Scientists warned California’s biggest faults were under stress. Then the ground shook

Scientists warned California’s biggest faults were under stress. Then the ground shook

A magnitude 5.6 earthquake struck Northern California on Wednesday, marking the region’s strongest earthquake since 1940 and renewing attention to a recent study that found Southern California’s two largest fault systems are carrying the highest stress levels in at least 1,000 years. The U.S. Geological Survey placed the epicenter about 7 miles northwest of Willits in Mendocino County. The quake struck at a depth of roughly 5 miles. Officials sa…