A newly mapped 7 km (4.3 miles) segment of the Concord Fault, now identified as the Madigan Avenue strand, has been confirmed as actively creeping beneath residential neighborhoods in Concord and Walnut Creek, California.

The Concord Fault is a major branch of the Pacific–North America plate boundary system in Northern California, linking the Bartlett Springs–Green Valley Faults in the north with the Greenville and Calaveras Faults to the south. Like many faults in the Bay Area, it releases some of its long-term motion through slow, steady creep rather than sudden earthquakes.

The newly defined trace, located 170–500 m (558–1 640 feet) west of previously mapped fault lines, represents a major shift in how seismic hazard is understood in the area.