Residents of Northern California's Humboldt County were rocked by a magnitude-5.9 earthquake on Thursday, but officials said there were no immediate reports of major injury or damage from the second large temblor to hit the area within a month.
The US Geological Survey reported the quake struck at 12:20 pm (2020 GMT) about 35 miles (55 kilometers) northwest of the community of Petrolia and nearly 50 miles west (80 kilometers) of Eureka.
The shaking was felt within a 150-mile (240-kilometer) radius, as far north as southern Oregon and as far south as Sonoma County, according to the USGS Web site.
Local officials and residents reported feeling a rolling sensation that caused items to fall from walls and shelves. Humboldt County Sheriff's Office spokeswoman Brenda Godsey, who was in a restaurant at the time, said the quake lasted 25 to 30 seconds, with none of the violent jolts felt last month.
"Everybody was very calm and just sort of waited it out," she said, adding that sheriff's dispatchers received no significant calls.
Many said the movement didn't feel nearly as severe as the magnitude-6.5 quake that struck the same region January 9 and caused more than $40 million in damage and one serious injury _ an elderly woman who fell and broke her hip.
Steve Walter, a seismologist at the USGS in Menlo Park, said Thursday's quake was not an aftershock because it occurred on a different fault, but "we could speculate it might have been triggered by the one last month."
The temblor initially reported by the USGS as magnitude-6.0 but later revised to magnitude-5.9, did not trigger any tsunami warnings.
Walter said the far-northern coast of California is the most seismically active area in the state, but the potential for damage and injuries there is smaller because it is less populated.