A strong earthquake was felt widely across Northern California on Thursday and authorities briefly issued a tsunami warning before cancelling it within an hour.
The quake struck at 10.44am local time west of Ferndale, a small city in coastal Humboldt County near the Oregon border, according to the US Geological Survey.
As far south as San Francisco, residents said they felt a rolling motion for several seconds, AP reported. It was followed by smaller aftershocks.
Marc Buller, a lawyer who lives in Eureka, a port city in northern California close to the offshore epicentre, said he had experienced a lot of quakes, but this one felt unusual.
"It was an intense jolt. When the big jolt stopped, it felt like the house was on rollers," Mr Buller told AFP. "It was like when you throw a big stone in water and the ripples go out. It was like the Earth was doing that."
The San Francisco Bay Area Rapid Transit District, known as Bart, has stopped traffic in all directions through the underwater tunnel between San Francisco and Oakland.
At least 5.3 million people in California were under a tsunami warning after the magnitude-7.0 earthquake, the US Geological Survey said in a yellow alert, which predicts localised but minimal damage.
More than 1.3 million people lived close enough to the quake that they could have felt it, the USGS estimated.
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.”
