People were told to prepare for a tsunami after a 7.0 magnitude earthquake struck off the coast of northern California.

Around 4.7 million people were under the tsunami warning in the state which was lifted around an hour after it was put in place.

The quake struck around 39 miles southwest of Ferndale, near the Oregon border, at around 10.44am local time (6.44pm), according to the US Geological Survey (USGS).

The tsunami warning was in place for a large stretch of the California and Oregon coasts.

It was predicted by the National Weather Service that a wave could reach the San Francisco coastline as early as 12.10pm local time.

Rachel Kennedy, a meteorologist with the service, called it a “pretty dangerous situation”.

Meanwhile, the San Francisco Zoo evacuated its visitors and made sure all animals were secured.

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The intensity of the tremors were very strong to severe south of Eureka, says the US Geological Survey

The quake was felt widely across northern California and as far south as San Francisco where residents felt a rolling motion for several seconds. It was followed by smaller aftershocks.

In the Santa Cruz area, phones buzzed with a tsunami warning from the National Weather Service that said: “A series of powerful waves and strong currents may impact coasts near you. You are in danger. Get away from coastal waters. Move to high ground or inland now. Keep away from the coast until local officials say it is safe to return.”

Several quakes have struck off the coast of northern California
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Several tremors struck off the coast of northern California

More than 1.3 million people lived close enough to the quake that they could have felt it, the USGS estimated.

The San Francisco Bay Area Rapid Transit District, known as BART, stopped traffic in all directions through the underwater tunnel between San Francisco and Oakland.

“It was a strong quake, our building shook, we’re fine but I have a mess to clean up right now,” said a shaken Julie Kreitzer, owner of Golden Gait Mercantile, a store packed with food, wares and souvenirs that is a main attraction in Ferndale.

“We lost a lot of stuff. It’s probably worse than two years ago. I have to go, I have to try and salvage something for the holidays because it’s going to be a tough year,” Ms Kreitzer said before hanging up.

“The kids were so great and terrified. It seemed to go back and forth for quite a long time,” she said.

Eureka Mayor Kim Bergel said evacuations were in place for people to move to higher ground in areas of the city under the tsunami warning and crews were assessing damage from the quake.

Ms Bergel, who works as a resource aid at a middle school, said lights were swaying and everyone got under desks.

California governor Gavin Newsom met with state emergency officials shortly after the quake.