LOS ANGELES — A powerful 6.5-magnitude earthquake struck off the coast of northern California, the US Geological Survey said.

The quake occurred 22 miles (35 kilometers) west of Ferndale and 224 miles (360 kilometers) northwest of Sacramento, at a depth of nine miles (16 kilometers).

The temblor hit at 4:27 pm (0027 GMT) and was followed by a series of four aftershocks measuring 3.7, 3.8, 3.5 and 3.6 on the open-ended Moment Magnitude Scale.

"Oh yeah, it shook," Ferndale volunteer fireman Manuel Enos told AFP, "windows broke or popped out of storefronts."

Local media also reported a brief powercut, ruptured gas lines and there were initial reports of damage to Ferndale's city hall building.

The Los Angeles Times reported the initial jolt was felt as far away as San Francisco.

"We've been through a lot of earthquakes but I can't recall there ever being any this bad," Sandra Hall, owner of Antiques and Goodies in nearby Eureka, told the Times.

She said the quake moved her store in all directions, with broken lamps, dishes and clothing now littered across the shop. Two women took cover under a table and a couple ran out of the main entrance.

There were no initial reports of injuries.

The National Oceanic and Atmospheric Administration said a tsunami was not expected. (AFP)