A magnitude-6.8 earthquake struck in the Pacific off the Northern California coast Sunday night and rattled a widespread area, but there were no reports of injuries or significant damage, according to the U.S. Geological Survey.
The powerful quake was first reported by the USGS as a magnitude 6.9, but was later downgraded.
The temblor was recorded at 10:18 p.m. about 50 miles west of the city of Eureka, the USGS said. The quake was followed by several aftershocks, including one that measured magnitude-4.6, that continued into Monday morning.
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A tsunami was not expected for North America's West Coast, according to the National Tsunami Warning Center. The agency did not issue a tsunami watch, warning or advisory.
The Eureka Police Department and Humboldt County Sheriff’s Office said there were no reports of damage or injuries.
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Eureka police said the initial shaking was felt for about 20 to 30 seconds.
"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."
There was a 90 percent chance that a “strong and possibly damaging” magnitude 5.0 or larger aftershock would strike in the next seven days, according to the Northern California Earthquake Data Center.
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.
Earthquakes are common in Eureka, a city of about 27,000 people about 270 miles northwest of San Francisco and 100 miles 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.
An offshore 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 25 miles closer to land than Sunday night's quake.