The quake hit at around 9:29 a.m. It had a depth of 10.8 km, the USGS said.
USGS initially reported it as a 4.6-magnitude earthquake before downgrading it minutes later to a 4.1, before updating it to a 4.2 later in the day.
A ShakeAlert was sent to Northern California residents about the quake.
There is no word of any injuries or damage.
This comes a day before the Annual Great ShakeOut, where emergency systems will be tested for earthquake preparedness. As a part of this, MyShake app users will get an earthquake test alert on Thursday.
This is also one day after the 34th anniversary of the devastating 1989 Loma Prieta earthquake.
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