A powerful magnitude-6.9 earthquake struck in the Pacific Ocean off the California coast early Monday, the United States Geological Survey reported.

The quake hit about 50 miles west of Eureka and occurred at 10:18 a.m. PDT, 4.3 miles beneath the seabed, according to the USGS.

It was followed by about a half-dozen aftershocks, including one of magnitude-4.6.

There is not believed to be any threat of a tsunami, according to the Pacific Tsunami Warning Center.

The Humboldt County Sheriff's Department, which oversees most of the populated areas near the quake, says there have been no calls about damage or injuries

'This lasted longer than any earthquake I've ever felt,' Raquel Maytorena, 52, who lives about a mile from the coast in Ferndale near Eureka, told The Los Angeles Times. 'It just kept going and going, very slowly and softly. It was not violent. It almost felt like you were in a boat that was rocking.'

Jana Pursley, a geophysicist with the National Earthquake Information Center, said that based on the area's tectonics and past temblors, damages or casualties were unlikely..