San Francisco Residents reportedly have being woken in the early hours of this morning as the tremor shook buildings in the California city.
The US Geological Survey (USGS) said the quake’s epicentre was two miles from Berkeley, California.
No damage or injuries were immediately reported.
But with a preliminary depth of eight miles, people 40 miles south in San Jose reported feeling the quake.
San Francisco is no stranger to earthquakes, and its residents live with the constant threat of tremors.
A devastating 7.8-magnitude quake in in 1906 all but levelled the city, killing an estimated 3,000 people.
And another measuring 6.9 killed 63 and injured 3,757 people and damaged countless buildings in 1989.
The city – like many major cities in California – sits on the deadly so-called “Ring of Fire” fault line.
It runs down the western coast of the Americas, across the Pacific and up through New Zealand, Indonesia and Japan.
The places situated along it have all seen devastating quakes in the past.
Experts say California is due another major apocalyptic tremor — which they have already dubbed “The Big One”.