The area around Ridgecrest, California, has been hit with two big earthquakes in two days—and experts say it could feel aftershocks for up to a year. According to the U.S. Geological Survey, there have been dozens of aftershocks strong enough to be felt since Friday night’s 7.1 temblor. At least four of them were magnitude 5 or higher, which is intense enough to cause damage. Some jittery residents were sleeping outside, or in their cars, or in relief centers until damage could be assessed during daylight.