediments can do more damage than a larger one on solid bedrock. That's why site-specific data matters more than regional generalizations.
Who Uses Earthquake Risk Data
Homebuyers researching a new area, homeowners considering earthquake insurance, real estate agents preparing property disclosures, and builders checking seismic design requirements all need access to location-specific seismic hazard data. Our reports pull directly from the same USGS data that engineers use for building code compliance, presented in a format anyone can understand.
Seismic Design Categories and Building Codes
The ASCE 7-22 standard assigns every US location a Seismic Design Category from A (minimal risk) to F (highest risk). These categories determine how buildings must be constructed to resist earthquake forces. Categories D through F, common in California, the Pacific Northwest, and parts of the Intermountain West, require the most stringent structural design. Even areas traditionally considered low-risk, like parts of the Midwest near the New Madrid Seismic Zone, can carry higher design categories than residents expect.