A magnitude-6.9 earthquake struck off the coast of Northern California Sunday night, the U.S. Geological Service reported.
The epicenter was 48 miles west-northwest of Ferndale and 50 miles west of Eureka at a depth of 4.3 miles, the USGS said.
The quake, which occurred at 10:18 p.m. PT (1:18 a.m ET), was initially reported as magnitude 6.1, but seismologists revised it upward to 6.9. It was followed by about a half-dozen aftershocks, including one of magnitude 4.6.
There were no reports of any damage 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.
NBC Bay Area reported that police in Eureka said the shaking lasted 20 to 30 seconds.
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.
The probability of a "strong and possibly damaging aftershock" of magnitude 5.0 or greater in the next seven days was 90 percent, the USGS warned, adding that there was a 5 percent to 10 percent chance of another quake as large as or larger than the initial one in the next week.
The Associated Press contributed to this report.
First published March 9 2014, 10:40 PM
Mark Stevenson is a Senior News Editor. He started this role in September of 2001. Stevenson is responsible for running news feeds for some clients and partners and for mobile platforms, news editing, distributing news via social media and producing the cover of NBCNews.com. Stevenson reports to Sean Federico-Oâ€™Murchu, Editorial Manager.
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Stevenson joined NBCNews.com in June of 1996 from the San Jose (Calif.) Mercury News, where he was Business Wire Editor/Copy Editor. In that role, Stevenson was responsible for helping produce the newspaperâ€™s award-winning business and technology coverage of Silicon Valley.
Prior to his work at the Mercury News, Stevenson was a Copy Editor for the Columbia (Mo.) Daily Tribune. Before that he was Copy Editor and Business Reporter for the Alabama Journal.
Stevenson is the recipient, along with the entire staff of the Mercury News, of the Pulitzer Prize for the newspaperâ€™s coverage of the 1989 Loma Prieta Earthquake. He is the only Graduate Teaching Assistant ever in Auburn Universityâ€™s journalism program.
Stevenson lives in Issaquah, Wash.