SAN FRANCISCO, Dec. 20 (Xinhua) -- A 6.4-magnitude earthquake jolted 12 km west-south-west of Ferndale City in the U.S. state of California at 1034 GMT on Tuesday, the U.S. Geological Survey said.
The epicenter, with a depth of 16.1 km, was determined to be at 40.523 degrees north latitude and 124.393 degrees west longitude. No tsunami warning, advisory, watch or threat were issued after the quake. ■