NAPA, California - Napa County has been rattled by a small aftershock to the strong and damaging earthquake that hit California's wine capital over the weekend.
The US Geological Survey says the 3.9-magnitude quake struck at 5:33 a.m. Tuesday about 7 miles south of the city of Napa.
A sheriff's dispatcher says the station shook a little, but there have been no calls reporting damage or injuries.
California's wine capital is still recovering from Sunday's 6.0-magnitude earthquake, which is estimated to have caused at least $1 billion in property damage.
There have been a series of small aftershocks, mostly in the 2.0-magnitude range.