Fifth quake in week hits off California coast

A magnitude 5 earthquake has struck off Northern California's coast, the fifth moderate or strong tremor to hit the state in a week, the US Geological Survey said.

"It was just another aftershock 200 km off the coast. Nobody that I'm aware of felt it," John Minsch, a geophysicist at the USGS National Earthquake Information Centre in Golden, Colorado, told Reuters.

The quake struck at 2:27am local time and its epicenter was 454 km northwest of San Francisco, the USGS said.

The strongest of the recent California quakes had a magnitude of 7.2 and hit just north of today's epicentre on Tuesday. It was followed by a quake of magnitude 6.6 on Thursday in the same area.

"Ordinarily, aftershocks get smaller in magnitude and decrease in frequency over time," Minsch said.

Tuesday's quake prompted a brief tsunami warning for the entire US West Coast and part of Canada.

A patchwork of faults crisscrosses California, and the Southern California Earthquake Center recently estimated a major earthquake beneath Los Angeles, the state's largest city, could cause up to 18,000 deaths and $250 (NZ$354.25) billion in damage.

Two other quakes in the past week had inland epicenters in Southern California.

On Thursday, a magnitude 4.9 earthquake shattered glass and jostled shelves in the immediate vicinity of its epicenter near Yucaipa, 126 km east of Los Angeles.

A 5.2 quake shook the Anza area of Riverside County on June 12.

- REUTERS