A powerful magnitude-6.9 earthquake struck Sunday night off the coast of Northern California, but there were no immediate reports of injury or damage and no danger of a tsunami, officials said.

The temblor struck at 10:18 p.m. PT and was centred 80 kilometres west of Eureka and about 6.5 kilometres beneath the Pacific seabed, according to the U.S. Geological Survey. It was followed by about a half-dozen aftershocks, including one of magnitude 4.6.

There were no reports of any damages or injuries though the quake was felt widely and strongly, according sheriff's and fire officials in Humboldt County, which includes most of the populated areas near the epicenter.

The National Tsunami Warning Centre said there was no tsunami danger for the region.

More than 1,000 people reported feeling the earthquake on the USGS website. Many reported a long, rolling shake that some said woke children or knocked items off shelves.

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

Earthquakes are very common in Eureka, a city of about 27,000 people about 435 kilometres northwest of San Francisco and about 161 kilometres south of the Oregon state line. Nearby Arcata is home to about 17,000 people and Humboldt State University.

The area had a magnitude-5.6 earthquake in February 2012 that did not cause serious damages or injuries.

A magnitude-6.5 quake struck offshore in 2010 and caused bumps and cuts among residents and broke glass in some buildings, but it was about 40 kilometres closer to land than Sunday night's quake.