Strong Earthquake Aftershock Shakes Napa

A significant aftershock from last weekend's magnitude-6.0 earthquake has rattled Northern California's wine country.

The U.S. Geological Survey says the magnitude-3.2 tremor struck five miles south of the city of Napa just before 2 a.m. Sunday.

Thomas Brocher, director of USGS' Earthquake Science Center, says it wasn't the strongest aftershock to rumble the region since the main quake a week ago caused as much as $1 billion in damage and multiple injuries.