Residents in the San Francisco Bay Area
The quake struck in the early hours around 2 miles (3 kilometres) from Berkeley, according to the US Geological Survey.
It was felt over a wide area, with many people tweeting that they had felt the tremors on Thursday.
There was no major damage caused after the quake hit at 2.39am local time (10.39 GMT).
The epicentre of the earthquake was just across the bay from San Francisco, at a depth of 8 miles (13 kilometres).
While initial reports suggested a magnitude of 4.7, this was quickly downgraded.
Many people tweeted that they had felt the tremor, with posts showing some were disturbed up to 40 miles (64 kilometres) north and south of the site, the Associated Press reported.
The Mayor of Berkeley warned residents to be wary of aftershocks.
In the event of an #earthquake while sleeping, stay in bed, cover you head with a pillow until the shaking stops. Today's #Berkeley quake measured a preliminary 4.4 near Claremont in the hills. We will be monitoring any damage reports, and always be cautious of aftershocks.
— Jesse Arreguin (@JesseArreguin) January 4, 2018
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