The quake hit at around 7:42 a.m. It had a depth of 8 km, the USGS said.
It was originally reported as a 4.0 but then downgraded to 2.9.
There is no word of any injuries or damage.
The quake that struck Isleton last week set off a ShakeAlert to Northern Californians because it was initially estimated as above a 5.0, but then later downgraded minutes later.
MORE: Bay Area expert explains why ShakeAlert overestimated 4.2 magnitude NorCal earthquake
Last week's earthquake came a day before the Annual Great ShakeOut, where emergency systems will be tested for earthquake preparedness.
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