The latest struck on Tuesday with a magnitude of 3.0.
The South Napa Earthquake struck on August 24, 2014 and measured 6.0. One person was killed and 200 hurt, while damage from the quake was estimated anywhere between $360 million and $1 billion.
It was the strongest earthquake in the Bay Area since the 1989 Loma Prieta earthquake which had a 6.9 magnitude.
Officials say that small aftershocks are rarely felt, but they are common whenever a quake ruptures the ground.