FERNDALE, Humboldt County (CBS SF) -- A magnitude 6.5 earthquake struck off the Northern California coast in the Mendocino Fracture Zone early Thursday morning, according to the U.S. Geological Survey.
The USGS reports that the earthquake struck at 6:50 a.m. about 100 miles west of Ferndale and 110 miles west-southwest of Eureka, at a depth of 6.2 miles. Earlier reports from the USGS said the earthquake was a magnitude 6.8.
The original quake was followed by an aftershock measuring 5.0 at 7:40 a.m.
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Visitors to the USGS website from Humboldt County reported light shaking. People from as far as the Bay Area, the Sacramento area and Southern Oregon also said they felt shaking.
Bonnie Brower, owner of the Ferndale Pie Company, told The Associated Press she was grabbing something from the fridge in the restaurant's kitchen when the quake happened. She didn't see any damage, but said says felt a "big jolt."
"I just felt this very huge jerk and I didn't know what it was," Brower said to The AP. Afterward, it felt like the ground was rolling, "like you were on a boat."
Lorri Asbury, who lives in the Freshwater area of Humboldt County, wrote on Facebook that the quake woke her up but not her husband.
"Woke me up," she posted. "I woke my hubby telling him earthquake is coming. I thought it'd be get tougher. We felt big swishing rolls movement. Surprised it was a 6.8!!!"
Steven Durrett lives in the Humboldt Hill area of Eureka posted that his home rocked for a while.
"Rolled for a long time," he posted on Facebook. "No damage here on Humbolt[sic] Hill."
Veronica Coleman in Cutten was surprised it was so large of a quake.
"Rolling for a long time, gentle swaying, no damages not the usual jolt and noises," she wrote on social media. "Felt like a 4 on land."
Eureka resident Marsha Hale said the quake rearranged her shelves.
"Felt strongly, 13th and F St., Eureka," she wrote on Facebook. "No damage, but cupboards got a bit rearranged."
There are no immediate reports of damage or injuries. The National Tsunami Center reports no danger of tsunami at this time.
PG&E said there were no electrical outages or gas leaks reported due to quakes.
Located in the area of the quake is the Gorda Escarpment -- a plate boundary between the Pacific to the south and Gorda Plate to the north and the site of frequent earthquakes.
Back in 1992, a magnitude 7.2 earthquake off the coast rocked the region, injuring 95 people and causing millions of dollars in damage. The temblor was followed by a magnitude 6.5 quake about 12 hours later and a magnitude-6.7 quake a few hours after that.
In January 2010, a 6.5 magnitude quake in the Pacific caused about $34 million in property losses in and around the nearby city of Eureka, including partial damage to at least nine buildings.
COMPLETE QUAKE COVERAGE: CBS Earthquake Resource Center
Strong earthquakes with an epicenter off the coast can trigger tsunamis, depending on the size and type of the fault movement. The Pacific Tsunami Warning Center tracks earthquake data for the West Coast.
WEST COAST TSUNAMI TRACKING:
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