Fault Line Map of the United States
An interactive map of the major active earthquake fault lines across the U.S., drawn directly from the USGS Quaternary Fault and Fold Database. Click any fault for details — or check the seismic risk at any address.
How to read this fault map
Each colored line is a mapped fault — a fracture in the Earth's crust where rock on either side has moved. The lines come from the U.S. Geological Survey's Quaternary Fault and Fold Database, the national catalog of faults believed to have been active in the last 2.6 million years. This map highlights the active ones: faults slipping at least one millimeter per year, which are the faults that drive most of the country's modern earthquake hazard.
Red lines are the fastest-moving faults (more than 5 mm per year) — the San Andreas, the Cascadia megathrust offshore of the Pacific Northwest, the Denali fault in Alaska. Orange lines slip more slowly, between 1 and 5 mm per year, including much of the Wasatch fault, the San Jacinto zone, and the Newport–Inglewood fault under Los Angeles. Click any line to see its name and slip rate, then jump straight to a full seismic risk report for that exact spot.
Why some famous faults don't appear as lines
The most important seismic zone in the central United States — the New Madrid Seismic Zone, source of the violent 1811–1812 earthquakes — does not show up as a bold line here. That is not an omission: New Madrid's faults are buried thousands of feet beneath the sediment of the Mississippi embayment and have almost no expression at the surface, so the USGS does not map them as continuous Quaternary fault traces. Earthquakes do not require a visible fault line at the surface. Large parts of the eastern U.S. carry real seismic hazard from faults that have never broken the ground in a way geologists can map.
The full USGS database catalogs more than 100,000 fault sections, most of them slow-moving or with no measured slip rate at all. This map deliberately shows only the active subset — roughly 33,000 mapped fault segments across more than 120 named fault systems — so the picture stays readable instead of becoming a solid smear across the West.
Check the faults near you
Click any fault on the map, or enter an address above, to generate a free seismic risk report: peak ground acceleration, seismic design category, the nearest mapped faults, and recent earthquakes within 100 km. You can also browse by state for geological background and notable historic earthquakes.
Browse Fault & Earthquake Risk by State
About this data
Fault geometry is sourced from the USGS Quaternary Fault and Fold Database of the United States (National Database layer). Lines are simplified for web display; for engineering, surveying, or legal use, consult the original USGS records. Faults are colored by their documented slip rate. This map is for informational purposes only and is not a substitute for a site-specific geotechnical or seismic hazard assessment.