An earthquake with a magnitude of 6.5 has been reported off the coast of northern California, the US Geological Survey says.
The quake on Thursday (local time) was centred about 165 kilometres in the Pacific Ocean west of Ferndale, California, at a depth of 10km, according to the USGS.
There was no tsunami warning, advisory or threat in effect following the earthquake, the Pacific Tsunami Warning Center of the National Weather Service said on its website.
The quake was first reported with a 6.9 magnitude but downgraded to 6.5.
Some social media users said they felt the tremor in San Francisco, about 418.43 km south.
"That was a big one... felt it in San Francisco," wrote Twitter user Antonis Papatsaras.