A moderate earthquake that was followed by dozens of aftershocks jolted sleepers awake and toppled goods from store shelves Saturday.
The quake hit at 3:37 a.m. and measured 5.0, followed three minutes later by a 4.0-magnitude aftershock, said Steve Bryant, a seismologist at the California Institute of Technology in Pasadena.
Other aftershocks struck throughout the morning. No injuries or serious damage were reported.
The quakes were centered within 13 miles of the epicenter of the 1994 Northridge quake, a 6.7-magnitude shocker that killed 72 people.
For unknown reasons, April traditionally is the month with the largest recorded number of earthquakes.