For the Valley 31 years later, the 1994 Northridge earthquake was a defining moment, testing the resilience of its residents and the strength of its community institutions.

N​early 75% of the country is at risk for a potentially damaging earthquake, according to a recently updated USGS map.

In the massive, 6.7-magnitude shake ... “In the wake of the Northridge earthquake, Mayor Riordan set the standard for emergency action,” she said last year, acknowledging the quake’s ...