Strong earthquake shakes northern California

A strong 6.0-magnitude earthquake centered off the western Pacific coast shook northern California on Thursday, the US Geological Survey reported.

The quake was initially measured at 6.0 on the Moment Magnitude Scale, and was only seven miles (11 kilometers) deep.

It was centered some 35 miles (56 kilometers) from the town of Petrolia, but was strong enough to be felt some 275 miles (440 kilometers) away in San Francisco, residents said.

Northern California was hit by two major earthquakes in 2005 and 1992, both of which measured 7.2.